Author Topic: material/rpm chart print out for VFD drill press?  (Read 1176 times)

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Offline coppercone2

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material/rpm chart print out for VFD drill press?
« on: April 10, 2022, 05:59:15 pm »
So I thought to upgrade my old drill press with VFD and a nice new chuck, and I was wondering if there is a good compact table that I can print out and physically stick on the drill press so I know what settings to use for what material.

Kind of like the proxxon micro mill has a table on the side which tells you material/cutter diameter and RPM with a checkbox.

I work on ALOT of different stuff (often grabbing it from shelves and repurposing scrap/old stuff).. and speed is very important to me. I was worried that if I just install a VFD on it, I will be stuck 'hitting the books' on how to drill stuff too much. I kind of wanted something small that I can glance at and would give me decent settings to use.

Does anyone have a favorite accurate table of this kind to enable me to do this project with confidence? I thought sticking a lamination on top of the drill press for obvious materials and for weird materials to hide it in the area with the belt system (on top of the belt enclosure lid). (i.e. aluminum, steel, common plastics on top and 'extras' like titanium, carbon fiber, copper, etc on the inside of the lid since those are kind of rare). Also not sure how much of a range of configuration changes there would be required for different kinds of woods.

Does anyone have shop success with this kind of setup ?


And, is there a really BIG comprehensive table that factors into account things like tip angle, rake angle, etc of drills, that can be put into a 'drill bible' laminated binder? (this would not be primary use because my shop gets trashed with grinder dust and oil in short order). I need like cliff notes that allow for rapid work because I get hung up by stuff too much and it slows down progress.
« Last Edit: April 10, 2022, 06:05:40 pm by coppercone2 »
 

Online geggi1

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Re: material/rpm chart print out for VFD drill press?
« Reply #1 on: April 10, 2022, 06:10:46 pm »
If the drillpress is a geared unit you must take the gear ratio in to account.
Basically you take the RPM of the motor and dived this on the gear ratio.
 

Offline coppercone2

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Re: material/rpm chart print out for VFD drill press?
« Reply #2 on: April 10, 2022, 06:13:33 pm »
Yeah I would need to verify how VFD setting adapts to drill. Is there a sensor that I could put a small magnet on the chuck or something and use a sensor to discipline RPM?
 

Offline mc172

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Re: material/rpm chart print out for VFD drill press?
« Reply #3 on: April 10, 2022, 06:31:24 pm »
Why is the spindle speed so important to you? It's not that critical.

I just calculate it each time and because I've done it so many times I've remembered certain cutting speeds for a handful of common materials. You only really need to remember three or four - steel, stainless, aluminium and maybe brass.

The formula is easy, it's the cutting speed in mm/min divided by the circumference of the moving part. The output is in RPM.
A working example: drilling a 10mm hole into stainless steel.
Cutting speed approx. 30 m/min = 30,000 mm/min.
Drill diameter = 10 mm
Speed = 955 RPM

But remember this is a maximum and you don't need to get the spindle anally close to that speed. Half that speed will still do the job.
You will also get an intuitive feel for it as time goes on. You won't need to calculate it each time as you'll get a feel for where the ballpark is.
With small diameter drill bits in soft metals like brass and aluminium, the equation will output speeds that you won't be able to achieve, like 10k RPM. Just run as fast as you can. If your pillar drill makes a racket at that speed, which it probably will, it's fine to go even slower than that.

Regarding rake angle and all that, just use good quality general purpose HSS drill bits like Dormer or Guehring. It doesn't need to be that complicated. It's totally impractical unless you're in a production enviroment to stock all those different grinds and absolutely bonkers if you're considering regrinding drills on a per material basis.
« Last Edit: April 10, 2022, 09:12:40 pm by mc172 »
 

Offline TimFox

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Re: material/rpm chart print out for VFD drill press?
« Reply #4 on: April 10, 2022, 06:31:50 pm »
With "regular" drill presses (multiple pulley diameters), the drill speed charts (simple or complicated) always refer to the rpms at the chuck, usually specifying the discrete set of rpms with four or more configurations of the drive belt on the pulleys.  I assume your VFD drive has a fixed ratio from motor rpm to chuck rpm.
For "really big" charts of cutting speed, you probably want a copy of the "Machinery's Handbook".  A free pdf of the 29th edition is at  https://engineeringbookspdf.com/machinerys-handbook-29th-edition-pdf-free-download/5424/
Using Adobe Viewer, you could print out only the pages you need.  (The current edition, from 2020, is the 31st edition, and costs about $120 in print or electronic form.  Used previous editions are easily found.)
 

