Steppers shuddering when I pull the belts through fast

Mostly Printed CNC - MPCNC Troubleshooting
1

Hi, I have built the MPCNC up to the point that I am ready to power on the Jackpot and start testing/calibrating it.

Problem is when I move the gantry around I get pretty bad shuddering. I loosened the easily accessible bolts on the trucks and most of the bearings can spin freely when turned by hand without the gantry moving.

That still didn’t fix things so I unscrewed the belt holders from the corners. Now the gantry moves around easily. I tried pulling the belt through the trucks by hand back and forth and I sometimes get shuddering that seems to come from the stepper motors. If I pull the belts through slowly the shuddering goes away.

What can I do to fix this? Is this a problem or is this normal? Is it a problem with the stepper motor itself?

Thanks,
Bob

2

You probably know this, but moving the steppers too fast when they’re electrically connected to the drivers induces a current and can ruin the drivers.

Otherwise, I don’t know that I’ve seen anything I would describe as shuddering, but I suppose that could indicate misalignment between the idlers and the pulley. Did you purchase all the parts from V1E or did you self-source?

If you purchased from V1E I’m sure @vicious1 will chime in.

1 Like
3

With the Jackpot board disconnected from power I unplugged the stepper motor and now the motor does not make noise when I pull the belt back and forth through it.

Having the steppers plugged in even without power to the Jackpot board must have been the problem. Hopefully I did not damage the drivers.

Thank you.

4

You really should not keep doing that.

When you run a stepper it turns into a generator, do not move them by hand more than you need to, especially if they are plugged into something.

5

Lesson learned.

One more question, should you be able to rotate the bearings by hand without the gantry moving? I want to make sure they are tightened properly.

6

Yes and no. Easily, no, can you, yes. You just want them touching, not clicking loose.

7

Thank you. Hopefully I will have it up and running and calibrated by the weekend.

Thank you for all your hard work.