1.2mm nozzle extrusion fail

Discussion in 'Volcano' started by sungod3k, Jun 25, 2016.

  1. sungod3k

    sungod3k Active Member

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    Hi,

    I recently strapped my e3d Volcano nozzle on my printer with a bondtech double drive gear extruder and tested the 0.6 and 1.2mm nozzle. and while the 0,6 worked very well, the 1.2 is showing some interesting extrusion.

    [​IMG]
    As you can see the first 20mm (middle of the picture) are a nice thick bead, perfectly squeezed out, but after that it almost starts blobbing. The filament feed stays constant at 20mms and the same pattern emerges in Cura and Simplyfy3D. The nozzle is not obstructed, not are there any other weird sounds. I would understand that there is something wrong if it starts coming out blobby but the first 20mm looking right really puzzles me. Only if I slow down to 10mms I get decent extrusion.

    Any ideas where this could come from?

    Cheers
     
  2. sga

    sga Member

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    Maybe avoid chewing the filament before feeding it to the extruder...
    No seriously.. I am thinking that it might be that the teeth of your extruder might be marking your filament too much and what you see is a oscillation in nozzle pressure due to the fed filament section variation.
    If you think about it your extruded diameter is not very different from your input diameter.
    I guess you wouldn't notice with smaller nozzle because the pressure in the nozzle is higher and it would even out in time
    So maybe reduce the force on the filament hub to reduce the marking I guess with large nozzle = lower pressure, a lower grip would work.
    you can see how much your filament is marked by feeding a bit in and taking it back out.
    Please consider this as a suggested theory I don't have any experience with your problem.
    the first 10-20mm would not be marked if you feed in the wire manually so that could explain your observations, I suppose you have a direct extruder not a bowden.
     
    #2 sga, Sep 23, 2016
    Last edited: Sep 23, 2016
  3. sungod3k

    sungod3k Active Member

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    I dont think thats it. I have a bondtec extruder with two drivegears to reduce the pressure on the filements and divide it between them.
    I actually tested a 3d solex nozzle and that enables me to print 30mms. So its a heat distribution issue as far as I can tell now.
     
  4. sga

    sga Member

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    I checked the bondtec extruder it has drive gear to reduce the ratio / torque on the motor but there is still only 1 hub so the pressure on the filament is what you actually set with the little screw. nothing to do with the ratio or gears...
     
  5. sungod3k

    sungod3k Active Member

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    Sry I meant hobbed bolts. and the V3 is actually spingloaded. So there are two hobbed bolts gripping from both sides. The teethmarks on the filament are actaully really small because the hobbed bolts have more and smaller teeth.
    even with pretty big teeth on your hobbed bolts the blobs thats it would cause should be much smaller.
     
  6. sga

    sga Member

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    ok good luck
     
  7. mike01hu

    mike01hu Well-Known Member

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    Are you using 1.75mm or 3mm filament as there is not much latitude between the nozzle size and the filament diameter for 1.75mm, so any drive configuration starts to have an increased effect. For example, gear engagement will produce minor variations in drive as each tooth contacts its mate and this will make a noticeable change in the flow pressure. I think others prefer 3mm filament for large diameter nozzles.
     
  8. sungod3k

    sungod3k Active Member

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    Update: I tested with a normal block and a 3d solex nozzle that claims to print up to 30mm³/s and even if my bowden tube doesnt handle the pressure at least the blobbing goes away with setting up to 20mms. I think I could reach 30mms with a better bowden clip (which im owrking on now)
     
    mike01hu likes this.

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