CNC Foam cutter

Discussion in 'Composites' started by Foundationer, Apr 4, 2019.

  1. Apr 10, 2019 #21

    ScaleBirdsScott

    ScaleBirdsScott

    ScaleBirdsScott

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    I've not used it with foam in a long minute, but for sticking aluminum sheet to the spoilboard of the CNC router, 3M Super 77 is readily available and cheap. I'm pretty sure if I dig into my memory holes that it was the choice stuff to use for bonding foams, so light contact spray on one side might get you enough positive adhesion while not making it a permanent, stronger than the foam itself, bond.
     
  2. Apr 10, 2019 #22

    ScaleBirdsScott

    ScaleBirdsScott

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    As for CNC hotwiring, I would love to have one. It would do great for generating specific shapes and potentially using them as a first step in a CNC process. If there was a good way for such a machine to generate more complex curves I'd be interested. As it is, a CNC router that can plow through foam and 3D surface with a ballmill isn't a hard task to tackle once one has figured out the steps to make this sort of CNC hotwire.
     
  3. Apr 10, 2019 #23

    BJC

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  4. Apr 11, 2019 #24

    poormansairforce

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    When I built foamies I built a 6 wire slicer to give me five 1/4" pieces out of a 2" panel held down by vacuum. They came out perfectly flat and straight since the heat was on both surfaces. Otherwise it warped a lot! Cutting both sides simultaneously would be a huge benefit.
     
  5. Apr 12, 2019 #25

    Foundationer

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    In the end I just put a big bit of wood and some weights on top of the block of foam and that did the trick! Next up gluing the foam to the MDF and facing it with polypropylene. I should probably start a build thread...

    It did occur to me that it's possible to hotwire cut a foam vacuum table pretty easily. Just take a block of foam the size you want, glue one side to some MDF, make a hole the size for your shopvac, cut grooves at 25mm spacing in both directions with the hot wire, fill the ends and TADA! Or just put some old plasterboard on top ;)
     
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  6. Apr 12, 2019 #26

    Vigilant1

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    Since you've got this very nice rig now, I wonder if a vibrating wire could be fitted in place of the hotwire to allow it to cut other materials (PU foam, PVC foam, giant blocks of cheese, etc). A wire dipped in adhesive then into sandblasting grit might be able to cut all kinds of stuff.
    A little motor with a flywheel and an eccentric shaft on one end of the wire and a spring on the other end might do it.
     
  7. Apr 12, 2019 #27

    ScaleBirdsScott

    ScaleBirdsScott

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    Interesting thought. So, if you had something that could vibrate at ultrasonic frequencies and was very fine, wouldnt it just zip right through all sorts of things?
     
  8. Apr 12, 2019 #28

    Foundationer

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    Surely you'd make it a loop, dip it in an abrasive and then pull it through like a really thin bandsaw?
     
  9. Apr 12, 2019 #29

    Vigilant1

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    It might. I imagine it would take some experimenting, since material that is not firm enough would probably just jiggle/buzz with the wire and not cut. A bandsaw-like rig with wheels and a one-way loop of cutting wire would cut a wider variety of materials, have a taughter wire, and maybe not be much more work.
    Edited to add: Ooops, cross posted with Foundationer.
     
  10. Apr 12, 2019 #30

    ScaleBirdsScott

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    Yeah I guess once you get beyond the stiffness of, well, what an xacto blade offers, you're just trying to cut things with what's essentially a really high-pitch guitar string?

    Then again if it's got drivers on either side and they're pulling back and forth in a sort of micro oscillating manner maybe you'd get a very nice ultrasonic saw without the logistics of running a loop?
     
  11. Apr 12, 2019 #31

    PiperCruisin

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    I saw the parts list, but it was unclear what is supplying power to the hotwire and how is it being controlled. I figured I would use a variac, but not sure if that is really controllable so wanted to get some more details.
    Thanks
     
  12. Apr 12, 2019 #32

    Foundationer

    Foundationer

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    Ah. That's just a cheap variable power supply. Though the RAMPS board can do it too if you want to go down that route.
     

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