Prometheus for Rapid Prototyping - Forget Everything You Know About PCB Milling

[rocco]

I just released a demo video of my Prometheus prototype making a double-sided PCB with through holes and edge cuts:

https://youtu.be/Tp81Aneil24. The end mill (bit) used in that video was only 7 mils in diameter.

Prometheus is a professional machine that can do 4-mil trace/5-mil space, runs at 50,000 RPM, and has a max feed rate of 150 IPM (3,810 mm/min). I engineered it to compete on specs with other pro machines in the $8,000 USD ballpark, but Prometheus will retail for $2,299 (currently in pre-order for $1,799). More pics are on the site, www.zippyrobotics.com.

[fonograph]

that looks very nice,I have noob question.If I have your Prometheus machine,does that mean I can make my own PCB in my home? Like,if I buy the PCB material,I think its called prepreg or something like that from Rogers,I can make PCB myself?

[rocco]

Thank you! Yes, you could use Prometheus to make PCBs at home, although it's more applicable to businesses and universities that want to prototype something same-day, or maybe multiple iterations in one day, as opposed to sending it off to a board house and waiting. That said, there are a few home hobbyists that have pre-ordered a machine. It just depends on how much you value the time savings.

As for materials, you would start with what's called "copper-clad". Copper-clad board comes in a variety of substrates - you could get FR-4, FR-1, or one of many Rogers materials. If the copper-clad you use has copper on both sides, you could make a double-sided circuit board.

[TJ232]

Looks like a very nice and clean implementation 

the youtube link above is not working. remove the end dot (.) from it:

https://youtu.be/Tp81Aneil24

[kripton2035]

idea for v2 : add a small dust extraction hose close to the drilling bit...
very nice machine !

[rocco]

Looks like a very nice and clean implementation 

the youtube link above is not working. remove the end dot (.) from it:

https://youtu.be/Tp81Aneil24

Thank you! Between the machine, software, and electronics, it's been 3 years in the making.

Thanks for letting me know about the link too; I fixed it.

[rocco]

idea for v2 : add a small dust extraction hose close to the drilling bit...
very nice machine !

Thanks!
I agree about the dust extraction - there's a small factory near me that does very affordable 3D printing in volume so once I design the mount that accepts the vacuum hose, I'll be able to add that.

[mikeselectricstuff]

Doesn't look like it's optimising the drill sequence - very noticeable on the DIPs

[mikeselectricstuff]

Looks like a nice implementation, but with the availability of many different PCB services, and trend for everything to be smaller, I wonder how much of a market there is for  in-house boards with no plated through-hole, only 2 layers and no resist ( and fairly limited size by the looks of it).

[rocco]

Looks like a nice implementation, but with the availability of many different PCB services, and trend for everything to be smaller, I wonder how much of a market there is for  in-house boards with no plated through-hole, only 2 layers and no resist ( and fairly limited size by the looks of it).

Thank you. The trace/space capability can support pretty much every SMD. BGAs may be the exception. You could probably even use very low ball-count BGAs that don't require breakout into 4+ layers. That's something I wanted to try to demo. Or an ATtiny in a WLCSP 

It's true that the services are a great solution if you don't mind waiting (most hobbyists, for example, would fall under that category) but for some engineers/businesses/schools they value the turn-around time. I don't view in-house prototyping and board houses as mutually exclusive. Just like you can prototype flyers or business cards on your home inkjet and then go online to get thousands made, there is a happy place for both methods and each have their pros and cons.

I do have a plan for a solder mask

Size is 6" x 4" which I think supports what most people would want to do with it. I mean, if you browse Adafruit, Sparkfun, or sites that make modules for Arduino or Raspberry PI, or anything really, how often is something bigger than that nowadays, with miniaturization? That's my estimate anyway, but maybe I'm wrong about that. If so I'd like to hear people chime in with the most common board sizes they design.

There's a lot you can do with two layers, but of course you are right that it's a limitation. At present day there's no real rapid prototype solution around that. Again, I plan to work on that 

Oh - and you're right about the drill sequence. Currently ProCAM drills them in the order that your Gerber exporter wirtes them into the file. It can easily be improved. Right now I have to prioritize the basic required feature set and software stability before I begin optimizing code.

[sprok]

.

[rocco]

What's the minimum track width/spacing this mill can do?


PCB services are stupidly expensive and slow for prototyping and hobby use.

I have demonstrated 4-mil trace widths, 5-mil spacing. Here is a pic of a test board that shows this. All gaps throughout the board are 5 mils wide: http://www.zippyrobotics.com/wp-content/uploads/2017/03/IMG_0944.jpg

It may be able to go even smaller, but I have not tried that yet.

[Mechatrommer]

Looks like a nice implementation, but with the availability of many different PCB services, and trend for everything to be smaller, I wonder how much of a market there is for  in-house boards with no plated through-hole, only 2 layers and no resist ( and fairly limited size by the looks of it).

i believe its the same market as how much people buying copper etchant in hobby quantity this days. not every place can order pcb services at cheap cost (time and money) esp for one prototype board and just a bit slower than "less than a day" completion time. we usually trade time with effort to stitch vias by hand (or just double side solder if we have components through that holes), and we cant bare to think of receiving 10 boards from the cheapest pcb house in China in weeks time just to realize we have design flaw in them yeah i experienced this, so much wasted boards with nice silk screen here. otoh we have processes to plate vias available in youtube for anyone interested in playing chemicals, or some "punched in copper tube" thats available in ebay. resist or solder mask or silk screening can be done in different process from this machine. i just watched Dave's uCurrent board production youtube, now i have some idea

btw i built my Bethan (similar functionality as Prometheus) at somewhere 1/10X the cost or less i guesstimate. the difference is it doesnt mill copper out, it only mill out etch resist ink applied earlier on the pcb board for later process of the usual board immmersed in etchant process. that method where i can reduce the cost of the machine the most by ruling out the necessity of very rigid machine. and i'm not a fan of pc connected machine so control is made from sd card and a number of GCode files for alignment etc. and i dont have to waste too much excess copper board to do the alignment housekeeping job, i can cut to the board size, 0 border excess, make the alignment manually, and etch i go with different GCode file. https://www.eevblog.com/forum/projects/hackable-3d-printer-for-research/msg1188994/#msg1188994

about optimising the drill sequence as you mentioned, i'm not sure what you meant and why its necessary, maybe you can give us some idea so we can implement it in our GCode generator PC SW. fwiw...

[Pitrsek]

We have one of the more expensive LPKF PCB machines(vacuum table,automatic tool changer,camera) in my day job. I can not imagine going back to days when I would wait days for pcb for experiments and proof of concepts  ...
In house proto manufacturing IMHO absolutely worth it .
Every time the guy who is in charge of the machine is off, or the mill has some problems(wit our heavy use, it breaks time to time...), there this sense of impeding doom among electronics designers
We have team of cca 25 electronics designers, and most of the day the PCB mill is working all day long. Also our colleagues from mechanical department discovered that you can make nice stuff from plexi and POM, so the CNC is used for this as well. We have used it for qfn, and even some BGA no problems.
For vias we use rivets and wire stitching
 
Regarding the working area - I would guess that 70% of the stuff(PCBs, no the mechanical stuff, that one is usually bigger) we do would fit.
For fine pitch stuff, I would argue that solder mask is more important than really fine trace/separation.
There absolutely needs to be a vacuum tube holder/ some other means of get rid of chips. 

Have you considered adding laser for exposing photo resist/solder mask?
Nice hack with the oil, what happens if I put more then optimum amount? Will it flow all over the machine, or is there defined way into some container?
How long does it take to change tool? Auto-changer would be a great upgrade.

[mikeselectricstuff]

What's the minimum track width/spacing this mill can do?


PCB services are stupidly expensive and slow for prototyping and hobby use.

Seriously ? What planet have you been on the last few years?
Have you not heard of OSHPark, Seeedstudio, PCBway etc. etc. ?

[mrpackethead]

We have one of the more expensive LPKF PCB machines(vacuum table,automatic tool changer,camera) in my day job. I can not imagine going back to days when I would wait days for pcb for experiments and proof of concepts  ...

I also had an expensive LPKF system and it was the biggest pile of junk and waste of money that i could ever imagine.   Terrible support from teh OZ agent,  who when it got returned to them to fix it, informed me that they dropped it off the forklift..    But seriously, with two or three day turn around on pcbs, and the need for 4 layers, milling is'nt an option any longer.    For any serious design work, i can't see it being an option any longer.

[Mechatrommer]

those fancy pcb houses have their own fixed format pcb in order to get cheap, once we need slightly bigger board, the price go up exponentially. for non local customer, shipping cost can just the same price as the item price, double or tripple if using express service. not justificable in design/prototyping process, mass production of proven design maybe.

[mikeselectricstuff]

about optimising the drill sequence as you mentioned, i'm not sure what you meant and why its necessary, maybe you can give us some idea so we can implement it in our GCode generator PC SW. fwiw...

It's moving more than it needs with the drill up.
e.g. for a DIP8 :
It appears to be drilling pin 1,8,2,7,3,6,4,5, so moving 7 x 0.3" plus 3 x 0.1" = 2.4"
if it did 1,2,3,4,5,6,7,8 , it would move only 6x0.1" + 1 x 0.3" = 0.9"

Although getting a completely optimal solution is hard ( travelling salesman problem), getting a huge improvement is very easy.
Simply :
Drill first hole, mark as drilled.
Move to nearest undrilled hole.
Repeat.

if you don't have enough memory to store the whole list, or the list is so long that searching for next undrilled hole is slow, split in to blocks and optimise within each block.

 
 

[nctnico]

We have one of the more expensive LPKF PCB machines(vacuum table,automatic tool changer,camera) in my day job. I can not imagine going back to days when I would wait days for pcb for experiments and proof of concepts  ...
In house proto manufacturing IMHO absolutely worth it .
Every time the guy who is in charge of the machine is off, or the mill has some problems(wit our heavy use, it breaks time to time...), there this sense of impeding doom among electronics designers

So your company is spending a whole year's salary + maintenance costs on having PCBs made quickly. How many next day PCBs with metalisation, solder mask, silkscreen, etc can you have made for that amount of money?

[rocco]

We have one of the more expensive LPKF PCB machines(vacuum table,automatic tool changer,camera) in my day job. I can not imagine going back to days when I would wait days for pcb for experiments and proof of concepts  ...
In house proto manufacturing IMHO absolutely worth it .
Every time the guy who is in charge of the machine is off, or the mill has some problems(wit our heavy use, it breaks time to time...), there this sense of impeding doom among electronics designers
We have team of cca 25 electronics designers, and most of the day the PCB mill is working all day long. Also our colleagues from mechanical department discovered that you can make nice stuff from plexi and POM, so the CNC is used for this as well. We have used it for qfn, and even some BGA no problems.
For vias we use rivets and wire stitching
 
Regarding the working area - I would guess that 70% of the stuff(PCBs, no the mechanical stuff, that one is usually bigger) we do would fit.
For fine pitch stuff, I would argue that solder mask is more important than really fine trace/separation.
There absolutely needs to be a vacuum tube holder/ some other means of get rid of chips. 

Have you considered adding laser for exposing photo resist/solder mask?
Nice hack with the oil, what happens if I put more then optimum amount? Will it flow all over the machine, or is there defined way into some container?
How long does it take to change tool? Auto-changer would be a great upgrade.

Nice! I'm curious - what kind of work does your company do?

I'm considering a few methods to give Prometheus the ability to make solder masks, laser being one of them but I first want to see if I can do it without adding more components to the machine. We'll see
I did solder the .5 mm-pitch QFP for the board in the video by hand without a solder mask without a problem. I just had to check it with a microscope and correct some bridging, but it wasn't bad. Of course a solder mask would be better, and I really want the capability for myself so I'm going to try to make that happen.

The oil will just flow onto the table if you put too much but it's not a big deal to clean up. The oil is great for milling operations. Prometheus can run at higher feed rates and it keeps the chips/dust in the oil and thus out of the air.

Changing tools takes maybe 10 seconds because you don't deal with wrenches. You can see it in the first part of the video. Yes, auto tool change would be a cool upgrade.

[Kjelt]

Great that you can build such a nice piece of equipment and software.
However I think you are a bit late, these kind of machines have seen their days in the past.
Nowadays with multilayer smt pcb's you need lots of (stitching) via's multiple inside power/ground planes etc.
Also I wonder if electrically these pcb's will perform identical to the produced pcb's esp. with higher frequency designs, because they are physically just not the same.

[sprok]

.

[rocco]

We have one of the more expensive LPKF PCB machines(vacuum table,automatic tool changer,camera) in my day job. I can not imagine going back to days when I would wait days for pcb for experiments and proof of concepts  ...
In house proto manufacturing IMHO absolutely worth it .
Every time the guy who is in charge of the machine is off, or the mill has some problems(wit our heavy use, it breaks time to time...), there this sense of impeding doom among electronics designers

So your company is spending a whole year's salary + maintenance costs on having PCBs made quickly. How many next day PCBs with metalisation, solder mask, silkscreen, etc can you have made for that amount of money?

Just to add some more info to this topic, the cheapest and fastest board houses I found via www.pcbshopper.com when searching for a 5"x4" board (which btw, takes 2 days total to receive) is $503.16, including shipping cost. There might be cheaper out there (or maybe you work across the street from a factory), but PCBShopper aggregates prices from many houses and that's the fastest/cheapest that it showed me (see attached screenshot).

You have to factor in the time value into the equation and when you do, this absolutely does make sense for some people. When the machine is $2,300 and not $17k-$20K, it makes sense for an even larger group.

[rocco]

Seriously ? What planet have you been on the last few years?
Have you not heard of OSHPark, Seeedstudio, PCBway etc. etc. ?

Some people say this but I think you're all on some hard core drugs. Please tell me any PCB service can give me an 6x4 board in 30 minutes for $2. Or a one-off 2x2 board for $0.25. It's not even possible, let alone at a price that isn't astronomically higher!

You're right sprok. I've found that disagreement always occurs if people don't assign a dollar value to the time they spend waiting, and if they don't realize that this time value varies greatly between users. For some, Prometheus or other rapid prototyping machines don't make sense at all. For others, they do.

[nctnico]

We have one of the more expensive LPKF PCB machines(vacuum table,automatic tool changer,camera) in my day job. I can not imagine going back to days when I would wait days for pcb for experiments and proof of concepts  ...
In house proto manufacturing IMHO absolutely worth it .
Every time the guy who is in charge of the machine is off, or the mill has some problems(wit our heavy use, it breaks time to time...), there this sense of impeding doom among electronics designers

So your company is spending a whole year's salary + maintenance costs on having PCBs made quickly. How many next day PCBs with metalisation, solder mask, silkscreen, etc can you have made for that amount of money?

