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My printer is no longer printing tpu with the .35mm printhead. I've tried running the "cleaning filament" through my printer, but it just takes so much force that the filament goes anywhere BUT down the tube to the hotend. Any help here? at this point, i'm looking at replacing the nozzle and the PTFE tubing going to and in the hotend.

What temperature are you using to print this stuff with? I would look at replacing the inner liner of the hotend, and putting a new nozzle in. With ABS, you could soak a nozzle in acetone for a while to help clean it, PLA you'd have to burn it out. TPU?

TPU is IIRC, a flexible filament that is rubber-like. I suspect it may be that there is crud in the nozzle (Pull it, blow-torch, then acetone soak), or that the PTFE liner is crooked/cooked. I'd also pull that and inspect it. I would also look at your bowden tube for kinks, or your filament route for issues, if it isn't getting all the way to the top of the hotend at least before it gets very resistant.

But TPU, if it is a flexible filament, is indeed a challenging one to print, and the .35 nozzle makes it more-so. I assume you managed to get it working if you're saying it no longer does so. Has anything, such as the spool of filament or nozzle diameter changed at all?

Mac The Knife wrote:What temperature are you using to print this stuff with? I would look at replacing the inner liner of the hotend, and putting a new nozzle in. With ABS, you could soak a nozzle in acetone for a while to help clean it, PLA you'd have to burn it out. TPU?

I run TPU at 212, at 12mm/s using the Ninjaflex settings.

Xenocrates wrote:TPU is IIRC, a flexible filament that is rubber-like. I suspect it may be that there is crud in the nozzle (Pull it, blow-torch, then acetone soak), or that the PTFE liner is crooked/cooked. I'd also pull that and inspect it. I would also look at your bowden tube for kinks, or your filament route for issues, if it isn't getting all the way to the top of the hotend at least before it gets very resistant.

But TPU, if it is a flexible filament, is indeed a challenging one to print, and the .35 nozzle makes it more-so. I assume you managed to get it working if you're saying it no longer does so. Has anything, such as the spool of filament or nozzle diameter changed at all?

Yeah, it was working. the PTFE liner is pretty well cooked, it has a nice maple syrup color on both ends, and a curious area where it constricts in diameter. Can you go through what you mean by blow torch the nozzle, just so i don't melt a nozzle or something?

Remove the nozzle from the block, then use a brazing torch and some vice grips to burn/melt crud off. Wait for it to mostly cool, then put it in acetone. If it starts glowing or the metal changes color, stop heating it immediately. use only as much heat as you really need.

Issue was the PTFE liner. Replaced it, worked for 5 minutes then the hotend melted. Posted a new thread, if you can answer a question about any firmware changes that might be required for an e3d v6 hotend