In article ,
Ignoramus24760 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?

Hmm. Good point. The chip shield on my lathe is none the worse for wear
either.

I may be mixing polycarb up with acrylic. Unless the heat of machining allows
the oil to get deeper into the material.

I did a little looking:
http://www.practicalmachinist.com/vb...arbonate-19645
9/.

It is the acrylic that is so oil sensitive. But still, water is the best
coolant.


Joe Gwinn