Hemera gears seizing mid print.

Discussion in 'HotEnds & Extruders' started by Zakm0n, Dec 26, 2019.

  1. Zakm0n

    Zakm0n Member

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    Got my Hemera from Filastruder and managed to get off some great 5+ hour prints, but for no reason, my gears have started seizing. I've ruled out a filament jam, because when it stops printing, I can remove the filament manually by pulling the tension lever back, and the extruder will still refuse to move until I loosen then re-tighten the screws holding the body of the extruder to the stepper. Anyone else seen this issue?
     
  2. kswaid

    kswaid Member

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    I started having similar issues after about 50 hours of printing. The extruder would randomly miss a step here and there for no reason, which continued to worsen until it completely stalled. After messing around a bit I took the Hemera apart 15 minutes ago and found two teeth had partially broken off of the pinion gear. The gears also look very rusty, but that may simply be dust from it trying to grind the broken teeth.


    Chipped teeth hemera.png
     
  3. Jai Stanley

    Jai Stanley Well-Known Member

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    How hot does the motor or your motor driver get? You might have the motor current too high, or even low?
     
  4. Impact

    Impact Member

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    First of all a shout-out to the fine folks at E3D I was blow away by Hemera performance on my CR-10.

    I made exactly the same observation, when dissecting my Hemera after roughly 1 week of service:

    My printer started to produce under-extrusion, then stopped completely.
    First assumption was a clogged nozzle, but manual feeding worked fine.
    I saw that the pinion gear came loose and is free spinning on the stepper Motor shaft.
    Strangely the gears seem to have a bit of corrosion like you mentioned.
    Maybe something wrong with this batch?

    I am expecting a replacement part from the reseller, hoping I will not encounter this again.


    IMG_6033.jpg IMG_6037.jpg IMG_6038.jpg

    Kind regards from Germany.
     
  5. John Ashby

    John Ashby Member

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    I have the same problem, managed about 3-4 hrs of prints all small, I have just printed out a test cube with no problem, then it stops on the next print, or part way through a larger print.
    Starts under extruding then just stops, if you pull out the filament and put it back in it will work again for a bit.

    Its not the stepper motor heating up, they are fairly constant I check with a laser thermometer.
     
  6. Zakm0n

    Zakm0n Member

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    Definitely not a current issue. Looking at the big gear, I can see some misalignment, like the gear isn't square to the face of the motor.
     
  7. John Ashby

    John Ashby Member

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    My unit is only 3 away from yours 21591
     
  8. Impact

    Impact Member

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    That doesn’t sound like a coincidence to me.
    Let’s hope it’s only a small batch showing these kind of issues.

    To my understanding the stepper motor nominal torque should be well below the mechanical strength of the gears/shaft. Temperature also measured ok, not even warm to the touch, therefore I would rule out too high currents (I am running TMC2130).
     
  9. Impact

    Impact Member

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    Hi Zakm0n, could you please provide more details about your observation? I assume you refer to kswaids picture?!?

    One more Thing: When I received my Hemera-kit the the thumb-wheel gear was so perfectly put into the socket and squeezed against the pinion gear, I couldn’t pull it out by hand (didn’t have to, so I left it where it was). Maybe this fit was too tight from factory?

    How about your Hemera “tightness” at arrival?
     
  10. John Ashby

    John Ashby Member

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    Mine was wound up tight, I found that it clicks if it isn't as loose as it gets, maybe that's wrong being loose
     
  11. Zakm0n

    Zakm0n Member

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    When I disassembled mine, the big gear was also VERY tight against the drive gear. My gears aren't corroded at all though. Batch 2259-3 here
     
  12. yngndrw

    yngndrw Well-Known Member

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    Are these gears meant to be greased? I couldn't see any mention of this in the assembly guides.

    There doesn't seem to be any adjustment for the clearance between the motor's pinion gear and the large drive gear, so my guess is that they are intentionally tight in order for them to wear their own clearances. It's probably a good idea to disassemble and clean them after a small amount of initial useage, then re-grease them.

    Edit: Just noticed that the blog entry for the Hemera mentions that lubrication is not required as the whole drivetrain is made from "hardened stainless steel". I'm not buying it though - Hardened stainless steel against hardened stainless steel will still wear so I'd use grease myself.
     
    #12 yngndrw, Dec 31, 2019
    Last edited: Dec 31, 2019
  13. MarkN

    MarkN Member

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    I have the same issues. Tonight I'll examing the gears as well. Let's see if I can find the box with the batchnumber.
     
  14. Impact

    Impact Member

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    Happy new year to everyone.

    I received The spare part yesterday, so far only difference seems to be the QR-Code. Will do the testing this evening and keep you updated.

    Edit: The broken one is on the right.
     

    Attached Files:

  15. kswaid

    kswaid Member

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    Similar to what others have said my gear set was extremely tightly meshed. It was very hard to remove the drive gear when I disassembled the extruder. My batch code is 2256-6.

    I am sending my Hemera in to E3D for replacement and they are going to inspect it closely. Hopefully it was simply a one-off issue during manufacturing.
     
  16. JoeyD

    JoeyD New Member

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    I think I have the same issue. Looking back at my prints I can see underextrusions occuring at an increasing amount while printing my second vase, so after only a couple of hours of printing.

    I've yet to receive any reply from E3D, any idea when they will be back from holidays?
     
  17. Joe Pomo

    Joe Pomo Well-Known Member

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    Thomas Sanladerer mentioned a similar problem with broken teeth in this video (@ 2:55):

     
  18. Wannageering

    Wannageering Member

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    One more with the same problem, no matter what I do after a short time my prints fail. Batch 2259-11 (24v).
     
  19. Maxbots

    Maxbots Member

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    I have two from batch 2259-4. Both are completely seized. I have not been able to feed a mm of filament. with the idler fully loosened, I can just barely get the unpowered extruder to turn using my thumbnail on the exposed edge of the drive gear, but it seizes when driven by the motor. Even a slight bit of tension on the idler and I can't even turn them manually.

    Pretty disappointed that no one from E3D has posted offering any guidance on the issue.
     
  20. Alpha418

    Alpha418 Member

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    Another batch 2259-11 (24V) over here.

    Just had mine completely lock up about 24 hours into a print. It locked up a couple of times during retractions but nudging the filament would be enough to get it going again. Tried adjusting the tension to no avail.

    So far I'm pretty disappointed in the Hemera. The poor documentation for both firmware configuration and the extruder mounts being incorrect for the model of printer I was installing it on (CR10S Pro) has left me pretty frustrated.
     

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