I’m having a lot of trouble breaking bits, mostly 0.254 mm (0.010") and 0.381 mm (0.015"). These are square end mills, mostly 3 flute Kyocera. I’m cutting exotic hardwoods such as Indian Rosewood, Ebony, Wenge. (The Indian is not nearly as hard as Brazilian, FWIW.) Currently, I’m mostly trying to cut simple slots, up to 1 mm deep, in which to embed powdered stone inlay.
I think I’'m being conservative with parameters; my last trial with a 0.254 mm was:
DoC 0.050 mm
feed 80 mm/min
plunge 15 mm/min
The CC suggested RPM was about half that which seems really low. I’ve read a bit, eonough to understand values can be too low as well as too high. I don’t mind going slow, I’ve got time but some sources state this can result in insufficient chip clearing, overheating and other maladies.
I’m not sure in what part of the process breakage is happening. I may try to video the process, it’s too much to sit and watch carefully enugh for long enough.
(I’ve also had issued cutting mother of pearl but noticed, early on, most of the breakkage there was on the plunge. My thought there was to use high speeds, low plunge rates and a very small DoC. I got somewhat better results but still had some issues.)