Prusa Mk4 not finding print bed properly
Hi,
I have a couple of Mk4 machines, one seems ok and the other when I try to print comes down ("Z") around half way then stops and looks like its trying to find the bed. Then after a while it creeps down a bit and tries again, this happens several times and sometimes I just get a crash detection error and sometimes "nozzle cleaning failed" - because it does not get low enough to sense the bed. other times it finally manages to find the bed. Its almost like the machine thinks the Z height is only half what it actually is.
The firmware is running version 6.2.4. I did calibration and everything (including load cell) passes.
The other mk 4 tries to find bed also at half way down but after then manages to always frin the bed and prints.
Both printers print ok.
RE: Prusa Mk4 not finding print bed properly
This usually happens because either the load cell isn't calibrated properly, or the PTFE tube is pulling up on the print head and causing it to falsely sense pressure. If you disconnect the PTFE while it is sensing the bed and the problem doesn't go away, try to recalibrate the load cell.
https://help.prusa3d.com/article/loadcell-mk4-s-mk3-9-s-xl_401253
Prusa MK4 since Jan 2024, Printables: @MikeB_1505898
RE: Prusa Mk4 not finding print bed properly
I tried with a very short piece of filament to make sure no catching and also did the load cell test and it passes. Neither of these help.
I found an older thread where others had same issue and one found tighting screws at back of extruder assembly helped. I tried this but still does not help.
The other Mk4 does the same thing but manages to get down and find the plate eventually without crash detection.
Both machines movement of Z up and down moves smoothly when I adjust and with machine off I can turn the threaded rods to move extruder up and down freely.