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mmihi
(@mmihi)
Active Member
What went wrong?

Hi. I recently purchased a MK3S kit and after hours (days) of setting it up i started making some sample prints from SD card. I found that the printer was always crashing so at some point I disabled crash detection (bad decision). I managed to print the treefrog and buddy without a problem. Since it was getting late (midnight), I decided to print a large file; castle 12hrs estimated, and when I woke up, there was a mesh of plastic around the print head and surrounding enclosing (see photo below). I now have to disassemble and I am wondering "what went wrong?" and what have I damaged?

Any advice would be grateful

 

Henry

 

Posted : 30/07/2019 12:04 pm
mmihi
(@mmihi)
Active Member
Topic starter answered:
RE: What went wrong?

This provides more detail. Seems like the hotend wiring has been fused to the PLA

Posted : 30/07/2019 12:16 pm
Dave Avery
(@dave-avery)
Honorable Member
RE: What went wrong?

raise the head,  preheat to PLA temps, wait a minute or two after it's heated , gently apply pressure on the blob being careful to not strain the thermister and heater wires and it should ooze free, using needle nose pliers ot tweezers continue to remove softened plastic till the hot end is cleaned , finish by wiping down the still hot heater block with paper towels.

Posted : 30/07/2019 1:20 pm
mmihi liked
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(@)
Illustrious Member
RE: What went wrong?

And - to prevent it from happening again, learn to keep the bed very clean. Any oil, especially finger prints, prevents PLA from sticking to the bed.

 

Hot Water wash: often, as needed, and after any of the following
            (not recommended for daily use on Powder Coated sheets, but sometimes required)

  • Handle the bed only by the edges.
  • Wash the bed in hot water, use a fresh paper towel as a wash cloth, with a few drops of plain dish soap (Dawn, unscented, no anti-bacterial, etc.).
  • Rinse well in hot water - if you have very soft water, rinse a bit longer.
  • Dry the bed with a fresh paper towel.
  • Handle the bed only by the edges.
  • Place bed on printer.

 

 

Alcohol wash: every few prints as needed

  • Gloves recommended.
  • Once in a while, an alcohol rinse is helpful to remove PLA residue. It does not remove finger oils well.
  • Pour a 5 cm puddle of 91%+ alcohol in the middle of the bed, with clean hands use a fresh paper towel to scrub the bed. Wipe up all the alcohol.

 

Acetone wash: infrequent as needed
            (Not recommended for USE on Powder Coated sheets, but some find it necessary)

  • Pour a 2 cm puddle of acetone on the bed, scrub it around with a fresh paper towel. It will evaporate fast as you clean. This step removes PEI oxides that form over time and with heat, and improves PLA adhesion to a like new state.

 

Streak test: when contamination is suspected

  • With a fresh piece of paper towel, and very clean fingers, dampen the towel with 91%+ alcohol, and wipe the bed side to side moving back to front, like you're painting it with alcohol. The alcohol should be thin enough on the towel it quickly evaporates from the bed. If you see any streaks, the bed is dirty and needs a wash.

 

Live Z Adjust: https://forum.prusa3d.com/forum/original-prusa-i3-mk3s-mk3-assembly-and-first-prints-troubleshooting/life-adjust-z-my-way

 

Posted : 30/07/2019 8:33 pm
mmihi liked
timo.m
(@timo-m)
Estimable Member
RE: What went wrong?

To remove it you can either heat up the aluminium block while attached to the printer or you can disassemble the hotend and heat up the blob of doom with a hot air gun. This can make it easier not to put too much stress on the wiring, especially for the NTC. The NTC has rather delicate wiring and is easily damaged.

Posted : 31/07/2019 8:56 am
mmihi liked
mmihi
(@mmihi)
Active Member
Topic starter answered:
RE: What went wrong?

Thank you all for the comments. I have managed to remove it although I ordered a spare hotend just in case.

Posted : 31/07/2019 9:49 am
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