Fat tips getting stuck leaving the extruder doing manual multi color
I get these sometimes fat, sometimes misshapen tips on filament changes with the MK4 while doing manual color changes, when utilizing a purge tower. These get stuck in the extruder heat break during the purge tower cooling/shaping process and also in in the upper end of the extruder filament path, during filament tool change events. It doesn't occur at any other time.
Trying to troubleshoot this before installing the MMU3. Can someone point me to the filament shaping sequence so I can use that knowledge to diagnose my problem.?
RE:
Glad to see I'm not the only one with this issue. Only happens with manual multi material prints, and only on the purge tower. Starts sounding like maybe it's doing the 'ramming' needed, then the print continues with no filament coming out because it's jammed.
Also, if it doesn't jam, and the print tower does continue, after a filament change, it spits out a huge blob that when cooled, collides with the nozzle and knocks the x/y axis out of alignment so it prints in places it shouldn't.
RE: Fat tips getting stuck leaving the extruder doing manual multi color
Since my original post, I decided this was related to the PETG CF filament I was using. Later on the black version of this filament started breaking off in the heat brake just above the heat block. This required removing the print nozzle from the machine, heating with a torch, and ramming the filament out the nozzle with with a 1.8mm rod. It was a real pain because the rod had to removed while it was still hot and some of the filament on the rod end would stick to the inside of the heat break, which had to be cleared out before I could insert filament down to nozzle. I decided that that filament will no be used again on a 0.4mm nozzle.
RE: Fat tips getting stuck leaving the extruder doing manual multi color
So this last "jam" was the worst yet. Could not get filament to load at all. Thought maybe it was a clogged nozzle. Replaced it. Still nothing. Ended up taking apart PG assembly and found a piece of filament stuck sideways in the hole (should have gotten a pic, but this is where it was stuck) for the main plate.
RE: Fat tips getting stuck leaving the extruder doing manual multi color
I'm embarrassed to say to say it took a couple dozen jams in that same PG assembly area, followed by the heartbreak plugs I mentioned above, before I gave up using the offending filament. I do have an assortment of picks and steel rods to clear out the filament passages, but even with those I had to remove the main plate to clear some of them. I can't say for sure, but for the past week, I haven't had any jams or misshapen filament ends, and the only difference is that I haven't tried to use that particular roll of filament.
I'm keeping my fingers crossed.......
RE: Fat tips getting stuck leaving the extruder doing manual multi color
Since you mentioned getting the MMU3: I have mine up and running. What I can say is that the procedure used to unload while running an MMU3 sliced gcode is NOT the same as the unload when you select "unload filament" from the printer or add toolchange gcode to the print for manual multi-color.
While my filament has not looked anywhere near as bad as pictured, it always strings. With the MMU3, when doing an MMU3 sliced print, the filament changes the filament that unloads has perfectly shaped tips. When not doing an MMU3 sliced file? My filament has a string when it unloads.
So the MMU3 filament unload procedure is amazing, in my as-yet limited experience. I'm not sure why Prusa doesn't adopt this unload procedure as the default unload procedure for the printer. Perhaps eventually they will. Hopefully, actually. Because if doing single-filament prints but through my MMU3, when done and the filament unloads it has a string, but if I had done it as an MMU print when the filament unloads there would have been no string!