Author Topic: Cutting rectangular openings in project boxes?  (Read 1669 times)

0 Members and 1 Guest are viewing this topic.

Offline elroy

  • Contributor
  • Posts: 21
  • Country: us
Cutting rectangular openings in project boxes?
« on: January 14, 2018, 06:27:42 pm »
When browsing writeups of projects, I'm always impressed by crisp rectangular openings cut in plastic or metal cases for LCD displays or other components.

I used to have a punch tool that would nibble away in a (more or less) straight line. This followed by cleanup with a straight file would result in adequate rectangular openings. (I.e. first I would drill a round hole, then use the nibbler tool to enlarge it to a rectangle, then use the file to clean it up.) But some of the examples I'm seeing online look really, really clean. Is there a slicker way to do this?


 
The following users thanked this post: cdev

Online IanB

  • Super Contributor
  • ***
  • Posts: 8399
  • Country: us
Re: Cutting rectangular openings in project boxes?
« Reply #1 on: January 14, 2018, 06:33:42 pm »
A panel punch, maybe?
I'm not an EE--what am I doing here?
 

Offline Messtechniker

  • Regular Contributor
  • *
  • Posts: 227
  • Country: de
  • Old analog audio hand - No voodoo.
Re: Cutting rectangular openings in project boxes?
« Reply #2 on: January 14, 2018, 06:46:56 pm »
I use a water jet cutter.  8)
Specifically this thing here:
http://www.perndorfer.at/en/products/wss-2d/wss-portal.html :)

OK. A friend of mine close by runs a machining shop so that I can simply hand in dwg files.
His water jet cutter is 6x4 m and accurate  to just under1/10th of a mm.
Capable of cutting through steel 20 cm thick , if needed. A pity they dont't come a bit smaller
(and cheaper).
Agilent 34465A, Hameg HMO1022, R&S HMC 8043, Voltcraft VC 940 and M-Audio Audiophile 192
 

Offline paulca

  • Super Contributor
  • ***
  • Posts: 1645
  • Country: gb
Re: Cutting rectangular openings in project boxes?
« Reply #3 on: January 14, 2018, 08:50:40 pm »
I wonder how much it costs and if the "PCB House" style companies are missing a spot, to have enclosures ordered to spec.

I mean, I have a small fetish for transparent laser cut acrylic cases, I might have to google and find out how much they cost for short runs and what software is needed to design them.
"What could possibly go wrong?"
Current Open Projects:  3 Channel Audio mixer with DAC, BT, pre-amps and h/phone amp, WS281x LED controller Version 2 5V/5A w/Atmega328, FY6600 Power supply, 5A DC Load (Still!)
 

Offline janekm

  • Supporter
  • ****
  • Posts: 469
  • Country: gb
Re: Cutting rectangular openings in project boxes?
« Reply #4 on: January 14, 2018, 08:59:50 pm »
I use a water jet cutter.  8)
Specifically this thing here:
http://www.perndorfer.at/en/products/wss-2d/wss-portal.html :)

OK. A friend of mine close by runs a machining shop so that I can simply hand in dwg files.
His water jet cutter is 6x4 m and accurate  to just under1/10th of a mm.
Capable of cutting through steel 20 cm thick , if needed. A pity they dont't come a bit smaller
(and cheaper).

They do come smaller & cheaper:

But apparently not cost-effective to operate due to the low momentum of the cutting medium needing a lot of material for making small amounts of cuts.
 

Offline ovnr

  • Frequent Contributor
  • **
  • Posts: 657
  • Country: no
  • Lurker
Re: Cutting rectangular openings in project boxes?
« Reply #5 on: January 14, 2018, 09:31:51 pm »
Well, the proper way to do it is with milling machines or routers, to be honest. Waterjets not so much.

I put a small X-Y table (Proxxon; do not buy the absolute cheapest shit) on a cheap shitty drill press, and added CNC control to the X and Y axes. Works a treat if you can put up with the slight peculiarities. I believe there are some fairly inexpensive ($200 and up) CNC routers on eBay, but they're probably also terrible in many exciting ways, and have fairly significant limits in the Z axis.
 

Offline RoGeorge

  • Frequent Contributor
  • **
  • Posts: 723
  • Country: ro
Re: Cutting rectangular openings in project boxes?
« Reply #6 on: January 14, 2018, 09:40:11 pm »
For plastic, also laser cutting.

CNC laser cutters are cheap enough now. Many fab-labs/maker-clubs/enthusiast have one. Also, laser cutting is available as an online service, similar with online 3D printing or PCB houses.

