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Second Extruder as PVA?

Discussion in 'Mods and Upgrades' started by OutsourcedGuru, Aug 4, 2017.

  1. OutsourcedGuru

    OutsourcedGuru Active Member

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    Daniel got me thinking about this on the shoutbox. I'm thinking that if I run with Mark's 2nd extruder upgrade, work up my own double-switch filament run-out upgrade and buy some PVA and Simplify3D...

    ...that I can use S3D's insert-a-PVA-layer option for the tops of supports (and between raft/part) and suddenly I've got much cleaner parts that I'm producing.

    Assumptions:
    * No heated bed at the moment since this is still a stock C2
    * The PVA works in the 160-180°C range so that's not a problem
    * This wouldn't require two STL files, right?
    * I'm noting the LCD hiccups that Mark saw regarding the 2nd extruder temperature

    Is this as easy as it seems?
     
    #1 OutsourcedGuru, Aug 4, 2017
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    It requires an STL designed for multiple extrusion (you can see that sometimes as two STLs, one for each extruder).
    If you are only going to make the supports a different material then you are probably fine with ANY STL file.
     
    #2 mark tomlinson, Aug 4, 2017
  3. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    We have not had a chance to go back and finish up our experiments with the second extruder, but I see no reason why this would not be workable. It is on our plate to get back to it as soon as our shop relocates :) Everything is packed up at the moment.
     
    #3 mark tomlinson, Aug 4, 2017
  4. OutsourcedGuru

    OutsourcedGuru Active Member

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    I'm trying to take advantage of that new S3D v4 feature. Assuming that the red is in the left extruder and the PVA is in the right and you've got the single STL of the dog, doesn't S3D just make magic happen here?

    Optimized-Soluble-Supports.jpg
     
    #4 OutsourcedGuru, Aug 4, 2017
  5. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Have not experimented with that at all, but once I get the printers relocated I'd be happy to play with it.
     
    #5 mark tomlinson, Aug 4, 2017
  6. Geof

    Geof Volunteer Moderator
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    You can assign 2nd extruder to supports or infill or whatever in s3d. The saving pva while only using a little bit on the model is a novel idea but youd better have a extreemely dry enviroment otherwise the spool will go bad before you use half of it.

    All that said...i design a 2nd model for "support" most time that literally touch the model so its perfect when removed.

    Pva is expensive and often not worth it IMO. There are jobs that need it but if your designing your models design in a way that doesn't need supports
     
    #6 Geof, Aug 5, 2017
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  7. OutsourcedGuru

    OutsourcedGuru Active Member

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    For example, I'm printing the replacement filament run-out switch box right now. I know the flat ("for show") side of the part will be the least pretty but that's just how it needs to be printed or it will be a nightmare for supports. So I'll then need to do my standard post-processing with a clothes iron and wax paper to make that prettier.

    Note of course that I don't have a heated bed and I have to use a raft at the moment. (I've tried numerous times but I just can't get adhesion and 1st-layer happiness without one.)

    I get that PVA is fussy but I could create a dry enclosure for that I'm sure, (similar to the one on Thingiverse).

    It just seems a shame to me that this printer is capable of creating super-smooth surfaces but I'm thwarted with raft-separation problems. And then again, maybe this is Cura and S3D would lay down a better transition.
     
    #7 OutsourcedGuru, Aug 6, 2017
  8. Geof

    Geof Volunteer Moderator
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    Even with a cold bed if the first layer settings are correct pla should stick no issue without a raft. If the part is seperating off the raft look at your seperation distance, its to high.
     
    #8 Geof, Aug 6, 2017
  9. Geof

    Geof Volunteer Moderator
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    Pva is much more difficult than a dry box but by all means dont let me discourage, just be sure to get small spools of it to experiment with. There are other breakway materials that work well as well.
     
    #9 Geof, Aug 6, 2017
  10. OutsourcedGuru

    OutsourcedGuru Active Member

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    I'm currently troubleshooting to see if I have a leveling problem. The start of a raft (as produced by Cura) always starts in the left/front corner, lays a left-to-right front line, runs to the back, runs right-to-left, runs to the front corner again and then each u-shaped bend in that front/left corner peels away. I routinely then hover over the print and try to smash it down flat immediately before it's completely solid.

    It doesn't do this on the right side nor the back. It's always that front/left corner.

    (This doesn't have to turn into a troubleshooting session, btw.)

    All in all, it's like the entire bed is higher on the right side versus the left. I frequently push in the magnetic pieces under the bed to make sure that they're "bottomed out". If not, I get more pronounced problems in this area.

    Is it dialed in? I think so. The first layer looks pretty, flat across its face... I'll keep watching things, though. I'll try to pick up a replacement bed to see if that was the problem.
     
    #10 OutsourcedGuru, Aug 6, 2017
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  11. OutsourcedGuru

    OutsourcedGuru Active Member

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    Alright, have tweaked the startup GCODE (thanks for the advice) and it's now starting first layers from the initial lay-down. It was that it retracts too much after printing the priming line and wasn't waiting long enough for the 210-degrees to come down to 190-degrees.

    I now have my second hotend assembly (thanks, Robo) @ 19V and another filament tube, etc. I'll get the bowden stepper from PS. I have a variety of plugs/connectors from digikey. Got some connector specs from Allen and saw the new Robo R2 print bed design which looks sexy enough.

    I'll try to work up a 2nd-extruder-as-PVA solution first since it seems to me to be low-hanging fruit as compared to two-color printing.
     
    #11 OutsourcedGuru, Sep 15, 2017

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