Print crashed and damaged hotend - what to do next?
Hello everyone,
I would like to ask for your opinions / suggestion regarding an issue I have had recently. I have a CoreOne(+), self-assembled. Past 14 days (thats how old the printer is) it has been running most of the time, mostly without issues and with successfull prints However, now this has happened:
I came to the printer and found this situation - the printer reported the error “Nozzle heater overcurrent” ( https://help.prusa3d.com/article/nozzle-heater-overcurrent-31308-core-one-35308-core-one-l-26308-mk4s-13308-mk4-27308-mk3-9s-21308-mk3-9_405604 ). I assume this was caused by the entire hotend “sinking” into the printed object.
The silicone sock from the hotend had fallen to the bottom of the printer, so the printer must have been moving around, crasing into print and spewing spaghetti for some time.
Condition after cleaning:The hotend got pressed against the cooling duct outlet and slightly melted it (probably not that big issue), and the sleeve around the (heater?) cables going to the hotend is damaged.
After cleaning, I tried to print a Benchy, which succeeded.
However, during the next print (Prusa nozzle replacement tool) the filament stopped coming out during printing, and the usual simple cleaning steps haven’t fixed it so far.
I think I’ll be able to deal with cleaning myself (when I have time I’ll try replacing the nozzle and see whether that helps), however:
1) My main question is whether I can continue printing normally with the hotend in this condition (as long as it works), or whether this is a serious issue and the hotend likely needs to be replaced.
I also started thinking about why the crash happened. It looks like a Z-axis issue. After restarting the printer, the Z-axis was completely miscalibrated (the printer thought it was much higher than it actually was). I recalibrated it, and during that I noticed that the front-left rod visibly vibrates or oscillates off-axis when the bed is in the lower roughly one-third of its travel. Once it moves higher, the vibration and noise stop (see video).
2) Is this normal, or do I need to disassemble everything and reinstall that rod?I tried the usual tightening and loosening of the screws; the screws have to be quite loose for it to move properly. If I tighten them even slightly, the movement along that rod jams in the lower part.
Thanks a lot for any and all constructive feedback 🙂
RE: Print crashed and damaged hotend - what to do next?
I would just also like to add two things to this issue:
1) I have tried to unscrew the trapeizoidal nut when the bed was on bottom and it can move along the rod freely.
2) When i turn the printer off and turn it on later, the Z-axis always things its at 0 (so on top), even though its not (this time it was almost on bottom). I have to recalibrate it to get the correct values again.
RE: Print crashed and damaged hotend - what to do next?
These are the usual default values after powering on. The printer does not store the old values before forcing anywhere. Don't worry about it, the printer will find the correct reference before printing. Or you can give it a "Home" from the printer menu. Or "Calibrate Z".
RE: Print crashed and damaged hotend - what to do next?
As above, it will zero itself before every print, but with one caveat. AFAIK, the only time it synchronizes the three Z screws is when you do a Z calibration, and it runs all the way to the bottom. The assumption is that the motors then never lose any steps, that you don't turn one by hand or adjust the nuts. If you do anything like that, re-run the Z calibration. Being paranoid, I run calibration before anything critical.