Core One - Rear Z axis lead screw stopped responding while bed was raising to start print.
This is a new Core One. Factory assembled.
This morning I woke up to a failed print. Big glob of TPU all over the extruder, a crunched fan shroud, and a torn silicone block sock. This was a routine print that has never failed before. No change in filament (same spool), etc. The print file is an array of small, short parts that cover the entire bed from front to back. The first quarter of the bed printed correctly (the front quarter). I cleaned the head and restarted the print, but when the bed began to rise toward its home & leveling position, the rear lead screw froze, causing the bed to ramp/angle up toward the front as the forward leadscrews continued. I'm not sure how bad the off-level condition got before I reset the printer, but it was pretty bad.
What just happened? Do I have a bad stepper?
RE: Core One - Rear Z axis lead screw stopped responding while bed was raising to start print.
you could try to switch off the printer or turn off the motors in the menu and manually turn the lead screw to see if something is binding... maybe some little piece of dirt went the wrong way and blocked the trapezoid nut... this is what I would it this were my printer. If everything seems to turn smoothly you could try to level the bad in this way and then moving the bed back down using the manual controls. Possibly the last 10mm I would release again the motors and manually bring all the lead screws to the bottom. If all this works, try setup routine with all the axes check.
If anything goes wrong here... I'd contact prusa support.
RE: Core One - Rear Z axis lead screw stopped responding while bed was raising to start print.
Check your trapezoid nuts. Lower the bed at the maximum, undo the 3 M3*18 screws that holds the nut and see if it rotate freely
It just happened to my C1, on the Front right lead screw. The nut was barely spinning, wich caused the stepper to skip and the bed to tilt...
Support sent me a new nut after a short discussion
RE: Core One - Rear Z axis lead screw stopped responding while bed was raising to start print.
Yeah I contacted them. I have a little list of problems that the machine has been throwing.
Leadscrew is totally free, and I've been lubricating it since the beginning.
To level it, I moved the bed all the way to the bottom, disabled the motors, and then bottomed it out on the base of the chamber by hand. It's perfectly level now.
Idk though - I'm definitely concerned that it will happen again while I'm away from the machine - if I hadn't been there to hard-reset it, idk how far out of level it would've gone and I'm not sure if the off-axis torque on the trapezoidal nuts would break them.
Anyway, thanks for the input.
RE: Core One - Rear Z axis lead screw stopped responding while bed was raising to start print.
One more thing to note. When the printer is powered off any pressure on the print bed will push the build plate out of "true" so if you clean the plate or even just remove and reinstall while the printer is off (or the z-axis motors are turned off via g-code) you can easily push the bed out of alignment. I discovered this very early on in my journey with the Core One. Normal print profiles do not disable the z-axis motors after a print completes so that the motors retain their position and the bed remains level.
Regards,
Steve
RE: Core One - Rear Z axis lead screw stopped responding while bed was raising to start print.
I see. That makes sense. I generally leave it on 24/7, even when it isn't on a job. I should measure the draw at the wall to see how much electricity I'm wasting.
So, this is a little off topic, and I've read it elsewhere, but PETG and TPU are my main materials and I'm finding that the nozzle cleaning stage fails at least once on every print. All of them. It's a huge time waster for me because I have to babysit the machine for maybe 10 minutes. I wish there was a way to set the target threshold for failure to less strict parameters, if necessary, in the UI. Moreover, the nozzle cleaning leaves these tiny blobs across the front right corner of the plate that are a huge pain to remove after every print. I have to remove them or nozzle cleaning fails 100% of the time. I think the purge/priming stage at the very start of the print where it lays down a bead in the front right corner of the plate should be aligned with the nozzle cleaning strips (both of them) so the thick layer of the bead bonds to the blobs. That way, when you peel the priming beads away from the bed, they bring the nozzle cleaning blobs away with them. Finally, I think that the priming bead needs to be longer. By the time TPU is cleaned off of the nozzle enough for a "pass" vs "fail", it's been drained from the hotend chamber. The priming bead isn't long enough to charge the chamber and it misses a few mm of material at the very start of the first layer. The priming bead would ideally lay over both cleaning strips to bond to them and that would prime the chamber sufficiently.
RE: Core One - Rear Z axis lead screw stopped responding while bed was raising to start print.
For the nozzle cleaning failure you may want to implement one of the many "nozzle brush" mods on Printables.com. Most use readily available Bambu A1 silicone brushes. A small g-code addition to the startup moves the nozzle to "scrub" on the brush prior to the nozzle cleaning operation. You might also search the forum here for information regarding nozzle cleaning failure as some have reported issues presumably caused by electrical "noise" caused by the hotend heater drive interfering with the load cell signal. There are small g-code mods for that as well which turn off the nozzle heater during the nozzle cleaning exercise.
Regards,
Steve
RE: Core One - Rear Z axis lead screw stopped responding while bed was raising to start print.
You could also lower the temperature used in the start gcode for testing the bed... I did have a similar problem with PCBlend and solved it permanently by reducing the temperature by 25C