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I've got zits!!!!

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    I've got zits!!!!

    Hi All,

    Can anyone help me with my zits!?!

    I'm setting up a new machine.

    I'm using Cura 3 software on Linux, my printer has a Bowden setup with a tube about 500mm long. I have stopped stringing by using the retract function (4mm) but when it primes it over extrudes and produces a blob where it starts. I've tried many different settings including negative numbers in the "Retraction Extra Prime Amount" (which does not seem to do anything) I've tried many different values for the retraction, 0mm seems to create a very small under-extrusion, 1mm seems to make a very small blob in some places but under-extrudes in others but still has bad stringing, I settled on 4mm retraction but blobs are a real problem.

    I'm quite sure the Marlin firmware is setup carefully but perhaps I'm missing some mechanical issue??

    If your 3D printer is facing under-extrusion issues, it could be due to hoards of reasons. For instance, the diameters of filament and the one set in the slicing software does not match. Or it could be due to inappropriate slicer software settings.
    As a solution, ensue the filament diameter to be perfect and remove any form of debris stuck at the hot end.
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      Thanks for the reply steve3dprinters. I know all the mechanical settings are very correct, the filament is of good quality, the hotend is clean and flowing well. I've made some inroads in this issue. I've found the issue is not under-extrusion, it's when the X/Y movement stops the pressure in the Bowden tube pushes a bit more out before the extruder retracts. I'm using Cure as my slicing software and have found aligning the Z seam helps in removing the Z scar but I would like to remove the Z scar as much as I can through settings.

      Can you suggest anything that might help relieve the pressure in the Bowden tube before retraction? I've tried coasting but this just makes a mess.

      My results are much better now than when I first posted this but would still like to make it as good as possible.

      My future-self thanks you for any advice you haven't given yet...


        Sounds like you are suffering from ooze. You can add more retraction. I use 5mm on my Bowden-fed Anycubic i3 Mega.


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