Same motor model, several issues

I’m using tiny Chinese motors, with torque control=voltage and motion control=velocity. My setup works very well.

I recently purchased two additional motors, supposedly of the same model, although from a different reseller. The don’t work correctly.

First I can feel some very light scratching when turning them by hand. The original ones don’t have that. Second, they are more noisy, the motion is jerky, and the PP check sometimes fails. One of them have a strange behavior: it works almost perfectly in one direction, but very badly in the other.

I use the same encoder as before. I checked the polarities of the magnets: they seem fine (diametrically polarized).

Any idea or comment?


From the description it sounds a lot like these motors have some internal damage or bad construction that is causing friction?

That’s the reason for the scratching noise you hear, and why the PP check fails sometimes, and why the one motor works better in the one direction that the other.

If these are used motors, you might be able to fix them up if you open them up, clean them out and service them. If they were sold as new I would try to return them.

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