Incomplete Printing  

RE:

I don't think manually loading the file makes a difference because (AFAIK) the print only starts when file transfer completed successfully. I've worked with fairly large files that took several minutes to transfer (such as a LEGO plate with 900 studs, antistuds with fairly detailed features in 0.25mm). Once a firmware glitch gave a message "USB is too slow for file transfer" but that was unrelated and didn't persist.

Were you present when the printer stopped? If overnight print, I could imagine the filament flow stopped and the printhead then continued printing air. This is one reason why cameras are popular (in case you have the buddyCam, enable "permanent time lapse to SD card" after powering up. You need a SD card inserted, obviously).

Check the filament end whether the Nextruder wheel has carved out a slice. In this case I'd do a few cold pulls with PLA to clean the nozzle, and (possibly even more important) the cold end of the nozzle that may have filament residue sticking on the walls from heat creep. This is just one possible problem but one of my printer's favorites, at least in its early days.

RE: Incomplete Printing

While a failed transfer is possible, the printer should throw an error that the Gcode file is incomplete when it fails. Does the print continue or stop halfway? I'm inclined to agree with @mnentwig that this sounds more like an extrusion problem, e.g.,., clogged nozzle.

RE:

Thank you for the great informative reply, another school day for me 😅

I did find that the filament had broken inside the nextruder and a build up of filament on the nozzle. Not sure which was the cause of the fail, but either way I cleared with a few cold pulls, cleaned thw nozzle and got back to printing.

Alas, I got to a similar point in the print, actually a little further this time and noticed either the MMU3 or Nextruder clicking, like the gear was grinding through, rather than pushing/pulling filament and seemingly no layers being put down. Inspection of both gear elements, showed there to be no blockages, but I did notice some resistance on the rollers for the filament, which may of caused this to happen, although consistently around the same height of the print is odd, but maybe Im chasing a red herring? If idler tension of either the MMU3 or Nextruder is the cause, whats the best practice to tune this? I have printed quite a few models thus far and not had this many problems previously, although I did have a similar problem a while ago that was resolved by upping the idler tension at the print head. Is it possible that this has become slack with use?

Thank you again for the replies, just when I start to get somewhere with printing there is another thing to look at, but every day is a school day 😅

Edit: Thought it worth mentioning that Im trying to print in Prusament Galaxy Black PLA, if that makes any odds? 

Scott

RE:

Maybe I got lucky so far, but in my printer the idler tension settings (both Nextruder and MMU3) have been uncritical so far

But, pay attention to the condition of the filament after failed prints. If in doubt, discard the last 1/2 meter where you feel the pulley pattern when running it between two fingers. A single unload is uncritical, but I've had issues when the MMU did several unsuccessful attempts to load and unload - the print failed, but the problems carried over to the next print with the worn filament that then slipped through the pulleys. 

If (if!) the cold end of the nozzle gets clogged repeatedly (heat creep), you could try thermal paste on the copper ring and above. Also keep an eye on the heatbreak temperature (put it on the display's footer), it shouldn't go too far above chamber temperature. This gets more problematic with high chamber temperatures and prints where the filament moves slowly. If this is the failure mode, you can reduce retract distance and -speed to slow down heat transfer into the cold zone.

Also, if high flow nozzle, they are (reportedly) easily damaged by cleaning attempts with steel needles. Putting in a different nozzle might rule out quite a few potential problems on this end.

RE:

Also, if high flow nozzle

That's what I was thinking. I for one am not a fan of the high flow nozzles. Had some clogging issues with my first one, then put regular (well, Obxidian, but not HF) nozzles in all my printers and haven't seen any clogging issues since. 

Could be a tension issue but I find the core one to be much less sensitive to the correct tension than other printers. At least I've never had to futz around with it, even when printing TPU. 

RE: Incomplete Printing

So, I've done multiple cold pulls and no blockages found. I started a 1hr 30min print earlier and the same thing happened. Prints fine, filament is dry, not snapped like it was before, just the nextruder decided to stop pulling filament through, constant clicking, paused print, ejected filament, removed Bowden, pulled 300mm of filament out of the MMU to check, and other than a bit of a whispy end, almost like fluff, and a slight bend where the gear had been rubbing, nothing of note. Did a cold pull straight after and it fed filament through absolutely fine by hand. Is the whispy end an indicator of anything in particular?

Merry Christmas.

Scott

RE: Incomplete Printing

Made two prints which were fine with jet black and pristine white PLA no issues, then started another print with the white to have this happen again.

As soon as it happened I pinned the clicking down to the the nextruder. I left it running and opened the idler door to see what was what. The extruder gear didnt seem to be rotating, so im.unsure where the clicking was coming from other than maybe the planetary gear? I stopped the print, powered off the printer and proceeded with stripping down the nextruder gearbox, cleaning and reassembled. Ran calibrations and all went fine. I've ran 2 prints so far without issue, but let's see what happens with the Galaxy Black.

Also hoping this helps someone in a similar position.

Happy Holidays.

Scott

RE: Incomplete Printing

Posted by: @scotttomo

Made two prints which were fine with jet black and pristine white PLA no issues, then started another print with the white to have this happen again.

As soon as it happened I pinned the clicking down to the the nextruder. I left it running and opened the idler door to see what was what. The extruder gear didnt seem to be rotating, so im.unsure where the clicking was coming from other than maybe the planetary gear? I stopped the print, powered off the printer and proceeded with stripping down the nextruder gearbox, cleaning and reassembled. Ran calibrations and all went fine. I've ran 2 prints so far without issue, but let's see what happens with the Galaxy Black.

Also hoping this helps someone in a similar position.

Happy Holidays.

Scott

Double check the thin washer on the Nextruder motor shaft is still there. If it is not installed (i.e. went missing) then you will see problems like this. That is, it's working for a few prints then stops extruding. I had that happen to me when I built the MK4 awhile ago. 

RE: Incomplete Printing

Cheers for this.

Washer is present and correct, although there are some slight score/wear marks half way from the outer edge. Maybe I overtightened the gearbox cover? Another 2 prints in, and no reoccurrance as yet, fingers crossed.

Scott

RE: Incomplete Printing

Also make sure the outer toothed ring is installed with the chamfer side in the correct orientation (toward the motor). 

RE: Incomplete Printing

Cheers. Pretty sure it is, but will double check after this print finishes.

Thanks again.

Scott