On 2010-09-04, Mike Henry wrote:

"Joseph Gwinn" wrote in message
...
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

Igor,

I've milled plenty of acrylic using the Hansterfer S500 coolant that you
have and there has been no crazing in any of it. Some of the parts date
back nearly 3 years and I'd guess that would be enough time for crazing to
become visible..


Mike, I totally love that coolant. It is the best!

Has yours started to rot or stink yet?

i