Hi,

I am hoping someone may be able to help me here. Whilst trying out ABS, the filament broke part way through a print and for a while the printer was running with no filament feed. Whether this caused the ensuing problem I do not know! But I had a major nozzle clog and could not clear it. So I ended up dismantling my Mk8 Extruder. I have cleared out the blockage but have found that there is a piece of white tubing in the threaded pipe that is between the nozzle and the extrude mechanism. Clearly the base of this (at nozzle end) became too hot and both shrunk as well as burnt (see picture). This piece of pipe is 22mm long; 4mm diameter and 1.75 internal diameter. I guess it is intended to allow the filament a friction free passage to nozzle. I also guess it is high temperature plastic as it must be almost touching the nozzle (and is enclosed by the threaded pipe that is threaded onto the heat block. Any ideas what the pipe is and where I may get some?

Thanks for any help.

http://jheadnozzle.blogspot.com/2013/11/is-j-head-real.html

Probably PTFE (teflon) tube, as used in the genuine J-head and as a filament feed tube on Bowden extruder setups.....

It could also be PEEK... but it's essentially the same problem.

The liner is a high temperature plastic that, even though it's melting point is higher then the nozzle temperature, it still tends to wear out and become an issue as the nozzle ages.

As of right now, you can avoid this by going to an all metal hot end, or you can just replace the whole hot end assembly with a new, cheap j head.

Personally, I think it'd be more worth while to work on ceramic and glass connectors between the cold end and the hot end so that the teflon liners could be phased out completely without phasing in all metal pieces that require fans and can cause issues with prints, especially with high temperature materials like nylon.

Need to get myself some glass working materials....