SOLVED Hemera and cheap TPU (without oil)

Discussion in 'HotEnds & Extruders' started by johny, Mar 3, 2020.

  1. johny

    johny Member

    Jan 20, 2020
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    I recently installed a Hemera onto my Sidewinder X1. As per the instructions I updated the firmware, adjusted the VREF and performed PID tuning. I've been successfully printing filaments such as PETG and PLA with great results and I thought it was time to try TPU. I purchased the cheapest TPU filament I could find and my first couple of attempts resulted in clogging within a few minutes. When I removed the filament I found that a bulge had formed in it, as described elsewhere on this forum. I was reluctant to oil the filament as others have suggested as I believe this just masks the problem. Instead I experimented and, after a couple of prints, I got some success.

    I am using a 0.4mm Nozzle X, but I don't think the printer or the nozzle really matter in this case (although the Nozzle X can require up to 10C more than the stock nozzle). I've also made some modifications to the spool holder and part cooling fan duct but, again, I do not believe these make any significant difference.

    For slicing, I am using Cura with its 'Generic TPU 95A' material settings and the 'Fine' profile. This includes the following settings by default:
    • Heatbed: Off - The recommended bed temp of the cheap TPU filament is: Off
    • Print cooling: Enabled (100%)
    • Initial fan speed: 0 (off for first layer)
    • Layer height: 0.1mm
    • Inital layer height: 0.3mm
    The only settings I modified in Cura were:
    • Extruder temp (Printing Temperature): 230 (the default was 228, which should've worked too) - The recommended extruder temp of the cheap TPU filament is: 190 - 210
    • Retraction (Enable Retraction): Off (If you do use retraction start with 0.5mm distance and never exceed 2mm. The Cura default is 6.5mm!)
    • Print Speed: 20 mm/s
    Theses settings improved the result of the following prints. The first few layers went down well, but it still failed at around the hour mark.

    The final piece of the puzzle was to adjust the tensioner:
    • Tensioner: Backed off completely (i.e. first click)
    With the tensioner backed off completely, I have successfully completed several flawless 5 hour prints.

    It is possible that some of the settings listed above could be adjusted (such as increasing the print speed), but these settings will hopefully offer a starting point for others.

    If you try this, please share your findings.
    #1 johny, Mar 3, 2020
    Last edited: Mar 6, 2020
    Controllore and Luis Montalva like this.
  2. Luis Montalva

    Luis Montalva New Member

    Aug 22, 2020
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    Worked perfectly for me on cr10v2 with the hemera. Finally printed without any issues. Thanks!!!!!
  3. Controllore

    Controllore Member

    Sep 29, 2020
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    Tried this after so many attempts that ended up in air printing...
    Cheap unbranded TPU, layer height 0.2, speed 80mm/s, temp 225 - everything else as the OP did. Thanks for the heads up. So the tensioner seems to be the crucial detail here. The print was only slightly more than 2 hours but still... it finished and it was as good as it could be. Previous attempts always jammed within the first 3-4 layers.

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