stepper hard to turn = normal?

[forgetcolor]

I'm building a JGRO. Bought three steppers from Keiling (KL23H284-35-4B). Was just hooking up the third motor and found that it's really hard to turn and 'clunky' feeling compared to the other two. I thought maybe my alignment was off but i took it off and it's hard to turn without anything attached to it. Much harder to turn than the other motors are while attached to their screws.

Is it defective? Or is there some variance in these?

If I try to turn it faster I notice that it slips occasionally too. This is just turning the shaft by hand with a coupler on it.


thanks

[forgetcolor]

ok, strange. after turning it with a little wrench for a while it all of the sudden got smooth and easy to turn like the others. did it just need a bit of break-in?

[forgetcolor]

i got a hold of keling. they say that there was residual magnetism in the motor and by touching all the wires together and releasing them it will make it smooth again. i must have done that by accident when turning it. thought i'd post this in case someone else has the problem.

[H500]

Yes. When your wires are shorted together, the motors will be hard to turn. That's normal for all steppers.

[Claude Boudreau]

One of my axis was hard to turn by hand so I unhooked the motor to the screw and notice my axis was ok, the motor itself was hard to turn and after turning it a bit all of a sudden it will break free and be easy to turn for what seem to be like a quarter of a turn, then block again and be hard to turn again. It will do this always, as far as I can tell.

Is this a tell tale sign of a bad stepper? I have burn a xylotec board recently and Im a bit scare to burn another. I have order another stepper to be on the safe side. Wondering if I should use my router with that stepper in the meantime?

P.S. Can you burn a motor by turning it too fast with a drill when its not connected?

[RomanLini]

That's normal, when connected to the driver it will charge a capacitor in the PSU when you turn it and get hard to turn.

If you have handles on your steppers you should really have a switch to disconnect the driver from the main PSU so you can turn the handles.

[Claude Boudreau]

That's normal, when connected to the driver it will charge a capacitor in the PSU when you turn it and get hard to turn.

If you have handles on your steppers you should really have a switch to disconnect the driver from the main PSU so you can turn the handles.

the motor is not connected

[Wolfesmetalfab]

Its posted below, and its an old post, but it had me fooled, so to clear things up for others, if the stepper motor is not hooked up to any power supply or anything, but some of its own wires are touching some others of its own wires (in a sense shorted, but no sparks, cause there is no power) it will be hard to turn and feel like its defective. Try it, its kinda fun not touching, turns freely as can be, but as soon as you start touching wires together, its like it turns on the brakes. Anyways, hopefully it makes it clear as mud for someone.

Brian =)

[James Newton]

You can even use that fact to figure out the wiring of the motor:
Stepper Motor wiring

[Al_The_Man]

if the stepper motor is not hooked up to any power supply or anything, but some of its own wires are touching some others of its own wires (in a sense shorted, but no sparks, cause there is no power) it will be hard to turn and feel like its defective. Try it, its kinda fun not touching, turns freely as can be, but as soon as you start touching wires together, its like it turns on the brakes. Anyways, hopefully it makes it clear as mud for someone.

Brian =)

This occurs on all motors that have permanent magnets.
In fact this used to be a method of braking in large DC motors, where a low value resistor would be connected across the motor armature at switch off.
Al.

[Wolfesmetalfab]

You can even use that fact to figure out the wiring of the motor:
Stepper Motor wiring

Very interesting and informative read! Sadly I couldn't take the time to read it all, but the spin test is cool.

Ive got it Bookmarked so when I need it I got it.

Thanks!