Just to add some more info to this topic, the cheapest and fastest board houses I found via www.pcbshopper.com when searching for a 5"x4" board (which btw, takes 2 days total to receive) is $503.16, including shipping cost. There might be cheaper out there (or maybe you work across the street from a factory), but PCBShopper aggregates prices from many houses and that's the fastest/cheapest that it showed me (see attached screenshot).

You have to factor in the time value into the equation and when you do, this absolutely does make sense for some people. When the machine is $2,300 and not $17k-$20K, it makes sense for an even larger group.

I have two sort-off generic remarks about what you write:
1) The LPKF machines are notorious for needing a lot of baby sitting and learning time to get them to run right (there are various factors contributing to this but let's not get into that in this thread). This has given PCB milling a bad reputation in general which is hard to combat especially with low cost machines.

2) When you need boards quick then there usually is something wrong with the planning. When I work on a project I get the PCB design out first, work on a different (part of the) project and continue when the PCBs arrive. In many cases the PCBs are waiting for me instead of the other way around. I can't see how a board which is designed in a rush will work properly anyway. That leaves milling interesting for small prototype boards which may as well be build on veroboard and RF microstripline circuits.

[fcb]

I've used an LPKF years ago - a real faff, long learning curve and a lot of baby-sitting (as someone else mentioned). The biggest PITA was stitching all the vias with this paste, very unreliable & time-consuming.

I can see the value of a PCB mill if you do RF/stripline stuff - but all other cases just a bit of organisation and wait a week for the boards to come back.  For example, I've got a 160x160mm PTH board going off this weekend: PCBWay will do 5 copies for $73 ($48+$25 shipping) total, if I can cope with no-solder mask and I need one in a hurry, then I use "PCB Train" by Newbury Electronics - proper PTH board, next day service for about £120+VAT, just send it to them by 9AM and they ship it out that evening on a courier.

And if you've tried assembling a board without solder-mask, it can be a nightmare.

[Mechatrommer]

And if you've tried assembling a board without solder-mask, it can be a nightmare.

i can finish assembling those before the masked pcb order arrives. and by the time the masked pcb arrived, i know my design is working on non-masked pcb and ready for mass production board order. my desk is only fit for one project, barely enough for 2 small projects. organization of 3 or more projects at a time just doesnt cut it. anyway, this is "you like blue i like red" problem, both are true.

if soldermask is important, i'll prefer this..


but since the material is not yet available to my place, i'll try this...

[G0HZU]

In house proto manufacturing IMHO absolutely worth it .
Every time the guy who is in charge of the machine is off, or the mill has some problems(wit our heavy use, it breaks time to time...), there this sense of impeding doom among electronics designers
We have team of cca 25 electronics designers, and most of the day the PCB mill is working all day long. Also our colleagues from mechanical department discovered that you can make nice stuff from plexi and POM, so the CNC is used for this as well. We have used it for qfn, and even some BGA no problems.
For vias we use rivets and wire stitching

I agree. At work we have been using milling machines for about 25 years. Mostly for RF prototyping but they can also be used for making front panels and other structures using various materials. Here at home I have an old T-Tech 7000S machine that I use quite regularly for RF PCB prototyping and for making various tools, spacers, panels etc. I've actually got two of them but the other one is really just for backup.

If you want to design and prove some novel RF filter designs on an exotic RF laminate and maybe do a few iterations over a couple of days then I'd be keen to know from the experts here how I could do this as efficiently as having a PCB mill sat next to me? It's going to be slow and expensive and highly irritating to have to keep waiting for the next batch of prototypes to arrive by courier if I do it all at a PCB house.

The Prometheus machine looks promising but it would be nice to see it do some isolation/rubout in order to make the PCB nicer to work with once milled. Also, it doesn't seem to use a stabilising foot or maybe I missed it in the video? My T-Tech machine is an early model with the very basic stabilising foot. This works well as long as the operator is knowledgeable and sympathetic of its limitations. So I sometimes have to mill certain parts of the PCB in a specific order to get the best results. Newer models are much better with a better designed foot. At work we moved across from T-Tech to LPKF many years ago and have had very good results.

[rocco]

In house proto manufacturing IMHO absolutely worth it .
Every time the guy who is in charge of the machine is off, or the mill has some problems(wit our heavy use, it breaks time to time...), there this sense of impeding doom among electronics designers
We have team of cca 25 electronics designers, and most of the day the PCB mill is working all day long. Also our colleagues from mechanical department discovered that you can make nice stuff from plexi and POM, so the CNC is used for this as well. We have used it for qfn, and even some BGA no problems.
For vias we use rivets and wire stitching

I agree. At work we have been using milling machines for about 25 years. Mostly for RF prototyping but they can also be used for making front panels and other structures using various materials. Here at home I have an old T-Tech 7000S machine that I use quite regularly for RF PCB prototyping and for making various tools, spacers, panels etc. I've actually got two of them but the other one is really just for backup.

If you want to design and prove some novel RF filter designs on an exotic RF laminate and maybe do a few iterations over a couple of days then I'd be keen to know from the experts here how I could do this as efficiently as having a PCB mill sat next to me? It's going to be slow and expensive and highly irritating to have to keep waiting for the next batch of prototypes to arrive by courier if I do it all at a PCB house.

The Prometheus machine looks promising but it would be nice to see it do some isolation/rubout in order to make the PCB nicer to work with once milled. Also, it doesn't seem to use a stabilising foot or maybe I missed it in the video? My T-Tech machine is an early model with the very basic stabilising foot. This works well as long as the operator is knowledgeable and sympathetic of its limitations. So I sometimes have to mill certain parts of the PCB in a specific order to get the best results. Newer models are much better with a better designed foot. At work we moved across from T-Tech to LPKF many years ago and have had very good results.

Thank you, G0HZU. Yep, a full copper rubout (exact Gerber duplication) is something I want to demo. I have some RF clients who use Roger's so this is high on my list.

You didn't miss it in the video - there is no pressure foot because Prometheus doesn't need one! Instead, ProCAM runs a ~90 second probing cycle before milling begins, where the tip of the tool moves down until it makes electrical contact with the copper-clad surface. When it does, it records the height with 1.25-micron resolution. After probing a grid of points, ProCAM forms a surface map behind the scenes and automatically tells Prometheus how to adjust the Z axis on the fly to keep a consistent milling depth. Basically, it follows the peaks and valleys of the board on its own. This has proven to produce fantastic results and users don't have to worry about pressure foot limitations or the pad wearing or snagging or anything like that. It just works.

[Pitrsek]

My recommendation was not aimed particularly at LPKF, but in house prototyping in general. 
LPKF - since I'm not the one the one taking care of the machine, I can't comment much about user friendliness. But my colleague is not complaining about it. We've had several warranty repairs and post warranty repairs, also local distribution is mediocre at best(delivery dates sux). So in general I can see that there is a place for quality competition...

@nctnico - Yes, and I believe it's well worth it. For lot of stuff I don't need silkscreen, when I do I order express from fab house. You can test an idea within a single day, that is priceless. Re-use value is very high. If I decide to use the design, the schematics is already drawn and I have first rough layout as well. So when time comes for proper layout, most of the stuff on board is already verified by means of simple small boards from CNC.
Also if project manager likes your new gizmo and needs 5more pcs to show off, its way easier to make more. For stuff we do, it's been really beneficial. Off-course there is a lot of areas where 2l board for prototype won't cut it.
 
@Roco - we do cool medical stuff  . The thing is we do develop and sell the devices as well. Basically marketing department is our customer. So there is a lot of going forth and back during the development before spec is frozen(that happens quite late in development). It's not like you have closed specification at the beginning. Branches, some dead ends, lot of experiments, circles, figuring out what market(ing) wants... So you come in on Monday morning and you hear PM "we've had a meeting, and I wanted to ask you would it be possible...." Its very fluid development, and I like it a lot. The way our company works has obviously effect on how we value the prototyping possibility.

[ebclr]

I like the idea of drone motor, I will try to set one on my delta 3 printer

[mrpackethead]

We run 2-3 proto boards a week and have 1 or 2 production boards as well.  Board sizes vary from tiny to A4 size.  Mostly boards are 4 layer. 4 layer often ends up cheaper as It's more compact and more importantly it's quicker and easier to design and gives a better result in general.  Low cost pcbs are only $100 for something I have in hand in 72-96 hours.   Milling also implys
Not having a stencil ( at least not a stainless one and plastic/Mylar laser cut just don't cut it at fine pitch ).

While I applaude what you have done I just don't see this being something that would be truely cost beneficial

[rocco]

While I applaude what you have done I just don't see this being something that would be truely cost beneficial

Thanks. I would never argue that it makes sense for everyone to have something like this on their desk, but I will absolutely say that there exists a segment of the population out there for which Prometheus or other high performance PCB mills do make sense, as we have seen from some of the previous comments. In your case, you pay $100 for something you get in 72-96 hours. It's safe to say that someone else would pay a certain amount extra to have that board in hand in say 48 hours... maybe it's only $5 more. Maybe it's $500. That depends on the end user. Almost every board house I've seen or worked with offers faster service if you're willing to pay more for it.

Quick cost analysis: I posted previously a snapshot from a PCB service price aggregator where I searched for the cheapest price for a 2-day turnaround in the US for a 2-layer board, and the result was $503.16. You are not one of the people doing this (and that's great if that works for you!) but they do exist. if you were ordering 2-3 boards per week at that price, you'd have Prometheus pay for itself in less than two weeks! Not to mention that you'd have the added convenience of getting your boards in minutes (or maybe an hour or so if it's a bigger job) - not 2 days.

Board houses will always be slower than Prometheus and more expensive as well, since you're also paying for a truck/plane to expedite it to you unless your board house is across the street. Or until teleportation is invented and they can beam it to you.

[usagi]

people will be cross shopping the othermill, which as a generic cnc mill can do pcb and everything else.

[rocco]

people will be cross shopping the othermill, which as a generic cnc mill can do pcb and everything else.

I'd be happy to invite anyone to compare Prometheus and the Othermill Pro on specs and price. For Othermill specs, visit https://othermachine.co/othermill-pro/ and scroll to the bottom. For Prometheus specs, visit the bottom of the home page http://www.zippyrobotics.com/

In my opinion, there is a very clear winner.

[ebclr]

Othermill Pro
$3,199

239,99

https://www.amazon.com/Machine-Engraving-Milling-5-12x3-94-Effective/dp/B01LWBLVYS/ref=sr_1_1?ie=UTF8&qid=1492920412&sr=8-1&keywords=pcb+cnc

What one have that the other doesn't

[usagi]

people will be cross shopping the othermill, which as a generic cnc mill can do pcb and everything else.

I'd be happy to invite anyone to compare Prometheus and the Othermill Pro on specs and price. For Othermill specs, visit https://othermachine.co/othermill-pro/ and scroll to the bottom. For Prometheus specs, visit the bottom of the home page http://www.zippyrobotics.com/

In my opinion, there is a very clear winner.

can you do anything other than PCBs? e.g. can you mill aluminum or brass bar stock?
how much Z do you have?
do you support standard Gcode?

[mrpackethead]

Thanks. I would never argue that it makes sense for everyone to have something like this on their desk, but I will absolutely say that there exists a segment of the population out there for which Prometheus or other high performance PCB mills do make sense, as we have seen from some of the previous comments. In your case, you pay $100 for something you get in 72-96 hours. It's safe to say that someone else would pay a certain amount extra to have that board in hand in say 48 hours... maybe it's only $5 more. Maybe it's $500. That depends on the end user. Almost every board house I've seen or worked with offers faster service if you're willing to pay more for it.

Quick cost analysis: I posted previously a snapshot from a PCB service price aggregator where I searched for the cheapest price for a 2-day turnaround in the US for a 2-layer board, and the result was $503.16. You are not one of the people doing this (and that's great if that works for you!) but they do exist. if you were ordering 2-3 boards per week at that price, you'd have Prometheus pay for itself in less than two weeks! Not to mention that you'd have the added convenience of getting your boards in minutes (or maybe an hour or so if it's a bigger job) - not 2 days.

No, Promethues woudl never be cost effective to me.  The cost of using milled pcbs, that have no vias, are only 2 layer, and where i have no solder stencil would cause me a a massive increase in labour.  The 'time' benefit of having somethign in a few hour's would be negated very rpaidly, when someone had to put 200 vias in by hand.  And the two layer restriction is a big one.   

[/quote[
Board houses will always be slower than Prometheus and more expensive as well, since you're also paying for a truck/plane to expedite it to you unless your board house is across the street. Or until teleportation is invented and they can beam it to you.
[/quote]

But what a mill produces and what you get from a board house are not the same product.   

[rocco]

Thanks. I would never argue that it makes sense for everyone to have something like this on their desk, but I will absolutely say that there exists a segment of the population out there for which Prometheus or other high performance PCB mills do make sense, as we have seen from some of the previous comments. In your case, you pay $100 for something you get in 72-96 hours. It's safe to say that someone else would pay a certain amount extra to have that board in hand in say 48 hours... maybe it's only $5 more. Maybe it's $500. That depends on the end user. Almost every board house I've seen or worked with offers faster service if you're willing to pay more for it.

Quick cost analysis: I posted previously a snapshot from a PCB service price aggregator where I searched for the cheapest price for a 2-day turnaround in the US for a 2-layer board, and the result was $503.16. You are not one of the people doing this (and that's great if that works for you!) but they do exist. if you were ordering 2-3 boards per week at that price, you'd have Prometheus pay for itself in less than two weeks! Not to mention that you'd have the added convenience of getting your boards in minutes (or maybe an hour or so if it's a bigger job) - not 2 days.

No, Promethues woudl never be cost effective to me.

I think you misunderstood. I'm not trying to say that it would be cost effective for you. Just that entities do exist for which same-day prototyping is valuable, even with it's limitations. I get that you're not one of those people, and that's cool.

"But what a mill produces and what you get from a board house are not the same product."

True, but again the product that a mill produces still has value to some people (I understand that's not you) and more importantly, a board house doesn't produce any product that you can hold in your hand within an hour of ordering it.

[usagi]

True, but again the product that a mill produces still has value to some people (I understand that's not you) and more importantly, a board house doesn't produce any product that you can hold in your hand within an hour of ordering it.

this market is going to be incredibly small.

businesses and universities serious about pcb prototyping will buy something with a commercial onsite support contract. if they are so dependent on 1hr turnaround, then they will want a support engineer on site to fix it NOW.

your average hobbyist doesn't need 1hr turnaround, and wants something like oshpark silkscreened PCBs with vias anyway.

[rocco]

people will be cross shopping the othermill, which as a generic cnc mill can do pcb and everything else.

