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[Solved] New Factory Assembled MK3s - Dropping Charred Blobs  

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RocketRob
(@rocketrob)
New Member
New Factory Assembled MK3s - Dropping Charred Blobs

Seems to be working well on shorter duration prints but If I print anything over 1-2 hours it collects molten filament around the hot end and drops charred blobs on the print where they harden.  Sometimes it falls either inside or outside of the print and other times directly on the print - setting up a crash.  I am using prusament Pla and prusa Petg and both materials are having this problem.
I need to pause the print every hour raise the extruder use a fine brass detail brush to clean nozzle/hot end to keep the print going and try to prevent a crash. - Please save me from being chained to my printer and cleaning it every hour 🙂

PLA has been 215 nozzle and 60 bed and Petg 230-240 nozzle and 80-90 bed temps..  

Help!

Best Answer by Alan B.:

This sounds like an issue with your hotend, most likely there is a gap inside the heatblock between the heatbreak and the nozzle, which causes filament to leak out and work its way up the threads and up over the top and sides of the heatblock and down onto your nozzle and print.  Have you by chance attempted to change the nozzle yet, or are you still using the nozzle they shipped your printer with?  This problem can often occur with an incorrectly installed/changed nozzle.

Posted : 19/03/2021 4:49 pm
Alan B.
(@alan-b)
Eminent Member
RE: New Factory Assembled MK3s - Dropping Charred Blobs

This sounds like an issue with your hotend, most likely there is a gap inside the heatblock between the heatbreak and the nozzle, which causes filament to leak out and work its way up the threads and up over the top and sides of the heatblock and down onto your nozzle and print.  Have you by chance attempted to change the nozzle yet, or are you still using the nozzle they shipped your printer with?  This problem can often occur with an incorrectly installed/changed nozzle.

Posted : 19/03/2021 5:34 pm
RocketRob
(@rocketrob)
New Member
Topic starter answered:
RE: New Factory Assembled MK3s - Dropping Charred Blobs

Alan,

Thank you for your reply - that makes perfect sense. Yes I changed the nozzle and I will go back and check it.

Again thank you!

Posted : 19/03/2021 5:40 pm
RocketRob
(@rocketrob)
New Member
Topic starter answered:
RE: New Factory Assembled MK3s - Dropping Charred Blobs

@alan-b

I think you nailed it!  As I have a tendency to be a bit ham fisted when tightening threaded fasteners and after reading about the fragility of the hot end, i think i erred  conservatively  and left my nozzle a bit loose. Would have never thought the molten plastic could work out through the nozzle threads? Backed up the hot end with a 17mm wrench and cranked on the nozzle a bit more, recalibrated Z and checked first layer settings  and I am 2 1/2 hours into a print with no indication of leakage.  Thank you so much Alan-b , I am very grateful for your help!

Posted : 20/03/2021 12:55 am
Clarmrrsn
(@clarmrrsn)
Honorable Member
RE: New Factory Assembled MK3s - Dropping Charred Blobs

@rocketrob

There is a very nice guide on changing a nozzle if it helps any.

https://help.prusa3d.com/en/article/changing-or-replacing-the-nozzle_2069

It is recommended to use a torque driver to set the nozzle to 2.5nm  I bought an adjustable screwdriver 1-5nm for this.

Tank you very much!...
Posted : 20/03/2021 9:54 am
RocketRob
(@rocketrob)
New Member
Topic starter answered:
RE: New Factory Assembled MK3s - Dropping Charred Blobs

@clarmrrsn

Great add - I was following the written 3D Printing Handbook. It does not list the torque settings  - as a licensed aircraft mechanic, I greatly value torque settings!     thank you

Posted : 20/03/2021 2:40 pm
Alan B.
(@alan-b)
Eminent Member
RE: New Factory Assembled MK3s - Dropping Charred Blobs

@rocketrob

Glad that I could help.   Yes any gap between the nozzle and heatbreak and the liquified filament will find its way out eventually.  Sounds like you've got it sorted now.  Happy printing!

Posted : 20/03/2021 4:25 pm
cwbullet
(@cwbullet)
Illustrious Member
RE: New Factory Assembled MK3s - Dropping Charred Blobs

@alan-b

It is a common finding - good printing!

--------------------
Chuck H
3D Printer Review Blog...
Posted : 21/03/2021 6:10 pm
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