[MikeRags]

Hello, looking to get some help with my PCNC1100 series 2. After I have been running for a while under load, maybe 10 minutes, I get an issue where the spindle shuts down in the cut. I have a load meter and it is staying in the green when operating with spikes into yellow in the corners.

After a recent shutdown, I quickly opened the cabinet and the VFD is shut down without power. There is no error code displayed since it is shut down. The stepper motors still operate. Any idea what is going on? Something must be overheating, as I have to let the machine sit for a while before operating again. Thanks for the help.

[tmarks11]

Maybe your C2 contactor is starting to fail, or the spindle door switch is loose?

If the VFD thinks your motor is overheating or drawing too much current, than the VFD will shut down with an error and stay powered up. For the VFD to be powered down, the main controller board must be executing an e-stop, or the contactor is opening for some other reason (spindle door registering as open, loose wires to/from the C2 contactor).

There is troubleshooting guidance on page 202 (current version of the manual).

If the C2 contactor won't shut to restart the spindle until it cools, than I am guessing the C2 contactor is failing.

[MikeRags]

Maybe your C2 contactor is starting to fail, or the spindle door switch is loose?

If the VFD thinks your motor is overheating or drawing too much current, than the VFD will shut down with an error and stay powered up. For the VFD to be powered down, the main controller board must be executing an e-stop, or the contactor is opening for some other reason (spindle door registering as open, loose wires to/from the C2 contactor).

There is troubleshooting guidance on page 202 (current version of the manual).

If the C2 contactor won't shut to restart the spindle until it cools, than I am guessing the C2 contactor is failing.

Thanks for the input. I have been troubleshooting and I do in fact get an error code "UU" for a few seconds after uncommanded shutoff, same as when the VFD is shutting off or a safety switch activates. I think this indicates the VFD is loosing power.

I started to lean towards contactor C2 as well, as C2 is deactivated when the fault occurs and would explain the loss of power to the VFD. When I restart the spindle, after a stall and feedhold, I hear it turn back on. Also, issue is getting worse, occurring at lower loads, indicating C2 versus a mechanical switch.

Has anyone else experienced a failed contactor? Either way, I will get a replacement and let everyone know how it goes.

[tmarks11]

Have you tried just cutting air? Just start the spindle manually and let it run for 30 minutes and see if you get the shutdown.

If the C2 contactor is dying, than the load the spindle is under shouldn't matter; the current through the contactor coils (and the heating of those coils that conceivably is leading to it tripping) is constant regardless of the load.

Another thing you might try is jumpering out the spindle head door switch. Since you can jog the table after the spindle trips, that tells us that you aren't getting an un-commanded estop. The spindle door secures power directly to the C2 contactor when it opens, but has no effect on the rest of the controller. The fault could also be the key switch, but this seems unlikely, as it is less prone to mechanical vibration and probably hasn't been cycled very often (mine has never been used).

[MikeRags]

Have you tried just cutting air? Just start the spindle manually and let it run for 30 minutes and see if you get the shutdown.

If the C2 contactor is dying, than the load the spindle is under shouldn't matter; the current through the contactor coils (and the heating of those coils that conceivably is leading to it tripping) is constant regardless of the load.

Another thing you might try is jumpering out the spindle head door switch. Since you can jog the table after the spindle trips, that tells us that you aren't getting an un-commanded estop. The spindle door secures power directly to the C2 contactor when it opens, but has no effect on the rest of the controller. The fault could also be the key switch, but this seems unlikely, as it is less prone to mechanical vibration and probably hasn't been cycled very often (mine has never been used).

You seem to be running about 30 minutes ahead of me. The failure happening under load was not sitting right with me, since it seems to happen most with 1/4" end mills at high speeds where the highest resonant frequencies happen. Just before the last shutdowns, I was running a 3/8" endmill with higher steady state loads, little chatter and no issues. After switching to the 1/4" with corner cuts and some chatter, it shut down.

Motor cover seemed a little loose, so I tightened it up. Going to try it again tomorrow and might short out the switch to see if it improves. Again, thanks for the help.

