TomS: Thanks as always
Its a really old benchmaster, I don't have any sort of oiling system, I just rub the oil onto the ways, when I get a chance should I disassemble, degrease, strub, and reoil the ways until it comes out clean? I just now thought maybe some ground up cast iron from the ways might be providing grit which could be causing the wear (if it is wear) what else could it be?
My cam software also calculates ramping, but I'm in the grey area of what I should be doing, and what the mill is capable of doing, I suppose learning by experimentation is possible but with all the harping about knowing speeds and feeds it seems odd that it completely disregards the depth of cut (!?)
You really need to make sure you are getting oil between the sliding and stationary way surfaces. Instead of a one-shot lube system you can install Gits oilers. These are the spring loaded ball oil ports installed on most machinery where oiling is necessary. You can get them from McMaster-Carr and they don't cost a lot of money. Lack of oil may be contributing to what you are seeing with plunge rates.
Tom S