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Any experiences with dual extrusion and PVA?


foehnsturm
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Posted · Any experiences with dual extrusion and PVA?

It looks like printing PVA is kind a nightmare. I managed to get good printbed adhesion and to print slow enough to get reliable results. Also I learned that fans are a no go.

But once PVA support starts on top of a PLA surface there's virtually no adhesion. Hey that's the main use case why I would consider using PVA ...

Any good advice?

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    Posted (edited) · Any experiences with dual extrusion and PVA?

    Hmmm... maybe the adhesion between PLA and PVA can be influenced with the thickness of the first PVA layer? Please don't ask me how to do e.g. a thin first PVA layer on top of PLA with the current software but it might be interesting to see if this is a way physically anyway.

    Maybe rising the ambient temperature helps? Are you currently printing with an open printer at room temperature? What about a heated chamber for that purpose?

    Just ideas...

    Edited by Guest
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    Posted (edited) · Any experiences with dual extrusion and PVA?

    No real solution yet. So far:

    Forget slicer created supports. Just make up a simple box shape and do a bolean subtract with the part. Use the remaining as support.

    PVA doesn't stick to PLA. So, if you print PVA on top of a PLA surface make sure it isn't an island but instead connected to some PVA structure nearby. It will still curl up and need some millimeters height to recover.

    I don't use stuff like priming towers. In this case there had to be to separate towers because of the poor adhesion I think.

    Edited by Guest
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    Posted · Any experiences with dual extrusion and PVA?

    I have heard PVA doesn't wash off that easily as well. Have you experienced this?

    I guess you wouldn't want PVA to melt into the PLA as it could dis-color it?? if this is the case then the adhesion between the two would be a difficult balance to allow it to stick but not melt into it.

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    Posted (edited) · Any experiences with dual extrusion and PVA?

    It takes some time but it mostly washes off by itself. But hidden cavities are difficult to clean completely.

    P1080661.thumb.JPG.f227b88f1bed6866ed53dc0226bc77a0.JPG

    Edited by Guest
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    Posted (edited) · Any experiences with dual extrusion and PVA?

    Overhangs are ok. Surface is a little rough even on vertical walls. The adjacent PVA affects the PLA surface. Should use an offset shell operation next time before subtracting the part, so there's some gap in between.

    P1080675.thumb.JPG.f9b86fd4545c051eb008b63e916fe23f.JPG

    Edited by Guest
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    Posted · Any experiences with dual extrusion and PVA?

    hmm.. I thought PVA should have some bond with PLA.

    Have you tried different types of PVA, could there be a difference?

    Have you tried your PVA with ABS? Is there a difference?

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    Posted · Any experiences with dual extrusion and PVA?

    Faberdashery PLA & Scaffold

    Support could be removed very cleanly within 5 mins. The print shows impressive surface quality at overhangs.

    propeller.thumb.jpg.ebe1e4a7e7b62300dde60787574dab9c.jpg

    P1090178.thumb.JPG.224dfe14f70291e6acf106d21e1f210e.JPG

    propeller.thumb.jpg.ebe1e4a7e7b62300dde60787574dab9c.jpg

    P1090178.thumb.JPG.224dfe14f70291e6acf106d21e1f210e.JPG

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    Posted · Any experiences with dual extrusion and PVA?

    Can you please add a picture from below... that't the interesting side... ;)

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    Posted · Any experiences with dual extrusion and PVA?

    from below

    P1090182.thumb.JPG.eb6a1c5a1743286c0089b6ae5bd74fba.JPG

    from above

    P1090184.thumb.JPG.67462e2d884acf67fb0b70cf54585fcc.JPG

    P1090182.thumb.JPG.eb6a1c5a1743286c0089b6ae5bd74fba.JPG

    P1090184.thumb.JPG.67462e2d884acf67fb0b70cf54585fcc.JPG

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    Posted · Any experiences with dual extrusion and PVA?

    Looks really nice... thank you. I guess you had no gap between PVA and PLA?

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    Posted · Any experiences with dual extrusion and PVA?

