Synth-DIY Yahoo! Groups Archives

help - cutting/routing ABS plastic enclosures

2005-06-10 by David McNab

Hi,

Sorry if this is a bit OT, but it is connected with the overall PCB process.

Now I've got a good PCB, I'm needing to mount it into an ABS plastic
enclosure, whose specs are at:
http://www.industrial-enclosures.com/html/ks019-plastic-enclosures.html

What do people find the best/quickest/easiest way to cut the required
holes in ABS plastic, and get it to a nice finish?

In my situation, I've got:
- 5 cylindrical PCB-mounted push buttons
- 1 PCB-mounted slider switch
- 1 16x2 LCD module connected to the PCB via header pins

All these parts require holes to be cut in the top side of the enclosure.

The pushbutton holes are no big drama - a big drill bit will suffice,
after drilling small pilot holes.

But the LCD window is a large rectangle, and the power switch a small
rectangle.

After spending the best part of an evening cutting the openings by hand
with various drill and router bits, I've ended up with a very rough job
which will take hours to get to a nice finish.

Apart from the considerable expense of sending the cases out to a
laser-cutting shop, are there any ways I can make this cutting process
any easier and get better results?

I'd rather not have to spend more time routing out the enclosure than it
takes to print/etch/populate/solder the PCB.

All suggestions welcome.

--
Cheers
David

Re: [Homebrew_PCBs] help - cutting/routing ABS plastic enclosures

2005-06-10 by Les Newell

Hi David,

Get/make a small CNC router :-). If you shop around it does not cost all
that much to do. Of course you can use it for drilling the boards as well.

The other alternative is to make a jig and use a guide on a router. This
is fine if you are making a number of the same shape holes. You need to
spend some time getting the hole in the jig right but once that is done
you can knock out the holes in less than a minute.

Les

David McNab wrote:

Show quoted textHide quoted text

>
>Apart from the considerable expense of sending the cases out to a
>laser-cutting shop, are there any ways I can make this cutting process
>any easier and get better results?
>
>I'd rather not have to spend more time routing out the enclosure than it
>takes to print/etch/populate/solder the PCB.
>
>All suggestions welcome.
>
>
>

--
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.323 / Virus Database: 267.6.6 - Release Date: 08/06/2005

Re: [Homebrew_PCBs] help - cutting/routing ABS plastic enclosures

2005-06-10 by Stefan Trethan

For the round holes, you want a step or tapered drill:
<http://www.werkzeug-news.de/news4/img/h-ruko-stufenbohrer.jpg>

a tapered drill is just like a cone, without the steps.

The advantage over a big drill bit is the hole will be perfectly round and
need no post-processing, while when using a normal bit it will not be
completely round when you drill big holes in thin material, and there will
be loads of burr. You will like this tool a lot. sizes under 20mm are
reasonably cheap (like under 5eur) but if you go up to like 30mm it
quickly gets expensive.

For square holes, you have several options. the best is avoid whenever
possible ;-)

You can use a punch with a square cutter (might need several applications
to form the hole).

For larger holes i like to use a nibbler:
<http://www.samstagsales.com/Gedore/gd426026t.jpg>

these allow small (2cm or so insertion length) cutouts, in flat material
without deforming it. Ideal for rectangular cutouts. You will still want a
bezel for the dispaly.

the slider switch is a bad choice, you might get a obong punch that is
acceptable. I have yet to find a bench punch i can afford. Also, with most
punches it is not possible to punch a enclosure with side walls, only flat
plates.

Of course, you could also build a CNC drill for your PCBs, and use it to
route the holes.

best is, all round 'cause that is easy with a step drill, and if it isn't
possible (like display) get a bezel for it so you can nibble it out and
hide it.

ST

On Fri, 10 Jun 2005 12:54:01 +0200, David McNab <david@...>
wrote:

Show quoted textHide quoted text

> Hi,
>
> Sorry if this is a bit OT, but it is connected with the overall PCB
> process.
>
> Now I've got a good PCB, I'm needing to mount it into an ABS plastic
> enclosure, whose specs are at:
> http://www.industrial-enclosures.com/html/ks019-plastic-enclosures.html
>
> What do people find the best/quickest/easiest way to cut the required
> holes in ABS plastic, and get it to a nice finish?
>
> In my situation, I've got:
> - 5 cylindrical PCB-mounted push buttons
> - 1 PCB-mounted slider switch
> - 1 16x2 LCD module connected to the PCB via header pins
>
> All these parts require holes to be cut in the top side of the enclosure.
>
> The pushbutton holes are no big drama - a big drill bit will suffice,
> after drilling small pilot holes.
>
> But the LCD window is a large rectangle, and the power switch a small
> rectangle.
>
> After spending the best part of an evening cutting the openings by hand
> with various drill and router bits, I've ended up with a very rough job
> which will take hours to get to a nice finish.
>
> Apart from the considerable expense of sending the cases out to a
> laser-cutting shop, are there any ways I can make this cutting process
> any easier and get better results?
>
> I'd rather not have to spend more time routing out the enclosure than it
> takes to print/etch/populate/solder the PCB.
>
> All suggestions welcome.
>