Hemera Under extruding and jamming/gauging filament

Discussion in 'HotEnds & Extruders' started by neushdw, Dec 10, 2019.

  1. neushdw

    neushdw New Member

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    around 12 prints tested so far trying to adjust idler spring tension from 0 to fully compressed and cannot get even a short print such as a benchy to finish printing without firstly under extruding and secondly ceasing to extrude at all as the filament gets gauged out or slips first then gauged.
     
  2. Greg Holloway

    Greg Holloway Administrator
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    Hi,

    What material are you printing and using what settings?
     
  3. Tony MacDonald

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    For PLA I simply slid the filament in a pre-heated printer head and slowly tightened it until I couldn't pull the filament up anymore without using the release. No need to crank it down.

    As for the jamming... Make sure you selected the correct thermistor setting when you set up your firmware to use the new hotend. If not, then your temps are going to be wrong.

    Secondly, you are going to have to fine tune your eSteps/mm as the measurement given in the manual only gets you in the ball park. For me it was 404 but the only way you will be sure is to heat up your print head and then use a ruler and a sharpy to put a line on your filament. Measure from the top of the filament entrance in to the extruder. I usually make a mark at 20mm. Then extrude 20mm of filament. If your eSteps are correct then the light should stop just before it goes in to the extruder. If not, edit your eSteps until that is the case. Good boards will allow you to do this from the advanced configuration section of the board but make sure to save your settings when you get it right. I use the TH3D Ezboard lite in my CR-10s and love it!.

    At this point you should be able to do the rest of your fine tuning in your slicer. Make sure to start with your retractions at .2mm and don't go over 2mm per the little instruction card that came with your extruder. You should be able to get a print to succeed at this point.

    Hope that helps.

    Greg's right though, If your going to ask for help, you should really post your current setup so that we have something to work with.
    There are way to many different variables involved to assist to any level of accuracy without it.

    Regard,
    Tony
     
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  4. scott mckenzie

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    I'm getting under extrusion and i'm struggling to get a setting that works. I have done over 50 test prints in the last 2 days and i'm still no closer than when I started.

    It's not under extruding all the time, just at the start of a layer/line, like there is a delay in the flow of material. This would normally be tuned out with an extra prim amount, but it seems to be inconsistent. It may be ok for the first 2-3 mm of a part then not for the next 4-5mm. At times it seem to both under and over extrude on the same print. This is clear to see as I also use a specified Z seam that runs from the bottom to the top of a part in one line.

    Setup
    Material:
    Colorfabb PLA
    Printer: Custom build, E3D Hemera, Duet Wifi.
    (I sell printed parts with this material and setup so know the machine is sound and I have been over the whole machine. It has produced literally thousands of parts (3000+) over the last couple of years with the previous Titan and V6 Combo)
    • PID tuning completed so temperatures are very consistent.
    • Step per mm set to 395 (Measured with 100mm extrude test)
    Settings tested:
    • Retraction on and off
    • Temperatures: 190 - 220c
    • Print speed: 10 - 60mm/s
    • Retraction: 0.2 - 2 mm
    • Retraction speed: 10 - 60mm/s
    • Extra Prime 0.05 - 1mm
    • Prime speed 1 - 60mm/s
    • Layer height 0.1 - 0.2mm
    • Combining on and off

    The closes I got was with a really slow prime speed of 1-2 mm/s. So slow y
    ou could literally see the head pause for a second on each prime of the nozzle. This brings its own issues.

    The attached image shows my the results so far from the hermera (Left) and the previous results with the Titan and V6 setup (Right).
    Sample.jpg
     
  5. Greg Holloway

    Greg Holloway Administrator
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    Can we have photos of the Hemera too please. There is a common issue with the idler tension being too low.
     
  6. Jai Stanley

    Jai Stanley Well-Known Member

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    Also: do you run pressure/linear advance, and have you remembered to re-tune of so?

    I needed numbers in the order of 0.6 for my Bowden, 0.2 for my BMG direct drive and 0.05 for the hemera with a PETG.
     
  7. Paul Coombs

    Paul Coombs New Member

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    Have you tried with a little more motor (extruder) current ?
    I too struggled at first, until up-ing from the pancake stepper value
     
  8. scott mckenzie

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    Have never need to with Titan but will look into it.
     
  9. scott mckenzie

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    Idler was quite low so I adjusted it and re-run the same file, the print was much better (Image 4). Then i move onto the next part and the same issue was there again (Image 1).
     

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  10. scott mckenzie

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    You can see clearly on the holes that it not starting with enough flow.
     

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  11. Greg Holloway

    Greg Holloway Administrator
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    do a test run of 100mm of filament see if it is easy to stall the motor.

    retraction should be about 1.25mm.

    what slicer are you using?
     
  12. scott mckenzie

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    It's not easy to stall the motor at all, its the one thing its really good. current set at 1A

    Retraction is currently set at 1.5mm and it using Cura.
     
  13. scott mckenzie

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    May be onto something now. Just spent the entire day tweaking and even completely redone the config file.

    When watching the first layer go down closely you can see that it starts the skirt perfectly. Then the perimeter go down perfectly, but as soon as it move over to do other features, a small amount of plastic oozes out and it under extrudes when it starts again. I disabled combing to force it the retract every time and now its perfect.

    I going to run the previous part tonight and see it has solved it.

    Additionally I'm wondering if this problem has been made worse due to the polyphobic coated on the nozzle X that is fitted. Plastic oozes much more freely on this nozzle than a brass one, Just a thought.
     
  14. scott mckenzie

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    Problem solved.

    It was due to the oozing during travel moves that did not use retraction. This is why no matter what retraction settings were used there was no change, because it was not cause by retraction.

    The only way I can overcome this issue if to use retraction on every move, not the best solution but it works well. I cant see how this can be the extruder itself, so I'm going to blame the nozzle. I'll swap over to the a standard brass nozzle and see what happens.
     

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    #14 scott mckenzie, Jan 2, 2020
    Last edited: Jan 2, 2020
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  15. Greg Holloway

    Greg Holloway Administrator
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    I use retractions for any travel movements further than 2mm. Good work finding the problem!
     

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