Z stepper fails after print cancellation

[bonelli 4]

Hello,

 

(print with PC on bay B for head 1, PVA on bay E for head 2)

 

I have a reproducible problem than happen during the startup process of a print (material loading...) in 2 cases :

- if a manually cancel the print

- if some errors occurs (actually ER56, the PVA breaks somewhere in the MS)

 

In theses cases, the Z stepper seems to be free, the plate fall down down to the bottom of the printer.

 

What's happening after this fail:

- reboot the printer (soo long) (thanks to the bad error handling of the UM5)

- happy because PC is still loaded on head 1, no need to reload/reprime it except if the firmware want to unload it

- not happy because the MS detected the wrong material on bay B !!!!

- reboot the printer after removing the spool on bay A (soo long) (thanks to the painfull RFID reader)

- ask the MS for material removal on bay E

- Clean the bay E = power off printer and MS

- reboot the printer (soo long)

- print again (seems to be good)

 

The PVA did beaks at the entry of MS, when the end of filament was just entering in the feeding box behind the printer