Does lost foam work for bronze?

Discussion in 'Lost foam casting' started by Tops, Aug 7, 2022.

  1. Tops

    Tops Silver Banner Member

    Just wondering, someone else making a boat part somewhere else on the interwebs.
    Part would need a couple cores otherwise.
    Thanks!
     
  2. Monty

    Monty Silver

    It's used for Iron, so I don't see why not. Should work better than aluminum because of the higher density, pour temp and thermal capacity.
     
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  3. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Though I've done lot's of aluminum LF, never bronze, but it is done routinely by art casters.

    Best,
    Kelly
     
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  4. Tops

    Tops Silver Banner Member

    Thanks! In this case I think it would reduce the pattern making costs from 1 split pattern and 2 coreboxes to 1 pattern that could be CNC'd in two halves, glued, sprued, dipped, etc...

    swiftsure_shoe.png
     
  5. Tops

    Tops Silver Banner Member

    I poked around on YouTube too and found some lost foam and bronze videos, including a couple from members here.
    Thanks again!
     
  6. Tobho Mott

    Tobho Mott Gold Banner Member

    I've done it but had some issues. Make sure your sand vibration is on point, maybe even lay some weights on the surface of the sand to prevent sand float defects when using denser alloys and/or or wider patterns. It's no fun cutting up a failed casting that's an inch and a half thicker than it was meant to be, just so it'll fit back in the crucible...

    Jeff
     
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  7. Tops

    Tops Silver Banner Member

    Thanks Jeff. I saw your belt buckles on YouTube.
     
  8. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Jeff makes a good point that higher density alloys make good vibration and packing more important. Positioning the pattern with less projected area toward the surface, placing the pattern at a greater depth in the flask, and/or weighting the surface (if vacuum is not used) will help prevent sand float since these alloys are denser than the mold media. What are the approximate dimensions of the part LxWxH?

    Best,
    Kelly
     
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  9. Tops

    Tops Silver Banner Member

    Thanks Kelly. I have asked for dims.
     
  10. Tops

    Tops Silver Banner Member

    Note from the OP on the other forum/thread:
    Total Length: ~230mm
    Width: ~65mm
    Height Forward: ~115mm
    Height Aft: ~65mm
    Thickness Around Keel: ~10mm

    Volume: ~38 cubic inches
    Weight: ~10lbs
    (These are with the bore for the rudder stock but no mounting holes)

    I won't have anything more accurate until I can get a hold of the shoe itself in a couple weeks but hopefully this is close enough.
    I would also like to ask if you can provide any input on material selection. I've found some very affordable ingots online of Everdur (C873), though it is sold as a sculpture material. That said the Port Townsend Foundry lists it as one of the bronzes they use for marine fittings. If you have any thoughts on this I would appreciate it.

    Here is a quick redo of the sketch, numbers check out +/- whatever I guessed on:

    cd99_2.png
     
    Last edited: Aug 10, 2022

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