[TXFred]

it seems to happen most with 1/4" end mills at high speeds where the highest resonant frequencies happen.

I had the same problem, and Tormach gave me the answer.

The Power Draw Bar board has a mechanical relay on it. This relay is used to trigger the door switch circuit. Whenever the drawbar fires, this relay tells the VFD that the door is open, so that the spindle cannot start while the drawbar has the spindle locked.

Vibration causes this relay to fall open, which shuts down the VFD.

The solution is simple. Disconnect the drawbar board from the wiring to the spindle door circuit. It's not needed, because if the motor did try to start while the PDB was in use, the motor would stall and the VFD would shut back off, no harm done.
In fact, new version of the PDB omit this safety circuit because it's no longer needed.

But if you prefer to keep the circuit in use, you can order a later version of the PDB board that has a non-mechanical relay. This later version isn't affected by vibration.

[R.DesJardin]

I had the same problem, and Tormach gave me the answer.

The Power Draw Bar board has a mechanical relay on it. This relay is used to trigger the door switch circuit. Whenever the drawbar fires, this relay tells the VFD that the door is open, so that the spindle cannot start while the drawbar has the spindle locked.

Vibration causes this relay to fall open, which shuts down the VFD.

The solution is simple. Disconnect the drawbar board from the wiring to the spindle door circuit. It's not needed, because if the motor did try to start while the PDB was in use, the motor would stall and the VFD would shut back off, no harm done.
In fact, new version of the PDB omit this safety circuit because it's no longer needed.

But if you prefer to keep the circuit in use, you can order a later version of the PDB board that has a non-mechanical relay. This later version isn't affected by vibration.

Yep. ^ Chances are if it isn't the door switch it's the PDB. I've upgraded to the new latch as well as the new PDB board.

[MikeRags]

Yep. ^ Chances are if it isn't the door switch it's the PDB. I've upgraded to the new latch as well as the new PDB board.

TXFred and R.DesJardin, thanks for the reply. I have not had time yet to test the mill after I tightened the door latch. I did take the PDB cover off and confirmed I have a mechanical relay. If tightening the latch does not work, I will try to disconnect the PDB relay. Do you recall how much the new PDB board costs?

[shred]

I've had chatter shake the PDB relay. Disconnecting it works fine.

[MikeRags]

I had the same problem, and Tormach gave me the answer.

The Power Draw Bar board has a mechanical relay on it. This relay is used to trigger the door switch circuit. Whenever the drawbar fires, this relay tells the VFD that the door is open, so that the spindle cannot start while the drawbar has the spindle locked.

Vibration causes this relay to fall open, which shuts down the VFD.

The solution is simple. Disconnect the drawbar board from the wiring to the spindle door circuit. It's not needed, because if the motor did try to start while the PDB was in use, the motor would stall and the VFD would shut back off, no harm done.
In fact, new version of the PDB omit this safety circuit because it's no longer needed.

But if you prefer to keep the circuit in use, you can order a later version of the PDB board that has a non-mechanical relay. This later version isn't affected by vibration.

Thought I would give a quick update for anyone else who has similar issues. After much troubleshooting and trying not to override safety features, this was the ultimate solution. Door was loose, fixed that, wires were loose, fixed them, still had issues with small diameter end mills and large depth of cut.

I have ultimately confirmed the issue was caused by the power draw bar (PDB) circuit board relay bouncing due to vibrations in the machine, causing the "cover open" spindle override to trigger. This is 100% expected from a mechanical relay and I have been told, is fixed in later versions with a solid state device.

It is literally like I have new machine and can final take full advantage of its performance. Just now I was using a 1/4" end mill to do a 0.75" DOC, 0.02" WOC at 22ipm without any issues. Before I had to back this cut off to around 8 IPM or the machine would shut down.

Thank you to everyone who offered help!

[tmarks11]

excellent news! thanks for the tidbit on the updated PDB relay.

[bevinp]

Another fix by the Mighty Tormach Forum (or the "Tormach Mighty Forum" or as per other language syntax "Forum Tormach Mighty"??).
Good stuff guys.