Y Axis errors during selftest, Can't find the problem
Hello, I am running 3.8 on my mk3s that I just finished assembling.
Once performing the selftest, It fails on the Y axis test every time. The bed will go all the way to the back (1st motion), then all the way to the front (still no issues) , then again to the back, (same spot as 1st motion) but this is where it fails every time. The first backwards motion has no problem, so I don't understand why the second, to seemingly the same spot, will crash. I have checked everywhere on the frame, and there is nothing blocking the path at all. The crash occurs the instant the linear bearing on the left side of the Y carriage (the side with 2 bearings) touches the back wall (I assume this is normal, and don't understand why this causes a crash). I cannot find any obstacle in the way of the Y axis, nor do I hear any irregularities when I manually move the axes. Every axis seems to be properly assembled, and all 3 move relatively smoothly when moving them by hand, or manually through settings.
Here's a list of things I have tried:
- disassembly of the bed, Y carriage, linear bearings and switched bearings around. I also lubed them up this time
- updated firmware from 3.7.4 to 3.8.0. The same issue still occurs
- Tried moving the linear bearing (the one causing the crash) farther away from the wall which it crashes on, to where it was uneven sitting in the indention. This did nothing, and I moved the bearing back to its original spot because so
if anyone has any ideas or tips I would be greatly appreciative
RE: Y Axis errors during selftest, Can't find the problem
While looking through the settings, specifically the belt tensions, I noticed that the X belt is listed at 90, while the Y belt is at 279.
90 seems completely inaccurate to me, as the tension is roughly the same as the other two belts, not to mention the fact that the X axis check always succeeds right before the Y axis fails. So I do not know if this has anything to do with the issue, or if I should try to re-assemble the X axis?
I am undecided on doing this because the X axis seems to be working fine, and the Y axis is still the only test that fails.
I'm completely baffled as to where exactly my problem lies, and this clue only has me even more confused.
RE: Y Axis errors during selftest, Can't find the problem
No help, but a couple of points:
1) Don't mess with something that is working well. Unless it is to lube the bearings.
2) You did everything I consider important. Hopefully other commenters are more useful to you. Good luck.
RE: Y Axis errors during selftest, Can't find the problem
@robert-rmm200
This is why I'm so stuck. Everything (seems) to be assembled and operating correctly. I can manually move all 3 axes' to their +-limits, all smoothly, with no obstructions. Its only in the calibration and self test that issues come up.
I'm particularly confused about the X belt tension reading, because before finding that, I would have guaranteed you that the X axis was for sure not the problem. I'm now torn between rebuilding the X axis, to see if I can fix the tension reading, or to just leave it alone since I am fairly certain that it isn't actually the problem.
RE: Y Axis errors during selftest, Can't find the problem
It sound like there is a problem with the length of the Y axis, measurement,
is it possible that the Y belt adjuster is the wrong way round?
are the ends of the Y belt trimmed flush with the outsides of the Y belt adjuster?
I haven't studied the motion of the Y axis, because mine have always worked... but I find it odd that the motion is being restrained by the bearings bashing the frame. the bearings are offset from the belt, so a collision with the frame will effectively cause the bed to twist a tiny bit...
I seem to recall on previous iterations of the Y belt fixing block was the endstop for setting up the printer... and that putting it in place reversed caused an error...
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Y Axis errors during selftest, Can't find the problem
Y moves to the rear until the bearing touches the rod holder. This is Y-HOME. The bed moves forward until the front bearing hits the front rod holder. This is Y-MAX. The bed then moves home. Y-Max minus Y-Home is Y-LENGTH.
Cable snags, loose U-bolts (hanging too low); bearings not centered; obstructions behind the printer; improper routing of the bed cable harness; improper routing of the extruder harness; over-tightened U-bolts (crushed bearings)... lot of reasons for a fail.
RE: Y Axis errors during selftest, Can't find the problem
@joantabb @tim-m30
Thank you for your input. To answer your questions,
- The Y belt adjuster/idler is orientated correctly. I have triple checked the orientation of all my Y axis components, and everything looks how it should in the build manual.
- Yes, the belts seemed trimmed correctly, and are flush with the ends of the belt adjuster/idler
- There are no obstructions with travel at all (I am positive. I've quadruple checked all wiring, and am able to manually move the Y axis as far as it is able to go with no issues. )
I should have clarified better in my original post, The crash occurs when the linear bearing hits the rod holder for the Y axis, not on the frame itself. During the Y test, it will go all the way back, until the linear bearing touches the rod holder, then all the way to the front (still without any issue), but when it goes again to the back, it will crash when the linear bearing hits the rod holder the second time. I will try to upload a video of this soon to maybe clarify a little better.
It seems to me like the axis is moving more/less depending on which direction it is moving. It will go from Y-Home to Y-Max (back to front) no problem, but when trying to go from Y-max to Y-Home (front to back again) it's like its sending it a farther distance then it just did travel and calculate, thus causing the crash when the bed stops earlier than it intends.
Any continued help or advice would be greatly appreciated
RE: Y Axis errors during selftest, Can't find the problem
I found the problem!
Turns out there was an obstruction after all, I can't believe I missed it. The nub on the zip tie of the front left rod holder, was rotated just slightly too high; Limiting the carriage's forward motion just millimeters before where it normally should. I can see why I missed it, but feel a little ridiculous that a zip tie being just barely in the way, has caused me to be down for 5 days now haha
My first self test after fixing the zip tie passed with flying colors.
Thank you everyone for your help
RE: Y Axis errors during selftest, Can't find the problem
Thank you for reporting back!
Every found problem helps the next person with the same problem.
Happy printing!