Smoothieboard Y-Min reaches and y-axis motor starts squealing/buzzing

I have read the troubleshooting instructions on the Smoothieware web site and I still need help.

Problem description

When I reach y-min, I expect my y-axis motor to stop, but instead the y-motor stops and makes a loud buzzing noise and the y-axis motor vibrates. This setup has been working fine for several years. I had been using the day it quite, had literally just finished one engraving and was starting another. When I turned the engraver on, everything appeared normal until homing of the y-axis. As soon as, and I mean the instant, the y-min was reached, movement stopped (as it should), but the motor started making a loud, somewhat high-pitched buzzing/squealing noise and vibrates…like a really loud electric razor…like the motor is unsure what to do. Has anyone encountered this issue before? If so, please share.

My system description

  • I have a Smoothieboard v1.1

  • I connect to my Smoothieboard via USB and Windows 10

  • My Smoothieboard controls a: laser

Two obvious candidates for the symptoms:

  1. One out of the 4 wires going to the stepper motor has a (maybe partial/only sometimes) faulty connection.
  2. Or there’s something going on with your speeds, squealing is often a sign it’s trying to go too fast.

Appart from checking your wiring, I’d recommend you reduce all speeds (including homing speeds and movement speeds) by a factor of 100 (as a test) and try again. If things start working then, move the speeds back up progressively.

Hi Arthur,
Thank you for the feedback. I’ve adjusted the homing speeds, but those speeds haven’t changed for several years…even with the speed change, it still does the same thing. I swapped out the motor, the only way I rule out the wires, still does the same thing. It’s just weird that it happens the instant Y-min is reached. I checked and re-checked my wires, checking for loose connections…everything seems to be well seated. One thing I’ve been researching is led2 goes out when the buzzing/squealing starts. Not sure if the led is a response caused by the motor buzzing/squealing or if the motor is a result of led2 going out indicating something is not in agreement on the smoothie. Sixteen hours in, I’ve eliminated things, but haven’t found the issue yet.

Don’t concentrate too much on the fact it didn’t do it before, you might have been at the edge of it happening and now it does for some weird reason.

Led 2 going out sounds like it’s trying to move at high speeds, which is consistent with the motor behavior.

This could also be that it’s trying to accelerate too fast, reduce the acceleration by a factor of 100 and try again.

Also, try extreme speeds (with F) and extreme accelerations (with M204) on the Y axis and see if you can see the same behavior but triggered manually.

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Can you shoot a video?

Motor wires, running too fast or too high of accel, bad endstop maybe…all things that can be checked.
It could be something mechanical binding also…