I believe you are going to have to adjust the output span of the digispeed to get the total span voltage inline with what the controller wants to see to be acuate. But just thinking out loud. YOu are going to have to limit your top rpm through the digispeed to prevent motor failure. (;-)TP

minPWM setting of 0 makes no difference to the spindle revs/control.
I will check out the digispeed manual re your suggestion.

tmsmith

Did you try setting the pulleys to 0 - 5000 ?

Yes I altered the pulley setting to 0 - 5000.
I have also tried the 'Timing' pins in stead of the 'Index' pin.
For this I uncovered the slots (4) on the sensor disk.
I obtained another straight line graph with I think better control..

Timing  gave   revs=1.35(S)- 650 compared with:-
Index            revs=3.0(S)-1000

On the general config window are 2 options that may be related to spindle control (on the right hand side).
Do you know the function of these?

tmsmith

I beleive the problem starts with the fact that you are over driving the voltage on the motor a good bit. THis throws the control span out of wack. So I think you need to reset the digispeed to output 0-5v instead of 0-10v. THis will get you closers to a normal rpm for the motor. you may have to readjust the span a little to get top rpm. this should put your rpm span  closer to normal and should allow Mach to regulate the RPM closer.

(;-) TP

I dont really want to slow the motor down and I am told it is quite happy running at 4200. This is apparently the normal condition for the Minimill, 130 volts and 4200revs max.
Of course the control system is completely different from normal apart from the Lenze534 speed controller which I managed to obtain second hand..
There are some adjustmants on the Lenze which I think I should check out as well, they may be for just this purpose.

I should be able to check the spindle speed using a tacho later in the week so will see the true speed.

tmsmith