The position reading from the driver keeps jumping.

[Brandi]

Good morning.

I modified a closed-loop stepper motor myself, adding a 500-line incremental encoder to the tail of a Nema 23 stepper motor, connected with a flexible coupling.

When running at low speeds, the position feedback displayed by the driver software occasionally jumps by a few pulses, causing the motor to vibrate. The encoder cable is a shielded twisted pair, and grounding has been done.

Could it be that the encoder and motor shaft are not concentric, causing slight speed fluctuations during rotation? Or is the encoder's resolution insufficient? How can I troubleshoot this?

I hope an expert can provide some guidance.


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[Martaine2005]

I’m no expert by any stretch of the imagination but I would first try a rigid coupler rather than a flexible one.

 

[bertus]

Hello,

A flexible coupling will always have slack.
The ones with those plastic or rubber pieces will have more slack than the ones of full metal with a spiral in it.
If you do not want to have any slack, use rigid couplings.

Bertus