I'd be happy to invite anyone to compare Prometheus and the Othermill Pro on specs and price. For Othermill specs, visit https://othermachine.co/othermill-pro/ and scroll to the bottom. For Prometheus specs, visit the bottom of the home page http://www.zippyrobotics.com/

In my opinion, there is a very clear winner.

can you do anything other than PCBs? e.g. can you mill aluminum or brass bar stock?
how much Z do you have?
do you support standard Gcode?

No to all of the above. I want to be clear here: Prometheus is only for PCBs. it's not a general purpose CNC mill (and neither are machines by LPKF or T-tech). Prometheus was engineered specifically for PCBs just like the other professional solutions that cost $8,000+. If you want a general purpose mill you should not buy Prometheus. Given the nature of this site, in my last comment I was referring to a comparison based on the desire to prototype PCBs, not other stuff. I feel like it's best to choose the right tool for the job. The requirements to do high quality PCBs are different than general purpose milling with the most important factor being the spindle. If you try to run a .007" square end mill with a hobby spindle, it will likely snap on contact with the copper-clad before you get any useful work out of it due to the large runout of those spindles. That's why you'll only see them run "V" bits (engraving bits) below a certain diameter. Also, when you go down to such small end mill diameters, the chip load necessarily needs to go down as well, which means that you'd want a high speed spindle to keep the feed rate reasonable without prematurely breaking the end mill. Prometheus's spindle is 50,000 RPM.

[mikeselectricstuff]

businesses and universities serious about pcb prototyping will buy something with a commercial onsite support contract. if they are so dependent on 1hr turnaround, then they will want a support engineer on site to fix it NOW.

..or if it's cheap enough, just buy two units.

However if you're so dependent on doing 1hr protos, chances are you're doing it wrong.
 

[Kjelt]

I do agree that a general purpose cnc mill is not good for pcbs, own one, tried that, and failed.
They usually have larger areas and lack the resolution on repeatability ( going back and forth and ending up in the exact position) due to the stepper resolution and backlash.
For normal milling jobs ending 0,02mm off track is not a big thing, you dont see it, with a small pcb it could ruin the entire design.
IMO you need better steppers and continuously calibration to pull it off.
The same way the other side up:  those affordable general purpose cnc mills also are not able to mill steel.
They dont have the weight, torque, power whatever, it just does not work.
Wood, aluminium are ok.
You need the special tool for the special job.

[mrpackethead]

I think you misunderstood. I'm not trying to say that it would be cost effective for you. Just that entities do exist for which same-day prototyping is valuable, even with it's limitations. I get that you're not one of those people, and that's cool.

who is it valuable to? Coudl you describe the use-case where it is valuable?

[mrpackethead]

IN summary,

The title of this post is quite misleading.  A PCB mill by itself does not provide 'everything' for rapid prototyping.   In fact it only provides a very small use-case for possibilitys.

[Mechatrommer]

For normal milling jobs ending 0,02mm off track is not a big thing, you dont see it, with a small pcb it could ruin the entire design.

you are out of luck then... seeedstudio can only do 6 mils reliably, thats 0.15mm. Thickness Tolerance: (t?0.8mm) ± 10% that translates to ±0.08mm error.
http://wiki.seeedstudio.com/wiki/Service_for_Fusion_PCB

jeez people you want to do physics package go find another tools, we know what a $2K (or $200) tools can or cant do, expecting it to do 6 digit priced tools is hilarious. if you can afford $100 in each iteration go for it, some people just dont have the luxury, or similar workflow/burden/profit as you are.

[Kjelt]

you are out of luck then... seeedstudio can only do 6 mils reliably, thats 0.15mm.

Messed up a digit should have been 0,2mm.

we know what a $2K tools can or cant do, expecting it to do 6 digit priced tools is hilarious.

Man you really missed my point, probably my English. My point was that Prometheus is excellent for these kind of pcb jobs and that general cnc mills are not.
You have different tools for different applications, as soon as your cnc has to travel more than 300mm on any axis the backlash and all is going to mess it up unless you have optical decoder or other ways of continuous knowhing where you are which are costing lots of $$$.
They are different beasts, a pcb routing cnc is a total different design than a generic <5k$ cnc and different from the cnc's that do steel, that is all I am saying.

[Mechatrommer]

Man you really missed my point, probably my English. My point was that Prometheus is excellent for these kind of pcb jobs and that general cnc mills are not.

my comment is not specifically directed at you. its more to general conclusion to what is being discussed here.

You have different tools for different applications, as soon as your cnc has to travel more than 300mm on any axis the backlash and all is going to mess it up unless you have optical decoder or other ways of continuous knowhing where you are which are costing lots of $$$.

i think you misunderstood backlash and manufacturing imperfection. backlash only happened when you reverse direction. manufaturing imperfection is something like a 1mm thread should move 1000mm in 1000 turns but its not, maybe 1001mm or 999mm. it can be easily fixed in FW but... who cares perfecting the FW if the margin is too small? and it produced in super mass volume with varying tolerance. what users (consumers) can do for cheap stuffs like this? they compensate in CAD if someone doesnt want to bother with this compensation mess, they should save 6 digits for a machine, or pay 3 digits to  someone who has 6 digits machine, if that is 6 digits, probably 5 digits tops with very good compensating skill personnels in the house. or maybe a 5 digits 2nd hand of a used 6 digits machine they have to refurbish to you dont know what happened in behind.

[janoc]

My recommendation was not aimed particularly at LPKF, but in house prototyping in general. 
LPKF - since I'm not the one the one taking care of the machine, I can't comment much about user friendliness. But my colleague is not complaining about it. We've had several warranty repairs and post warranty repairs, also local distribution is mediocre at best(delivery dates sux). So in general I can see that there is a place for quality competition...

@nctnico - Yes, and I believe it's well worth it. For lot of stuff I don't need silkscreen, when I do I order express from fab house. You can test an idea within a single day, that is priceless. Re-use value is very high. If I decide to use the design, the schematics is already drawn and I have first rough layout as well. So when time comes for proper layout, most of the stuff on board is already verified by means of simple small boards from CNC.
Also if project manager likes your new gizmo and needs 5more pcs to show off, its way easier to make more. For stuff we do, it's been really beneficial. Off-course there is a lot of areas where 2l board for prototype won't cut it.
 
@Roco - we do cool medical stuff  . The thing is we do develop and sell the devices as well. Basically marketing department is our customer. So there is a lot of going forth and back during the development before spec is frozen(that happens quite late in development). It's not like you have closed specification at the beginning. Branches, some dead ends, lot of experiments, circles, figuring out what market(ing) wants... So you come in on Monday morning and you hear PM "we've had a meeting, and I wanted to ask you would it be possible...." Its very fluid development, and I like it a lot. The way our company works has obviously effect on how we value the prototyping possibility.

Seriously, if you are doing that sort of volume, why don't you buy a proper etching tank/machine and UV exposure box? Way less maintenance and babysitting needed and likely faster to produce those boards as well, especially if you use precoated boards or the dry film. The exposure box will be also useful for solder mask application if you decide to do it.

CNC is good to have for cutting materials to shape and perhaps drilling holes if you are doing a PTH design, though. But for that you don't need any super-duper high precision machine.

[Kjelt]

i think you misunderstood backlash and manufacturing imperfection. backlash only happened when you reverse direction. manufaturing imperfection is something like a 1mm thread should move 1000mm in 1000 turns but its not, maybe 1001mm or 999mm.

I am not sure, let me explain you what I mean.
At my 5k$ cnc mill if the sw tells to move 100,0 mm it moves 100,0 mm no problem.
BUT if I tell it to do the same move lets say 50 times go back and again, in the end the mill will fail around few tenths of mm.
That is because it does not have linear calibration guidance on its axis and depends on the stepping motor accuracy.
I don't know the exact english term, we call it "speling" on the bearings probably slack or backlash.

Anyway if you want to keep the exactness of the work the mill should recalibrate on a known X,Y,Z position every few minutes at least or very delicate jobs go wrong.
That is what I am trying to say that for normal cnc jobs that is perfectly ok, but for a job like pcb milling even 0,1mm deviation could cause a trace to be severed or damaged.
Then there is another thing and that is that in my experience going to a bit with a diameter <1mm on these $5k machines also does not work that well.
You end up spending more money on bits than on the pcb. Just my own experience.

[Kjelt]

Seeing this movie I do think it is backlash that I am experiencing and the only way to correct is to upgrade to closed loop steppers or continuously calibrating with optical lineal or something similar , making it cost more than the cnc mill cost 

[Mechatrommer]

ok i think that a backlash buildup not considered in the FW... anyone can make the compensation in the FW but... well as you realized, nothing beats recalibrating it with our own hand.

[nctnico]

ok i think that a backlash buildup not considered in the FW... anyone can make the compensation in the FW but... well as you realized, nothing beats recalibrating it with our own hand.

I think it is not just backlash but also missing steps due to the mass the stepper engines have to put into motion. I don't hear any ramp-up or ramp-down. IMHO you shouldn't use stepper motors in an open loop configuration. That is asking for problems.

[Mechatrommer]

ok i think that a backlash buildup not considered in the FW... anyone can make the compensation in the FW but... well as you realized, nothing beats recalibrating it with our own hand.

I think it is not just backlash but also missing steps due to the mass the stepper engines have to put into motion. I don't hear any ramp-up or ramp-down. IMHO you shouldn't use stepper motors in an open loop configuration. That is asking for problems.

miss steps is possible. even if you manage to get a stepper motor in closed loop (with encoder), backlash is mechanical problem, the error will still build up. there is anti backlash bearing claim to solve this issue.

[nctnico]

I don't see how backlash can accumulate mechanically because that would mean the size of gears, lengths of lead screws, etc would have become physically different. If there is an accumulated error then this has to do with missing steps, wrong position readback and/or rounding errors in the firmware.

[Mechatrommer]

Seeing this movie I do think it is backlash that I am experiencing and the only way to correct is to upgrade to closed loop steppers or continuously calibrating with optical lineal or something similar , making it cost more than the cnc mill cost 
[youtube link cut to save space]

i just realized that video showing 0 backlash/miss steps. you must have some problem with your machine, too heavy head or too small motor. here is backlash/miss steps problem with $200 mdf built machine...

[usagi]

I don't know the exact english term, we call it "speling" on the bearings probably slack or backlash.

that's not backlash. that's skipped steps. backlash does not accumulate, it is a fixed error.

your video shows a large mass being moved by steppers and it appers you have zero deceleration, you are trying to full reverse at full speed and this simply is not possible without skipping steps. in the 3d printing terms, your jerk setting is much too high.

stepper motors don't need closed loop if you use them correctly. that is kind of the point of stepper motors. 

[Mechatrommer]

yeah you are right but the video is not his... no trace of miss steps there...

[ebclr]

Use deacceleration and acceleration routines will reduce miss steps

[nctnico]

stepper motors don't need closed loop if you use them correctly. that is kind of the point of stepper motors. 

In theory. Wait until the drill bit gets stuck or something else goes wrong which makes the stepper miss a step. AFAIK this is where the (older/cheaper) LPKF machines fail as well.

[Dubbie]

When I first got into electronics, I thought a pcb mill would be great. So I built a very nice one. It has ground ballscrews, double ball nuts, well overspecced linear rails etc etc. it is extremely accurate and fast. However I have cut the grand total of 1 board with it. The pain the neck and vastly sub par result compared to a commercial etched board put me off. Now I use the machine for general machining of housings etc. it works great for that!

Also on the topic at hand, steppers don't miss any steps if they are operated within their design constraints. If you have sized them properly to the task you can expect to never miss a step unless you have a crash.

[691175002]

stepper motors don't need closed loop if you use them correctly. that is kind of the point of stepper motors. 

In theory. Wait until the drill bit gets stuck or something else goes wrong which makes the stepper miss a step. AFAIK this is where the (older/cheaper) LPKF machines fail as well.

Servos won't solve that problem, only detect that something has gone wrong.  If you lose position the chances are that something has snagged, broken, or been cut in the wrong place and that can't be undone.

Fault detection is okay when continuing a job might damage the tools or machine, but does't really provide many advantages in a PCB mill.  The real advantage of servos is that a tight control loop is orders of magnitude more precise and rigid than a stepper motor, and you aren't running your motors at full current regardless of load.


I think if you could somehow do automatic vias prototyping would become very attractive, but I'm not even sure how one would approach that feature.

[usagi]

stepper motors don't need closed loop if you use them correctly. that is kind of the point of stepper motors. 

In theory. Wait until the drill bit gets stuck or something else goes wrong which makes the stepper miss a step. AFAIK this is where the (older/cheaper) LPKF machines fail as well.

if you miss a step or get stuck you are screwed even with feedback -- you will still have mangled output. feedback doesn't prevent that. in my experience you will break a bit sooner than you will skip steps.

run your steppers properly within their constraints, no problems.

steppers without feedback are sufficient for many $50,000 industrial machines. they're certainly ok for $2000 hobbyist machines.

[G0HZU]

You can test an idea within a single day, that is priceless.

I agree and I don't understand why the 'experts' here can't grasp this. They might as well claim that building a test board in dead bug style is a waste of time too because you can go to a PCB house instead and get a PCB with silk screen and vias

Maybe if they spent some time in a quiet corner they might eventually realise that there is a need (for some people) to be able to do rapid prototyping that takes the technology beyond dead bug style.

This could be for a rapid fix to a problem with a production board. eg a problem is spotted and a meeting takes place and the decision is to make a little piggy bodge board to prove the concept of the 'fix'. The chap who operates the mill often designs the piggy PCB in cases like this and this speeds things up. He may well fit components to the PCB and test it in time for a technical meeting the next morning.

How are you going to compete with that using a PCB house? It just isn't going to be as quick and if the piggy board needs a tweak to the circuit (or to make it fit in a tight corner) then you lose another two days to the PCB house.

In my case I might need to have a PCB milled rapidly to test out a special RF filter. This could be a regular printed filter or something more exotic using defected grounding. ...but the benefits here are the same. With a PCB mill you can do several iterations in a single day if needed?

In theory. Wait until the drill bit gets stuck or something else goes wrong which makes the stepper miss a step. AFAIK this is where the (older/cheaper) LPKF machines fail as well.

My T-Tech machine is over 20 years old and still operates on the original mechanicals and the only way the stepper motors play up is if I have recently serviced it and the thread on the linear ways gum up with excess grease. So each time I service it I have to make sure there is not any excess grease and I also run it back and forth several times in X and Y to make sure it won't gum up.

