Hot end holder melting and sagging?
I noticed that the hotend holder melting near the tip. It looks like it's sagging and seemed to be a little loose. Anyone else encountered this?
I mainly print in PETG at 240 degrees.
RE: Hot end holder melting and sagging?
Another pic of it.
RE: Hot end holder melting and sagging?
Wild guess here: You use an enclosure?
RE: Hot end holder melting and sagging?
Looks like a lot of heat and dirt. Your heater block was also covered in plastic at least once 😉
If your extruder is still fits firm and not moving, I would keep it like that. PETG just melted a little bit. You could use a silicon sock to prevent this and I think Prusa already updated this part and made it a little bit thicker.
You can also reprint this part in ABS/ASA/PC to withstand higher temperatures.
Often linked posts:
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RE: Hot end holder melting and sagging?
And watch for the PINDA sag, too. Somewhere there is a redesign of the MK3S to R4, that is supposed to help.
RE: Hot end holder melting and sagging?
Get the R5 versions of the extruder
body and back. My Pinda sensor
was leaning probably about 20
degrees off vertical. For extra
protection I printed the replacements in
PC. You'll also probably want to print
some spare fan shrouds.
RE: Hot end holder melting and sagging?
Darn... I'm really hoping that I don't have to disassemble it and reassemble it again...
RE: Hot end holder melting and sagging?
That light gray stuff is from the PETG thermal degradation. The overheated portions and the areas on which the off gassed material are depositing are both gray. Where it has deposited a thin film, you can wipe away with IPA, but the overheated portions are permanently changed.
Hot fins are another solution for avoiding full tear downs. Small, easier to print, separate pieces in high temp material can be swapped out in minutes. Despite the BNBSX being quite resistant to high temp degradation, it still includes hot fins as part of its design.
Even if you want to stay close to stock, bunnies have a version of the MK3S R4 with hot fins on Thingiverse. One may as well gain that option if one has to do a rebuild anyways. If you can't print in high temp plastics, you can also print several sets hot fins in PETG and swap them out. Not as good as PC or ABS hot fins, but you save yourself from another tear down.