Did I kill my stepper motors?

So here is my new problem.

My Z axis steppers no longer stay in position when powered up. I thought that I might have killed the Z driver so I swapped it out but that made no difference.

Measure the resistance of the coils of the Z-steppers… (should be somewhere between 1.5 and 3 ohm)

Can you see the shaft of the stepper rotating while the gantry is falling? It could be loose grub screws.

Yes the stepper shaft is rotating.

Measured at 6.8 ohms, at the end of the series cable.

Motors very rarely die. Very rarely. Most common problems are:

  • Loose grub screws on the coupler
  • Wiring problems, especially intermittent ones are a huge pain.
  • Leadcrew nut is over constrained and it is too tight. Or no grease.
  • Z motor speeds are too high (especially in the latest versions of free fusion).
  • The driver current isn’t right, or the motors are wired in parallel.

Is was running fine then suddenly on next run the problem came up.

Grub screws are tight.
Wiring correct, serial from Ryan’s kit
Lead screws move freely.
Not running any file speed is low just jogging.

Did you measure 2 x 2 wires? (left 2 and right 2)?

Yes. That’s The same measurement that I get on the Y Axis.

Then it is very unlikely that the steppers are the problem.

So I’ve taken the lead screws of completely and I can turn the shaft of the steppers by hand in both directions while powered and connected.

I’m now starting to think it’s the CNC shield, or the Arduino.

If Y is working, my troubleshooting would be to plug the Z wires into the Y connectors on your board and see if commanding a Y move makes the Z move. If they move, that tells you the steppers are ok and you can look elsewhere.

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They move, they just don’t hold in place and drop right away.

Problem has been solved! Thank you to everyone who responded, it always helps having multiple thoughts.

As it turns out somehow, my firmware became altered, I must have done it but don’t know how!

Somehow the step idle delay was changed to 25 instead of 255 ms.

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Oh, grbl! I should have guessed.