Novaturn Spindle Sped not steady

[boots]

Novaturn
S/N eo4733
March 1996
Elect. S/N oc00120136
SmartStep 3

Problem:
The spindle speed does not stay a steady rpm, it keeps varying wildly from 400rpm up to 2000 and down to low rpm and back up, rapid changes.
It is worse when using the G96 (constant surface speed control) code.

Is the Encoder going bad?
Or the Tach?

[Steve]

I would measure the Spindle analog out of the control card first If this is steady then it is either the drive encoder or the motor.

It may be a spindle analog fault.