Loving My TC

Discussion in 'Show-off ur skillz' started by Andy Cohen, Dec 30, 2019.

  1. Andy Cohen

    Andy Cohen Well-Known Member

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    I was about to start playing with PVA as a dissolvable support using Simplify3D's Dense support capability when I had a thought...
    Dissolvable support can be a major pain. The stuff soaks up the ambient moisture and goes out of tolerance SUPER fast which makes it very expensive. AND... The only use cases where dissolvable support is really needed are where the material cannot be removed because it's within the object structure. But... What if one uses two materials which do not bond? Like say PETG and PLA???
     

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  2. Paul Arden

    Paul Arden Well-Known Member

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    Very true, most of the time you’d use it just to get that great surface and make removal easier, the number of times you’d use it for crazy internal structures (like that spinning thing that Ultimaker always show) is likely pretty minimal.

    That’s a very cool test, and of course those materials are massively cheaper than PVA/BVOH. You definitely couldn’t do this with a mixing system like Palette or single nozzle system like Prusa MMU but the Toolchanger, no problems. Great use case!
     
  3. Andy Cohen

    Andy Cohen Well-Known Member

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    The above example is my own design from Fusion360. But what about all the use cases of objects I print from an stl?
    So next I took a try at using Simplify3d's dense support extruder setting. I put the separation to 0 and the density to 100%. This should give me PLA right up against the PETG object which in turn won't bond. Theoretically a smooth overhang result.
    Major fail. The separation never gets to 0. Theres a gap between the object and the support. Also S3d draws the surface of the dense supports really poorly. Thick lines. Yet another thing in S3d which does not actually work.
    I tried supports in meshmixer. I could not get it to work reliably in actually placing the supports.
    Now I'm trying my own supports by Boolean removal of the object from a basic shape (using netfabb) then cutting the basic shape down to minimal.
     
  4. Paul Arden

    Paul Arden Well-Known Member

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    Does S3D have a soluable specific support setting? PrusaSlicer has a specific profile for soluable which puts 0 separation in (there is also one for interface soluable which just uses the alternative filament in a small piece between to ease removal, but since PETG and PLA are both relatively inexpensive that’s probably not needed.

    I’d guess Cura would also have something decent for soluable, pretty surprising that S3D doesn’t, well actually, given the lack of significant updates I guess it’s not actually that surprising.
     
  5. Andy Cohen

    Andy Cohen Well-Known Member

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    Actually it was not S3d, it was me. S3D lets you set the regular supports to a tool and the dense supports to another tool. Turns out the gap setting was in the regular support area and not the Dense Support Area.
    After some settings hacking I was able to get S3D's Dense Supports to 100% and 0 gap. So I tried it with a VERY difficult shape for supports in PETG with PLA for the supports.
    The result is the attached pic.
    Not a perfect surface, but a heckalot better then the best break away support I've ever seen.
    I'll be trying a bunch of different material combos. IMG_6226.jpg
     
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  6. Greg Holloway

    Greg Holloway Administrator
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    Cura soluble support generation should work pretty well for this.
     
  7. 1013D

    1013D Active Member

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    the one down side of support material that does not stick at all to the primary material is the same down side of trying to print on a bed that your material will not adhere to. The material can curl up and stick to the nozzle and pull away as it is printing. I experimented in the past with "3DP overmolding", that is pausing the print, inserting a steel part, and then printing over it to encapsulate it.....I ended up adding some glue stick to the metal so that the material printed on top of it would stick (like a secondary print bed basically).....This might be a concern with your setup.

    Ideally a small amount of sticking to the support material would be good....You could try a fiber filled PLA. then the other material might adhere to the fibers that will slightly stick out. of course that defeats the cost benefit aspect.

    If only PVA glue came in a paste extrudable format...then you could use a syringe style extruder for the support material, and it would stay sealed most of the time so moisture issues should be minor.
     
  8. Andy Cohen

    Andy Cohen Well-Known Member

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    Yah, I found that out real quick. When using PLA for supports on PETG all supports have to start at the bed and not on top of the object and the PETG or it won't work. But that's easy to work around in many cases.
    One big take-away I found from playing with this is that the pattern used by S3D for the 100% dense supports makes for a patterned surface. You can see it in the pic I posted above. No doubt one would get that with dissolvable material too.
    So I tried again with my own supports. I made a support block in Netfabb. I then stuck the object on to the block and booleaned it out of the block making the block my support. Printed the support block as a separate object on one tool the main object the other. The result was a WAY cleaner surface then using Dense support. Much smoother... not perfect though. Certainly not as clean as the Fortus or Mojo. Rats.
     
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