best method for doing counter sunk holes in cast acrylic

[Graham Taylor]

What is the best method for counter sinking holes in cast acrylic so that you get clean repeatable holes with no fractures?

Is it best to go slowly with a normal wood counter sink bit or can they be laser cut by multiple engraving passes?

I plan on trying both methods but wondered what everyone else does.

[Ross Moshinsky]

Acrylic drill bits really make a difference. I wouldn't recommend you use wood drill bits at all. I've never had the need to counter sink holes in acrylic. I assume there is a bit out there that will do the job.

You could absolutely have the laser do the job. Multiple passes will get you down, but it may be messy and take a long time. A CNC engraver/router would do the job with very favorable results.

[Ian Johnson]

If you can cut the acrylic in a single pass, you can countersink in a single pass as well. Do some tests to see what speed and power you need for the raster pass to get the depth you need. If you need the bottom of the hole to the sloped rather than flat, a drill would be better.

[Michael Hunter]

I've found that the 3-bladed countersinks intended for metal do a good job.
Keep it just for acrylic : using it on wood or metal affects its efficiency on acrylic.

The single blade countersinks also work OK, but because they rub on the material there is a risk of melting the acrylic and making a mess unless you use a lubricant (white spirit/turpentine substitute).

The type which looks like a cone with a hole through it doesn't work well as the cutting edge grabs at the acrylic and causes splintering.
The type with lots of cutting edges are prone to chattering. Also the blades clog quickly.

(I've tried them all over the years)

[Clark Pace]

I've found that the 3-bladed countersinks intended for metal do a good job.
Keep it just for acrylic : using it on wood or metal affects its efficiency on acrylic.

The single blade countersinks also work OK, but because they rub on the material there is a risk of melting the acrylic and making a mess unless you use a lubricant (white spirit/turpentine substitute).

The type which looks like a cone with a hole through it doesn't work well as the cutting edge grabs at the acrylic and causes splintering.
The type with lots of cutting edges are prone to chattering. Also the blades clog quickly.

(I've tried them all over the years)


I do fabrication at my main job as profession, and we use counter sink bits. I work at plastics fab place. And so we work with acrylic and lexan. Yes you can do it with a laser but a counter sink bit will give you a better result. Minus the flame polish finish.

[Clark Pace]

I do fabrication at my main job as profession, and we use counter sink bits. I work at plastics fab place. And so we work with acrylic and lexan. Yes you can do it with a laser but a counter sink bit will give you a better result. Minus the flame polish finish.


Dang with my touch mouse on the laptop would not get in the way. I keep on typing over my words. It makes my spelling look horrible.

[Graham Taylor]

I will call in at B&Q later and get a 3-bladed countersink intended for metal

Thanks for the help guys

[Keith Colson]

Instead of doing a coutersink I do a counterbore using the laser. It can be done in raster or vector mode. The acrylic is already in the laser so its no trouble and means less handling.