z-axis stepper motors problem

Hello everybody,
I have a problem with my reprap. As I said in the title of the topic, the problem is that the z axis doesn't work... all other axis and the motor of the extruder work perfectly. I use Sprinter and Printrun with Ramps 1.4. When, in Printrun, I click on the z axis, up or down, I get this noise youtube link .. it looks like it wants to move, but is not able to, I don't know if the problem is mechanic or electronic, maybe with the sound, somebody will be able to tell me... I tried to turn the pot on the stepstick, but the sound just changes a bit and still doesn't move correctly. I also have the problem that none of my endstops are detected, but I'm going to take a problem after the other
any help highly appreciated. Thanx
Manu

Are the motors perhaps fighting each other - they both need to turn in the same direction.

Disconnect the carriage from the Z motors and see if the motors turn with no load. Perhaps the carriage is binding - the Z rods need to be perfectly parallel.

Finally, have you tried adjusting the stepper driver trimpot? Perhaps is just needs to be turned up a bit??

Hi jbernadis,
Thanks for the reply
I don't think motors are fighting each other for several reasons:
-they are connected in serial (so, same signal I guess, because connected the same way in the two motors both same orientation),
-they are not even able to turn just a little bit (I think if they were fighting each other, they would be able to turn at least a little before being blocked)
-when I try to activate the motors on z-axis with printrun, motors react, so I can see there is information sent to them, but it sounds like if voltage or I don't know what was not the proper one to make motors turning...??

Yes, motors turn with no load, I can easily turn them manually, even in opposite directions.
And yes, I tried to adjust the pot of the stepper driver, the sound of the motors changes a bit but still not move..
...

Ok, so what voltage have you set the driver to?

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Waitaki 3D Printer

Hi Waitaki,
The multimeter gives me 0.66V but tried tu turn it 360° without any big change...it changes a bit the sound but the motors don't turn

If they are stepsticks, then 0.8v is better.
Also, you say you have the Z motors connected in series - how did you do that on a Ramps board

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Waitaki 3D Printer

I was wondering about that "serial" connection too. If your motors are connected like color to like color, then that is parallel - and that is what you want. Multiple motors on RAMPS should not be wired serially.

Hook them like this ("in series") - [forums.reprap.org]. When you do this step, make sure that you put a thermoshrinkage tube on all of the joints as well as on the hole cable. It will avoid any shorts. If you do this, your motors will turn in the same direction and will have 1A on the each motor which means - maximum torque. I had some issues with my Z axis motors and I solve it by connecting them "in series". It's not so hard to make the joints. Just be careful to hook one coil of the first motor to the correspond coil of the second motor (it doesn't actually matter which motor will be the first and which will be the second).
Best regards,
Bobby

Edited 1 time(s). Last edit at 05/02/2014 06:46AM by BoByS.