Engraving acrylic, which bits

[LJN]

I am new to CNC and I am trying to engrave acrylic. I am doing small letters about .2" tall. I am using a small 'D' type V bit with a .01 tip and 50 deg angle. I have problems with heat build up and gumming up bits. My router will run from 1000 rpm up. I am cutting about .01 deep. I've tried multiple passes, light oil and water for lube. I've tried IPM from 8 to 20.
Still I am not getting 100% good engraving.
Any suggestions would be great.
Larry Naumann

[FatChips]

I like to use ball endmills, 3/64" is my tool of choice.
I typicaly engrave at 6000rpm and about 5-10ipm going about .005" deep.


I also use air to cool my parts.

[elogicca]

Either change to cast acrylic or use air to cool, i cut cast without any meltiing at .25 per pass and extruded at .125 per pass with air, no melting. spindle speed of 8000, about 40ipm

[big_mak]

Used a 1/16" ballnose endmill @8000 RPM

[Bob Shaw]

Larry,

I'm doing drag engraving of acrylic. No rotation = no heat.

I have posted a video here:

http://www.cnczone.com/forums/showthread.php?t=104920

The first part of the first video shows my first acrylic test.

Cheers,

Bob.