It's happen so sudden.
I found out that one of my NEMA not working properly after i printing a medium size project.

The NEMA moving in a weird pattern, so many vibration happen now and sometimes it's doesn't move and sometimes it's move on other direction.
I already check the NEMA itself, but nothing jamming the motor from inside.
I alrdy try NEMA on other axis and it's work well.
And also I try to remove all belt then just try the motor, it's just work like miracle, all NEMA moving so well.
But when i put all the system back, it's vibrating again.

I just found out that the NEMA going wrong a while when y axis reach 1/2 half of end stop, and when reach end stop of y axis, x axis doesn't turn but keep vibrating.
My friend who alrd know reprap before said it might be cable, but i already check cable, nothing going wrong there.
I try to update firmware but always fail on timing to do reset, but i think thats not the real problem.
Anyone can help what happen here?

It's either a cabling problem, or you need to adjust the voltage on the stepper driver, try adjusting the voltage.

If it has suddenly stopped working then the driver may have gotten too hot and been damaged.

actually I completed assembling my printer and basic functions seems to work fine like auto home, xyz axis moving using both lcd and through software. then I removed the connections from my mks gen2z 1.2 to organize my wires as they were messy and reconnected everything as before. now one of z axis motor is making sound, vibrating and not rotating so I googled up and found that might be because of Pololu, which were mounted on motor drivers..and I adjusted them like turning clockwise and anticlockwise.

now the motor started rotating but sill vibrating and making noise..(not running smoothly like it was before)...while in rotation some times it stops rotating and sometimes rotating in the opposition direction doing all weird possible things..:-(

is there anything else I should look into apart from Pololu, which I tried, but no luck..this problem isn't there when I assembled the printer and now I feel like I should have left those messy wires as it is :'(

I have exchanged the motor driver with the one which is working on the other z axis, but no luck what might be the reason..it is responding with pololo

Edited 1 time(s). Last edit at 11/01/2015 09:57AM by setti.

If you removed the wires while the thing was powered up you may have killed the motor driver modules. If you have an intermittent wire/connector to the motor, when it opens up it can kill the driver module. The tiny pots on the driver modules are extremely easy to break and it is easy to short them to other conductors on the PCB when trying to adjust them. It is easy to kill the modules by overheating them by setting current too high. Sometimes the module will work for a few minutes and heat up then shut itself down if it gets too hot, then restart after it cools a little. Put the tiny heatsinks on the driver chips and keep a small fan blowing on the RAMPS board. Always keep a few spare motor driver modules on hand- they tend to fail when you need them to work most.

Oh, yeah, to the original poster: NEMA is a designation that means National Electrical Manufacturer's Association. A motor is commonly referred to by its size- NEMA-17, NEMA 23, etc. The number refers to a standard size for the motor mount that will fit that motor. You can put any NEMA 17 size motor in any NEMA 17 size mount. So it isn't a "NEMA x axis" that's vibrating, it's the X axis motor that's vibrating.

One more thing, it's not a Pololu, it's a stepper driver module. Pololu is one brand of stepper driver module (they make other stuff, too: [www.pololu.com]) but there are about a million chinese knock-off brands out there.

Edited 2 time(s). Last edit at 11/01/2015 10:33AM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

If it vibrates and rotates in random directions then only one coil of the pair is being driven. Either a bad connection of a half blown driver.

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[www.hydraraptor.blogspot.com]