Stepper motor has no torque

One of my stepper motors (z axis control) wasn't turning at all. I started messing with the screw on the ramps board to control the volts and it started rotating. The only issue is that it seems to be rotating slightly fast than the left one and also, if I touch it, it starts rotating the other way. I can also hold it it and it will stop rotating, versus the other one which will start making sounds trying to turn if I hold it. How can I troubleshoot this.

If both of your Z stepper motors are of the same type and connected to a common driver, then I am fairly certain that you have either an open circuit winding in the motor, or else a bad connection to that motor. Check with a multimeter.

Edited 1 time(s). Last edit at 08/19/2015 03:40PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

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

If each of your motor is connected to a different driver, try to invert the driver to see if the problem persists.

Did you try a different wire? I have seen this on other devices using stepper motors when one of the leads is broken.

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Newbie with Folgertech 2020 i3.

I don't know how to do that so ill research. But ill tell you this : when the printer is off power: the stepper motor when connected to the cable is rough to turn. But when I take of the cable it spins freely. Is this normal ?

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meeuuch
I don't know how to do that so ill research. But ill tell you this : when the printer is off power: the stepper motor when connected to the cable is rough to turn. But when I take of the cable it spins freely. Is this normal ?

Yes. Spinning the motor causes it to generate a voltage, which feeds back through the body diodes of the mosfets in the stepper driver to put a voltage on the 12V rail, which then powers whatever else draws current from that. I can make the backlight of my colour touch screen controller light up when move the carriages of my printer with the power off - and the panel normally takes about 300mA current. The load on the motor has a braking effect.

Edited 2 time(s). Last edit at 08/22/2015 03:27PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

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

Well, I don't know whats going on with this motor. I turn the screw on the ramps boards and I turn it to a point where both motors will start to spin in the same direction. But sometimes the motor on the left just stutters and even changes directions some times. Don't know what to do.

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meeuuch
Well, I don't know whats going on with this motor. I turn the screw on the ramps boards and I turn it to a point where both motors will start to spin in the same direction. But sometimes the motor on the left just stutters and even changes directions some times. Don't know what to do.

We have already told you what is wrong: either one of the stepper motors has an open-circuit coil, or (more likely) one of the connections between the motor and the electronics board is bad. So turn the power off, remove the motor connector from the electronics board, and use a multimeter to measure the resistance between the pins of the connector.

Edited 1 time(s). Last edit at 08/23/2015 04:45PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

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