Countersink for acrylic

[Joe Pelonio]

I've discovered that we can countersink installation screw holes on acrylic
with the laser. Someone else may have done this before but I don't remember it.

I'm using 1/4" frosted. For each hole, I'm engraving at 400 dpi, speed 5 100% power. The solid black circles are just a hair larger diameter than the flat screw heads. I combine this with a vector cut just larger than the screw shaft, so it drops in loosely so tightening will not crack it. Doesn't have the nice taper you get from a countersink bit in the drill press, but if you have to cut out the acrylic anyway it's only a few minutes longer on the laser, and the screws are nice and flush. No mess, accurate placement, and you can work on other things instead of standing at the bench with the drill press.

[Phil Garcia]

Great idea Joe, thanks for the tip. I'll have to try it.

[Frank Corker]

Looks good Joe, certainly a better all around finish than just a hole. I suppose you could always do a contour inwards in shades of grey and engrave it although it would be time consuming.

[Darren Null]

3D or rubber stamp (if you can ajust the ramp) would get you your taper.

[Doug Griffith]

This reminds me... A while ago, I experimented with lasering a radiused edge. It came out pretty good in acrylic with a 1/8" radius but the surface showed the resolution "dots" at close view. What I did was offset 16 vector paths and applied different color map settings to each. I then etched a greyscale gradated bitmap over the top to smooth it out. I never tried defocusing the etch but that might have smoothed it out better.

I'll dig up the settings and post a pic when I find what I did.

Cheers,
Doug

[art baylor]

Using tapered head screws is asking for trouble (cracking) . Allow .060 per foot for expansion and contraction. You can fudge it if it will only be indoors.

Art

[Joe Pelonio]

Yes, these are for indoors, I make the holes large enough for the screws to remain free and when I install I am careful not to tighten too much. Being 1/4" thick it's not as likely to crack as 1/8". I also use ds foam tape on the back first which helps.