Parts Melted to Heater Block
I very recently assembled a MK3S and have been doing a few prints with great success. I woke up this morning to a clicking sound and the printer still moving but no filament was coming out. I bounced around a few topics on here and finally sorted it out; I wound up replacing a jammed PTFE tube. I started printing again and it seemed like all was fine, until I realized the printer was now leaking filament from between the heater block and nozzle. In my attempt to troubleshoot the initial problem myself I had removed the nozzle and, being a newbie, didn't check that things were appropriately tightened when I screwed it back in.
So I heated the hot end back up, removed the nozzle, tried to swab the excess material out of the hole and then tried to tighten it all back together. I was following some steps that I had found (and now cannot find, despite combing through my browser's history) that involved rotating the heater block an extra 45 degrees while it's hot so you can get a tighter fit between it and the nozzle. Looks like I went a little too far and wound up melting the black printed part that sits around the hot end to the heater block itself. While disassembling again (in an attempt to straighten the hot end back out) I broke the heater block off of the black printed part. I think the parts will still work but I'm left with a blob of black (nylon?) on my heater block:
Melted portion of black printed part:
I'm at a loss for the best route forward. The black blob makes it pretty much impossible to mount the hot end back in at the correct orientation, but I think heating it up might be the only way I can get it off (it is very very stubborn). I happen to have an spare heater block, and a fresh nozzle, that I would like to swap in. However, I can't thread off the current heater block without heating it up. Is it ok to heat up the hot end assembly outside of it's enclosure? If I can't do that then I think I may just need to order another hot end from Prusa.
RE: Parts Melted to Heater Block
the printer extruder housing is PETG.
yes you can heat the extruder up outside the housing, but you need to be very careful not to burn yourself or anything else
make sure the 40mm fan is somewhere it can run, without getting damaged while you work, (probably best to tuck it carefully through between the toothed belt so it's behind the extruder,making sure the blades are free to turn)
work gloves, welding gloves or oven gloves will help you prevent burns. a brass wire brush should remove the softened plastic.
here is a report on changing your nozzle which may help
https://help.prusa3d.com/article/fJa7GxLSG6-changing-or-replacing-nozzle
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Parts Melted to Heater Block
"yes you can heat the extruder up outside the housing, but you need to be very careful not to burn yourself or anything else
make sure the 40mm fan is somewhere it can run, without getting damaged while you work, (probably best to tuck it carefully through between the toothed belt so it's behind the extruder,making sure the blades are free to turn)
work gloves, welding gloves or oven gloves will help you prevent burns. a brass wire brush should remove the softened plastic."
Thanks for the quick reply! For a resting surface while the hot end is heating is it advisable to place it on the heated? (With the steel sheet in place)
RE: Parts Melted to Heater Block
"yes you can heat the extruder up outside the housing, but you need to be very careful not to burn yourself or anything else
make sure the 40mm fan is somewhere it can run, without getting damaged while you work, (probably best to tuck it carefully through between the toothed belt so it's behind the extruder,making sure the blades are free to turn)
work gloves, welding gloves or oven gloves will help you prevent burns. a brass wire brush should remove the softened plastic."Thanks for the quick reply! For a resting surface while the hot end is heating is it advisable to place it on the heated? (With the steel sheet in place)
NO. you will melt and damage the PEI.
RE: Parts Melted to Heater Block
Is there an existing strategy for how to support the hot end while it's outside of the printed enclosure and heating?
RE: Parts Melted to Heater Block
perhaps a metal tray with an air gap below it to prevent heat transfer
make sure you dont short circuit the heater wires
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Parts Melted to Heater Block
I use a silicone baking sheet, but a glass pie pan would also work well
RE: Parts Melted to Heater Block
Thanks! I wound up using a small cooling rack for cookies, did the trick:
(sorry if this is sideways, not sure why it shows up like that when I place it)
I'd call the following print at least 80% successful:
I did run into some issues after this though and am wondering if they're related to the hot end reassembly I did or not:
- The print finished but the edges had peeled up away from the build plate in some spots. A little higher up there's a few layers that seem to stick out from the side, making a raised ridge that goes around the print. Did the part warping upwards, away from the build plate, cause this issue in the layers?
There was also some warping on a secondary part that was trying to print above the larger part. It's just a disk that was hovering in space slightly above the large part (show above). There was a pretty weird rippled texture to the top of it as well:
- Despite having some support geometry in the G-Code I got a pretty hairy area. It seems like the support material for this area maybe broke off from the build plate early on, leaving the area unsupported, and leading to the printer depositing strands of filament in random areas (material that was supposed to be deposited onto the support geometry had nothing to grab onto so would wind up sticking out at random areas elsewhere)
- The print was still usable and I figured that maybe, if I just did a better job putting in support material, I would be fine. I just tried starting a much simpler print, one with no overhangs, and I seem to be coming back to the original issue that started this whole thing: no filament coming out and a clicking sound. When I went to "unload filament" and the hot end got up to temp I couldn't remove it, it seems to be stuck again. I have another clog it seems. Any thoughts as to the cause? Any further information from me that would help?
Thanks again!