Centroid Community CNC Support Forum

First, the symptoms. Several months ago I started having several different issues with controlling my CNC. The MPG started responding strangely. Sometimes it would work but with an unreal lag time for updating the display. Other times it would cause an axis to move in a jerking motion in both directions when using the dial to jog. I have found that restarting the computer resolves that issue for a week or so. Around the same time there were a couple instances when I would start a run and the spindle speed would just continue to ramp up until going into fault. It would run fine after stopping and restarting the program. The issue seemed to go away for several months, though the MPG issue has persisted.

Around a week ago the spindle started randomly ramping up and down during a run. Since this was different than the spindle simply ramping up and going into fault, I started with checking the VFD. I tried changing the VFD settings to allow me to control it directly from the unit and not through the VCP. It was unresponsive to direct control. Figuring that the unit was done for I replaced it with a different model.

After getting all of the connections switched to the new VFD I tried controlling it through the VCP. I turned on and ramped up the speed. The VCP buttons worked but the constant ramping up and down randomly was still an issue. The readout on the VFD was set to display frequency and was showing random increases and decreases in step with the motor speed fluctuations.

Then I decided to check the 10v supply from the Acorn board. It too was fluctuating up and down. I disconnected the spindle and ran the spindle voltage bench test. The first voltage failed having fluctuated around the 1.3v to 1.5v range instead of the 1.66v target.

I'm assuming that I'll need a new Acorn unit but I thought that I would check to see if anyone happens to be familiar with the problem and knows a way to fix it.

Thanks

Jim

Based on you comment on the WMPG and the fact that it has spindle override, I would shut the WMPG off when conducting these tests.
It is possible the WMPG is having a problem and commanding the spindle changes.

Jim Klawon wrote: ↑Fri Jan 24, 2025 8:56 am The MPG started responding strangely. Sometimes it would work but with an unreal lag time for updating the display. Other times it would cause an axis to move in a jerking motion in both directions when using the dial to jog. I have found that restarting the computer resolves that issue.

I've also observed this behavior and reported it: https://centroidcncforum.com/viewtopic. ... 132#p93132

It still happens, quite reproducibly, when I leave my whole system on without a daily shutdown. Like you, restarting the computer (in my case a NUC) resolves that problem. Haven't seen any problems with the spindle.

please post a fresh report.zip

grossmsj wrote: ↑Fri Jan 24, 2025 11:40 am

Jim Klawon wrote: ↑Fri Jan 24, 2025 8:56 am The MPG started responding strangely. Sometimes it would work but with an unreal lag time for updating the display. Other times it would cause an axis to move in a jerking motion in both directions when using the dial to jog. I have found that restarting the computer resolves that issue.

I've also observed this behavior and reported it: https://centroidcncforum.com/viewtopic. ... 132#p93132

It still happens, quite reproducibly, when I leave my whole system on without a daily shutdown. Like you, restarting the computer (in my case a NUC) resolves that problem. Haven't seen any problems with the spindle.

hello. are you saying you can reproduce this? if so i'd like to see it, can we remote into your machine?

Yes, it will eventually occur after I've left the machine on for a few days. I just restarted it yesterday so it may be a few days.
The next time this happens I'll leave it alone and give you guys a call so you can remote into it.
It would be helpful for me if someone could PM me a phone number I could call to expedite things.

If it happens after a few days, it sounds like Windows sleeping the USB port and not waking it back up.

tblough wrote: ↑Fri Jan 24, 2025 5:02 pm If it happens after a few days, it sounds like Windows sleeping the USB port and not waking it back up.

yeah! that would be a good place to look, could be windows setting or a bios setting.

I turned off the remote control, removed the dongle, and changed the WMPG setting in the PLC to "none". I then ran the spindle bench test with the spindle disconnected. All 4 voltage readings were within the specified range. (1.66v,3.38v,6.76v,10.13v) I ran the bench test again with the VFD connected. The first reading, measured at the VFD 0-10v input was 1.0v but steady. I entered the previous values so the test would let me move forward. All of the additional measurements were really low and began fluctuating more as the voltage was increased. The final reading, which should have been close to 10.13v, fluctuated between 1.7 -3.4v. It's as if something is drawing current from the Acorn 0-10v supply. To check the VFD, I connected a 9v battery to the 0-10v input. The voltage and current were both steady while the spindle was running.

Here's a current ZIP