At work our LPKF machine must have milled a lot of PCBs in the time we have had it. I would guess well into the thousands. Plus various panels and spacers and tools. I think it must be getting towards 15 years old because the CAM SW that came with it is dated 2001/2. Our first T-Tech mill was purchased by a director back in about 1992 and we bought another one a few years later. Then we upgraded to the LPKF in about 2002.
What are we doing wrong in order to get such success? Have we just been lucky for 25 years? Because according to the 'experts' here we should have thrown these machines into the skip years ago?

[G0HZU]

You didn't miss it in the video - there is no pressure foot because Prometheus doesn't need one! Instead, ProCAM runs a ~90 second probing cycle before milling begins, where the tip of the tool moves down until it makes electrical contact with the copper-clad surface. When it does, it records the height with 1.25-micron resolution. After probing a grid of points, ProCAM forms a surface map behind the scenes and automatically tells Prometheus how to adjust the Z axis on the fly to keep a consistent milling depth. Basically, it follows the peaks and valleys of the board on its own. This has proven to produce fantastic results and users don't have to worry about pressure foot limitations or the pad wearing or snagging or anything like that. It just works.

Sounds impressive. How well will that work with very thin PCB material that tends to bow/flex upwards? eg 0.02" Rogers 4003C or thinner?
The thinnest RF PCB material I've milled on my old T-Tech machine was two sided copper with a 60 micron thick dielectric. It was like copper paper. However, that is very much a rare extreme

[mrpackethead]

You can test an idea within a single day, that is priceless.

What are we doing wrong in order to get such success? Have we just been lucky for 25 years? Because according to the 'experts' here we should have thrown these machines into the skip years ago?

(a) perhaps the jobs are reletively simple.
(b) I'd challenge you to think about your overall workflow.

[G0HZU]

(a) perhaps the jobs are reletively simple.
(b) I'd challenge you to think about your overall workflow.

It doesn't matter if the jobs are simple and in the real world you can't plan for a perfect workflow. Our production RF boards are typically a complex sandwich of Rogers material on the outer layers with a multilayer FR4 core. The one off price might be £1000 for a bare prototype PCB but some of the larger boards cost many thousands each. The mill can be used as a rapid prototype machine to try out new/alternative concepts for the various circuits that will eventually go on the finished RF PCB. Sometimes we want to experiment with alterations to the copper on these exotic boards but this can be done on a milled copy of the relevant section.

We generally go to Graphic PLC or Exception PCB for our production boards but we also use Labtech and Trackwise for some of our RF boards. Eg metal backed RF boards for RF power amplifier design. But despite this we still have a PCB mill and it is in regular demand. You don't have to just convince me that the mill is a waste of time, you would have to convince many of my colleagues over a 25 year span

[Mechatrommer]

(a) perhaps the jobs are reletively simple.
(b) I'd challenge you to think about your overall workflow.

if i am a designer of a pentium xeon extreme motherboard with length matching, differential pair traces with anual margin in at least 5 digits from the job, then i will be in the same boat as a bunch of you. but i'm not. maybe this thread is about a fight between professionals and hobbiests where professionals chime in to tell how suck the machine is. well, hobbiests should get a life.

[ebclr]

This machine is a total nonsense, making pcb's with UV Light is very easier,  faster, better results and cheap.

[mrpackethead]

It doesn't matter if the jobs are simple and in the real world you can't plan for a perfect workflow.

Oh yes, you can.   You've absolytely confirmed my suspsisons.

Do we get it wrong.  Yes of course we do.  But  we get it wrong a lot less because we take the time to catch as many problems as pssible before we commit to somethign physical.

Anyway, glad that milled pcb's work for you.  My suspision is that for most folks. its not viable.

[janoc]

your average hobbyist doesn't need 1hr turnaround, and wants something like oshpark silkscreened PCBs with vias anyway.

That's not really true, I would love to have 1h turnaround time as a hobbyist. OTOH, I am certainly not going to spend so much money for a small dedicated machine doing only PCB milling.

[mikeselectricstuff]

You can test an idea within a single day, that is priceless.

I agree and I don't understand why the 'experts' here can't grasp this. They might as well claim that building a test board in dead bug style is a waste of time too because you can go to a PCB house instead and get a PCB with silk screen and vias

If you want to test an idea, you rarely NEED a PCB to do it.

[mikeselectricstuff]

This machine is a total nonsense, making pcb's with UV Light is very easier,  faster, better results and cheap.

Totally agree. The only downside of this is the drilling, but it's way cheaper in terms of initial investment, and by the time you factor in tools & wastage is probably not much more expensive in materials.

I don't think anyone would argue that there is no demand for in-house PCB making. There will always be some niches where it makes total sense.
But it will always be a niche market, for users that need it quickly and can live with the substantial limitations.
A lower cost and/or better performing solution is always welcome, and will increase the size of the market for whom it makes sense, but it's still a small market and always will be.

[nctnico]

You can test an idea within a single day, that is priceless.

I agree and I don't understand why the 'experts' here can't grasp this. They might as well claim that building a test board in dead bug style is a waste of time too because you can go to a PCB house instead and get a PCB with silk screen and vias

If you want to test an idea, you rarely NEED a PCB to do it.

Unless it is for RF where the PCB itself is a component. But then again you can do a lot using RF simulation software these days and get results within minutes.

[fcb]

It's really simple. If there is a demand for the product at that price point then the OP will make money.

If the demand is high, then they will hopefully make tons of money as we flock to buy something that we have largely survived without all these years.  If the demand is low, then so be it.

I have a three axis CNC here, which gets used once or twice per year for CNC things. Only once did I try to mill a board on it - it was painful. Also I have several kg's of ferric chloride and a large UV light box, used it once perhaps 15 years ago on an RF project.  These days I do little prototyping (dead bug or other methods), lots of simulation (LT Spice) - mainly I spin boards and wait a week, much more efficient use of my time.

[rocco]

You didn't miss it in the video - there is no pressure foot because Prometheus doesn't need one! Instead, ProCAM runs a ~90 second probing cycle before milling begins, where the tip of the tool moves down until it makes electrical contact with the copper-clad surface. When it does, it records the height with 1.25-micron resolution. After probing a grid of points, ProCAM forms a surface map behind the scenes and automatically tells Prometheus how to adjust the Z axis on the fly to keep a consistent milling depth. Basically, it follows the peaks and valleys of the board on its own. This has proven to produce fantastic results and users don't have to worry about pressure foot limitations or the pad wearing or snagging or anything like that. It just works.

Sounds impressive. How well will that work with very thin PCB material that tends to bow/flex upwards? eg 0.02" Rogers 4003C or thinner?
The thinnest RF PCB material I've milled on my old T-Tech machine was two sided copper with a 60 micron thick dielectric. It was like copper paper. However, that is very much a rare extreme

It's really funny you mention that - I have Rogers 4003C arriving in the mail later today. It's only .012" and .008" thick. I'm testing it out for a  large aerospace customer that has pre-ordered Prometheus. Thicker Rogers 4350 worked out great so far. We shall see...

[G0HZU]

This machine is a total nonsense, making pcb's with UV Light is very easier,  faster, better results and cheap.

UV light boxes and PCB mills have been around for decades and both are valid ways to make a prototype PCB. If PCB mills are 'total nonsense' compared to UV light then how come T-Tech and LPKF have been making and selling these expensive machines for decades now? Maybe someone should have told them 30 years ago that their business plan for the next 30 years was 'total nonsense' and they should be selling cheap UV light boxes instead 

I still can't fathom why the experts on here can't accept that there is a market for these machines and there has been for decades. It may well be a shrinking market because of the low cost of buying cheap FR4 boards from fab houses but these machines are often popular with companies that do RF design on exotic laminates. Plus there is the value of being able to make several iterations of a design the same day.

UV light boxes and smelly/staining chemicals aren't for everyone. At my place of work we stopped using the UV method about 25 years ago in favour of a T-Tech mill. No more complaints of chemical smells wafting through the labs on hot days, no more complaints of drips and stains left by clumsy or lazy engineers, much easier production of (accurate) 2 sided boards, much easier to drill, much easier and faster to produce PCBs with accurate custom outlines and with accurate custom cutout areas. No more sounds of engineers furiously filing the edges of PCBs to make them fit or drilling and filing out apertures within the PCB

[G0HZU]

It's really funny you mention that - I have Rogers 4003C arriving in the mail later today. It's only .012" and .008" thick. I'm testing it out for a  large aerospace customer that has pre-ordered Prometheus. Thicker Rogers 4350 worked out great so far. We shall see...

You might get away with it because your machine has a limited PCB area so there is less chance of flexing or bowing.

My T-Tech 7000S is way too big for most jobs as it can do boards or front panels up to 19" x 13" and I rarely use a sheet of PCB material larger than 12" x 8". I tend to buy PCB sheets in this size or guillotine them down to this size. Usually this bare PCB size will cope with several jobs but it does mean that the thinner PCB materials tend to bow upwards in the middle of the large PCB area. This isn't an issue for the foot system but it might cause you problems on very thin materials when you mill up near your PCB size limit.

[usagi]

I still can't fathom why the experts on here can't accept that there is a market for these machines and there has been for decades.

there is a market, but OP's market is a niche within a niche. and despite the pretentious title doesn't revolutionize pcb milling.

[rocco]

businesses and universities serious about pcb prototyping will buy something with a commercial onsite support contract. if they are so dependent on 1hr turnaround, then they will want a support engineer on site to fix it NOW.

My data doesn't agree with your statement. I've already pre-sold to businesses and universities. Not a single one has requested a "commercial onsite support contract".

[rocco]

UV light boxes and PCB mills have been around for decades and both are valid ways to make a prototype PCB. If PCB mills are 'total nonsense' compared to UV light then how come T-Tech and LPKF have been making and selling these expensive machines for decades now? Maybe someone should have told them 30 years ago that their business plan for the next 30 years was 'total nonsense' and they should be selling cheap UV light boxes instead 

I still can't fathom why the experts on here can't accept that there is a market for these machines and there has been for decades. It may well be a shrinking market because of the low cost of buying cheap FR4 boards from fab houses but these machines are often popular with companies that do RF design on exotic laminates. Plus there is the value of being able to make several iterations of a design the same day.

UV light boxes and smelly/staining chemicals aren't for everyone. At my place of work we stopped using the UV method about 25 years ago in favour of a T-Tech mill. No more complaints of chemical smells wafting through the labs on hot days, no more complaints of drips and stains left by clumsy or lazy engineers, much easier production of (accurate) 2 sided boards, much easier to drill, much easier and faster to produce PCBs with accurate custom outlines and with accurate custom cutout areas. No more sounds of engineers furiously filing the edges of PCBs to make them fit or drilling and filing out apertures within the PCB

All great points.

[nctnico]

But these point are extremely focussed on RF prototyping which is a tiny niche.
I understand you want to make your product look like it's a solution to everyone's problem but most just don't have the problem you are trying to provide a solution for.

[rocco]

But these point are extremely focussed on RF prototyping which is a tiny niche.
I understand you want to make your product look like it's a solution to everyone's problem but most just don't have the problem you are trying to provide a solution for.

nctnico, I think your remarks have been pretty reasonable but guys, I've never said it's for everyone or even implied it. I don't know how I could have been more clear on that after re-reading my posts. Seems like every critic wants to insist that either I, or anyone saying anything positive, believes that this is for everyone and then proceeds to argue with us about why it isn't.

It is not for everyone. Hope that's clear now

[usagi]

your subject title was really asking for it. then you profess surprise when people challenge your claim.

if it were a whole lot less clickbaity and less pretentious you wouldn't be getting hammered like you are.

[G0HZU]

The only pretentious people I see are the ones pretending to be experts on why milling is a waste of time. This seems to happen a lot when PCB milling gets discussed. Clearly a lot of effort has gone into designing and building this piece of equipment although I get the impression that it hasn't been fully trialled yet for various PCB types and PCB designs.

For me, the footless design that uses optical tracking is interesting and so is the use of the oil. However, I would have some doubts how well the oil copes when doing a fairly thorough rubout and I think the manual use of the vacuum isn't attractive in its present guise. But the price looks really low.

How long it lasts before wear becomes an issue would be one concern but I guess this is offset by the low price. My milling machine has lasted over 20 years because I have used it with care and skill and I've serviced it regularly. I've never needed to use any of the parts in the service kit that came with it apart from changing the tiny grub screw for the tool chuck at recommended intervals. The identical model at my place of work only lasted a few years because we made the mistake of letting any engineer play with it. So it inevitably lost performance and was eventually damaged so much the wear and 'lack of true' in the spindle became so ridiculous it couldn't mill anything beyond a basic outline for a tool.

We replaced it with an LPKF machine and only a trained operator is allowed to use it. So despite being used many times a week for maybe 15 years it is still running. It has needed a few repairs in this time but nothing too serious or costly.

[mrpackethead]

This machine is a total nonsense, making pcb's with UV Light is very easier,  faster, better results and cheap.

UV light boxes and PCB mills have been around for decades and both are valid ways to make a prototype PCB. If PCB mills are 'total nonsense' compared to UV light then how come T-Tech and LPKF have been making and selling these expensive machines for decades now? Maybe someone should have told them 30 years ago that their business plan for the next 30 years was 'total nonsense' and they should be selling cheap UV light boxes instead 

I can't tell you how many people who have been duped into buying LPFK machines and then they have been left lying idle.  So many universitys and fab.. ( and ourselves.. )..   Good marketing and hype sold lots of these machines..

I still can't fathom why the experts on here can't accept that there is a market for these machines and there has been for decades.

You've missed the point.   There is a small niche market, but if you really think hard about it, you'll work out that what milluing does is just let you be sloppy with your design work and then you run lots of prototypes, rather than modeling, checking, rechekcing and running 1 or 2 protos and then getting a product to market much faster.     Does it work. Of cours.. Does it make real economic sense.  no. the limitations it presents are significant enough.. Now if you coudl produce a 2 layer, through plated board you'd move the equation significnatly, and if you coudl do a 4 layer board, you've massively changed the game.   

It may well be a shrinking market because of the low cost of buying cheap FR4 boards from fab houses but these machines are often popular with companies that do RF design on exotic laminates. Plus there is the value of being able to make several iterations of a design the same day.

Are you dealing with unknown science?    Why not spend your time on designing it correctly to start with.   And there are so many packages and tools to help you!!

UV light boxes and smelly/staining chemicals aren't for everyone. At my place of work we stopped using the UV method about 25 years ago in favour of a T-Tech mill. No more complaints of chemical smells wafting through the labs on hot days,

Substituted for the high pitched whine of drilling and the inhalliation hazzard of very fine powered laminate.    You are substituing one hazzard for another.  No matter which way you make PCB's, its got some uglyness attached to it!!

[mrpackethead]

your subject title was really asking for it. then you profess surprise when people challenge your claim.

if it were a whole lot less clickbaity and less pretentious you wouldn't be getting hammered like you are.

