Can't get stepper motor to turn

I bought one of these: [www.aliexpress.com]

But I can not get the motor to turn.

It has the same connector as my old extruder-motor so I just replaced it.

My previous motor was a little bit bigger and did not have a gearbox, since this motor is smaller I adjusted the motorcurrent to 0.245 vref, 4988 stepstick and a 0.4A motor it seems.
Even tried to change back to my old motor and it turned just fine at that setting as well (no load, just trying to get it to turn).

But no go with the new one, am I missing something?

EDIT: It does make noise but it doesn't turn.

Edited 1 time(s). Last edit at 07/14/2015 09:06AM by Koenig.

Check the wiring. Just becaue they have the same plug doesn't mean they are wired the same

It´s always worth disassembling and inspecting things, especially when they are from china
-Olaf

Quote
cat.farmer
Check the wiring. Just becaue they have the same plug doesn't mean they are wired the same

Sure but I can't find any info on the motor anywhere.

All you need is an multimeter for ohm-measure.
Find out, which of the 6? wires are the coils or only the centerpoints of the coils ( half the resistance )

Then you have 4 wires sorted out, representing two coils, which needs to be connected to the Ramps:
one coil to the inner two pins,
the other coil to the outer two pins.
If it still doesn´t run, switch around ONE of the coils.
When it runs, but in the wrong direction, use the firmware to invert direction.

Quote
o_lampe
All you need is an multimeter for ohm-measure.
Find out, which of the 6? wires are the coils or only the centerpoints of the coils ( half the resistance )

Then you have 4 wires sorted out, representing two coils, which needs to be connected to the Ramps:
one coil to the inner two pins,
the other coil to the outer two pins.
If it still doesn´t run, switch around ONE of the coils.
When it runs, but in the wrong direction, use the firmware to invert direction.

Thank you!

Switched one coil.
That did it!

Now I have another problem with this, can't get it to produce enough force to push the filament in a good way.

I do not know how much current this motor can stand.

I have my vref at 343mV right now, and from the looks of it this seems to be only a 0.4A motor.
When I measured the coils they were 1.8Ohms each if that tells anything.

Bought it because of the gearbox and thought it would produce more torque than the existing motor I had (no gearbox, 1.5A)
But when just trying to hold the filament while extruding my old motor produces a lot more force.

EDIT: did some googling on the markings of the motor from the picture from the Ali-link and it seems it is a 1.7A motor, so I'm turning up the current.

Edited 2 time(s). Last edit at 07/16/2015 03:34PM by Koenig.

If it's a Nema 17 motor and the coils are 1.8 ohms each, then the rated current of the motor is much higher than 0.4A, probably more like 1,5A. You can also check how hot the motor is getting at 0.4A, because at the rated current it will almost certainly be too hot to touch for more than a second or two. If there is a part number on the motor, look up its specifications on the web.

---

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Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42
If it's a Nema 17 motor and the coils are 1.8 ohms each, then the rated current of the motor is much higher than 0.4A, probably more like 1,5A. You can also check how hot the motor is getting at 0.4A, because at the rated current it will almost certainly be too hot to touch for more than a second or two. If there is a part number on the motor, look up its specifications on the web.

Thing is there is no markings on the motor I have, but I took the markings of the motor of Ali-express's picture and it seems it is a 1.7A motor.