retraction: can anyone explain it to me?

Discussion in 'Calibration, Help, and Troubleshooting' started by R Design, Apr 29, 2016.

  1. R Design

    R Design Well-Known Member

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    It's the start of the weekend.

    There are these two settings: retraction distance and retraction speed.

    And most of us have v6 and volcano nozzles to play with, and a range of different filaments.

    I keep thinking that they're really important settings that could change a lot.

    But have no idea how to optimise.

    Now with the arrival of the Titan, this should be a hot topic.

    What's the deal?
     
  2. Spoon Unit

    Spoon Unit Well-Known Member

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    retraction - pulling back the filament
    retraction speed - how quick to pull it back

    when retraction is on - if S3D calculates it needs it, it will retract prior to move, then refeed that same amount on arrival
    if you have extra restart distance it will add or subtract to the amount refed on arrival
    if you have z-lift it will retract, then lift, move, drop, refeed
     
  3. Spoon Unit

    Spoon Unit Well-Known Member

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    ram purge is a technique to purge the nozzle

    the idea is to extrude at a high enough speed to get coldish filament all the way to the bottom of the nozzle then retract it quickly enough to get it out of the melt zone before it does melt
    this is not managed by the inbuild S3D retraction system, but as part of a script (tool change script)
     
  4. R Design

    R Design Well-Known Member

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    Thanks!

    So the default s3d PLA profile settings were, I think, 1.6mm and 75mm/s.

    I've heard people insisting on much lower - or hoping for much higher - numbers for the speed? I've heard people changing them according to the type of filament: and some people just leaving them the same? Some people think it's important to adjust... others see no difference?
     
  5. Henry feldman

    Henry feldman Well-Known Member

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    By the way for the Taulman3D filaments they post settings for retraction given how exotic some of their materials are...
     
  6. R Design

    R Design Well-Known Member

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    Interesting.

    On the other hand I've heard people say that for a v6 nozzle - kind of irrespective of filament - a certain retraction configuration is appropriate.

    It's a mystery!
     
  7. Henry feldman

    Henry feldman Well-Known Member

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    Oh, I've found that different materials (due to elasticity, etc need more/less retraction) in my limited experience so far on the BB.
     
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  8. R Design

    R Design Well-Known Member

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    A while ago on G+ I asked RichRap what he considered to be "good retraction".

    He just posted the following reply:


    Richard Horne
    +R design I hate to say it all depends, but... If using an E3D V6 for example, I never - ever go over 5mm retraction, even in a Bowden system. 'Normal' would be 1-2mm.

    And speed really depends on what torque and gearing you have set - and how tightly clamped it is. Try to go as fast as you can without slipping or grinding. I'm not happy with an extruder retraction if it's not over 32mm/sec and I try to make them always go at least 40mm/sec.

    As little retraction as you can get away with and as fast retraction - and that to me is 'good retraction'

    Other people may have a different strategy, but that's what I do.



    Here's the post:

    https://plus.google.com/u/0/100264134938466402588/posts/YN8AdyWNGni?cfem=1
     
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