so, mach's cv mode is causing me grief. on my milling machines, which are slow moving, it works great in general, however on my router which is capable of a much higher speed and acceleration im getting very odd effects.
when i set the motor tuning, my system is quite capable of 400ipm and 60 for acceleration. these are conservative safe settings ive been using.
in running a program like a pocket or a circle in exact stop mode, its all fine. in cv mode with all options turned off its usually fine as well.
when i run 3d contouring im seeing my issues. my program for today is about 100000 lines making up a waterline type contour. most of the g1 segments are only a mm long or so, some less. when the program gets to the end of the waterline it wants to transition down to the next. on some levels the transition is very sharp, like 150-170 degrees. its these sports the machine will stall. for any given mach setup or feed rate, the stall will be 100% consistent. also if i interupt these corners with a go retract they are fine.
occasionally it will also stall on the retract out of the part, or a goto zero command from the ui.
yesterday i tried alot of settings, and they all seem to have an effect, but no complete cure. high acceleration doesnt help. lower speed somewhat helps as you might expect, but that gets counter productive in a hurry. i also tried motor settings, pulse timing, various cv options, kernel speeds, etc. they all have an effect of some sort, changing the stall point, but no cure.
the closest thing to fixing it i found was lowering the accelleration to 25, leaving everything else as it was. while it no longer stalls in that program, this made a very audible diagnosis of the issue.
a straight line point to point, and most other transitions are smooth, since the acceleration is now so low, it doesnt jerk the lightweight machine around. on some corners though you still get a hard jerk. these as it turns out are the ones it was prone to stalling at. its almost as if its not decellerating properly, or cant manage to round the corner correctly and overloading the motors if the acceleration was too high.
so the question is why? i have only one theory at the moment hinging on the fact it only fails in complex short segment contouring. the theory is that the rounding radius is actually bigger than the motion segment its trying to round. this could be confusing the look ahead and not giving it time to slow down for the corner. lowering my accelration may not be fixing it at the root, but might be giving my motors enough overhead that they wont stall. when i break the corner with a g0, it would negate the need for rounding, so it doesnt stall.
so anyone every get an issue like this or have any thoughts?