Boxford TCL , Spindle motor problem

[m_c]

Is the voltage remaining constant under load?

The drive output voltage should remain reasonably constant even under load.
If the output voltage from the drive is dropping, then it's a problem with the drive.
If the output voltage is remaining reasonably constant, then the problem is else where.

[John11668]

So voltage is pretty steady.
With 9,5 v analogue input driver puts out 93v. (Forget readings above I was reading positive to ground. positive to negative is 93v) and this gives me 2000 rpm which is all I expect to use .
At about 5v input I get a spindle speed just over 1000 with output voltage of 55v or so and all very smooth. Clearly getting nowhere near the 170 v which the drive is rated for but I am guessing that would be giving me around 4000 revs. which I think the motor is good for.

At 1000 revs the current is steady about 1.4 increasing to 1.7 or 1.8 under cutting loads , but whereas I used to see a torque boost when i applied a heavier cut there is now a hesitation before it compensates , and if I turn my ramp pot down to where I would expect the spindle to come up to speed in 2 seconds or so, it still seems to take 4/5 seconds to get up to speed.
Still stalls on screwcutting and current goes beyond range of Drive to 3.6 or 3.7
I do believe the problem is in the drive , but I think I may have problems persuading the suppliers