On Mon, 24 Jan 2005 20:27:26 -0500, "Dave in MD"
wrote:

OK, not really metal-related, but I need to machine some acrylic stock and
was wondering what a good coolant or lubricant would be? I've read that 30%
liquid Ivory soap-70% water works, but are there any others to consider?

Thanks,
Dave

Water works well. I dpn't know about the liquid soap. Cold air also
works well. Sharp tools for turning or milling. For drilling stone the
drill edges a bit to prevent grabbing. Most important: DO NOT USE ANY
OIL. NOT EVEN SOLUBLE OIL IN WATER. If oil is used, especially when
drilling holes, the acrylic will crack. It probably won't crack right
away. Sometimes overnight it will. Lots of times it takes a couple
weeks. Sometimes it may even take a couple months. But it will for
sure crack. An example of this is an acrylig pepper mill. All molded
without any drilling usually. But eventually the oil in the pepper
will make it crack. The cracks will usually start where the steel
grinder parts are pinned or screwed to the acrylic.
Eric R Snow,
E T Precision Machine