Offline Domagoj T

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Re: material/rpm chart print out for VFD drill press?
« Reply #5 on: April 10, 2022, 08:23:39 pm »
Unless you can also control feed (which I doubt you can on a drill press), it really doesn't matter all that much.
Wood - fast
Steel - slowish
Aluminium - fast if you have coolant (flood/mist/air, whatever as long as you're getting rid of the chips)
Brass - fast, but use a drill bit set ground specifically for brass, that's much more important than feeds and speeds (you can easily modify a regular drill for steel)
Stainless - slow, but keep that feed going
PCB - as fast as it will go

Big drill - slower
Small drill - faster
 
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Online jpanhalt

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Re: material/rpm chart print out for VFD drill press?
« Reply #6 on: April 10, 2022, 08:30:10 pm »
Good to hear something reasonable.  It seems you must have used a drill press a few times.  I would add that for some metals, like aluminum, there are big differences between alloys, coolants, and whether your cutter is HSS or carbide.
 

Offline BrokenYugo

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Re: material/rpm chart print out for VFD drill press?
« Reply #7 on: April 10, 2022, 08:52:10 pm »
Unless you can also control feed (which I doubt you can on a drill press), it really doesn't matter all that much.
Wood - fast
Steel - slowish
Aluminium - fast if you have coolant (flood/mist/air, whatever as long as you're getting rid of the chips)
Brass - fast, but use a drill bit set ground specifically for brass, that's much more important than feeds and speeds (you can easily modify a regular drill for steel)
Stainless - slow, but keep that feed going
PCB - as fast as it will go

Big drill - slower
Small drill - faster

This, it simply isn't that critical without full control of the speed/feed, and even then slower usually just works slower. With a manual feed it's all fairly subjective. Sounds terrible? slow it down. Burned the edge off the HSS drill? Regrind the drill and slow it down. Drill coming out colored from heat? Slow it down. Have a lot of holes to drill? Speed it up until you see signs of trouble, then back off a bit. Of course you get into odd cases like grabby or work hardening materials, which require their own approaches, but as a rule of thumb you just eyeball it outside a production environment.

The big benefit I see with a VFD on a small drill press is more about the crawl/jog and reverse for power tapping.
 

Offline coppercone2

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Re: material/rpm chart print out for VFD drill press?
« Reply #8 on: April 10, 2022, 10:29:19 pm »
Well, I was never sure how big this table would be, that's why I was kinda hoping that someone had something that was generalized to manual drilling machines with variable speed control, based on typical operator performance or something. (there are some really fancy drill presses out there, I thought maybe some manufacturer had made this kind of table or it was a popular standard of some kind.

That's why I thought the existing information that I am aware of is not going to be useful because of the down pressure element. But I thought maybe someone knew about a manufacturer that happened to have a chart or something because they did some kind of large scale research on a population group to have 'general' settings that are a good point to start for a manual operator....


Like what I am saying maybe some one saw an attempt by a manufacturer to provide this information.. like I know you have some drill press that have continuously adjustable RPM rather then the typical belts on pullies, they might have bothered to try to dial in some specific numbers along a best fit line or something.
« Last Edit: April 10, 2022, 10:35:00 pm by coppercone2 »
 

Offline Domagoj T

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Re: material/rpm chart print out for VFD drill press?
« Reply #9 on: April 11, 2022, 02:01:17 pm »
This seems reasonable, it assumes usage of HSS drill bits (I wouldn't use carbide on a drill press unless it's very rigid and has good workholding, other than for PCBs which are very abrasive and will eat away the HSS):
https://wiki.ideashop.iit.edu/images/f/f7/DrillPressRPMs.png

It lacks data for stainless, but you can eyeball it to about 20% - 40% of steel data.
jpanhalt raised a good point. There are different alloys of the "same" material that behave very differently. Most stainless steel alloys like to work harden and going slow (slow feed) will not work. You must be a bit aggressive and not allow the bit to rub because that will produce a very hard surface that you'll have trouble penetrating later on. Also dull bits are just not gonna cut it.

This chart is more aimed at CNC machining but might also help you.
https://lfptools.com/wp-content/uploads/2019/10/HSS-Drill-Feeds-Speeds.pdf
Keep in mind that "Speed SFM" is not RPM, it's surface speed in feet per minute, aka cutting speed.

All this being said, VFD is nice and all, but if you plan on drilling a lot of big holes in steel, it might be better to keep the belt and pulley system since it provides the torque at low RPM, which VFD might struggle with.
 
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Offline Gregg

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Re: material/rpm chart print out for VFD drill press?
« Reply #10 on: April 11, 2022, 08:32:57 pm »
Get a copy of Machinery's Handbook; it has answers to everything you are asking.  They are readily available on ebay used and you don't need the latest edition.
 

Online jpanhalt

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Re: material/rpm chart print out for VFD drill press?
« Reply #11 on: April 11, 2022, 08:56:48 pm »
Get a copy of Machinery's Handbook; it has answers to everything you are asking.  They are readily available on ebay used and you don't need the latest edition.

