Well, using the keyboard to bang the Z up and down I was surprised how lazy it really was!
I had 10% rate set and a max Z of 1300mm/min, Now I have 1500mm/min and upped the THC rate to 20%, It could handle 30% easily but 40% screeched and did nothing so I know I have a bit of slack still from 20 to 30%.
Now, this brings me on to a serious point that is baffling me - I have been bashing the crap out of my Z all morning, hammering it up and down with the keyboard, messing with tuning etc and it has behaved flawlessly all day apart from when being pushed too hard by my setting.
BUT, I put some code on and cut some tests and bugger me if the first time it hit a G00 Z3.8 for the pierce, it just sat and screeched, then next time it did IHS the rapid part of the G28.1 move screeched and was missed then it dropped at the slow rate all the way and carried on as normal.
This appears to be Mach3 not using the acceleration on the G00 move or the G28.1 move - is this a known bug/flaw/defect ??
I really do NOT think it is motor tuning as it has done it before and did not do it once using the keyboard to rapid the hell out of my Z axis.
Any ideas???