Exactly..    In fact, what it did was Remdin me about everything i do know about pcb milling and why its such a bad idea for us, and almost everyone i've talked to. ( apart from our RF black magic people )

[mrpackethead]

The only pretentious people I see are the ones pretending to be experts on why milling is a waste of time. This seems to happen a lot when PCB milling gets discussed.

Im not talking from some made up theortical position.   I did spend a large sum of money, and invested a lot of time into PCB Milliung after being suckered into the hype of it.    Talking from real experince, i can tell you that it not only wastes time, but also ends up costing money.   It encourages poor design and poor engineering, because people start thinking that they can just spin another board and solv things if it doe'snt work.. If theres a bit of pain in having to wait 2-3 days for a pcb, then that is good, bcause people are much much more careful.  And as they guy who has to pay the bills, i'm actually much more interested in the bottom line.

Clearly a lot of effort has gone into designing and building this piece of equipment although I get the impression that it hasn't been fully trialled yet for various PCB types and PCB designs.

Indeed. I hope the creator has put as much effort into understanding the market that he hopes to sell this device to.

and so is the use of the oil.

Yes, it is.  but it may well increase tool wear, if the material is not being ejected out..  Tool wear at 50krpm on .3mm tools in FR4 is a major factor.     They just dont' last very long.

We replaced it with an LPKF machine and only a trained operator is allowed to use it. So despite being used many times a week for maybe 15 years it is still running. It has needed a few repairs in this time but nothing too serious or costly.

Your lucky. the two machines LPKF sent us where both disasters. ( though i largely think the software was to blame ).. 

[mikeselectricstuff]

I think the manual use of the vacuum isn't attractive in its present guise. But the price looks really low.

FR4 dust is abrasive, and needs to be kept away from bearings, so local vacuum extraction is pretty much essential if you want it to last a decent amount of time.
 

[rocco]

your subject title was really asking for it. then you profess surprise when people challenge your claim.

if it were a whole lot less clickbaity and less pretentious you wouldn't be getting hammered like you are.

What claim did I make that people are challenging? The only thing some people are challenging is market size, something that I've made no claims about. Also, I've professed no surprise.

The title is "Prometheus for Rapid Prototyping - Forget Everything You Know About PCB Milling". If you'd like to know why I said, "Forget Everything You Know About PCB Milling", it's because some people have an impression that PCB milling has to be extremely slow and only produce boards for through-hole components or large SOICs. They don't realize that you can support .4 mm-pitch components with the right equipment. They might get this impression from the hobby machines on YouTube or from trying it out on a general-purpose mill with high spindle runout. On the other hand, others who are familiar with professional machines like LPKF, T-tech, Mits, etc. do know that you can get good results but they also know that the machines cost many thousands of dollars.

For example, if you were to search for a machine that can do 4-mil trace/5-mil space or better, you might come up with something like this: https://web-beta.archive.org/web/20160325161141/http://www.lpkfusa.com/Store/pages/ProductDetail.aspx?cat=51&cid=51&pid=364
Notice the $8,500 price. I had to use archive.org because it appears that you now have to call for a quote. I'm providing 4/5 trace/space for a fraction of that price - $2,300.

Relevant Prometheus specs to also consider when you compare machines are:
Spindle Speed: 50,000 RPM
Max X/Y Speed: 3,800 mm/min (150 IPM)
Spindle Runout (TIR): < 2.5 microns, 10 mm below the spindle bearing (static)

In summary, PCB milling no longer has to be as slow or as expensive anymore. I won't debate whether it's still too slow or too expensive for any given purpose; that is subjective. It's not for everybody.

[G0HZU]

Im not talking from some made up theortical position.   I did spend a large sum of money, and invested a lot of time into PCB Milliung after being suckered into the hype of it.    Talking from real experince, i can tell you that it not only wastes time, but also ends up costing money.   It encourages poor design and poor engineering, because people start thinking that they can just spin another board and solv things if it doe'snt work.. If theres a bit of pain in having to wait 2-3 days for a pcb, then that is good, bcause people are much much more careful.  And as they guy who has to pay the bills, i'm actually much more interested in the bottom line.

My impression is that just need to hire better, more committed engineers rather than blame the fact that you/they can't make the correct decisions on what tools will or won't work for your business. Telling the rest of the world that milling is a waste of time because it promotes laziness in your engineers doesn't make me think that the problem is with having a fast PCB turnaround. It sounds to me like you are spinning a positive (fast turnaround) into a negative/excuse because you have lazy engineers working for you?

[rocco]

The only pretentious people I see are the ones pretending to be experts on why milling is a waste of time. This seems to happen a lot when PCB milling gets discussed. Clearly a lot of effort has gone into designing and building this piece of equipment although I get the impression that it hasn't been fully trialled yet for various PCB types and PCB designs.

For me, the footless design that uses optical tracking is interesting and so is the use of the oil. However, I would have some doubts how well the oil copes when doing a fairly thorough rubout and I think the manual use of the vacuum isn't attractive in its present guise. But the price looks really low.

How long it lasts before wear becomes an issue would be one concern but I guess this is offset by the low price. My milling machine has lasted over 20 years because I have used it with care and skill and I've serviced it regularly. I've never needed to use any of the parts in the service kit that came with it apart from changing the tiny grub screw for the tool chuck at recommended intervals. The identical model at my place of work only lasted a few years because we made the mistake of letting any engineer play with it. So it inevitably lost performance and was eventually damaged so much the wear and 'lack of true' in the spindle became so ridiculous it couldn't mill anything beyond a basic outline for a tool.

We replaced it with an LPKF machine and only a trained operator is allowed to use it. So despite being used many times a week for maybe 15 years it is still running. It has needed a few repairs in this time but nothing too serious or costly.

Thanks. Just to answer some of the points you brought up...

I'll make a full rub-out video and post it at some point.

There will be a vacuum mount - I just haven't designed it yet so I hold it in the video.

As for machine lifetime, I won't know until they're in the field but I believe that it would be comparable to other professional machines. Even though the price is much lower, I'm still using quality parts. For linear bearings, Prometheus uses precision ground steel linear guides, similar to what you see in LPKF's "educational" line of machines (in fact, I think they are even from the same manufacturer). When the spindle bearings eventually go, it'll be less than $50 to replace the spindle block. The cost of lead screw replacement if ever needed will be about that price also. The lead screws are custom-made in the US. The lead accuracy is +/-.0003 inches/inch. They use anti-backlash nuts on the X and Y axes (Z doesn't need one as the weight of the carriage takes out the backlash). Out of curiosity, did you get that damaged spindle at work replaced? If so, do you remember how much it cost?

Also, just a small correction so no one is mislead - the surface tracking isn't optical. What happens is that Prometheus probes points on the board via electrical contact and creates a surface map. Armed with that surface map, ProCAM projects the 2D tool paths to the 3D surface so the bit follows the hills and valleys.

[usagi]

that's not backlash. that's skipped steps. backlash does not accumulate, it is a fixed error.

This is not strictly true - the backlash itself doesn't accumulate (except over time with wear) but you can show that backlash can contribute to a cumulative error with the following pseudo code:

the point is an axis can never be more than backlash offset from true position. you can accumulate error but it can never be more than backlash.

[mrpackethead]

FR4 dust is abrasive, and needs to be kept away from bearings, so local vacuum extraction is pretty much essential if you want it to last a decent amount of time.

Extremely..   it wears out tools faster than anything else i've ever machined.    Probalby the combination of high speed and small tools doe'snt hlep..   the oil idea is helpful to keep the dust down, but i'm wondering how much oil ends up in the FR4?  and if that is even an issue.

[mrpackethead]

My impression is that just need to hire better, more committed engineers

Yes, i'm always looking for better more committed engineers.  Its a great thing to hire great people.   

rather than blame the fact that you/they can't make the correct decisions on what tools will or won't work for your business.

We made a decision on buying a mill based on the information that the LPKF distributor provided.  Sometimes you have to trust people.  Sadly that trust was misplaced and the system comp failed to deliver on what it promised.    LPKF aggreed that it did'nt do what was promised either, and refunded our money.  Sadly we wasted a LOT of time, but the right decision then was to quit, and not waste any more time. 

Telling the rest of the world that milling is a waste of time because it promotes laziness in your engineers doesn't make me think that the problem is with having a fast PCB turnaround.

Sounds like you are content with sloppy work, where you endlessly iterate over a problem just because you can, and you've covninced your self that your making progress becaue youre continastnaly producing new boards..   What i'm interested is shortening the time frame from concept to billing.    Time put in up front to design properly is time ( and money ) well spent 

It sounds to me like you are spinning a positive (fast turnaround) into a negative/excuse because you have lazy engineers working for you?

Yeah, thats it. We are lazy.  its why we've gone from being a tiny 1 man band to somethign much larger. Its why we have customers who place repeat orders..  If my team is lazy, then i congradulate them for doign what they have done and being able to take the afternoon off to play golf.    < sigh>     

If lazy means, doing your design properly upfront, then we are lazy. 

Anyway im going to be more lazy and call it quits on replying you now, beucase your comments moved from being constructive discussion to something else which im not going to enterrtain.

[mrpackethead]

What claim did I make that people are challenging?

The title of your post.

The title is "Prometheus for Rapid Prototyping - Forget Everything You Know About PCB Milling". If you'd like to know why I said, "Forget Everything You Know About PCB Milling", it's because some people have an impression that PCB milling has to be extremely slow and only produce boards for through-hole components or large SOICs.

I knew this. already, so not sure why you wanted me to forget it.   But what the title asked me to do was also forget that the business case for PCB Milling does'tn work for me.    And that is challenging.   

[mrpackethead]

In summary, PCB milling no longer has to be as slow or as expensive anymore. I won't debate whether it's still too slow or too expensive for any given purpose; that is subjective. It's not for everybody.

Could you tell us who it is for and what use-case it provides a positive return?   I cant' see it, but i'm big enough to know that i dont' know everything and if there is a use-case that might work for me, id love to know what it is. 

[G0HZU]

Out of curiosity, did you get that damaged spindle at work replaced? If so, do you remember how much it cost?

I think someone at work replaced a bearing in it and they may have fitted a new motor to it. When the machine was new it came with a spares/service pack including quite a few components from the main head assy.

I actually bought this damaged machine from the company to use as a spares donor for my main T-Tech 7000S machine. I looked through my documentation and I contacted T-Tech UK (Wessex Electronics) back in 2002 to ask how to take the assembly apart to repair it. Their response wasn't very detailed but they did fax diagrams and instructions how to take it apart and reassemble it. This was in May 2002 so I must have bought this 7000S machine around that time. I can't remember how much they quoted for the parts but I think the bearings may be standard types anyway. I've only used this worn/damaged machine for milling basic aluminium tools a few times since I bought it. It definitely isn't repaired properly so it can only do basic milling tasks now.

I bought my first 7000S some time around 2000. The original owner was HP but they hardly used it (they lost the dongle for the SW for one thing) and they traded it in for a modern LPKF machine. I got it cheap because they had lost the parallel dongle for the software.  I quickly managed to hack the Isopro SW so it didn't need the dongle although I inherited our company dongle when I bought the second 7000S machine a couple of years later anyway.

I do remember the UK T-Tech rep saying that the lead screws were quite cheap to replace and I think he may have said the same about the stepper motors. I've got two sets of spares for a lot of the main items in the service packs and so far I've not needed any of them for my main machine

[rocco]

In summary, PCB milling no longer has to be as slow or as expensive anymore. I won't debate whether it's still too slow or too expensive for any given purpose; that is subjective. It's not for everybody.

Could you tell us who it is for and what use-case it provides a positive return?   I cant' see it, but i'm big enough to know that i dont' know everything and if there is a use-case that might work for me, id love to know what it is.

Sure. I don't know if there's a use-case that works for you, but I think the best way I can answer the question of who it's for is by telling you who I've seen order one. I've noticed a nice portion of orders have come from electronics consultants. Universities have been another group that have placed orders. The largest business that has ordered is a private aerospace company that will use it for RF designs. It looks like some individuals/hobbyists have even purchased but it's tough to say how many because they might use their personal email address to order but really be consultants are have a small business. It's safe to say they are the minority though, and businesses and universities the majority.

One of the Ivy League schools here and a "makerspace" affiliated with another university inquired, but those did not lead to purchases (they ended up buying a different PCB mill).

I don't really want to opine on general use-cases and positive returns because that's just asking for someone to jump on here and begin arguing, and I'm not really interested in that. On the other hand, actual sales can't be argued with.

I don't know if that's a very satisfying answer. There were also a couple of PCB mill users on here that voiced their happiness with other machines (and of course others that voiced their unhappiness), so maybe some of them can elaborate on specific use-cases and returns for them.

[mrpackethead]

Sure. I don't know if there's a use-case that works for you, but I think the best way I can answer the question of who it's for is by telling you who I've seen order one.

Not really.. It just tells me whos bought it.  I'm really interested i knowing what and how you would use pcb milling and get a truely postivie return from it, when you consider all aspects of the process of getting from concept to finished product.

The largest business that has ordered is a private aerospace company that will use it for RF designs.

This does seem like somethign that might be viable, as the pcb is truely part of the 'component' list. ( at least considerably more than than in many designs, where the pcb ).

I don't really want to opine on general use-cases and positive returns because that's just asking for someone to jump on here and begin arguing, and I'm not really interested in that. On the other hand, actual sales can't be argued with.

The problem is that sadly PCB milling has been sold for a long time, with a lot of hype and its failed to deliver for many folks.     But your asking me to forget that.   So i'm assuming that this system does something different and will deliver something that the others cant.        So far, we know that it might be useful for some RF designs,  but I can't see any use-cases for anything else yet. 

[rocco]

The problem is that sadly PCB milling has been sold for a long time, with a lot of hype and its failed to deliver for many folks.     But your asking me to forget that.   So i'm assuming that this system does something different and will deliver something that the others cant.        So far, we know that it might be useful for some RF designs,  but I can't see any use-cases for anything else yet.

Ok, I see. That's not what I'm asking you to forget... it's not that Prometheus does anything that no other system can't, it's that it does what professional systems do for a significantly lower retail price. I'm asking you to forget how expensive professional PCB milling machines have to be. Or put another way, nothing near it's price (AFAIK) can do what it can do as fast as it can do it. That's all that I meant by the "Forget..." phrase. The big disconnect in price between every other professional machine and Prometheus is what's new.

Maybe I could say "forget having to spend $8,000 to get professional results from a PCB mill, where "professional" means sub-6-mil trace/space with a spindle greater than 30,000 RPM and forget spending $2,000 on a machine that doesn't give you professional results". That's too many characters to fit that into the title though. Yes, the title is advertise-y - I'm not asking everyone to literally forget everything about milling - I thought that would be obvious, and I elaborated on all this price/performance stuff in the first post that explained what's different.

