I am using a NEMA 17 (17HD4005-22B) with a Big Easy Driver and an Arduino Uno R3. I am using the motor to move a threaded rod, which then pumps a liquid. The system basically functions as a linear actuator.

After trying to move a much too high load, I noticed that the stepper motor was not turning correctly. It moved erraticaly forwards and backwards a couple of steps. I also noticed to following:

  • When I give it the signal to turn, I can turn the shaft very easily with my hand in either direction
  • When it is powered and without any signal to turn, I can turn the shaft easily with my hand in either direction most of the time. If I crank the potentiometer all the way, I can not move it anymore
  • I connected the motor to the stepper drivers of an i3-clone printer, and the motor does not turn. The previous two observations remained
  • I connected the Big Easy Driver and Arduino to one the motors of the 3D-Printer and the 3d-printer motor did not turn
  • Both windings of the broken motor have the same resistance

My doubts:

  • Is it possible that the high load caused the stepper to break?

  • Is it possible the driver is also broken?

  • How can I check any these possibilities?

  • \$\begingroup\$ What are the winding R’s of each coil and motor \$\endgroup\$ – Tony Stewart EE75 Jul 31 '18 at 15:26
  • \$\begingroup\$ @Tony , both windings from the broken motor have 1.6 ohm resistance. I did not measure the good motor from my 3d-printer \$\endgroup\$ – Keine Jul 31 '18 at 15:31
  • \$\begingroup\$ Now you know the problem \$\endgroup\$ – Tony Stewart EE75 Jul 31 '18 at 15:42
  • \$\begingroup\$ Some of the older magnet types could be damaged from excessive winding current, heat, or even disassembly. But the most likely suspect is that you've just chosen too small a motor - NEMA 17's are tiny, maybe okay for little 3d printers but not much else. You probably want a full-length NEMA 23. You might also consider a gear motor. \$\endgroup\$ – Chris Stratton Jul 31 '18 at 15:49

Motors fail from inadequate current controlled torque.

Your testing and results in your question must include;

  • coil DCR of each motor, current setting / rating, max acceleration, max velocity threshold for slip errors

It unlikely you have a faulty motor and more likely excessive acceleration for the new load.

  • \$\begingroup\$ I am testing the broken motor and the driver without any load now. Even so, both seem not to work. \$\endgroup\$ – Keine Jul 31 '18 at 15:48
  • \$\begingroup\$ You have not answered my questions on acceleration , velocity and current limits. The problem lies here. I found these extremely useful to obtain maximum power with GRBL Panel software. What is step interval, rate etc? \$\endgroup\$ – Tony Stewart EE75 Jul 31 '18 at 22:34

A quick Google on the part number reveals that your stepper motor is a four-wire stepper motor, rated for 2.4VDC and 1.3A. That works out to 1.8 ohms for the coil resistance, and your measurements are close to that. You don't say whether windings are shorted together, but I strongly doubt that they are.

My FIRST guess would be that your controller is not able to supply enough current to drive or hold the motor. In motion, or in hold, your controller must supply 2.6 amps (1.3A to each winding).

Stepper motors generally don't break if the applied mechanical load is too high. They just sit there, slipping steps and getting hot.

You don't mention a heat sink on your controller. My guess is that you've smoked your controller.

  • \$\begingroup\$ That would explain why I couldn't drive my 3d-printer motors with the controller. But it would not explain why I can't drive the "bad" motor with my 3d-printer drivers \$\endgroup\$ – Keine Jul 31 '18 at 16:00
  • \$\begingroup\$ @Keine: Does your 3D printer use the SAME motors? \$\endgroup\$ – John R. Strohm Jul 31 '18 at 17:03

It's probably the motor controller. If the motor were to fail usually its from heat and it either seizes up or the winding's fail.

Check the windings with an ohm meter and make sure the winding's are continuous and low resistance (or check the datasheet if it has a winding resistance).

To check the driver, get a motor that you know works and use it with the driver. If the motor works, then it must be the driver. My bets are that the driver is broken.


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