Offline elroy

  • Contributor
  • Posts: 21
  • Country: us
Re: Cutting rectangular openings in project boxes?
« Reply #7 on: January 15, 2018, 03:34:18 am »
Well, the proper way to do it is with milling machines or routers, to be honest. Waterjets not so much.

I have a vertical mini-mill and a router, but am still a little stuck -- how do you get crisp corners with either of them?
 

Online IanB

  • Super Contributor
  • ***
  • Posts: 8399
  • Country: us
Re: Cutting rectangular openings in project boxes?
« Reply #8 on: January 15, 2018, 03:45:08 am »
I have a vertical mini-mill and a router, but am still a little stuck -- how do you get crisp corners with either of them?

Perhaps many connectors or other things that go in the opening might also have rounded corners?
I'm not an EE--what am I doing here?
 

Offline phil from seattle

  • Frequent Contributor
  • **
  • Posts: 379
  • Country: us
Re: Cutting rectangular openings in project boxes?
« Reply #9 on: January 15, 2018, 04:28:04 am »
use the smallest bit you can find and then gently file the corners. 

If you can find or make (3d print) a bezel, that's how you get a good looking package.
 

Offline Cyberdragon

  • Super Contributor
  • ***
  • Posts: 1323
  • Country: us
Re: Cutting rectangular openings in project boxes?
« Reply #10 on: January 15, 2018, 05:08:24 am »
Cut a rough hole then use corner files.
*BZZZZZZAAAAAP*
Voltamort strikes again!
Explodingus - someone who frequently causes accidental explosions
 

Offline cstratton

  • Contributor
  • Posts: 41
  • Country: us
Re: Cutting rectangular openings in project boxes?
« Reply #11 on: January 15, 2018, 06:12:40 am »
I wonder how much it costs and if the "PCB House" style companies are missing a spot, to have enclosures ordered to spec.

Some people simply use the PCB process to make a front panel.  It's not a bad way to commission a small CNC machining job, if FR4 is an acceptable material and you're already familiar with generating files for that process as a result of designing the circuit boards.

Quote
I mean, I have a small fetish for transparent laser cut acrylic cases, I might have to google and find out how much they cost for short runs and what software is needed to design them.

There are of course companies providing this service too, ranging from upload files and money, get express package to more hackerspace like places that will let you take a class and then book time on their machine.

And then there are FDM type 3d printers and increasingly accessible photopolymer machines.

Or in a pinch you use what is on hand at a startup's office by drilling a bunch of holes and wire cuttering the webs between, then pick up a mini hacksaw for $4 at home depot on the way home figuring the smaller blade will work better for that the next time around.
« Last Edit: January 15, 2018, 06:14:34 am by cstratton »
 
The following users thanked this post: nanofrog, cdev

Offline cdev

  • Super Contributor
  • ***
  • Posts: 3278
  • Country: 00
  • I love science, stars, nature and electronics.
Re: Cutting rectangular openings in project boxes?
« Reply #12 on: January 15, 2018, 06:20:31 am »
It seems that I am able to get a fairly good cut with my nibbling tool if I am not thinking too hard about it and the piece of metal I am cutting through is something I have already dismissed in my mind as junk. 

However, I hate to waste money so much that the thought of spending a bit of money on a nice case and then screwing it up is getting in the way of my finishing projects at this point.
"What the large print giveth, the small print taketh away."
 

Online edpalmer42

  • Super Contributor
  • ***
  • Posts: 1297
  • Country: ca
Re: Cutting rectangular openings in project boxes?
« Reply #13 on: January 15, 2018, 06:38:36 am »
They're not cheap, but there are companies that will produce custom front panels.  They give you the software, you design your front panel, pick the material, colors, etc. and they produce it for you.  One company that I've heard of is https://www.frontpanelexpress.com .  No experience or association with them.

Ed
 

Offline cdev

  • Super Contributor
  • ***
  • Posts: 3278
  • Country: 00
  • I love science, stars, nature and electronics.
Re: Cutting rectangular openings in project boxes?
« Reply #14 on: January 15, 2018, 12:01:50 pm »
what about "dremel" style tools? - with aluminum, not steel..
"What the large print giveth, the small print taketh away."
 

Offline cdev

  • Super Contributor
  • ***
  • Posts: 3278
  • Country: 00
  • I love science, stars, nature and electronics.
Re: Cutting rectangular openings in project boxes?
« Reply #15 on: January 15, 2018, 12:21:14 pm »
I recently got a small XY-table also, quite similar to the Proxxon but built a bit more sturdily, but still very similar..  Its one that is also used in milling, I know the table is capable of it. the manufacturer says so.

but Ive only done drilling using it, no lateral cutting yet.

