Instructables

How to drill through acrylic plexiglass the right and wrong way

video How to drill through acrylic plexiglass the right and wrong way
Here is a video on how to properly drill through acrylic plexiglass. First you need to drill a small diameter pilot hole to get started. The gradually go up in drill bit sizes until you reach your desired diameter. If you just drill a pilot hole then jump right to a big size bit you will likely crack the plastic.

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Oziam4 months ago

Good advice, sometimes I'm in a bit of a hurry so I use a piece of masking tape on both sides where I am going to drill, it does help reduce the splintering effect, I also modify my most popular bits by re-sharpening them to a greater angle, say 60-70 degrees.

To avoid chipping, you might want to try a special drillbit for plexiglass.  See http://www.professionalplastics.com/DRILLBIT  You can use these bits on your standard hand drill.
Ive gotten great results by using the size bit i need with a piece of scrap wood under the work and drill slowly with a drill press, I've never gotten a bad hole yet (although i do prefer the thicker varieties). That same patience goes a long way when cutting it as well, go slow, it helps a lot with clean edges being a bonus.
 Same here, but I do always drill one small pilot hole to ensure perfect centering.
thebetatesters (author)  The Ideanator4 years ago
 I'm sure that works really great. This method works best with a portable drill.
Ahh, in that case being slow and methodical would help.
A decent grip also helps.
janw4 years ago
If you want to drill in acrylic without the steps, use special drills for plastics. Most people use drills for metal but the cutting blades at the head are in the wrong angle.

thebetatesters (author)  janw4 years ago
 Where do you get those?
You have to buy them at specialist stores. But I am sure that you can find them at the internet too. look for HSS drills with a cutting angle for plexi.

They look like this. Note the sharp angle of the head and the long stretched spiral.

You have to use them at low speed.
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thebetatesters (author)  janw4 years ago
 Cool thanks for the info!
i0scan4 years ago
 I use standard bits, but I put the drill in reverse and go slower. But this is interesting... I might have to give it a try.
klee27x4 years ago
Much slower speeds and better support are definitely a good idea, if possible. Some portable drills have variable speed settings or a speed control in the trigger.

Failing that, you have 2 other options on sheet plexi, besides a step bit.

On any hole much larger than 1/8", you can drill a 1/8" pilot hole, then route the hole out with a Dremel tool. You can finish the hole, directly, if you have a routing table. Or get the hole pretty close, then finish with a drill bit.

Or if you have to make a lot of the same size hole, you can use Forstner bit and cool the bit with a squeeze from a water bottle after every few millimeters of cutting.
 Use a step bit and fogetabout it...
thebetatesters (author)  mr.incredible4 years ago
 That's a great idea for sure. I don't feel comfortable using one without a drill press because I need the size of the hole to be exact.