probably not too relevant, but where i work we machine parts out of a 2 part compound, probably pretty similar to plaster in terms of hardness and how it would machine. However we machine on a pretty big scale, we use a 20mm ballmill, and occasionally a 25mm endmill. we use a spindle speed of 10500 - 11000, and a feed rate of 18m/min for our final cuts (no more than 3-4mm depth of cut). Any more than that (ie where the goop has pooled and may be 20 or 30mm deep, we have to go a lot slower, about 30% feed. It makes dust like you wouldn't believe! |