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I know that you need a special nozzle to extrude abrasive filament (carbon fibre, copper, ...). I do have such a nozzle (coated steel) and am printing carbon fibre and copper filament. Last time I used it to print carbon fibre PLA. It worked well, however when I removed the nozzle from the hotend I realized that I could no longer screw the non-abrasive nozzle in (the dirt cheap 0.1$ china nozzles that work well enough for most materials) and the thread of the hotend was completely loosened up.

I had been working on a few other things with my printer, so I am not entirely sure what caused the thread to become loose, but I was wondering, are there some requirements to the hotend excluding the nozzle when printing abrasive filament?

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  • $\begingroup$ Empirically speaking the answer is yes. Printed a few millimeters of copper filament and immediately the hot end was completely messed up $\endgroup$
    – Yanick Salzmann
    Oct 9, 2021 at 19:17

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Abrasive filaments require a stronger nozzle indeed. They also require an all-metal hotend. If your hotend wasn't all-metal, there's a good chance you've damaged it.

The PEEK/PTFE in your hotend doesn't like going above 240 Celsius and tends to be irreparably damaged if used too long above 250 Celsius.

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  • $\begingroup$ Interestingly my PTFE tube has been working well for very long periods of 260° polycarbonate printing, but it probably never got this hot near the PTFE tube. My hotend is all metal, still the threads the nozzle is screwed in somehow wear out almost instantly... $\endgroup$
    – Yanick Salzmann
    Oct 11, 2021 at 19:25
  • $\begingroup$ my orginal v6 with ptfe tube is printing with 285° (PC CF Blend) for about 40 hours straight - no problem at all. $\endgroup$
    – Rufinus
    Oct 19, 2021 at 9:09
  • $\begingroup$ @Rufinus The tube isn't the problem, it's about the lining in the hotend. The heater block. $\endgroup$
    – Mast
    Oct 19, 2021 at 14:07
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The hotend itself consists of basically 3 parts:

  • The filament path, aka Coolend. It consists of the heartbreak, cooling solution and anything up from it.
  • The heater block, that holds everything together
  • The nozzle, in which the filament melts and is pushed out.

The part of the hotend assembly that gets to be in the most contact with the particles that are inside the abrasive filament is the nozzle through which the molten polymer gets out. Unless you have heat creep and the filament melts in the heartbreak, it is the only part that ever will encounter the abrasive particles even.

Since even the most abrasive filaments come as rather smooth filaments, only the nozzle needs to be special. Hardened Steel will hold some kilos, while people printing a lot of carbonfiber filled material swear on ruby nozzles.

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  • $\begingroup$ It is really weird, when I use my stell nozzle and print just a little bit of abrasive filament the thread in the metal hotend the nozzle is screwed into becomes loose and is essentially no longer threaded... $\endgroup$
    – Yanick Salzmann
    Oct 11, 2021 at 19:26
  • $\begingroup$ That sounds odd, as the threads are outside of the heartbreak. Or do you mean the part comes loose? You need to hot-tighten nozzles before use: heat to 240°C, then tighten the nozzle against the heartbreak. Only then print. Btw, if you print something higher temperature than ABS, your hot-tighten temperature goes up $\endgroup$
    – Trish
    Oct 11, 2021 at 20:16

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