Mold casting

Discussion in 'Construction' started by ish311, Feb 2, 2015.

  1. ish311

    ish311 Active Member

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    I have the materials to make a silicon mold and a vac chamber if i need it. I'm trying to cast turrets for my Shimakaze but having issues with making it hollow. anyone have any pointers on casting? or should i just do a split cast or put some sort of filler foam in the mold to reduce the weight.
     
  2. rcengr

    rcengr Vendor

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    I've used both foam and two part molds to do turrets. The foam works OK if you just want to reduce the resin used and make the casting lighter. But if you plan to arm the turret, it really needs to be hollow. I cast the first turret solid and then hollow it out with a Dremel. Put the hollowed out turret back in the mold and use it to make the second half of the mold. Of course you need some mold release so that it doesn't stick to the first part of the mold. Use some sharpened brass tubing to put holes in the second half of the mold for pouring in the resin and vents.
     
  3. rcengr

    rcengr Vendor

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    Top row: 1:96 US 5" secondary plug, mold, mold for foam insert, turret cast with foam insert.
    Bottom row: 1:96 Capitani Romani turret plug, mold, cast turret hollowed out, second half of mold, and cast turret. On this one I CNC'ed the inside of the turret out, which is why it looks so smooth. I also glued a wood dowel to it to form the pouring sprue in the center. The vent holes can be seen around the outside.
    molds.jpg
     
  4. Lou

    Lou It's just toy boats -->> C T D <<-- Admiral (Supporter)

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    When you hollow out the turret, have you removed it from the first part of the mold? If so, how do you stop the second coat of the mold from creeping in?
     
  5. rcengr

    rcengr Vendor

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    Yes, you do have to remove the casting from the mold before you can hollow it out. But with the silicone molds you can put it back in and it will be a very tight fit. If you get any silicone from the second part of the mold creeping in past the plug, it will be very thin and easily removed. Easy to remove if you have a good coating of mold release that is.