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PTFE inside hotend moves up over time resulting in filament getting stuck inside hotend.

Jan 13, 2019 1:16 pm

Everyone and then my Filament will require a sharp pull to remove. Nothing too strong, but you can feel the resistance when you try to remove it. On my printer it seems to be catching the lower end of the PTFE tube and pulling it up over time. I confirmed this by checking the extruded gears and the PTFE top is visable just below the gears. Now that’s I’ve seated the tube the PTFE is about 1-2mm lower. Still visable but barely. Now is there a way to stop this happening? I’ve been printing with pretty much no issues at all since delivery. I’ve attached a picture of the filament once I disassembled the hot end.
Thanks for the help.
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78739327-2BDA-4788-9524-7E1950E43706.jpeg (2.42 MiB) Viewed 73 times
101BB370-A63C-46FF-BDA1-0D74DB8A6DC9.jpeg (2.48 MiB) Viewed 73 times

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Joined: Nov 16, 2018 6:52 am
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Re: PTFE inside hotend moves up over time resulting in filament getting stuck inside hotend.

Jan 14, 2019 9:04 am

1. You can make the filaments easy to remove if you ALWAYS first let it melt and extrude a few mm before having printer unload the filament. Melting and extruding a bit gives you a fresh, soft filament end that cleanly comes out. You can do so via the setup menu. Heat up your extruder and then advancing the e-axis. This prevents formation of thick filament ends.

2. You can also add a collet clip to help lock down the PTFE tube. Prusa doesn't include one, but you can print one out of PETG. Adding the collet clip requires removing the entire extruder. Once removed, push down the PTFE until it full seats. Pull up the collar while continuing to push down the PTFE tube. Slip your locking ring under the collar to hold the collar in its up "engaged" position.

(Unrelated to Your Main Issue)
BTW, please check the axle pin of your extruder idler. It looks like one pin end is flush with the outer edge of the mount. The supplied pin is a bit short and typically must be positioned with both ends recessed to solidly engage BOTH sides of the mount.
axle pin.jpeg
axle pin.jpeg (1.07 MiB) Viewed 44 times

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