Z Rod screw grinding
I have noticed that when moving the z axis from the menu there is this sound like something resonates. I found that the z rod screw is touching the metal frame in the bottom part. This happens only either all the way up or near the bottom of the length of z axis. It looks like it doesnt go straight inside the bottom hole and the hole diameter is not big enough for the tolerances.
How can I center it? In order for it to not grind?
Original Prusa Mini + Smooth PEI
Prusa Slicer 2.6.0
RE: Z Rod screw grinding
Update:
I unscrewed the 2 screws on the z rod lead screw and then tightened them while holding the rod centered. This fixed the problem and also helped with the resonating sound. Now the z axis moves with no sound. Probably needs more adjusting but its a huge improvement.
Original Prusa Mini + Smooth PEI
Prusa Slicer 2.6.0
RE: Z Rod screw grinding
As far as I can tell, there is no bearing on the lead screw, so the only attachment points are at the the motor, and the trap nut (which you adjusted).
Otherwise the lead screw floats inside the Z bottom, there is nothing to stop any wobble.
RE: Z Rod screw grinding
Otherwise the lead screw floats inside the Z bottom, there is nothing to stop any wobble.
As it should be. The leadscrew should never be physically restrained on the other end.
Prusa Mini Silicone Bed Leveling Mod: https://bbbenji.github.io/PMSBLM/
RE: Z Rod screw grinding
@bobcousins
Yes you are right. Seeing the design parts, there is no other support.
@benji
I wonder if adding another lead screw on top would make the rod behave better or make the whole design worse.
Original Prusa Mini + Smooth PEI
Prusa Slicer 2.6.0
RE: Z Rod screw grinding
The leadscrew should only be restrained in two places. The point of energy transfer from the motor and the point of linear movement.
Even then, sometimes it is attached to the motor with a flexible coupler.
Adding a third point of restraint might cause seizing because the leadscrew is not 100% straight. You want the leadscrew to wobble. However, if it wobbles too much or isn't aligned well, you will get grinding somewhere, probably the far end, like in your case.
Prusa Mini Silicone Bed Leveling Mod: https://bbbenji.github.io/PMSBLM/
RE: Z Rod screw grinding
@benji
Ok I see. I think at the moment its fixed by aligning it and then tightening the screws of the lead nut as I say above. I was just thinking about the design in general as its my first printer so I am pretty new to this.
Original Prusa Mini + Smooth PEI
Prusa Slicer 2.6.0
RE: Z Rod screw grinding
I am having the same issue as you. When I move the Z towards the top and bottom I get a horrible grinding/rattle noise. I tried tightening those screws when holding the center rod but it doesn't seem to center the rod still. Was there anything else you did?
RE: Z Rod screw grinding
No nothing else I did. I had to perform the same procedure twice because there was grinding sounds once while the Z axis was towards the top and the other towards the bottom but after adjusting it the sound went away.
Original Prusa Mini + Smooth PEI
Prusa Slicer 2.6.0
RE: Z Rod screw grinding
Woke up this morning to my Z screw squeaking (it never has before). Found this thread, and loosening the two screws on Z bottom did make the squeak go away. But every time I re-tighten these screws snug again, the squeak returns. They're not completely loose. I can feel a small amount of friction, so I know head of the screws are touching Z bottom. But I'd normally turn these screws another 1/4 to 1/2 turn before I'd consider them snug. It feels wrong to leave them this loose, and I worry they could loosen more over time. Any thoughts?
P.S. My biggest noise problem is right around 27mm on the Z axis. Above and below that aren't really a problem, so I don't understand why it started and I don't understand why keeping those screws looser make it go away.
Thanks!
RE: Z Rod screw grinding
@jbienz
I just started having a similar issue, when the z moves down towards the bottom, it'll make the sound you're talking about.
I'll try adjusting the screws and see if it stops.
RE: Z Rod screw grinding
I just started having similar behavior as that from @jbienz and @retr0vers3 ; somewhere on the lower trajectory of the Z axis (some 30mm perhaps) there is a metal griding noise and then it goes away. Would this be associated with the 2 screws on the z rod lead screw ?
RE: Z Rod screw grinding
I fixed mine by applying a bit of lube, and loosened the screws holding the Z axis motor.
I made the Z axis move all the way down, tightened the screws a bit, made it go all the way up, tightened em a bit, repeat.
After a little bit the grinding sound went away entirely.
RE: Z Rod screw grinding
screws holding the Z axis motor
Are these the 2 screws on the z rod lead screw as shown on the picture earlier on this thread?
RE: Z Rod screw grinding
Yes
RE: Z Rod screw grinding
Thank you. I have applied a small amount of lube to z-rods and lead screw and the noise is gone. I did not see the z-screw rubbing against the housing, but I'll keep an eye on that.
RE: Z Rod screw grinding
I had this issue, and didn't see the z-screw brushing up against anything at the bottom. I put a small amount of lube on the z-screw, and the issue went away.
RE: Z Rod screw grinding
Thanks! Had the very same issue when the print head was between the 165-146 height, which made 'squeaking' noise. Now it moves smooth without any squaking sound.