Motor tuning issues

[bencarlson]

I just swapped the encoder and encoder wire from the x-axis to the z-axis (and vice-versa) no change. The issue remains on the z-axis.

-Ben

[cncsnw]

Do you mean that the issue remains with the control's Z axis output (so that the message on the screen still says "410 Z axis(3) position error", even though it was the X servo motor which was supposed to turn?

Or do you mean that the issue remains with the Z axis servo motor (so that the message on the screen says "410 X axis(1) position error")?

Did you swap cable connections at the Allin1DC? Or did you swap cable connections at the motors?

[cncsnw]

On a separate but important note: are you (1) using the OUT9 relay on the Allin1DC unit to directly switch the 90VDC circuit to release the brake?

Or are you (2) using the OUT9 relay to control a separate ice cube relay or small contactor, which switches 90VDC to the brake?

Or are you (3) using the OUT9 relay to switch the AC power going in to your 90VDC power supply, which then feeds its output to the brake directly?

Method (1) is not recommended. The small relay cannot reliably interrupt 90VDC.
Method (2), using two poles of a small contactor, is preferred. That also gives you a good place to hang a freewheel diode to further protect the relay or contactor contact points.
Method (3) is workable as well, but will probably result in some lag time, both releasing and re-applying the brake.

[cncsnw]

Going back to motor/drive troubleshooting: instead of trying to use the PID tuning interface to run the motor, just use either the jogging controls or the MDI prompt. That way you can do one move at a time, and you can see the message window while you are doing it.

If the problem remained with the Z motor, even when it was connected to the X axis output, then I recommend some creep-speed testing.

At the MDI prompt, enter a move like "G1 G91 F0.5 Z0.2" and press Cycle Start. This will move the motor about two turns, at a very slow speed.
If you get a "411 ... full power without motion" stall, mark the motor shaft at that position. Then turn it a quarter or half turn by hand, and repeat the move. Do that a few times, then try it going the other direction: e.g. "G1 G91 F0.5 Z-0.2".

If the motor consistently stops at the same place, then you have a dead spot on the commutator or a broken winding.

If it stops at random places, and sometimes goes a full turn without stopping at all, then the problem is more likely to be in the cable or on the servo drive (though the Z/X connection swap should have told you already whether the problem is with the Z axis output of the servo drive, or with the Z axis servo motor).

[bencarlson]

Sorry for the confusion - yes, I swapped cables at the AIODC as well - so the X-axis cable & encoder are now on the z-axis. The error is still on the Z-axis, even with the new cable & encoder. FYI: I'm using cables & encoders from Centroid on my existing motors.

Great ideas on the motor testing! I'll try that here momentarily!

On the z-brake question, I bought a 24VDC contactor, so I can use Output 9 to trigger the contactor, which allows 90VDC to flow from the transformer. So, number 2 in your questions above.

-Ben

[bencarlson]

Hrm. Manual jog @ 2% didn't cause the motor to kick out. Same with running the MDI you supplied - I ran it 1.6" positive and negative - no issues.

I then ran it again, running it for an inch, instead of .2", and wiggled cables, wires connectors, etc. no issues, in plus or minus.

Any other ideas on testing the motor? Thanks!

-Ben

[cncsnw]

If you move it repeatedly plus and minus a half inch, at 30 in/min, do you eventually get a stall error?

[cncsnw]

Sorry for the confusion - yes, I swapped cables at the AIODC as well - so the X-axis cable & encoder are now on the z-axis. The error is still on the Z-axis, even with the new cable & encoder. FYI: I'm using cables & encoders from Centroid on my existing motors.

So, if I understand correctly, you were still running the Z axis motor using the Z axis output from the servo drive; it was only the intervening power and encoder cables, plus the encoder itself, that you swapped from the X axis.

Is that correct?

If so, the next step -- once you are able to reproduce stall problems again -- would be to connect the cables that lead to/from the Z servo motor onto the X connections of the Allin1DC, and to connect the cables that lead to/from the X servo motors onto the Z connections of the Allin1DC. That way you will be able to distinguish whether the problem is with the Allin1DC drive output, or is with the servo motor.

[bencarlson]

If you move it repeatedly plus and minus a half inch, at 30 in/min, do you eventually get a stall error?

Using the PID tuning program, yes - absolutely. My video is nearly done uploading which shows this. It sometimes kicks out immediately, sometimes it runs 5-10-15 cycles, but I don't believe it's ever gone past about 15 cycles before erroring out with the SV_STALL_ERROR.

-Ben

[bencarlson]

So, if I understand correctly, you were still running the Z axis motor using the Z axis output from the servo drive; it was only the intervening power and encoder cables, plus the encoder itself, that you swapped from the X axis.

Is that correct?

Yes, exactly. I swapped the motor power cables a couple of days ago, and swapped the encoder and cables this morning. I'll try swapping the port on the AIODC in a bit here (trying to run some parts on another machine ), for the z-brake, should I just hard-wire the 90v temporarily? Actually - I could try hard-wiring it before I swap the encoder port! That might show us something... maybe?

-Ben