Cutting cast acrylic

[dewey_dog]

I am cutting a channel for a seal in cast acrylic that needs to have the bottom of the cut machined as good as the sides. I have done tests with several different bits and the best finish has come with a freud 5/16" up spiral (brand new) at 18K and .25 Move speed. If I use more feed speed it chips seen under a 10X loop. It needs to be near perfect due to the high Vacuum that it will be under. Any input would be welcomed. An 0 flute did not work, 1 & 2 flute. Thanks in advance. T

[br928]

I have used an Onsrud Super O in cast acrylic with good results. Seemed to cut like butter. I was using a 65-023. The surface quality you are looking for may be higher than what works for me though. Is this for an O ring?

[dewey_dog]

I believe it is for a flat seal. It has a .6" radius in the inside corners. It is going to under a 8 tor vacuum I was told. This is 1.5" thick acrylic. I have a acceptable finish, was wondering if there was anyone with similar experence that could shed some light.