You mentioned that you were sold on the idea of a PCB mill by a sales rep who promised something and the machine didn't deliver. I'm curious, could you tell me what kind of work you intended to do on you machine that made you disappointed (if it's not confidential)?

[mrpackethead]

Ok, I see. That's not what I'm asking you to forget...

" Forget everything you know "...  You asked me to forget everything i know...   



I'd still like to know what use-cases you think that PCB Milling provides a positive return on.   *on any platform) Other than RF, i'm not seeing one.      I woudl have thought this woudl have been quite a fundemental part of any strategy to sell it.   Other wise its a solution lookign for a problem..  I'd really like to know what problems its trying to solve.

[nctnico]

I'd still like to know what use-cases you think that PCB Milling provides a positive return on.   *on any platform) Other than RF, i'm not seeing one.      I woudl have thought this woudl have been quite a fundemental part of any strategy to sell it.   Other wise its a solution lookign for a problem..  I'd really like to know what problems its trying to solve.

I can imagine lots of customers for a PCB mill are just set in their ways and in their mind & workflow they require extremely quick prototypes. Messing with chemicals is usually surrounded by all kinds of environmental regulations so for a company it might be cheaper to buy a PCB mill compared to investing into a workspace where people can etch boards and have someone monitoring health & safety yadda yadda yadda.

[mikeselectricstuff]

I actually think the strapline is well-chosen - if it had been "forget all you know about in-house PCB production" that would certainly have been over the top.

What most people know/believe about PCB production is that LPKF machines are over-promised, expensive and often troublesome. Considering how long they've been in the business it's surprising they've not produced anything better/cheaper. These days they seem to be focussing more on expensive high-end lasers for stencils and PCBs.

If this machine can reliably and consistently do 5 mil track/space with minimal babysitting then I have no doubt that some people will find it genuinely useful, and undoubtedly more useful than an expensive, over-sold machine with poor software. As has been mentioned, LPKF have ruined the reputation of milling for some people.
Time will tell if that the resolution spec and good reliability is actually achievable in practice.

IME around 10 mil is the limit for reliable chemical etching using laser printed artwork, and drilling is a PITA. Even if you have a small CNC it's borderline impractical to CNC drill a chemical-etched PCB due to difficulty of alignment and small size errors in the laser-print process.
The mess and hassle factor on chemical etching isn't much an issue if you have room to set up a permanent dedicated space for it.

A couple of questions :
Have you done tests on achievable resolution vs. copper weight ? e.g. do you need to use 0.5 oz copper to get maximum resolution reliably?
What is the running cost in terms of tool usage?

Auto tool change would be a killer feature, especially for the drilling. I wonder if it would be possible to make a chuck that used a combination of friction/magnets for initial hold/release, plus centrifugal force to increase clamp pressure while running. At 50Krpms you potentially have a lot of force without much mass.

[ultrasmurf]

One possible use case, at least theoretically since I sometime wished I have one of those nice PCB milling machine : When doing a repair job, and you found out that one of the EOL chip has given up the ghost, and you could actually fix it with a different chip only that you need to have an adaptor to it. Or even replace the whole board with an implementation of simple microcontroller instead of transistor and IC. Most of repair I'm doing will be "please fix it by yesterday..." so having one tool that can make a simple PCB while im repairing other board will be superb... etching tools sometimes are not practical even for the industry, as some region have a stringent requirement to even have a license to obtain chemical (let alone use it...) and it will be too difficult to meet..

[janoc]

I can imagine lots of customers for a PCB mill are just set in their ways and in their mind & workflow they require extremely quick prototypes. Messing with chemicals is usually surrounded by all kinds of environmental regulations so for a company it might be cheaper to buy a PCB mill compared to investing into a workspace where people can etch boards and have someone monitoring health & safety yadda yadda yadda.

That's probably true, the safety regulations can be crazy, but you don't have the same problem with a workshop equipped with stuff like a milling machine producing fine FR4 dust? At least ferric chloride isn't carcinogenic, FR4 dust is. Other materials' dusts/shavings can be fire/explosion hazards. Then you have the coolants, cutting liquids (that's mostly for machining metal, though) - those need to be properly dealt with, etc.

I would expect that an expensive dust extraction/air filtering setup would be a minimum requirement, but I have never had to comply with these regs. What are the typical rules for these things?

Then there are the usual workplace safety trainings and such, but that likely applies the same whether you are etching or milling. Getting finger burned from the etchant or cut/torn off by a CNC machine is a hazard in either case.

[rocco]

I can imagine lots of customers for a PCB mill are just set in their ways and in their mind & workflow they require extremely quick prototypes. Messing with chemicals is usually surrounded by all kinds of environmental regulations so for a company it might be cheaper to buy a PCB mill compared to investing into a workspace where people can etch boards and have someone monitoring health & safety yadda yadda yadda.

That's probably true, the safety regulations can be crazy, but you don't have the same problem with a workshop equipped with stuff like a milling machine producing fine FR4 dust? At least ferric chloride isn't carcinogenic, FR4 dust is. Other materials' dusts/shavings can be fire/explosion hazards. Then you have the coolants, cutting liquids (that's mostly for machining metal, though) - those need to be properly dealt with, etc.

I would expect that an expensive dust extraction/air filtering setup would be a minimum requirement, but I have never had to comply with these regs. What are the typical rules for these things?

Then there are the usual workplace safety trainings and such, but that likely applies the same whether you are etching or milling. Getting finger burned from the etchant or cut/torn off by a CNC machine is a hazard in either case.

Nctnico's point may explain why universities like this - they don't have to deal with the regulations of chemical etching.

Note that I've found nothing that indicates that FR4 is carcinogenic but if you have a source, please post it - it would be good to know what regulatory body classifies it that way. We can compare the SDS of FR4 copper-clad with ferric chloride (links below). Both substances are, "Not classified or listed as a carcinogen by IARC, ACGIH,
CA Prop 65, or NTP" according to the SDSs by MG Chemicals. On the other hand, we see that ferric chloride causes "serious eye damage" (p. 2) while for FR4 copper-clad it says "Based on available data, the classification criteria are not met".

The exposure limits for the dust are shown on p. 5. For a vacuum/filter, you could choose a ULPA filter over HEPA if want the best in filtration but the extra fraction of a percent difference costs way more. FR4 is no picnic but on paper it looks like ferric chloride gives more to contend with, from a regulatory standpoint.

Section 11: Toxicological Information
FR4
Symptoms Summary
Eyes May cause redness and mild irritation.
Skin May cause mild irritation.
Inhalation May cause nose, throat and lung irritation.
Overexposure to dust or metal fumes may lead to respiratory tract
irrititation.
Ingestion No effect known
Chronic No effect known

Ferric chloride
Symptoms Summary
Eyes Causes burns, severe irritation, redness, or pain.
Skin Causes redness, pain, or brown stain on skin.
Inhalation Inhalation of vapors or mist may cause irritation, coughing, or sore
throat.
Exposure to large doses of hydrogen chloride can cause cough,
labored breathing, and shortness of breath.
Ingestion May cause severe irritation to the mouth, throat, esophagus, and
stomach. In large doses, it may also cause abdominal pain, nausea,
vomiting, diarrhea
Chronic No known effects

Links:
SDS for FR4 copper-clad: http://www.mgchemicals.com/downloads/msds/01%20English%20Can-USA%20SDS/sds-500-series.pdf
SDS for ferric chloride: http://www.mgchemicals.com/downloads/msds/01%20English%20Can-USA%20SDS/sds-415-l.pdf

[tooki]

I still can't fathom why the experts on here can't accept that there is a market for these machines and there has been for decades.

Because many people are incapable of seeing beyond their own needs: if a product isn't a good fit for them, then it's not a good fit for anyone. (Look at the computer and phone platform wars: most of it is simply refusal to accept that a competing platform might be a better fit for someone else.)

[rocco]

A couple of questions :
Have you done tests on achievable resolution vs. copper weight ? e.g. do you need to use 0.5 oz copper to get maximum resolution reliably?
What is the running cost in terms of tool usage?

Auto tool change would be a killer feature, especially for the drilling. I wonder if it would be possible to make a chuck that used a combination of friction/magnets for initial hold/release, plus centrifugal force to increase clamp pressure while running. At 50Krpms you potentially have a lot of force without much mass.

All of my testing has been with 1 oz. copper (FR4 and Rogers). I could imagine 0.5 oz copper yielding even better results since the tool doesn't need to plunge as deep.

Tool cost is the most significant consumable cost. I'm going to offer 3 classes of bits: economy, performance, and accuracy. Economy bits are estimated to retail at $12 each and should do a few boards with them (not many; a few). The disadvantage is that they need to be run slower, around 13 IPM. You can do 8-mil trace/space with them. Performance class bits are 15 degree tapered end mills that can do 4/5 trace/space at high speed. The bit in the video that did the milling was a 7-mil diameter bit of this type, and in the video it's max feedrate was 85 IPM, which is insanely fast for that size tool. These will range from $16 to $19 each depending on size (smaller tend to cost more). With volume, I'll be able to offer these even less, which is really cheap if you shop similar tools on competitor sites. The Accuracy class are standard square end mills (the cutting profile has right-angles; it's not a "V" shape). These cost about the same and are in between economy and performance in terms of speed. They have the shortest life though, so they're offered if you're really crazy about trace consistency. You might just get one or two full-size boards with these before they break. Anything more is a bonus (I mean, if your boards are only 2"x1", then you'll get many more - I'm talking about full-size boards). I imagine the performance class of bits will be much more popular because the are nearly as accurate and last longer and cut faster.

A good estimate for the bit depreciation cost of a double-sided 5"x4" board could be anywhere from $4 to $20, depending on which kinds of bits you choose. This is a rough estimate. Cut the board area in half and same goes for the cost.

An important thing I should mention: the bits are somewhat custom for the current spindle design and they should be purchased from us to work properly, which I know doesn't sound great but the spindle design is a huge part of the reason I can build this tool for thousands of dollars less, so that's one of the compromises I had to make. The bits I'll retail are cheaper than those offered by the other guys by 15% or more anyway, so it shouldn't be a huge drawback for people. However, I am also working on a universal spindle that could accept all types of bits and still have great runout specs (if it passes testing).

[mikeselectricstuff]

the bits are somewhat custom for the current spindle design

But will your spindle take standard carbide PCB drill bits ?

[rocco]

They are carbide, yes. The part that's custom or hard to find is that the depth ring needs to be set at .587" for a standard 1.42" long tool (that's not a big deal). The more difficult spec to meet is that our bits have a shank diameter of .1248" +0/-.0001. Very tight tolerance window. But like I said, they're actually cheaper, probably because I'm ok accepting a lower profit margin on them. I also work directly with US manufacturers.

A universal spindle design is something I'm working on and would like to see. I'm not intentionally trying to lock people into using my bits - it was a compromise I made that enabled me to design a spindle that achieves .0001" Total Indicated Runout and 50,000 RPM max speed, for something not costing $1,000 - $2,000, just for the spindle. At that point, Prometheus would be approaching the price point of the other professional machines on the market and there wouldn't be a point. So that was the compromise.

If anyone knows of a spindle with those specs or better that I could buy off-the-shelf for $150 or less, please, please, please let me know! I'm not being sarcastic - I would gladly put that in there and then as a bonus Prometheus could accept universal bits. I just don't know that anything that cost-effective exists. I've looked and haven't found anything, so I was forced to make my own in order to hit my price target. A typical import spindle with an ER collet will usually yield .003 - .005" of runout. A European manufacturer of a rotary tool quotes that their tool has just .001" of runout (which is 10 times more than Prometheus but at least closer than the others) so I got one but actually measured that it was .003". You can find the right specs for 4 figures; at 3 figures I have had no luck.

[rocco]

Oh sorry - you were asking about drill bits. The same answer applies, but those are significantly cheaper than the end mills.

[mikeselectricstuff]

Oh sorry - you were asking about drill bits. The same answer applies, but those are significantly cheaper than the end mills.

Yes - because you may need quite a few different sizes, so using off-the-shelf bits would be useful. Shaft precision is probably less important as drills should mostly self-guide, and there won't be any lateral force.
Will your system produce enough torque at lower speeds for bigger drill bits- say up to 3mm or so ?

[rocco]

It's still important to be less than or equal to .1248" shank diameter otherwise the current spindle won't accept them. I totally agree it would be useful. Makes my job easier too because I won't have to stock so many parts. That's why I'm hoping the universal spindle design works out. Fortunately, my bit manufacturers are understanding of this and willing to deal in smaller quantities as I get going.

I've tested that 3.175 mm drills work. That's the size that you see in the video that made the first two holes for the alignment pins.

[mrpackethead]

I still can't fathom why the experts on here can't accept that there is a market for these machines and there has been for decades.

Because many people are incapable of seeing beyond their own needs: if a product isn't a good fit for them, then it's not a good fit for anyone. (Look at the computer and phone platform wars: most of it is simply refusal to accept that a competing platform might be a better fit for someone else.)

Despite being asked, and dodging the question the OP has to yet provide some idea of what use-cases this method provides a positive return on.     Its not a question of acceptance. I'm declaring that despite trying ( with considerable money and time ) I can not see a proposition ( other for some corner case RF stuff ) that is better than i can do with getting pcbs made in a more traditional way ( which is resonably quick and fast ).   If this process can be shown to save me time/money ( the two are largely interchangable ) i'd be all over it.    Even if this device was free ( as in $0 ) the full picture economics dont' seem to work for me.    But i'm completely open to seeing how it can work.

[free_electron]

small question. You do through hole . how ?

[rocco]

small question. You do through hole . how ?

When it comes to vias, I've not added anything beyond the known methods - either slip a wire through the hole and solder top and bottom pads, or use rivets made for this purpose. I've personally never used the rivets, but I've heard that other people have had success with them.

Vias are another pain point and one that I'm going to play with. For now, my immediate goal was just to deliver a machine that competes with the professional ones on specs but costs 1/3 or 1/4 the price. Then I'll work on a better via system and ability to add a solder mask (resist, as some call it) as well.

[mikeselectricstuff]

small question. You do through hole . how ?

When it comes to vias, I've not added anything beyond the known methods - either slip a wire through the hole and solder top and bottom pads, or use rivets made for this purpose. I've personally never used the rivets, but I've heard that other people have had success with them.

Rivets are OK but reduce the hole size - fine for vias but less so for through-holes. Can be a little fiddly - need good tweezers.
Snap-off through-linking pins are about the quickest, but they could do with making smaller ones.
The trick for using wires is to bend a wire into a "U" and feed it through 2 holes, solder then  cut off - the U makes it much more stable and easier to solder neatly and stops the other end wiggling about when the second side is soldered.
 
