PWNCNC Spindle Speed Inconsistent with Masso

Good Afternoon,

I have an Elite Foreman running a 2.2kw 220V 80mm PWNCNC Spindle.

Over the weekend I was working on a few projects and for about the first 2 or 3 hours everything was going just fine. Randomly a few hours in the spindle speed starting fluctuating. Masso was calling for 14000rpms and it would ramp up to 14000 briefly but would then fluctuate from 5000 to 14000 it did not make a difference whether it was cutting or just spinning freely. I originally thought that it might be a power issue. I checked voltages from the panel and all was within spec. The material, bit, and feed speeds were unchanged between the projects so I was pretty sure I wasn’t overloading the motor. Only running an 1/8" bit @ .1 depth passes cutting zebra wood. VFD was in Auto mode as it has been since it was setup in November. When I switched the VFD to Manual mode and set the RPM to 14000 it ran consistently as always. This makes me think it is something in the Masso sending mixed/incorrect signals to the VFD. Any way to check this? Anyone else had an issue like this?

I have the same exact setup.
On the Masso G3:

With G3 on and 1F homed:

Do the measurements following for each of the below circumstances:

  1. VFD Cable Disconnected from VFD
  2. VFD Cable Connected VFD Off
  3. VFD Cable Connected VFD on (Spindle will run, put in safe positionm

Ensure Speed set to zero:
Measure Spindle 1 terminal to GND to the left of it: Should read about .5mv dc
Set spindle speed to 14000:Measure again : Should be 5.89vdc
Set spindle speed to 24000: Measure again: Shoudl be 10.1vdc

I did this 5 minutes ago to get you real world readings. Mine is working fine.

If the voltages are close, it is likely a VFD issue (or intermittent MASSO, not likely)
If the voltages are off, especially with cable disconnected it is likely MASSO
If voltages are close cable disconnected but off when connected, it is likely the VFD.
There are other possible variations but these are the big ones.

This seems consistent from your post, so these steps should point you in the right direction.
Interconnecting wiring is always the most likely problem, especially if you have connectors.


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Thanks for the info. I will give this a try when I get home tomorrow evening and post what I find.