I'd like to try that.. if I can be confident- of its safety by some means of being sure the tool wasn't going to fall out unexpectedly. (???) And only going very slowly as to not cause the bit to become deformed.

What kinds of bits do you use to do that? and how do you keep them in? Do you heat up the drill's part that accepts the chuck's arbor so as to make it expand so it then can contract around the arbor? (I may have the terms backwards here)

First I would like to try that for doing one off on PCBs, especially very simple ones.. cutting lines etc, first.. with a small router bit or something like that.

Cutting holes sideways, I am kind of worried about detachment. The problem is drills are not meant for lateral motion and mills are. On a drill the only thing holding the chuck in is the taper. A mill actually locks the cutting tool in.

Until I'm satisfied enough with my knowledge that Ive figured out a way to eliminate what I see now as significant risk the of drill bit and chuck detaching and falling out, becoming a projectile, I am not so eager to do it.

This is mostly because I still have very little experience with using it in the normal fashion.

Well, the proper way to do it is with milling machines or routers, to be honest. Waterjets not so much.

I put a small X-Y table (Proxxon; do not buy the absolute cheapest shit) on a cheap shitty drill press, and added CNC control to the X and Y axes. Works a treat if you can put up with the slight peculiarities. I believe there are some fairly inexpensive ($200 and up) CNC routers on eBay, but they're probably also terrible in many exciting ways, and have fairly significant limits in the Z axis.
« Last Edit: January 15, 2018, 12:37:42 pm by cdev »
"What the large print giveth, the small print taketh away."
 

Offline Dubbie

  • Supporter
  • ****
  • Posts: 610
Re: Cutting rectangular openings in project boxes?
« Reply #16 on: January 15, 2018, 12:45:50 pm »
cdev,

For endmills (the name of the tools that you use) you need a collet holder to hold the endmill in. These grip the tool very tightly and with high precision. A common type for small machines is an ER16 collet. You use a different size collet of each different size tool that you use. It must match very closely within 1/2 mm to get it nice and concentric.

A jacobs chuck is very wrong for milling. It is not designed to withstand lateral forces nor, to prevent the tool pulling out. Because an endmill is helical, it constantly wants to pull itself out of the holder.
 
The following users thanked this post: cdev

Offline ovnr

  • Frequent Contributor
  • **
  • Posts: 657
  • Country: no
  • Lurker
Re: Cutting rectangular openings in project boxes?
« Reply #17 on: January 15, 2018, 12:51:50 pm »
And only going very slowly as to not cause the bit to become deformed.

What kinds of bits do you use to do that?

You use endmills; there are a breathtaking variety, but if you're cutting straight through the material it's not very critical. Buy cheap ones, because they don't deform - they break. You will break a number of them.


On having the chuck fall off of the taper: I had it happen once, and just jammed it on with a large helping of force. Hasn't come off since. YMMV.

If it does fall off, it'll just drop straight down. You might wreck the workpiece, but it's not going to go chase you across the room.


In my experience, milling soft plastics like ABS works without any fuss whatsoever. Harder plastics like PMMA/plexiglass works fine, but it's noticeably less happy. Aluminium works OK, but it's obviously not thrilled about it. Steel is a no-go.

If you want OK surface finishes, you need to take a roughing cut and leave 0.5-1mm of material, which you then take off in a finishing cut. If you can, avoid angles of engagement (how much of the endmill is actually in contact with the workpiece) higher than 90 degrees; that means slotting right through the material is something to be avoided if you can, but I'll usually just deal with the chattering and complaining.


One last word of warning: You want to clamp your workpiece in properly. You'd be surprised how easily it can come loose, and in the best case you'll ruin the workpiece - worst case it smacks you in the face. Wear safety glasses!
 
The following users thanked this post: cdev

Offline ovnr

  • Frequent Contributor
  • **
  • Posts: 657
  • Country: no
  • Lurker
Re: Cutting rectangular openings in project boxes?
« Reply #18 on: January 15, 2018, 12:53:27 pm »
A jacobs chuck is very wrong for milling. It is not designed to withstand lateral forces nor, to prevent the tool pulling out. Because an endmill is helical, it constantly wants to pull itself out of the holder.


Well, you can't put an endmill holder onto a drill press taper. Yes, chucking endmills is a terribly bad practice, but I do believe the purpose of this thread is "ghetto-machining"; if you actually have a proper milling machine, you probably also know better.
 