One advantage of a  cnc mill type system over chemical etch is it makes it potentially possible to use the same plating process as 'proper' PCBs, where the holes are drilled first and then plated before patterning. I don't know much about the chemistry involved to know how practical it is to do in-house - I know it involves a catalytic process to make the inner walls conductive, followed by electro-plating.

[m98]

LPKF has a nice product for via plating, the ProConduct paste. Just apply a protective adhesive film before drilling the vias, then after drilling apply the paste with help of some kind of DIY vacuum table contraption and cure it in an oven.

[janoc]

Nctnico's point may explain why universities like this - they don't have to deal with the regulations of chemical etching.

Um ... no. Even universities have to follow the same regulations as industry does. There could be exception for research labs and similar situations but not when they are running a workshop making PCBs (or anything else) for their internal use. The safety rules are the same.

Note that I've found nothing that indicates that FR4 is carcinogenic but if you have a source, please post it - it would be good to know what regulatory body classifies it that way. We can compare the SDS of FR4 copper-clad with ferric chloride (links below). Both substances are, "Not classified or listed as a carcinogen by IARC, ACGIH,

Haven't found the studies, but the FR4 material sheet (http://www.tlm.co.th/download/msdsesd3000.pdf) shows this:

Fibrous Glass: This product contains fibrous glass. Although early studies showed possible links between fibrous glass and cancer,
current research indicates no links between fibrous glass and human cancer. Glass wool, which differs form glass in it morphology,
continues to be evaluated as a possible humancarcinogen. (Group 2B) by the IARC.
OSHA PEL = 5 mg/m3
 (resp); 15 mg/m3
 (total)
ACGIH TLV = 5 mg/m3

and

Machining, grinding or sawing this material may generate harmful dusts. Continuous filament glass fiber is not considered fibrogenic,
however, it is woven from E-Glass fibers which are listed by IARC as "special purpose glass fibers" and designated as "possibility of
carcinogenic in humans." Inhalation of copper fumes, while not expected to occur under typical conditions of use, may cause metal fume
fever.

I think the problem is the production of fine particles that are known to cause human cancers when inhaled in general (similar like particulate air pollution, silicosis, etc.), not necessarily FR4 specifically.

The exposure limits for the dust are shown on p. 5. For a vacuum/filter, you could choose a ULPA filter over HEPA if want the best in filtration but the extra fraction of a percent difference costs way more. FR4 is no picnic but on paper it looks like ferric chloride gives more to contend with, from a regulatory standpoint.

Not sure about that - the FeCL3 health hazards are about the same or smaller than for many domestic cleaning products, where strong acids and hydroxides are common, some even produce chlorine gas (!). So I wouldn't expect some crazy requirements beyond basic safety training, fume exhaustion and proper disposal arrangements being required unless working with it on a huge scale.

The hydrogen chloride part doesn't apply unless you mix hydrochloric acid there, which is not normally done.

[rocco]

Nctnico's point may explain why universities like this - they don't have to deal with the regulations of chemical etching.

Um ... no. Even universities have to follow the same regulations as industry does. There could be exception for research labs and similar situations but not when they are running a workshop making PCBs (or anything else) for their internal use. The safety rules are the same.

I meant that universities may prefer milling because if they're milling (and not etching), then they don't have to deal with regulations regarding chemical etching (because they're not doing it in the first place if they use a PCB mill).

[mrpackethead]

What is this machine useful for.  how could i justify it to my boss.

[janoc]

I meant that universities may prefer milling because if they're milling (and not etching), then they don't have to deal with regulations regarding chemical etching (because they're not doing it in the first place if they use a PCB mill).

Ah okay. I read it as you saying that universities have somehow looser safety/environmental regulations than the industry.

However, what you are saying goes certainly both ways. If the uni has a machine shop then milling is a logical choice. If they have chemistry/biology labs, adding an etching machine for the electronics/robotics/EE department would be a no-brainer but they may not have the trained staff to run and maintain a CNC. Most places I have been to had both kinds of facilities though, including for student use. So this is not really a major issue -  the "mess" is there because of some other department already, so some more doesn't matter much.

[Mechatrommer]

What is this machine useful for.  how could i justify it to my boss.

here again... https://www.eevblog.com/forum/reviews/prometheus-for-rapid-prototyping-forget-everything-you-know-about-pcb-milling/msg1189948/#msg1189948 and nobody is forcing you to justify it to your boss...

i just realized the OP claim 5 mils tolerance, i believe this is highly optimistic value. we need proof for that. in the video already showing inconsistencies in isolation/mill thickness, that i estimate between 0.5mm - 1mm milling. 20 mils (0.5mm) tolerance maybe believable/achievable. my 0.5mm drill bit may break at an instant.

[mrpackethead]

What is this machine useful for.  how could i justify it to my boss.

here again... https://www.eevblog.com/forum/reviews/prometheus-for-rapid-prototyping-forget-everything-you-know-about-pcb-milling/msg1189948/#msg1189948 and nobody is forcing you to justify it to your boss...

No body is. But I'm desperately trying to figure out what the tangible benefits to owning one is.  Because clearly there are people who believe there is.   But as yet, nobodys provided a 'full cycle' story about how it helps.

[Mechatrommer]

But I'm desperately trying to figure out what the tangible benefits to owning one is.  Because clearly there are people who believe there is. But as yet, nobodys provided a 'full cycle' story about how it helps.

are you dead serious? where in the world cubicle are you live in? we have small project, or pcb that doesnt need 6 mils small trace, and we need it quick less than an hour, for prototype or a one-off, or an arduweeno project shield. how many times do people here have to explain? i dont do chemicals, or consumer market laser printer is not printing black enough toner for pcb transfer hence i over etch. drilling by hand using dremel is suck etc etc, hence i need a 3d drilling machine, pcb mill, or etch resist remover is another bonus for the machine. i also can make it to carve my project enclosure, or shape some plastic or wood or even light aluminium. etc..

just like how do you justify a sewing machine to your boss? everybody try to explain so you can knit your shirt easy fix this and that, and you said... i dont knit! you are doing it all wrong you should send it to tailor shop. you dont knit you dont buy sewing machine period, but many other people do knit. many people buy a car but some cant justify it since they work just the next block, same as the market where they buy stuffs etc and they will spend the rest of they entire life in the neighborhood. you should buy printer, no! whats the point if i can send it to the computer shop next door that can print at insanely cheaper price. everybody should have a dog, no! dog shits everywhere. etc etc. its a matter of interest, and as you said... workflow. nobody should be forced to follow your workflow.

[aandrew]

What is this machine useful for.  how could i justify it to my boss.

If you can't think of any reasons then I don't think it's for you. I've contemplated this kind of machine even in the day and age of quick turn protos, oshpark, etc.

I'm just a one man shop but even I have those 3am "hm, I'd love to be able to test this out" moments. Making a couple of boards for a kid's project or quick hack/test. Being able to route out a quick board within hours rather than days. I don't even need through hole. I can think of lots of things to use this machine for.

As I mentioned earlier in this thread, I think he's even got the price point right. It's a bit of a tough sell for me, but because I'm a cheapskate, not because his price is wrong.

[mrpackethead]

What is this machine useful for.  how could i justify it to my boss.

If you can't think of any reasons then I don't think it's for you. I've contemplated this kind of machine even in the day and age of quick turn protos, oshpark, etc.

I can think of multiple reasons why there is appeal to this machine.     The lure of nearly instant results.   the concept that you can have something much faster than you think you coudl previously.   There was a time i thought this would be amazing..     Running lots of prototypes is expensive. ( lets exclude materials they actualy are not much more than a rounding error for lots of stuff compared to the cost of time ).       When its easy to run prototypes ( like using a mill )  the tendency is that the quality of engineering goes down.   The we'll work it out and see what happens approach... 

Im convinced that spending more time on actual engineering and produce higher quality work acutally saves time and money overall.   Rush jobs never quite hit the quality level, because they are just that.. rush jobs.

[Kjelt]

You are thinking businessmarket but this is consumer market machine.
For the hobbieist it is great to do some experimenting, they did this normally on breadboards and protoboards but with smt that is not easy. Using SMT-> TH adapters might also change the behavior of the circuit for instance with buck converters where you want every part (ic, caps, coil) close together and a firm groundplane. Yeah for >2 layers it is not going to work but there are few hobbieists that make 4 layer board due to cost and complication. So to test and improve a new design before sending it to the pcb fab this could be IMO be a worthwhile investment.
But for your boss and a company, naah unless they are a small time shop  they have next day pcb delivery without extra cost contracts as long as they also let the same fab do the production run in the end.

[mikeselectricstuff]

What is this machine useful for.  how could i justify it to my boss.

If you can't think of any reasons then I don't think it's for you. I've contemplated this kind of machine even in the day and age of quick turn protos, oshpark, etc.

I can think of multiple reasons why there is appeal to this machine.     The lure of nearly instant results.   the concept that you can have something much faster than you think you coudl previously.   There was a time i thought this would be amazing..     Running lots of prototypes is expensive. ( lets exclude materials they actualy are not much more than a rounding error for lots of stuff compared to the cost of time ).       When its easy to run prototypes ( like using a mill )  the tendency is that the quality of engineering goes down.   The we'll work it out and see what happens approach... 

Im convinced that spending more time on actual engineering and produce higher quality work acutally saves time and money overall.   Rush jobs never quite hit the quality level, because they are just that.. rush jobs.

You're looking at it with a mindset of your own business. There are lots of other types of businesses with different constraints and requirements.
People building 1-offs or small volumes  on a tight schedule ( due to their customer, not their own bad planning) would benefit from anything that can speed up turnround.

For example I've done a job where there was less than a week from initially being called to shipping a couple of hundred tested boards with firmware, to rescue a time-critical installation for an exhibition.
The ability  to verify a PCB before ordering 10 panels on an expensive 24h turnround could cover the cost of a mill in a single job. 
The ability to quickly knock up a breakout board to evaluate an oddball part can also be very valuable - this is something I still occasionally use my PCB etch tanks for.
There isn't always something else you can be doing while waiting for PCBs to arrive. '

There is no such thing as "good" or "bad" engineering, only more or less appropriatefor a given situation.
 If you can't see the potential benefit of a consistent and  reliable way of doing PCBs in house, you're looking a things with too narrow a view.

[G0HZU]

I've said it many time on many threads here but these things are at their best (IMO) for doing RF research work on various exotic laminates. If you are into this kind of business the mill is a fabulous and very powerful tool.

But they aren't for everyone. Probably the worst thing you can do with a mill is make lots of large 2 layer digital boards with lots of 8 or 16 bit data bus lines strewn across the board and loads of vias to stitch/fit. The double whammy worse thing would be to try and do this with a 4 or 5 mil track width/space because you would probably wear out several 5 mil end mills by the time the board is finished. A large and complex digital board with lots of fine traces and a fair bit of rubout could take several hours to mill. The finer tools cost more and also wear out quicker. You get the board the same day but it will be expensive and time consuming to make. Plus the chances of mistakes goes up due to the complexity and you may trash the PCB at any time during the milling process. That's where the skill and experience of the operator really makes a difference. I rarely trash a board during milling but then I take extra time and I know how to set up the milling algorithm to get good results.

The newer machines may be better at all of this with less need for a skilled operator but you will still have the issue of rapid tool wear on the ultra fine end mills. At work we generally use the V or pointed tools as much as possible and try for a non critical 8-10mil trace width as a minimum. We only use finer traces where absolutely necessary. Any critical stuff gets done with an accurate end mill and then the rubout gets done with an end mill near the end of its tool life. By critical I mean traces or shapes that have to be accurate in terms of width or spacing. This would typically apply for filter design or oscillator design where the dimensions have to be right in order for the milled filter to be representative of the actual design itself. We have milled RF filters up beyond 10GHz with excellent results over the years.

But in a typical R&D environment there will be loads of uses for these machines. They are at their best doing small boards that can be milled quickly. So I don't see the small size of the Prometheus' work area to be a problem. Nearly every board I make could be done on Prometheus. My 7000S table area is 19" x 13" and I think I'd rather have the smaller 5000S version of my machine if I could swap. The 7000S is a very big mill and needs lots of bench area to operate in.

[ebclr]

It's time to finish this thread, already advertised the obsolete machine, very few interests let's go forward,

[G0HZU]

It's time to finish this thread, already advertised the obsolete machine, very few interests let's go forward,

Just click off to another thread if you are bored? I won't miss you

[rocco]

What is this machine useful for.  how could i justify it to my boss.

here again... https://www.eevblog.com/forum/reviews/prometheus-for-rapid-prototyping-forget-everything-you-know-about-pcb-milling/msg1189948/#msg1189948 and nobody is forcing you to justify it to your boss...

i just realized the OP claim 5 mils tolerance, i believe this is highly optimistic value. we need proof for that. in the video already showing inconsistencies in isolation/mill thickness, that i estimate between 0.5mm - 1mm milling. 20 mils (0.5mm) tolerance maybe believable/achievable. my 0.5mm drill bit may break at an instant.

I'm happy to share pictures of the 5-mil isolation! Here are two (which you can also view on www.zippyrobotics.com):
http://www.zippyrobotics.com/wp-content/uploads/2017/03/IMG_0944.jpg . This entire board was done with the same 3.9-mil end mill.
and
http://www.zippyrobotics.com/wp-content/uploads/2017/03/1.png under microscope.

The gaps are cut to 5-mils, to within the tip diameter tolerance of the bit. The end mill used was 3.9-mil diameter, 15 degrees, fluted. 50,000 RPM and 7 IPM feed rate to make those examples. IMHO, Prometheus could probably support an even lower trace/space but the bits become more expensive and the feed rate must decrease even further.

20 mils is super-easy for Prometheus. 7-mils is routine even with square end mills (as opposed to angled ones). The trick is to use an accurate spindle that has really low runout ("wobble"). Large spindle runout is the major limiting factor that causes small tools to break instantly. Another reason is the runout of the bit itself, meaning how concentric the center of the cutting helix is to the center of the shank, so it is important to use high-quality bits when micro milling also.

[nctnico]

IMHO there is no reason to over-obsess about minimal widths. A board needs to be soldered as well and very small clearances are easy to bridge. When I etch a prototype I use minimal clearances of 0.25mm and preferably much more.

[Dubbie]

Thats quite impressive Rocco, given the price of the machine. nice work.

[mikeselectricstuff]

IMHO there is no reason to over-obsess about minimal widths. A board needs to be soldered as well and very small clearances are easy to bridge. When I etch a prototype I use minimal clearances of 0.25mm and preferably much more.

