Large casting of skinny cap creates issues

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    • #1547
      Jean
      Guest

      Im trying to cast a cap out of resin for an industrial use tool.  There are some odd constraints and I need advice.

      The cap initially started as a 3D created piece.  Its 2 inches in diameter, 1.5 inches in height, and about 3/16 of an inch in wall thickness.  So far, pretty easy.  Now add a rectangular cutout of 1 inch by 1/2 inch centered in the top of the cap and a ridge about a quarter inch inside the interior that works as a locking mechanism and is only about 1mm deep and 3mm high.  The kicker is that the exterior of the cap must be consistent in thickness, smoothness, and shine.

      If I build a mold (I have been using Alumilite #2 silicon mold makng rubber) that puts the cap top at the bottom of the mold (giving me the consistency in thickness, smoothness, and shine I want), I havent been able to remove the part without destroying the mold because of the rectangular cutout.  If build the mold with the topside exposed for the pour, I lose the consistency necessary for the part.

      Is there a way to build the cap interior mold so that it can be removed from the exterior mold, rather like a a sink plug which can be removed before removing the new resin part?

      I am open to any and all suggestions.  I am bumfuzzled by the mold for this part.

    • #1548
      Katherine Swift
      Guest

      Hi Jean,

      Have you tried making this as a two part mold?

    • #1549
      Jean
      Guest

      Hi Katherine,

      No I havent tried a two piece mold.  Can you point me to some existing threads for pointers on how to build such, and maybe a suggestion of what sort of silicone to use for each part?

      Thanks!

    • #1551
      Jean
      Guest

      OMG!  Light Bulb!

      Thanks so much for the video link, Katherine.  That was too cool and right on the money.
       
      So, now I have to ask: Would you use: Alumilite Rubber to Rubber Mold Release, the Ultra 4 Polyester Parfilm Paintable Mold Release
       or the talcum used in the video, and which version of the Alumilite silicones would you recommend to use, as flexibility wont be as important as in the one piece mold.

      These things I need to know before ordering that modeling clay!

      Thanks again!

    • #1550
      Katherine Swift
      Guest

      You can still use the Alumilite silicone, but you will need modeling clay.  We sell that as well.  https://shop.resinobsession.com/products/alumilite-synthetic-modeling-clay

    • #1552
      Katherine Swift
      Guest

      As for the mold release when pouring the second half of silicone onto the first half, I would use the Alumilite rubber to rubber mold release or I would try our new Petrolease mold release.  I haven’t used the second one yet for this purpose, but I think it would work.  You can find it here:  https://shop.resinobsession.com/products/petrolease-non-silicone-food-grade-mold-release

      The talcum powder is to help with the surface tension when pouring the epoxy or polyurethane resin.  It won’t do anything to help with silicone sticking to itself.

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