Cut Holes in Acrylic Overlay

[eyal8r]

Hey guys-
Am getting ready to cut holes in the CP. I bought some high impact acrylic at Lowes tonight ($14 OUCH!). I also bought a spade bit for the buttons and a regular hole saw for the tbs. 

Question-  I'm worried about the spade bit and hole saw splitting/chipping/breaking the acrylic overlay. It says it's high impact, but it's only 0.80" thick, and I've easily split this stuff before drilling holes. I know I can tape the holes with Duct Tape and cut the holes slow, but, I'm still worried about it. Mainly worried about the Spade bit doing it- should I go back and get the hole saw instead of the spade bit?  Or, will the spade bit be ok?  Any insights?
Thanks!
D

[GGKoul]

Make sure the acrylic is sercure and there's no chatter when you drill.  Also, don't push hard when drilling.

[Pacific Ripper]

The hole saw works much better than a spade bit. The spade has a higher chance of cracking the acrylic, and with a hole saw you get a somewhat cleaner cut.

[eyal8r]

Hmmm- that's what I was afraid of. The hole saw was more expensive, but, cheaper than buying another piece of acrylic, that's for sure!

Also- I will tape the areas before I drill, but, should I also sandwich the plastic between boards?  Run the drill in reverse as mentioned in other posts?  Or is some of this not needed?

Thanks for the input...
D

[Pacific Ripper]

Well, I sandwiched mine between boards and I used C clamps so that the acrylic wouldn't move around so much I didn't bother running the drill in reverse. You might still get a gunky build-up of melted acrylic due to the heat caused by the friction but it's easy to clean off and much better than cracking it. By the way, some places like Tap Plastics: http://www.tapplastics.com sell acrylic for a lot cheaper. I bought mine for less than $9.

[Xiaou2]

actually, a spade bit will make a smoother hole.

[eyal8r]

wow- this is great advice!  Maybe I'll go get that hole saw since I don't have a press or guide. I'll let you guys know when it's done. I still don't have the graphics done yet- not even started. In fact, I'm lost for ideas. I might just cheese out and take a pre-made overlay- lol... and to think I got my Master's Degree in Computer Graphics!  LOL!!!  Oh well, time is money, and this is just a fun little project, so design isn't overly important. 

Thanks for all the help guys!
D

[teef two]

I sandwiched mine between the control panel and a bit of scrap plywood. Freehand drill using a spade bit and it worked perfectly. No cracking whatsoever. If you have a steady hand you really dont need a drill press.

Test on a bit of scrap to make sure.

[PedroSilva]

Hi,

I've used a spade bit also ... I think that the holes get to be much more smother then if you use hole saw ...

How I did it:

- Drill the acrylic attached to a piece of wood, preferable with the same size of the CP / plexi (no need to sandwish it)
- Do not remove the protective cover ...
- Use high speed (2000 rpm) and drill very very slowly ... this rotation speed will heat a little bit the acrylic and then it comes out as little strips of soft rubber ... the surroundind of the holes look perfectly smooth ...

For the trackball, I used a dremel with the wall cutter bit ...