How to cut square/triangle holes in ABS project boxes

Step 3 Setting up the plastic

To set up the plastic you will need to score in using a stanley knife or other sharp implement the shape to be cut. If the plastic is too small to plot out the square using a ruler and knife you can print the diagram on a sheet of paper to size, tape it to the box in the right place and then drill out the corners and if you can do it score out the lines through the paper mask.

I actually recommend using a very small diameter drill bit to drill out markers for the corners.

Once you have the shape in the plastic fire up the gascat with the new tip. You will need to practice quite a few times. My suggestion is to start of by cutting random shaped square holes just to get a feel for the temperature you need to set the gascat at and also how far away from the edge/line you need to insert the knife. The thinner you can get your blade the better - even thinner than the one shown in the image. If the tip is too thick then a lot of excess plastic will bubble up which will need sanding away at a later point.

The knife should go through the plastic like a knife through butter so be carefull how much pressure you apply - several times in my first attempt then knife went through too far!

Another point is make sure you keep the flat unground side towards your line - this will result in a smoother/straighter line. Unless of course your grinding is perfect :)

After the hole is made you will need to do some small amount of sanding to get any plastic which has bubbled down smooth.

WARNING - make sure you do this in a well ventilated place - the fumes are toxic and can be harmful if too much is inhaled.

To make the hole look even better cut out a small rubber sleeve for the hole. Get a peice of thin rubber material and cut out a square slightly larger than your hole ( this will cover any imperfections). Then cut out the centre so whatever it is which want to poke through can. I use this method for holes for cat5 keystones. I actually cut out the centre of the rubber square in such a way that it leaves a small sleeve around the keystone. ( More on this in another instructable! )

I am still experimenting with mine attempting to get the perfect finish but it still seems to be the fastest way to cut plastic. The gascat has been a boon in more than one way for me - a decent temperature controllable soldering iron and a way to cut plastic.

I have a few Gascats for sale at my ebay store.
http://stores.ebay.co.uk/Electronic-Widgets-Inc

Comments

[tilmen]

Hello, once I've seen this image in the net.Maybe it helps.

[GTechno13]

I've also been looking for a good solution for square holes. Something just occurred to me. What if a square (hollow center) hot air rework nozzle was sharpened at the (inner) edges and was heated up and pressed through the plastic. The square would need to be the exact size or smaller than the desired hole. A method of quickly removing the nozzle may be needed so air isn't trying to blow onto the center of the hole as rework air cannot be immediately stopped.
I'm in the market for a rework machine so this may be interesting to try.

Also
It would be nice if there were some pictures of the actual box being cut.

[AlphA303]

Thanks for the post! This is way better than my technique of drilling big gross holes and filing them into the shapes I need.