Z-axis metal/metal squeal
After about 250 hours of printing I have started to notice an alarming metal/metal squeal when the Z-axis is homing. It is only noticeable when the Z-axis is moving a large distance and typically only when moving the print bed up, such as when homing. I was planning on lubricating the linear rails to see if that helps, but the XL maintenance page says not to do that in bold. Could it be the lead screws instead? Lubricating those is apparently ok as long as you don't overdo it.
RE: Z-axis metal/metal squeal
I ended up putting a dab of lubricant on both Z-axis lead screws and a bit in the bearing at the top of the screws and the noise seems to have gone away.
RE: Z-axis metal/metal squeal
I'm having the same issue, only difference is that it only happens when the z-axis is going down, not up, near homing point. Chat Support told me it was just resonance, but man it's a scary noise.
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Mine is also when I move the Z-axis downard, at around 150mm something on the left side starts to bind, creating a loud "resonating" or squeal/chatter sound. It's strong enough of a bind to actually start to cause the stepper to stall. IOW, I can see a marked difference in movement speed when it happens. If I take off the left-side Z-axis threaded rod cap, the threaded rod actually vibrates horribly around this section, but otherwise seems concentric with the stepper. If I use the Z-axis cap as a bearing and pull on the threaded rod toward me and then move the axis, I don't get any chatter at all. I should note, I cleaned the threaded rod using a paper towel just to make sure it wasn't some kind of debris on the rod, to no avail. I'll try adding some lubricant later to see if it helps, but I'm wary of relying on that as a fix, since the bearing surface here is plastic on metal.
This seems to be a twist or something equivalent in the bed frame. Loosening the threaded rod nuts and the mounting screws for the frame does affect this, but I can't get it to completely go away using this method.
Going to talk with support about this.
RE: Z-axis metal/metal squeal
Chatted with support. They had me take the threaded rod bushing off of the bed and move it up and down on the threaded rod to see if there was any binding -- naturally there wasn't. To do this, I removed screws from the corners of the heat bed, and then the bushing screws on the left, moved the bushing manually up and down the rod, and then did the same on the right.
No binding. The bushings moved super smooth with no trouble. Checked the linear rails, no binding there, either.
Reassembled the heat bed loosely, dropped the Z all the way down to 371mm (the limit), tightened up the screws, then recalibrated the Z axis. Now it doesn't bind quite as much, but it's still chattering a little in the same direction at the same point on the rail. So if you're having this issue, it may be something to do with the metal frame alignment to the two Z-axis carriages.