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Sanding, smoothing, post-processing

Discussion in 'General Questions' started by OutsourcedGuru, Jun 14, 2017.

  1. OutsourcedGuru

    OutsourcedGuru Active Member

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    I'm currently working with PLA, for what it's worth.

    I recently put some parts and a few rafts into my rock polisher for 24 hours to see if I could do some post-processing like that. I tried a variety of dry materials and slurries (including toothpaste) but honestly, saw no positive result. (One attempt with some recycled rock grit polish merely stained the plastic so that was no good.)

    I'd like to revisit this with better abrasives. Was thinking sand, glass beads (from sandblasting media), diatomaceous earth, pellet pins, shot/B.B.'s and baking soda, basically anything harder than the plastic itself.

    Tried using sandpaper but it doesn't feel to me like the sand itself is hard enough for the job. Haven't tried wet-sanding, though. Haven't tried compounding cream yet.

    Ideas?
     
    #1 OutsourcedGuru, Jun 14, 2017
    Last edited: Jun 15, 2017
  2. WheresWaldo

    WheresWaldo ☚ (<‿<)☚
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    OutsourcedGuru likes this.
  3. mark tomlinson

    mark tomlinson (⌐■_■)
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    For metal infused filaments (CopperFil, BronzeFil, Magenetic Iron, etc.) a rock tumbler with metal screws works wonders (brass screws for bronzelfil and copperfil, steel ones for iron/steel). Run it for a day or so.
     
    #3 mark tomlinson, Jun 14, 2017
    Last edited: Jun 15, 2017
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  4. Geof

    Geof Volunteer Moderator
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    straight PLA no fills use xtc 3d (or some other epoxys, some work the same as xtc) or sand and filler primer. :D
     
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  5. OutsourcedGuru

    OutsourcedGuru Active Member

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    Brilliant stuff. After polishing, I think I'll flash a thin zinc layer on top of an exotic filament (using that method) then see if I can electroplate either copper/silver on top of that. (I have maybe twenty lead/acid batteries here from an earlier project.)
     
  6. OutsourcedGuru

    OutsourcedGuru Active Member

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    I'm liking this approach. You start with filament which includes metal (hopefully increasing the internal/external conductivity of the part), this allows the tumbled media to give up some of their coating, you attempt to "fix" that somehow without losing the conductivity and then you can plate on top of that.
     
  7. OutsourcedGuru

    OutsourcedGuru Active Member

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    I've seen the XTC in action. It reminds me of some of the work I did with acetone in the plastic manufacturing plant (we used high-density polyethylene there. Check out some of those (huge) parts in the gallery we did.

    For whatever reason, I'm not in love with painting plastic (unless it's that Iron Man suit). ;)
     
  8. mark tomlinson

    mark tomlinson (⌐■_■)
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    We did some electroplating tests and you can find the thread here on this forum. We were messing around with copper plating (mostly because it is the least toxic chemicals)
     
  9. OutsourcedGuru

    OutsourcedGuru Active Member

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    Ultimately, I envision creating 3D parts with their own internal wiring. I watched this video by Disney Research that I found really inspiring. So I hope to get some pause-at-x style of plugin going soon so that I can (at least at this stage) just drop into the middle area of a part the internal circuitry but later, I'd like to actually 3D print that, too.

    If I can at least 3D print a copper-infused "run", post-process that to be externally conductive, plate that with more copper... I now have one of the internal runs for the circuit (in my mind at least).
     
  10. OutsourcedGuru

    OutsourcedGuru Active Member

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    IMG_0115.JPG Bought some of the exotic PLA filament today. And last night at Barnes & Noble, got inspired by a variety of metal coin packs which somebody had done up in bronze, copper, brass and "gold".

    So I think I'll do up some copper PLA coin halves in ultra-high resolution with an empty space in the middle for an actual penny (to add some weight). Next, I'll "glue" them together with melted PLA to trap the halves together. Then, they'd go into the tumbler for a few days with the tumbling media and finally, they'd go into a copper electroplating bath (or brushing).

    The theme would be a Harry Potter knut to see if I could get something awesome-looking. Pretty sure I had lots of these at one time, having ordered some online.
    Harry-potter-gringotts-bank-coin-collection-by-noble-collection-collectibles-us.jpg
     
  11. mark tomlinson

    mark tomlinson (⌐■_■)
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    The Brassfill/Copperfill infused filaments look absolutely awesome after a good stretch in the tumbler with copper or brass nuts/bolts/screws/etc.

    Copper electroplating we also did and while more of a pain it also works fine. You want to paint the PLA with some graphite infused in substitute MEK.
     
  12. mark tomlinson

    mark tomlinson (⌐■_■)
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    We have a thread on here somewhere showing some copper electroplating we did on PLA a while back. It needs to run a good long time to get enough plating to look its best, but it is certainly feasible.
     
  13. OutsourcedGuru

    OutsourcedGuru Active Member

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    By the way, the brass-infused filament is looking beautiful so far. Pretty excited about these exotics. yep, yep...
     
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  14. Pilsnerboy

    Pilsnerboy New Member

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    Good for you then.
     
  15. Ed Ferguson

    Ed Ferguson Active Member

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    I have a Raytech magnetic pin polisher (broken at the moment with a bad motor). It does an awesome job on small parts - burnishes metal to a mirror shine. The stainless steel pins get inside and polish the smallest of crevices. Would be fun to try on an infused filament part.
     
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  16. OutsourcedGuru

    OutsourcedGuru Active Member

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    Wow, I never thought about using moving magnets for this particular application. I just happen to have some pharmaceutical magnetic stir bars that you'd use in a carboy (which they discard here after a single fill/finish job). I'll look into this, thanks.
     
  17. Ed Ferguson

    Ed Ferguson Active Member

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    Because the motor burned out on my little magnetic polisher, I started building a large one similar to this:



    Mine differs in that I'm using an aluminum battery box (made for race cars) for the enclosure, and a cast aluminum disk to hold four round disk magnets. The poles of the four magnets alternate. What the video above does not show is that the container normally is filled part way with water & powdered soap.

    Anyway, I thought this might be a good technique for metal infused 3D parts. It won't smooth rough surfaces, but the burnishing action will polish metal (and get inside crevices) without using greasy compounds.
     
  18. OutsourcedGuru

    OutsourcedGuru Active Member

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    Alright, I'll make one of these. The spin bars are very strong magnets but I guess I'll need to add four more opposite-polarity permanent magnets at 60 degrees. I just bought a bunch of brass-, copper- and bronze-coated small screws from Ace Hardware for this and I'll see if those gyrate any in the magnetic field.
     
  19. mark tomlinson

    mark tomlinson (⌐■_■)
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    Those will work wonders in the tumbler :)
     
  20. OutsourcedGuru

    OutsourcedGuru Active Member

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    I do have a spare power supply from a computer, lots of dead hard drives (bad discs with working motors), I know how to cheat the ON switch on the PSU and I have lots of magnets of various kinds. It might be worth a go just quickly Gorilla-gluing some to the top of the disc to see if I can make the screws dance through the bottom of the rubber tumbler. Could probably rig up a potentiometer to the 5V line on the motor to try to adjust the speed.
     

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