How to remove E3 hotend for filament jam

My new MK3 jammed and stopped extruding filament. I cannot clear the jam by feeding new filament into hotend or by clearing nozzle. I suspect the jam is at the heatsink to thermistor/heater joint.

How do I remove the entire E3 hotend from the printer without dis-assembling the entire assembly?

Also, I have seen other users asking for help with jams on the MK3 with similar symptoms. I had a slump of filament above the hotend, below the Bondtech pulley.

Is there any consensus on the cause? My printer is in an enclosure, so my first thought is that the hotend heatsink is getting too warm and softening the filament before it should.

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Sorry for the out-of-focus bit.

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@jakoob I have found the problem. The PTFE tubing within the hotend has a flaw in it. I do not know if it happened before assembly of the hotend or was caused by something else.

First let me suggest that as you write the instructions for disassembling the E-axis assembly, have the users remove the heater cartridge and the thermistor from the heat block (see E3D instructions here ).

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Having the wires separate from the hotend makes it much easier to disassemble the E-axis assembly and remove the hotend from the Prusa Extruder body. Also, step 18 of the Prusa E-axis assembly instructions is very difficult in reverse. The heatsink of the E3D V6 hotend snaps into a printed ridge on the Extruder body. When I removed it, a portion of the print broke off from the Extruder body.

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The E3D V6 hotend has a collet that retains the PTFE tube within the hotend. Mine is broken, with one of the four tabs snapped off. It was inside the heatsink. The E3D instructions show a blue collet clip that locks the collet in place to keep the PTFE tubing from retracting from the hotend. My printer does not have this collet clip.

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The problem that kept the filament from extracting or moving forward was that the PTFE tubing has some sort of flaw in it that is slightly darker than the white PTFE, as seen in the photo. Filament cannot pass this flaw. I have no idea what caused it. The Prusa I3 MK3 printed fine for several print jobs before this happened.

If Prusa uses the E3D collet clip, them mine was missing from the beginning.

I am going to need a replacement collet and PTFE tubing before I can reassemble my printer. I will see if E3D has replacement parts.

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Hi Gene, guides for parts replacement are on its way, but it will take some time. It is great to see you managed it yourself, thumbs up ;) Regarding the PTFE tube contact E3D or our support (info@prusa3d.com). The local jam can be caused by a filament, which is stuck there. Let me know if you need more help.

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Hi Gene, I have the same problem with my MK3 which has printed flawlessly since I received it over 3 months ago. Having to tear down the extruder/hotend assembly to fix this was not on my "favorite things to do" list but it's the only way to correct the problem. However, now I'm stuck not being able to remove the hotend from the PETG Extruder bracket (without breaking the bracket). Does anyone know how to remove the hotend from the bracket without breaking it? I could not find any documentation on this.

Update: I was able to get the hotend out without breaking the bracket but getting the PTFE tube out of the hotend is not going to be easy either...I sure hope this doesn't happen again - lol. I did order the Capricorn XS series PTFE (with a collet and retainer clip) from E3D which will hopefully last longer than the one that came with the printer. I am not looking forward to putting this thing back together.

Update #2: getting the clogged PTFE tube out of the hotend was much easier than I thought...holding the heater block in a vise or adjustable wrench (being very careful not to stress the wires) then unscrewed the heatsink. Once the heatsink is separated from heat block, it was easy to push the clogged PTFE tube through the heat sink and pull it all the way out. There was a piece of filament about 30mm long stuck at the top of the PTFE tube. The top of the PTFE tube is pretty mangled and definitely needs to be replaced. BTW: Although my collet was not broken, there was no retainer clip installed in my MK3 either. This might be by design but I'll wait for PRUSA to explain that.

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Jeff- Agree with all you wrote; found out from Jakub that Prusa does not use the E3D retaining clip to hold the collet in the locked position. Mine has been fine since I replaced the PTFE tubing, although I continue to struggle with filament blobs just below the extruder gear and above the PTFE tubing.

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Hi Gene,

to disassemble the extruder (to get to the hotend), please use the Chapter 5 from the MK3 assembly.

Start at the end and proceed with the opposite direction of the steps until you reach the hotend.

Hotend disassembly guide is on its way. I will speed it up.

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Jakub,

Thank you for the reply. It appears that I need to work backward from step 45 to step 18. Should I remove the cables from the Einsey board and unwrap the cable wrap as well?

I am uncertain how far I need to disassemble to find the jam, as I don't know where it is.

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Hi Gene, it is better to unwrap about 4-5 cm of the spiral wrap from the extruder. It is then easier to move the front/hotend fan to the side.

Regarding "jam location" you must disassemble the hotend, but have you tried all the tricks described in the Handbook or here? https://help.prusa3d.com/l/en/article/WW...

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@jakoob I tried everything but inserting a 1.5mm rod into the hotend from the filament loading side (above). I don't have anything appropriate to use.

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Gene Simonalle will be eternally grateful.
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