Hi,
my MPCNC Primo with SKR Pro V 1.2 was working just fine. Since yesterday the y-axis motor on the right seems to have weakend/is having problems.
When I’m attempting to move the y-axis by 10mm (via Display) the left Motor moves but the right one isn’t. It is trying though. (If I help it a little bit by hand, it’s working)
I tried tightening and loosening the belt but it made no difference.
Does anybody have any suggestions from this information alone? Or do I maybe need to make a video?
Greetings, Michael
P.S. I’m generally unsure about how loosened the belt has got to be. It was too tight at first and the machine didn’t move. I loosened it quite a bit until the machine was moving adequatly.
In general: It is pretty hard to move the machine by hand (when powered off). Is that some kind of indicator for something that might be generally wrong with my build?
Belt tension. Here is what I do. When homed, tension the belt until pushing it into the tubing it “feels” like a belt on a car, takes some effort, it should have enough that it takes a bit of effort to push the belt to get it to deflect. The machine takes a bit of pressure to move when tension is correct, but should not be real easy, or real hard to move.
I agree with Tim above, sounds like a bad/loose motor connection. There is always the possibility that the stepper driver is failing as well, so try the wiring first and eliminate that in the variables.
Also check the pulleys on the stepper, the set screw can get loose
As John indicated, the most likely cause of your symptoms is a loose grub screw on the pulley attached to the stepper motor. If the grub screws are fine, swap the Y1 and Y2 motor cables at the control board and retest. If the problem moves to the new motor, your issue is most likely in the wiring. If the issue stays with the same motor, your issue will most likely mechanical.
Belts should not be very tight. Also, if you strum them, each pair should make the same “note.” Given that you started with them so tight the machine was difficult to move, consider loosening them more.
In general: It is pretty hard to move the machine by hand (when powered off). Is that some kind of indicator for something that might be generally wrong with my build?
There is some resistance when pushing each axis, but I would not describe mine as “difficult.” It should move smoothly if you move the axis by the middle of the tubing. Pushing at each end can cause binding.
If the above suggestions don’t solve your problem, a video would be helpful. In addition to what happens visually, the sound it makes can tell us what is going on.
You need the belts to be tight enough that the motors won’t jump a tooth, but that’s not very tight, especially in the MPCNC orientation where the idlers wrap the belt 180* around the pulley.