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prusa3d / Prusa-Firmware-Buddy

Firmware for the Original Prusa MINI, Original Prusa MK4 and the Original Prusa XL 3D printers by Prusa Research.
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[BUG] M600 with MMU3 behaves unexpectedly #4027

Open firetech opened 1 month ago

firetech commented 1 month ago

Printer type - MK4, with MMU3

Printer firmware version - 6.0.1+14848

Original or Custom firmware - Original

USB drive or USB/Octoprint - USB drive

Describe the bug M600 is handled weirdly on MK4 with MMU3. Instead of unloading the filament to MMU3 and asking which slot to load instead (which MK3S+ etc. seem to do since this PR), it ejects the current filament out of the front of the MMU and asks the user to change the filament in the currently used MMU slot, as if the filament in the slot ran out.

I know you can add color change based on layer while slicing for MMU3, but some use cases for printing with M600 instead are:

  1. You want a quick color change by layer, but haven't got any guess regarding correct purge volumes for the filaments in use, so you'd rather do it manually.
  2. You're printing with a nozzle size other than 0.4mm (at the time of writing, MMU3 profiles for MK4/3.9 only exist for 0.4mm nozzles).
  3. You're printing G-code supplied by someone else.

How to reproduce Slice something using a normal (non-MMU3) MK4 profile, and add an M600 color change before exporting the G-code to the printer. Print on a MK4 with MMU3. Probably also affects MK3.9, possibly also MK3.5.

Expected behavior For the M600 color change G-code, unload filament to MMU, ask user what slot to load instead.

G-code M600 test_0.4n_0.2mm_PETG_MK4IS_1m.zip

ojrik commented 1 month ago

My problem is the same. I also prefer to use the M600 method for single extruder color printing. I was used to my MK3S+ MMU2S, after upgrading to MK3.5 MMU3, I'm a little disappointed that they didn't add the option to select a slot for the MMU.

CertainLach commented 1 month ago

Furthermore, If you try to use buttons on MMU to choose the filament manually (which it allows you to do), it will get stuck in "disengaging idler", because it is confused, and doesn't know what to do next, completely failing to continue the print in result.