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Extrution issue at different speeds  

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Sven
 Sven
(@sven-9)
Active Member
Extrution issue at different speeds

Hello,

i have very ugly blobs at my prints. (MK2S) That's why I've looked at the amount of extrusion.

I am trying to calibrate the amount of extrusion. But I found that the amount of extrusion is dependent on the speed.

Example:
The GCODE extrude 94mm of filament: G1 E100 F150
and the GCODE extrude 90mm of filament: G1 E100 F300

These values ​​are reproducible on the mm. What could be the reason?

I have checked the following things:

  • The extrusion gear have no play.

  • The contact pressure is neither too strong nor too weak. I think.
  • I hope someone can help me and understand my bad english.

    Greetings
    Sven

    Posted : 10/07/2017 12:48 pm
    PJR
     PJR
    (@pjr)
    Antient Member Moderator
    Re: Extrution issue at different speeds

    Did you reset the extrusion before each test?

    G92 E0

    Peter

    Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

    Posted : 10/07/2017 2:25 pm
    Sven
     Sven
    (@sven-9)
    Active Member
    Topic starter answered:
    Re: Extrution issue at different speeds

    Hello Peter,

    thanks for your answer.

    No i don't reset the extrusion before each test.
    Why should i do this? I'll test it.

    Sven

    Posted : 10/07/2017 2:48 pm
    Sven
     Sven
    (@sven-9)
    Active Member
    Topic starter answered:
    Re: Extrution issue at different speeds

    It makes no difference at all.

    Posted : 10/07/2017 2:59 pm
    PJR
     PJR
    (@pjr)
    Antient Member Moderator
    Re: Extrution issue at different speeds

    In that case, the only reason why you would get different feed lengths is because the filament is not feeding properly.

    The same number of motor steps is being issued in both cases. Either the extruder motor is missing those steps (unlikely at the speeds you are using) or something is preventing proper feeding.

    Maybe the grub screw on the drive pulley is loose, the filament feed is impeded, the tension is wrong or the temperature is too low.

    Peter

    Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

    Posted : 10/07/2017 3:04 pm
    Sven
     Sven
    (@sven-9)
    Active Member
    Topic starter answered:
    Re: Extrution issue at different speeds

    Hello Peter,

    I know however the speed should not be too high, that the stepping motor loses steps. Also the grup screw in the pulley is not loose. I use 220°C with PLA and the tension is according to instructions (1cm springs). Have also tried other tension already.

    Sven

    Posted : 10/07/2017 3:12 pm
    Sven
     Sven
    (@sven-9)
    Active Member
    Topic starter answered:
    Re: Extrution issue at different speeds

    What is the default value?

    161,30 steps per Unit?

    Posted : 10/07/2017 3:29 pm
    Sven
     Sven
    (@sven-9)
    Active Member
    Topic starter answered:
    Re: Extrution issue at different speeds

    Okay, it seems as if the speed was too high. With 50 and 100 the exact same value now comes out.

    Posted : 10/07/2017 3:37 pm
    PJR
     PJR
    (@pjr)
    Antient Member Moderator
    Re: Extrution issue at different speeds

    300mm/min is 5mm/sec, which is 12mm^3 per sec, just over the maximum melt volume of the E3D if you have the nozzle attached.

    Of course, when calibrating the extruder, the nozzle should be removed...

    Peter

    Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

    Posted : 10/07/2017 4:14 pm
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