View Full Version : Mach 2/3 with VFD setup

10-13-2005, 09:49 AM
I am using a VFD to control my spindle. Using a 10V analog output board, and step/dir setup only (no PWM) in Mach.

I am struggling to get the acceleration of the spindle to a reasonable rate. Takes 5-6 seconds to wind up to 2000 rpm.

Any ideas here on setups? I have tried all kinds of different motor tuning parameters, and can't seem to make any progress.


10-13-2005, 09:53 AM
Does the VFD have Auto-tuning? There is usually a parameter for accel & decel rate.
If you shorten the decel too much you can run into a overvoltage situation which may require a braking resistor.

10-13-2005, 11:01 AM
How many horsepower is your motor?

How stiff is the spindle to turn, ie., does it spin up easily by finger and coast for 10 seconds, or does it take a wrench to turn it?

10-13-2005, 12:14 PM
The VFD is a KB 2hp. I have it set for external control by the 10VDC signal. When I run it off the VFD keypad - all is good. I can set it for 2.5s accel/decel and it runs right up nice.

After lunch here I will put the scope on the spindle step signal and see how quickly it is reacting to a spindle speed change. I have a strong feeling it is something I am setting up wrong in Mach motor tuning or something. Its either Mach or the spindle speed board - since when I look at the 10VDC analog out of the spindle speed board it also comes up to 10V very very slowly.