What I meant by "not works" is that my mill is not working with those parameters and no other changes. The tormachspindle routine has other params that may or may not be screwing this up, and I'm going by guesswork here. These are pretty much those from the Tormach HAL. Is there any known public documentation of tormachspindle?
The 25KHz max figure is right from the documentation of the C11 BoB. Scott may be correct about PWM but that is wishful thinking since the BoB doesn't have that.