HELLO,
I have the CNC Router Parts CRP800 control box driving a 2.2kw Huanyang vfd and spindle.
M3 commands work and the rpms match the VFD and verified with an RPM laser meter.
The problem is that there is a 400 rpm fluctuation up and down which makes the spindle unusable.
If I put the VFD setting back to control it with it's on board panel, the rpm is rock steady and I have used it this way for the past 2 years.
Voltage checked at the VFD with a digital volt meter "appears" to be steady but I'm not sure this is a valid test.
Any help would be greatly appreciated.
Thanks
Art

If you have an analog volt meter or an O-scope it would show the fluctuation better if there are any to be found.
Some digital meters have a bar graph representation of the voltage below the digits and this can be used to see if there any fluctuations. It won't tell you the exact size of them but  if it is bouncing back and forth it means the voltage is too.


Mike

Did you ever figure this out? I have anew Huanyang VFD with an air cooled spindle, and when using the anaolg input for speed control, the rpm will fluctuate by ±1000 rpm, depending on the commanded rpm. At 24,000, it's very steady. But at 12,000-15000, it slowly increase by up to 1000, then will slowly decreases by about 2000rpm, then slowly go back up again. It never seems top stay steady.

This may not be an issue under load, though, as I'm just bench testing it right now.