Offline cdev

  • Super Contributor
  • ***
  • Posts: 3278
  • Country: 00
  • I love science, stars, nature and electronics.
Re: Cutting rectangular openings in project boxes?
« Reply #19 on: January 15, 2018, 12:54:07 pm »
I do have a very nice Jacobs chuck which is not currently on my cheap drill. I just got the drill also and the chuck it came with is the default one. So suppose I wanted to put a collet holder on there for milling from time to time, what would I buy to do this? Its the cheapest harbor Freight drill, its not a fancy one at all. that said I'm willing to go very slowly. Its just the occasional square hole that i would like to make.. infrequently. Safely.

the milling table is actually ideal for that if I can cross all the ts and dot all the i's so to speak.

Its quite heavy duty for what I paid for it. Its made by the same company that makes the green cheap ones and its also fluorescent green :)

But its their bigger brother..  and its quite substantial.

cdev,

For endmills (the name of the tools that you use) you need a collet holder to hold the endmill in. These grip the tool very tightly and with high precision. A common type for small machines is an ER16 collet. You use a different size collet of each different size tool that you use. It must match very closely within 1/2 mm to get it nice and concentric.

A jacobs chuck is very wrong for milling. It is not designed to withstand lateral forces nor, to prevent the tool pulling out. Because an endmill is helical, it constantly wants to pull itself out of the holder.
"What the large print giveth, the small print taketh away."
 

Offline bson

  • Supporter
  • ****
  • Posts: 970
  • Country: us
Re: Cutting rectangular openings in project boxes?
« Reply #20 on: January 15, 2018, 01:05:42 pm »
I've been eyeing a Carbide 3D Shapeoko (https://shop.carbide3d.com/collections/machines/products/shapeoko3?variant=42721918086) exactly for this purpose - to cut panels out of (opaque, dyed) acrylic.  They use regular trim routers, so won't get super high speeds, but I figure for acrylic or even aluminum prototyping it's fine.  I'd also make or find a hood for it to make cleanup easier, just something I can put over it while it's running to contain the mess and any accidents.
<This space intentionally left blank>
 

Offline cdev

  • Super Contributor
  • ***
  • Posts: 3278
  • Country: 00
  • I love science, stars, nature and electronics.
Re: Cutting rectangular openings in project boxes?
« Reply #21 on: January 15, 2018, 01:19:20 pm »
Here is the X-Y table I have now. This was when I was re-lubricating it with better grease, so it hadn't been used at all yet.

The base fits my drill perfectly.



"What the large print giveth, the small print taketh away."
 

Offline CatalinaWOW

  • Super Contributor
  • ***
  • Posts: 2343
  • Country: us
Re: Cutting rectangular openings in project boxes?
« Reply #22 on: January 15, 2018, 01:36:30 pm »
While panel punches, CNC and other methods are good and widespread, many of those beautiful holes in panels are done by hand.  It is a skill, enhanced by the possession of proper tools.  Much like hand lettering of signs.  Rectangular holes are much easier than lettering signs, and the skill can be developed by most.

I am sure there are other approaches, but mine involves a rough cut undersize hole and then improvement of the hole with successively finer files.  Files with dead edges help a lot.  Different sizes allow access to narrow holes and also do quick work on larger hole sizes.  I am sure you are aware of running the file as close to parallel to the panel as possible.  The quality of the hole depends on how much time and effort I am willing to put into it.  The time to completion drops as your skill improves.  It isn't quick, but not that much slower than doing the programming for a CNC and then getting everything set up on the machine (which is a whole set of skills in itself) and running it.
 
The following users thanked this post: cdev

Offline Dubbie

  • Supporter
  • ****
  • Posts: 610
Re: Cutting rectangular openings in project boxes?
« Reply #23 on: January 15, 2018, 01:53:22 pm »
if you aren't confident in your filing skills, you can cheat a little by clamping a couple of pieces of scrap steel either side of your line you are filing to and using them as a guide/stop. You can get very precise results this way.
 
The following users thanked this post: cdev

Offline elroy

  • Contributor
  • Posts: 21
  • Country: us
Re: Cutting rectangular openings in project boxes?
« Reply #24 on: January 15, 2018, 06:19:27 pm »
Thanks for all the suggestions. In my situation, it sounds as though the best solution would be to use a small end mill to cut openings, and optionally finish off the corners with a hand file. I've got a 3D printer on order, so using it to fabricate either bezels or entire front panels may be an option too.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf