Hi Dan,
I've done a fair number of Macor parts and I think that flood coolant is mandatory. The material comes off as a very fine powder that gets every where and no doubt causes wear in places that you don't want. Using flood coolant keeps the powder in the liquid and also keeps the temperature of the Macor down.
We used to turn it on a 13" South Bend fitted with a cake pan that I cut up and re soldered with a dogleg in it to fit under the collet nose. It mounted under the Aloris toolpost (sealed with a little putty) and drained through some cheesecloth into a Graymill's self-contained 5 gallon coolant system that was used only for Macor.
In the mill, a flat pan under the vise works well. Just make sure that you clean the vise well afterward.
I guess my point is, you can get by without going to much trouble or expense.
Macor is really bad about breaking as you exit a cut. I try to always keep a backup piece at the end of a cut. If you don't, it will likely chip off a big flake. If a backup can't be used, then be sure to climb cut it.
I found that tapping it was a challenge too. It seemed like the fine powder would wedge between the tap and the Macor when you tried to back the tap out. The tap would jam tight and if you applied more force the part would break! I made it a habit to tap through holes only so I could clean out the powder before removing the tap.
Hope that helps,
Mike
