Hemera TPU fix

Discussion in 'HotEnds & Extruders' started by Mk4ever, Nov 9, 2020.

  1. Mk4ever

    Mk4ever New Member

    Nov 9, 2020
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    I've had my Hemera for months, and it was working great with TPU, among other kinds of filaments, until yesterday. TPU was severely under-extruding, so I increased the temp, which worked for minutes, until it stopped extruding TPU all together. PETG kept printing fine.

    I read all the TPU threads here and elsewhere, but none had a real solution. So I started troubleshooting.

    I'll keep it short and save everyone's time. My 2 observations:
    1. The Hemera heartbreak was partitially blocked. Cleaning it reveals most of what was stuck was TPU, as it was elastic. I only retract in my prints, and with TPU I use 1.5mm. It could be the reason, but a small price to pay for the many fine prints I did with minimal stringing and no issues even at high speed. Cleaning it allowed the Hemera to start extruding again, but didn't fully solve the problem. TPU kept under-extruding. PETG looked perfect now though.
    2. I noticed then how before entering the Hemera, my PETG was obviously thicker than my TPU, and my TPU kept stopping nearly half the time. Both are sainsmart. I measured PETG, near perfect 1.74. My glow in the dark sainsmart TPU though was a shocking 1.30. It still could slip with a bit of pull even at the tightest tensioner setting. I switched to my blue sainsmart TPU, it measured 1.6, and performed significantly better, no more skipping, but not the perfect extruded thickness. I switched to a TPU sample from spool3d, and it measured 1.72. It extruded just like PETG. I went back to the glow in the dark sainsmart TPU, skipped 2 metres to a 1.6 section, and it performed way better than the 1.3 section, no more skipping, but still under-extruded, so thickness was still an issue. No wonder I had to increase my multiplier significantly for TPU..

    I love sainsmart, and they offer TPU colours almost no one else offers, but I guess the recommendation I read here to avoid sainsmart has a good reason. Their pro PETG is still top notch in my opinion, but their TPU's tolerance, not good.. I won't stop using it, but I'll pay more attention to it's diameter from now on.

    By the way, my nozzle is a 0.6 tungsten carbide from spool3d, to handle any abrasive filaments, so I knew that wasn't my issue here.

    I created an account just to post this, hoping it would help someone.
    mtngeek likes this.

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