Exactly.  I have 3 copies.  Two in paper form and one on CD.  I never look at the one on CD.  But, I designed a hangar door 18' high by 50' wide using one of the paper versions, and it has withstood almost 40 years of Minnesota thunderstorms.  Adjacent hangers have not been so lucky. (attached)
 

Offline coppercone2

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Re: material/rpm chart print out for VFD drill press?
« Reply #12 on: April 11, 2022, 08:59:58 pm »
Get a copy of Machinery's Handbook; it has answers to everything you are asking.  They are readily available on ebay used and you don't need the latest edition.

Does this book have information that 'accounts' for the variation in hand pressure to choose optimum numbers or does it assume a power feed? I don't have a power feed. I thought machinerys handbook was for equipment that is totally mechanized. I figure you might need to fudge the numbers a little to account for the average operator.

Not sure how reasonable a power feed modification would be, It does look like I can add a motor to the drill press quill (on the side opposite of where I have the handles, since you can setup right/left handed operation by deciding where to screw in the grip rods.. it does look like I could thread a left handed thread there (after boring a hole) to add a attachment point for a motor... not sure how well that kinda mod would work out or what kinda motor I would need. That would be some kind of torque control? Can it even be done without a strain gauge in the quill or something like this to actually measure tool pressure? I assume this would need a specific motor, a motor controller, some kind of gear box and also a feedback sensor. But I have heard of robotic arms that measure motor current to regulate pressure finely. The easiest solution for me to understand (maybe its not practical) would be to drive a linear gear with a hydraulic cylinder so that it rotates a gear fixed to the quill and measure cylinder pressure, and vary the RPM of the hydraulic motor to control pressure on the cylinder.

The tables posted seem like a reasonable starting point because it looks like they had a hand operated drill press in mind when making those tables.
« Last Edit: April 11, 2022, 09:07:35 pm by coppercone2 »
 

Online jpanhalt

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Re: material/rpm chart print out for VFD drill press?
« Reply #13 on: April 11, 2022, 09:44:37 pm »
So far as I know, Machinery's Manual gives speeds and feeds.  The feeds is up to you.  All it takes is a little "feel."
 

Offline BrokenYugo

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Re: material/rpm chart print out for VFD drill press?
« Reply #14 on: April 11, 2022, 10:14:25 pm »
Power feed drill presses are generally geared to the spindle to provide a selection of feeds in thou per rev.

Now I'm curious enough I'll check my old WW2 era copy of Machinery's, if such data exists it's probably in there.

 

Offline mc172

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Re: material/rpm chart print out for VFD drill press?
« Reply #15 on: April 12, 2022, 04:40:32 pm »
Get a copy of Machinery's Handbook; it has answers to everything you are asking.  They are readily available on ebay used and you don't need the latest edition.

Does this book have information that 'accounts' for the variation in hand pressure to choose optimum numbers or does it assume a power feed? I don't have a power feed. I thought machinerys handbook was for equipment that is totally mechanized. I figure you might need to fudge the numbers a little to account for the average operator.

Not sure how reasonable a power feed modification would be, It does look like I can add a motor to the drill press quill (on the side opposite of where I have the handles, since you can setup right/left handed operation by deciding where to screw in the grip rods.. it does look like I could thread a left handed thread there (after boring a hole) to add a attachment point for a motor... not sure how well that kinda mod would work out or what kinda motor I would need. That would be some kind of torque control? Can it even be done without a strain gauge in the quill or something like this to actually measure tool pressure? I assume this would need a specific motor, a motor controller, some kind of gear box and also a feedback sensor. But I have heard of robotic arms that measure motor current to regulate pressure finely. The easiest solution for me to understand (maybe its not practical) would be to drive a linear gear with a hydraulic cylinder so that it rotates a gear fixed to the quill and measure cylinder pressure, and vary the RPM of the hydraulic motor to control pressure on the cylinder.

The tables posted seem like a reasonable starting point because it looks like they had a hand operated drill press in mind when making those tables.

It's a pillar drill, none of this needs to be worried about. For any drill bit between 1 and 13 mm just turn it on, set it to any speed between about 400 and 1000 RPM, drill your hole and be done with it.
 

Offline BrokenYugo

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Re: material/rpm chart print out for VFD drill press?
« Reply #16 on: April 12, 2022, 07:35:39 pm »
From my 11th edition (1942), though those numbers are more production oriented and the carbon steel drill table below where the numbers are halved is probably closer to reality on a small manual feed drill press.

 
« Last Edit: April 12, 2022, 08:31:17 pm by BrokenYugo »
 

Offline coppercone2

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Re: material/rpm chart print out for VFD drill press?
« Reply #17 on: April 12, 2022, 09:02:42 pm »
Is that pressure table in PSI? I see a scleroscope is some kind of hardness tester. Not sure if the units are whatever is used in a scleroscope?

And a normal point means like one that has a small flat on top?
 

Offline BrokenYugo

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Re: material/rpm chart print out for VFD drill press?
« Reply #18 on: April 12, 2022, 09:35:44 pm »
I read that as downfeed pounds force, standard drill grind with the web in the middle, not split point.
 


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