On Sep 3, 1:50*pm, Ignoramus24760 ignoramus24...@NOSPAM.
24760.invalid wrote:
On 2010-09-03, Joseph Gwinn wrote:





In article ,
*Ignoramus24760 wrote:

I have a little project where I want to mill some holes and slots in
1/8" Lexan (polycarbonate).

What is the best way to do it. Really fast feeds, medium speeds, and
lots of coolant?

Clean all the oil from the tools and fixtures, as polycarb will craze form oil. *
(Do not use emulsion coolant either.)

Use lots straight tap water as a coolant. * Go as fast as you can without the
polycarb softening from the heat.

Polycarb can be a bit grabby.

Joe, I have my chip shield made from polycarbonate. It sees plenty of
oil, but does not seem to craze?

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Window-grade stuff has an anti-scratch coating on it, which may slow
things down. Anywhere you've got a hole that's exposed to oil,
though, it'll start cracking eventually. Won't be instantaneous.
Doesn't necessarily have to be mineral-based oil, either, have a look
at how many Stir-Crazies are in the thrift shops without tops,
vegetable oil did them in.

Stan