MK4 fails to print a purge line
More than half of the prints I start fail to lay down any plastic in the purge line although the head goes through the motions. I've used PLA and PETG filaments from Prusa and Hatchbox (I have no others) and it doesn't seem related to the filament type or the manufacturer. I have no custom gcode for start of print. It happens sometimes on the first print after power-on as well as other prints later in the day. It will sporadically purge correctly and later start failing again. It happens on prints that worked correctly on my MK3. I''ve had to add a 3-loop skirt to each of my Print Settings to ensure that there's plastic in the nozzle with the actual object starts printing.
Any ideas or suggestions? TIA for your time and help.
RE:
“Prints that worked correctly on the MK3.” Are you running the MK3 gcode on the MK4, or files sliced specifically for the MK4?
RE: MK4 fails to print a purge line
Mine does a similar thing, I use PETG exclusively. Purge line happens after filament change, but otherwise it's seldom. I haven't noticed any issues with the actual prints though, so I just ignore it for now.
RE: MK4 fails to print a purge line
I don't keep gcode in files; I always freshly slice when I want to print something. BTW I'm on Prusa Slicer 2.6.0.
RE: MK4 fails to print a purge line
I've noticed that too, though not every time. Prints come out fine though.
RE:
That seems odd. I don't have an Mk4 but what you can always do is to make the purge line substantially longer by editing the start g-code accordingly, maybe add some rows to it.
With that you could also see the consistency of the lack of extrusion. You can then increase the initial extrusion before the purge line if there is a systematic lag for whatever reason. If however there is a big variation maybe your extrusion gear tensioner isn't tense enough and you have some slipping in the very beginning? Or maybe there is a partial clogging issue (a precautionary cold pull can never hurt).
Mk3s MMU2s, Voron 0.1, Voron 2.4
RE: MK4 fails to print a purge line
Today my MK4 did the same. It dropt the purgeline in the air instead of on the bed. Printing is OK. I noticed that de gcode files that came with the printer had a purgeline close to the object in stead of on the front left edge. Might be something in the gcode that Pruca Slicer causes. I do not know yet what.
RE: MK4 fails to print a purge line
Today my MK4 did the same. It dropt the purgeline in the air instead of on the bed. Printing is OK. I noticed that de gcode files that came with the printer had a purgeline close to the object in stead of on the front left edge. Might be something in the gcode that Pruca Slicer causes. I do not know yet what.
Sounds like you got a prusaslicer configuration update. The original profiles for MK4 (circa March-April) put the purge line near the print. Then there was an update that placed it at the front-left, outside the print area. Then another update kept that location, but started the purge "in the air" (first 10-15mm) while moving right and downward to the bed for the remainder of the purge.
Stored Gcode (like those which came with the printer) will, of course, reflect the purge behavior that was in the slicer profile at the time it was sliced.
RE: MK4 fails to print a purge line
Same. it starts purging in mid-air, and proceeds diagonally down and to the right until it hits the bed and purges like before.
Seems pretty clever actually. That pre-spooge always blobs on the bed and never sticks to the nozzle. I frequently had some nozzle drool getting stuck and dragged over to my print on the old MK3
When someone asks you if you're a god, you say, "YES!"
RE: MK4 fails to print a purge line
Same. it starts purging in mid-air, and proceeds diagonally down and to the right until it hits the bed and purges like before.
I actually like this compared to what the MK3 did. When it works it leaves a smll "handle" for easy removal of the purge line.