It's about margin - if a system will only just do 10mil/0.25mm, chances are it will be unreliable long-term if you expect it to do dense boards with those design rules.
However if it will comfortably do half that, chances are you will get a good yield from more relaxed design rules, and the capability to go more dense when necessary.

[rocco]

IMHO there is no reason to over-obsess about minimal widths. A board needs to be soldered as well and very small clearances are easy to bridge. When I etch a prototype I use minimal clearances of 0.25mm and preferably much more.

I agree with that in general - it's always good to design with larger trace/space if you can do it. Though minimal trace and space can become very important if you select components that have smaller clearances between their pads (or if they only come in smaller packages). For example, many QFPs have a clearance between pads in their recommended footprints of only .2 mm (8 mils) or less, so in those cases if your machine only supports 10-mil spaces you won't be able to do it at all.

For the rest of the board, you could always rub out a larger clearance around the traces using a larger and more durable bit or just remove all of the unwanted copper completely.

[rocco]

IMHO there is no reason to over-obsess about minimal widths. A board needs to be soldered as well and very small clearances are easy to bridge. When I etch a prototype I use minimal clearances of 0.25mm and preferably much more.

It's about margin - if a system will only just do 10mil/0.25mm, chances are it will be unreliable long-term if you expect it to do dense boards with those design rules.
However if it will comfortably do half that, chances are you will get a good yield from more relaxed design rules, and the capability to go more dense when necessary.

Yup.

[nctnico]

IMHO there is no reason to over-obsess about minimal widths. A board needs to be soldered as well and very small clearances are easy to bridge. When I etch a prototype I use minimal clearances of 0.25mm and preferably much more.

I agree with that in general - it's always good to design with larger trace/space if you can do it. Though minimal trace and space can become very important if you select components that have smaller clearances between their pads (or if they only come in smaller packages). For example, many QFPs have a clearance between pads in their recommended footprints of only .2 mm (8 mils) or less, so in those cases if your machine only supports 10-mil spaces you won't be able to do it at all.

In case of prototypes you'll always have to be creative and tailor the PCB design to the process used to create the prototype. A QFP has a 0.5mm pitch so if you have a space of 0.25 between the pads there is still 0.25mm of pad width. Not a real problem and the bigger spacing will probably improve the solderability of the board as well (*). Don't mix absolute accuracy and minimum clearance here.

(*) Not every contract assembler is happy with the manufacturer's PCB footprints!

[G0HZU]

It's about margin - if a system will only just do 10mil/0.25mm, chances are it will be unreliable long-term if you expect it to do dense boards with those design rules. However if it will comfortably do half that, chances are you will get a good yield from more relaxed design rules, and the capability to go more dense when necessary.

Yes, I'd agree with that. I think most/all of the high end machines from T-Tech and LPKF advertise 4 mil trace capability, even on old machines like my 7000S from the mid 1990s. But I think it is worth mentioning that things get very expensive very quickly if an attempt is made to mill using a 4 or 5 mil end mill to get a tiny trace and width across loads of address and data lines on a large and complex CPU design for example. You might end up using three tools to finish the PCB.

The price of the 4 mil end mills (eg $320 for 10) is nearly three times that of a 31mil end mill and about double the cost of a 15 mil end mill from T-Tech and these tiny 4 mil end mills have a much reduced life. Things get much worse on materials like Rogers 4003C or 4350 if you use fine end mills because the wear rate is much higher still. I think the top grade LPKF tools are even more expensive but at my place of work this isn't an issue. We just buy what we need. The bonus for me is that I can salvage the part worn tools from work for free so I rarely buy new tools here at home. I think the LPKF tool timer is very aggressive so I often get tools with loads of life left in them and I get them at a rate that far exceeds my usage at home. The only tools I won't salvage are drills and contour routers. I always buy these new and they are generally quite cheap anyway.

[rocco]

IMHO there is no reason to over-obsess about minimal widths. A board needs to be soldered as well and very small clearances are easy to bridge. When I etch a prototype I use minimal clearances of 0.25mm and preferably much more.

I agree with that in general - it's always good to design with larger trace/space if you can do it. Though minimal trace and space can become very important if you select components that have smaller clearances between their pads (or if they only come in smaller packages). For example, many QFPs have a clearance between pads in their recommended footprints of only .2 mm (8 mils) or less, so in those cases if your machine only supports 10-mil spaces you won't be able to do it at all.

In case of prototypes you'll always have to be creative. A QFP has a 0.5mm pitch so if you have a space of 0.25 between the pads there is still 0.25mm of pad width. Not a real problem and the bigger spacing will probably improve the solderability of the board as well (*). Don't mix absolute accuracy and minimum clearance here.

(*) Not every contract assembler is happy with the manufacturer's PCB footprints!

Finer trace/space support gives you more freedom. Period.
Also, .4 mm-pitch QFPs exist and have a *recommended* pad width of .3 mm. A .25 mm end mill would destroy ALL of your pads in that case. There'd be nothing left to solder to.

Who's mixing accuracy and minimum clearance? You're saying that the recommended clearance isn't really the minimum. That's fine, it's good to get creative if you have to. I truly applaud it. There are reasons to do use a larger bit and not to obey recommended footprints, like faster milling speed and cheaper bits. But I know you're not asking me to apologize for making a more capable tool that has the ability to do fine trace and space if you need it. It's not like I'm charging more money for it! Right?? It's only an option, there if you need it.

[G0HZU]

The other thing is that it's worth trying to find the optimal spindle motor spin speed and tool travel speed for each type of board material and tool type.

T-Tech gave me this data many years ago although I was scared away by the very high tool travel speeds they were suggesting. A case of my ignorance of what is OK against what seems 'not OK' when you watch the machine going that fast. So I tend to run my machine slower. Also it's worth having a fast/variable motor speed. One limitation of my old machine is that it is stuck at 23k rpm max.

Also, if you want to produce some nice marketing samples then try doing some pretty looking RF filters on Rogers 4003C as it looks very professional once milled. The white substrate against the clean copper looks great especially if the cuts are clean. I often feel a bit sad when soldering parts to the board because it spoils the beauty of a freshly milled board on 4003C

[rocco]

It's about margin - if a system will only just do 10mil/0.25mm, chances are it will be unreliable long-term if you expect it to do dense boards with those design rules. However if it will comfortably do half that, chances are you will get a good yield from more relaxed design rules, and the capability to go more dense when necessary.

Yes, I'd agree with that. I think most/all of the high end machines from T-Tech and LPKF advertise 4 mil trace capability, even on old machines like my 7000S from the mid 1990s. But I think it is worth mentioning that things get very expensive very quickly if an attempt is made to mill using a 4 or 5 mil end mill to get a tiny trace and width across loads of address and data lines on a large and complex CPU design for example. You might end up using three tools to finish the PCB.

Yes, this is true. Small bits can get expensive.

The price of the 4 mil end mills (eg $320 for 10) is nearly three times that of a 31mil end mill and about double the cost of a 15 mil end mill from T-Tech and these tiny 4 mil end mills have a much reduced life. Things get much worse on materials like Rogers 4003C or 4350 if you use fine end mills because the wear rate is much higher still. I think the top grade LPKF tools are even more expensive but at my place of work this isn't an issue. We just buy what we need. The bonus for me is that I can salvage the part worn tools from work for free so I rarely buy new tools here at home. I think the LPKF tool timer is very aggressive so I often get tools with loads of life left in them and I get them at a rate that far exceeds my usage at home. The only tools I won't salvage are drills and contour routers. I always buy these new and they are generally quite cheap anyway.

Whoa! Our bits won't cost that much. I'm not saying they're cheap, but there's a significant difference. I'm estimating we're going to retail the 3.9-mil for less than 200 USD for 10, certainly no more than 230 USD. The reason I don't have a firm price yet is because I'm waiting on one of my manufacturers to quote me (I work with several). I do have solid pricing for the 5-mil ones. A 10-pack of those will be 185 USD. 31% cheaper than their 6-mil 10-pack.

[rocco]

Thats quite impressive Rocco, given the price of the machine. nice work.

Thank you!

[rocco]

The other thing is that it's worth trying to find the optimal spindle motor spin speed and tool travel speed for each type of board material and tool type.

Yes, that info is coded into ProCAM. You just select the bit you're using from the drop-down menu. You don't have to manually punch in any feeds/speeds.
If you're curious, here are the current parameters:
Square profile
7-mil: 20 IPM (inches/minute)
10-mil: 40 IPM
30-mil: 150 IPM

15 deg. fluted profile (these last significantly longer than the above and go much faster given their size).
3.9-mil: 7 IPM
5-mil: 40 IPM
7-mil: 85 IPM (this is what you see in the video)

60 deg. and 90 deg. engraver
13 IPM - slowest but cheapest. 120 USD for 10. Last longest. Bottoms out at 8-mil space though.

T-Tech gave me this data many years ago although I was scared away by the very high tool travel speeds they were suggesting. A case of my ignorance of what is OK against what seems 'not OK' when you watch the machine going that fast. So I tend to run my machine slower. Also it's worth having a fast/variable motor speed. One limitation of my old machine is that it is stuck at 23k rpm max.

Just one tip if I may - and this might not be your problem but make sure you're not going too slow in terms of feed rate, because there comes a point where you're not creating chips with each rotation and instead rubbing (burnishing) the end mill teeth wearing them down faster. This could cause you to break bits at a higher frequency than if you went to a higher feed rate.

Also, if you want to produce some nice marketing samples then try doing some pretty looking RF filters on Rogers 4003C as it looks very professional once milled. The white substrate against the clean copper looks great especially if the cuts are clean. I often feel a bit sad when soldering parts to the board because it spoils the beauty of a freshly milled board on 4003C

I did this with Rogers 4350 to show a client! It does look pretty. It was all done with the 3.9-mil bit. I wish I could show it, but it's covered under NDA. If you have some small designs you don't mind me milling and posting pictures of on here, you can message me or get in touch through the contact form at www.zippyrobotics.com and I'll do a test. Probably have to wait a week or so because I'm super busy with package testing right now, but I'd get to it. I would need Gerbers or preferably the project file so I can tweak the Gerber output if necessary.

[nctnico]

Who's mixing accuracy and minimum clearance? You're saying that the recommended clearance isn't really the minimum. That's fine, it's good to get creative if you have to. I truly applaud it. There are reasons to do use a larger bit and not to obey recommended footprints, like faster milling speed and cheaper bits. But I know you're not asking me to apologize for making a more capable tool that has the ability to do fine trace and space if you need it. It's not like I'm charging more money for it! Right?? It's only an option, there if you need it.

No need to get upset. A big part of running is business is managing the customer's expectations. Ofcourse you are proud of what you have made (as an engineer with appreciation for mechanical stuff I think you should be) but IMHO you are way too focussed on the narrow clearances which will lead to dissapointed customers because of the high wear on milling bits and slow speed. Customers really don't care that you devoted a lot of time and effort in getting it the way it is especially if the machine is slow and eating tools. This is probably one of the things LPKF has done wrong so don't repeat that mistake. A better approach would be to paint a more balanced picture where potential customers can get a good feel on the tradeoffs between speed, tool wear and minimum clearances.

[rocco]

Who's mixing accuracy and minimum clearance? You're saying that the recommended clearance isn't really the minimum. That's fine, it's good to get creative if you have to. I truly applaud it. There are reasons to do use a larger bit and not to obey recommended footprints, like faster milling speed and cheaper bits. But I know you're not asking me to apologize for making a more capable tool that has the ability to do fine trace and space if you need it. It's not like I'm charging more money for it! Right?? It's only an option, there if you need it.

No need to get upset. A big part of running is business is managing the customer's expectations. Ofcourse you are proud of what you have made (as an engineer with appreciation for mechanical stuff I think you should be) but IMHO you are way too focussed on the narrow clearances which will lead to dissapointed customers because of the high wear on milling bits and slow speed. Customers really don't care that you devoted a lot of time and effort in getting it the way it is especially if the machine is slow and eating tools. This is probably one of the things LPKF has done wrong so don't repeat that mistake.

  Not upset - the exclamation point was just to emphasize my point... which is that it's there if you need it, unlike some other machines. I didn't think I was really focused on the narrow clearances... the pictures were just a response to the poster who was skeptical (and rightfully so) of the 5-mil spaces and the discussion went from there. I just wanted to make clear that it can absolutely do it.

A better approach would be to paint a more balanced picture where potential customers can get a good feel on the tradeoffs between speed, tool wear and minimum clearances.

I think you make a good point here about familiarizing potential users with the machine and what to expect. Thank you for that. The way I see it, it will take time to educate the market. What I had in mind was to post a series of videos as often as I can (maybe once a week) to show Prometheus making different boards. Now that you mentioned the expectation part of it, I'll keep it in mind to show the slower bits and things to give people a full picture. A full picture is something that will just take time to convey though, I think.

[rocco]

Customers really don't care that you devoted a lot of time and effort in getting it the way it is especially if the machine is slow and eating tools. This is probably one of the things LPKF has done wrong so don't repeat that mistake. A better approach would be to paint a more balanced picture where potential customers can get a good feel on the tradeoffs between speed, tool wear and minimum clearances.

Ok, now that you made me think of this, another idea is that when I do these videos I can keep making copies of the board being demoed until the bit breaks this way I can assign a bit depreciation cost to each of the boards I demo. That will probably give people the best sense of what to expect if they see a variety of boards. 

[Mechatrommer]

Thats quite impressive Rocco, given the price of the machine. nice work.

yup +1.

I'm happy to share pictures of the 5-mil isolation! Here are two (which you can also view on www.zippyrobotics.com):

impressive compared to my $200 machine + the blunt mill (scratching) tip . you have very rigid and low runout machine there, well worth the price imho. but well i rarely needs that thin trace i only expect 1.27mm pitch soic and will limit myself to that since smaller pitch i will have trouble hand soldering even on the masked board. smaller pitch board should be solder pasted and baked for proper result anyway, more $$$ for another machine. precise machine like this the user will have a peace of mind and confidence in doing slightly larger tolerance. you've proven that.

[rocco]

Thats quite impressive Rocco, given the price of the machine. nice work.

yup +1.

I'm happy to share pictures of the 5-mil isolation! Here are two (which you can also view on www.zippyrobotics.com):

impressive compared to my $200 machine + the blunt mill (scratching) tip . you have very rigid and low runout machine there, well worth the price imho. but well i rarely needs that thin trace i only expect 1.27mm pitch soic and will limit myself to that since smaller pitch i will have trouble hand soldering even on the masked board. smaller pitch board should be solder pasted and baked for proper result anyway, more $$$ for another machine. precise machine like this the user will have a peace of mind and confidence in doing slightly larger tolerance. you've proven that.

Thanks, Mechatrommer!