    I set the distance to 0.05mm

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    Posted · Any experiences with dual extrusion and PVA?

    Was that the results of some tests or just an educated guess? I could imagine it looks better than if one would leave no gap.

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    Posted · Any experiences with dual extrusion and PVA?

    Probably the hardest thing I ever printed was a propeller.  This one came out very very nice!

    PVA prints up to about 170C which is probably not hot enough to melt the PLA below it. Consider maybe covering the top and front of the machine such that the PLA is at it's glass temp? Not sure if that will help as then you need even more fan.

    Maybe instead turn off the fan while printing PVA? And turn the fan back on when printing PLA?

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    Posted · Any experiences with dual extrusion and PVA?

    Maybe instead turn off the fan while printing PVA?  And turn the fan back on when printing PLA?

     

    That's one of the feature requests I have for new Cura. The other one is a dedicated printing speed setting for support bottom layers (especially those on top of PLA). But I'm still collecting ...

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    Posted · Any experiences with dual extrusion and PVA?

    This looks promising for the first time, thanks @gr5 for bringing up the temperature aspect. Now printing Scaffold with 215°C instead of 195°C (E3D claims it's good for 190-220)

    Fingers crossed ...

    PLA-Scaffold.thumb.jpg.cb9da87813df9cfe15930c548bae341b.jpg

    PLA-Scaffold.thumb.jpg.cb9da87813df9cfe15930c548bae341b.jpg

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    Posted · Any experiences with dual extrusion and PVA?

    ... and still collecting feature requests:

    I had to set support / horizontal expansion quite high (3mm) otherwise support would sometimes start with super tiny blobs on a slanted surface (which don't stick at all). Obviously now all support structures are inflated but the intention is to modify only the tiny ones.

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    Posted (edited) · Any experiences with dual extrusion and PVA?

    ... worked out somehow. Don't ask about the ugly surfaces, I took it from GrabCad and it's not designed for 3D printing.

    P1090194.thumb.JPG.a7171808eee5f1da5a2af9efc284c5db.JPG

    This one is pretty easy

    P1090200.thumb.JPG.8234bac52b0e0e142c5bde49464da35b.JPG

    P1090202.thumb.JPG.f38ec477fc7d5bf2a0d751b664bc2350.JPG

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    P1090202.thumb.JPG.f38ec477fc7d5bf2a0d751b664bc2350.JPG

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    Posted · Any experiences with dual extrusion and PVA?

    Trying a real challenge now ;)

    Support starting on a curved and slanted surface and inside the tube as well

    cura-pipe.thumb.jpg.6583512dab706bb876230c50af95b0c6.jpg

    cura-pipe.thumb.jpg.6583512dab706bb876230c50af95b0c6.jpg

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    Posted (edited) · Any experiences with dual extrusion and PVA?

    For some reason Scaffold extrusion is not that consistent (maybe I should disassemble the feeder...). But besides this it could become a success. Btw, the two support structures on the left aren't  connected, the upper one just starts on top of the pipe.

    pipe1.thumb.jpg.5e06fbd410c954185edb4b292733718a.jpg

    P1090226.thumb.JPG.eb543d0d28cdf2a6bd5a66707dc55cb4.JPG

    pipe1.thumb.jpg.5e06fbd410c954185edb4b292733718a.jpg

    P1090226.thumb.JPG.eb543d0d28cdf2a6bd5a66707dc55cb4.JPG

    Edited by Guest
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    Posted · Any experiences with dual extrusion and PVA?

    P1090232.thumb.JPG.628ecf3eb18b088a8a72860c4cf20323.JPG

    P1090241.thumb.JPG.49687d07b893cb9f2dc7b099b5a7c936.JPG

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    Posted · Any experiences with dual extrusion and PVA?

    >Now printing Scaffold with 215°C instead of 195°C

    In your photo with the support on top of the tube - it looks like it worked, right? Was it simply raising the temperature?

    Are you using your crossflow fan still? Or is this tube a "zero fan" print?

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