One motor not working

I have a ramps 1.4 with 4 stepper drivers one of my z motor's doesn't work it grinds I tried rewiring it and still grinding, I also tried swapping the x and y axis motor and they both work fine when connected to the z axis sockets. Connect 5 motors up and one grinds and always on the z axis. The nema is not turning even when ran unmounted.

I decided to replace the motor so I bought 2 brand new nema 17's (Prewired) swapped both motor's on the z axis and still the same grinding on the z axis on the new motor. So I swapped some of the working motor's and still the same grinding on the z axis only. I played with pot but no luck.

I've bought a new ramps 1.4 board and 5 stepper drivers off ebay so I'm hoping a straight swap of the ramps and steppers the problem will go away. Has any one else experienced this? I'm assuming I have a dodgy stepper driver but replaced the ramps board as it was cheap and had the 5v pins for the endstops which mine lacks.

These are the replacement motor's
[www.ebay.co.uk]

I originally bought a kit from nextdayreprap.co.uk everything else is from the kit, the motors that originally came with it have the same torque rating 44Ncm.

Thanks

Edited 4 time(s). Last edit at 04/12/2017 09:36AM by Desertboy.

[Solved hopefully] traced the motor not working to a bent threaded rod on the z axis it was binding stopping the motor's turning, I ordered 2 lead screws last week to replace the z axis (Upgrading the chassis a Graber I3) so hopefully they will arrive tomorrow not expecting the Graber frame till next week.

Oh well I've got 2 spare nema 17's, ramps 1.4 and steppers sure I can find something interesting to do with them like build another printer lol. Ordered another adruino mega 2560 from Hong Kong for £6 so will have spares

Edited 1 time(s). Last edit at 04/12/2017 11:19AM by Desertboy.

Today I stripped the z axis down and found it wasn't even close to aligned and that what was bending the threaded rod (I didn't build this printer) I straightened the chassis considerably and use new threaded bar and it all works fine. I think my motor couplings need replacing though as they seem slack and the threaded bar dropped off one of the z axis. I got my lead screws today but decided to hold off fitting them until I get the Graber frame which should be early next week they stick through the bottom off the mendel too far and I would have to raise it I think I will have to cut them down for the Graber.

Quote

The nema is not turning even when ran unmounted.

Be honest, you never tried to run the motors unmounted...or the binding leadscrew isn't the cause for your problems.