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XL Upgrade Stepper Issue

Posted: Tue Dec 25, 2018 11:31 am
by Tomdigi
I just completed the upgrade. I have been very particular in setting up all the parameters: squaring the frame and all extrusions, adjusting all the v wheels precisely and adjusting the new drive belts. Left and right side adjustments have been verified and are, as well as can be determined, the same. All of my testing has been done without the router installed; purely testing motion. X and Z motion is normal.

Essentially, the left stepper is very loud, vibrates badly and is jerky in motion. While moving the Y axis with UGS, the left side frequently lags behind the right. Have gone back thru all the setup procedures several times to no avail. I had another person go behind me and verify all of the setup parameters. I'm seriously thinking I have a bad stepper motor. I have disconnected the left side stepper and all the noise and vibration goes away. Disconnecting the right side stepper confirms that the noise and vibration is from the left stepper. HOWEVER, I have not swapped the left and right motors because of the inherent length of time involved and they are hard wired into the controller.

With all power turned off, the gantry moves easily up and down the side rails. With the belt removed from both steppers, each stepper spins up quietly under power.

These are the same steppers that were used on the SO3, so I'm suspicious that the motor has suddenly developed a problem, but it's the only thing that makes any sense. Is there anything else anyone can think of that might account for this issue?

Also, as an unrelated question, given that the gear pitch has changed on the X and Y axis, are there changes needed to the GRBL settings to account for that?

Any help is greatly appreciated.


Re: XL Upgrade Stepper Issue

Posted: Wed Dec 26, 2018 4:03 pm
by WillAdams
The most likely culprit is the wiring extension --- please test that using a multimeter if possible. If not, contact

The belt pitch is the same, but the stretch may be different, see: ... t-stretch/

Re: XL Upgrade Stepper Issue

Posted: Fri Dec 28, 2018 1:08 pm
by Tomdigi
You're spot on about a bad connection. Continuity from the junction at motor, going to the controller was perfect. Testing at the motor revealed no continuity between the blue and red wires. I disassembled the motor and found the blue wire barely connected. Once repaired, it runs great.

Thanks for you input!