Motor catching, stiff.

So after a few prints that turned out great, enough for now. I have new problem. I set it to print the spool bracket. 75min job, and left. I come back to most of the bottom complete and the middle a hot mess. I shut it off and look it over.

The X axis isn't moving smoothly anymore. It's catching and skipping. I took the belt off and tested bearings and pulley, they're moving freely. I use manual control and spin the X motor and it spins fine, but under load it's stiff and jumpy.

When i move the extruder by hand, i'm looking at the gear on the motor to see where it's stiff. It's stiff in the exact same spot. 1/4 turn, the other 3/4 turn is smooth until it get's to that one spot. It's not the belt either.

It didn't feel very hot.

Any ideas? I'm off to work for 8hrs..so i can test it until i get home.

Edited 1 time(s). Last edit at 02/12/2015 11:39PM by Badkitty.

A damaged bearing ?

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Collective intelligence emerges when a group of people work together effectively. Prusa i3 Folger (A lot of the parts are wrong, boring !)

check the resistance of the wires -a, a, and -b, b my guess is the current was too high for this motor and the winding melted, reducing torque. you could also have a driver issue, you will be better off testing with a multiplier the ohm resistance, rather than hooking another driver to that motor, with power off, you can quickly try connecting the driver to another motor under load just to see if it works ok. be sure any disconnecting and connecting of wiring is done with power off to machine. double check your current settings on motors instructions are here [reprap.org], and verify they are within current spec of motors.

figured it out..finally. I actually been working a lot so haven't touched it. It was the plastic X axis pulley...it warped while it was running. I'm sanding it down a lot , enough to make it work long enough to print a new one

Want to update with new info...for those searching threads on solutions to problems.


I tried another 2hr print today and halfway through, the X axis stopped moving AGAIN. I checked the plastic pulley and it moved freely. The stepper motor was really stuff. I decided to pull it apart and check the windings. When i removed the aluminum pulley from the motor, i noticed the shaft turns freely again. The aluminum pulley had some how shimmied it's way against the motor casing, making it grind to a halt. I spaced it 1/16'' from the housing and it's completely free moving again.

One set screw was hard to break free, the other was semi loose. Now they're both super tight and shouldn't be moving again. This also explains a loud vibration i was getting during X axis movement. now it's gone.

Edited 1 time(s). Last edit at 02/18/2015 04:14AM by Badkitty.