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Extruder blocked solid 55mm from top of the PTFE tube  

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01Pad
(@01pad)
Trusted Member
Extruder blocked solid 55mm from top of the PTFE tube

Good morning,

I have recently replaced my hotend assembly with a new one from E3D specifically for my i3 Mk3S, having suffered the worst blob ever.

I have been printing for some time with a CHT 0.6 nozzle, which has allowed significant improvements to my print speed, and the new assembly has performed very well for about 2 months.

I have been swapping between PLA META black and white a lot recently, running at 194°C for the  first layer and 188°C for subsequent ones.

However, yesterday I fed in my filament to start a new print, and nothing extruded. The filament advanced up to the point where the double speed feed slows down to single speed, and then stopped. I checked when cold, with the gears disengaged, pushing filament in manually, and there is a solid block just at the end of the PTFE tube.

I heated things up, and tried a cold pull with Nylon, but nothing came out.

I couldn't get an accupuncture needle up the nozzle as it's a CHT one, and there are 3 copper tubes converging just above the hole.

A photo of barrier looking up the hotend thread after removing the nozzle is attached.

I heated up to 260°C and removed the nozzle – it was un-blocked in any of the 3 channels. I was still unable, even at that temperature, to remove the blockage from the hotend.

I have now removed the hotend, from the printer, and taken out the PTFE tube: there was a blob of filament at the end of it, but it was only loosely attached. With the tube back in place, I can advance filament 55mm down, and then it hits a barrier.

It has to be plastic (or what’s left over when you heat residual PLA META up to 260°C) but I am at a loss how to remove it.

I would be grateful for some advice on how to proceed.

Cheers,

Pad

Postato : 22/05/2024 10:47 am
Eef
 Eef
(@eef)
Reputable Member
RE: Extruder blocked solid 55mm from top of the PTFE tube

also unscrew the heartbreak from the cooling part (read manuals first, to not break anything).  Now you can reach the blob to push it out. 
when reassembling be sure the ptfe is cut correctly (45 degrees angle) so it will fit tight against the heartbreak. Push the ptfe gently in and down. While doing that pull up the colletring and push a clip underneath it(so it will not accidentally loosen and create same problem again. )

We will do what we have always done. We will find hope in the impossible.

Postato : 22/05/2024 11:59 am
Diem
 Diem
(@diem)
Illustrious Member

It reads like you will need a new PTFE tube ... open the extruder and heat 20° above printing temperature then feed filament by hand; apply a little force and with luck you will force the blockage out and the nozzle will run freely.  If not pull the filament out as fast as you can, trim the end and try again - several tries might be needed.

If all else fails remove the nozzle and burn out the residues with a butane torch.

Cheerio,

Postato : 22/05/2024 2:19 pm
01Pad
(@01pad)
Trusted Member
Topic starter answered:
RE: Extruder blocked solid 55mm from top of the PTFE tube

Thank you.

It was so solid even at high temperatures that I persuaded myself that it was something weird that had happened. When I got it all apart, it was just a clog. Not apparently burned - it was white, not black - but much more solid than I've seen before. With determination (and a bit of belief!) it all came apart quite well, and the printer is back working with minimal re-calibration, to my surprise.

So many thanks, you guys - problem solved.

 

Postato : 23/05/2024 9:58 pm
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