Countersinks in 1/2" acrylic?

[Jay Maiers]

Here's an easy one for somebody...
I've got a bit of 1/2" acrylic to cut. I need to add several holes and countersink them for #8 & #10 machine screws.
I'm working on a Multicam CNC and I have 1/4, 3/8, and 1/2" collets. I'm looking for a countersink only; not a drill / countersink combo.

Who produces a quality countersink bit with a shank size to match our collets?
What RPM and plunge speed should I use with this bit and the acrylic?

Thanks,
Jay M

[Mark Giese]

MSC Direct part number 02463107. MFG is interstate.

Use these daily in a, 1/4" ER25 collet; spindle rpm 10,000 z feed 20, I would test on some scrap to verify your results before using on what is to be finished product. I also find that I need to stay after the tool with compressed air to keep it clear during the countersink operation, as buildup will either mar the top surface, or leave you with a poor quality finish in the countersunk whole, especially with multiple points to countersink. This style of countersink gives you a much cleaner cut in acrylic than the fluted countersinks

[Jay Maiers]

Thanks Mark, I'll put one of these on order this week and see how it goes.

Jay