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Thread: The PITA that is WAX

  1. #41
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    The feet are the difficulty. In thinking the entire procedure through, I quickly come to the question: How am I going to get the silicone mold off of the feet without breaking them? Several solutions come to mind.
    1. You could cut the feet off and make a mold of one or all of the feet (depending upon whether you want them to be identical or different) and then weld them onto the wax you make to invest.
    2. You could make the bottom part of the mold in two pieces. I think you could get the two pieces off without breaking the feet.


    Also, when you make the silicone mold, you must think about how you will get the mother mold off of the silicone mold after you have poured your wax. Undercuts spell disaster. Those feet present a problem. There are two ways to handle that.
    1. You can add enough silicone on the sides of the box to eliminate the undercut. (A bit pricey, given the cost of silicone.)
    2. You could make a three or four piece mother mold.


    Of course you would eliminate this problem if you cut the feet off and molded them separately.

    Richard
    When I die, Heaven can waitóI want to go to McMaster-Carr.

  2. #42
    Richard.. Just for learning sake, let's say I choose option 2. I envision using oil based clay and surround the outside of the box and feet up to the inside edge of the feet. From there, I would silicone the bottom of the box and up the back of the feet first. Then the clay could be peeled away, mold release sprayed on where the silicones would meet and the outside of the box siliconed. Next build a mother mold covering both sections of silicone so as to NOT trap the feet in the mother mold. Viable solution? Not that this is how I will do it this time, just trying to learn for my next piece.


    You guys are right. I'm chopping the feet off. I'll mold up feet separately and reattach before the shell investing. This will keep me from having a 2 piece mold just for the bottom. Problem solved. I just needed someone to TELL me to slice them off. After spending a bunch of hours on something, it always sux to have to do the inevitable. In the end, it's only a short amount of time to reattach them.

    Kelly, I'm going to try ceramic shell for the investment. The how and where I have no clue yet. Once again it will be the feet I think that will be a pain. I want to sprue this from the bottom, but need to get the bronze to go uphill into the feet. :-/ Cross that bridge later I suppose.

    John, the reason I choose rebound25 is because it is soft and suitable for a few molds. And it's cheaper than pour style silicones. You are probably right about not needing mold release from wax, but I've got moldease so why chance it I suppose. The guys at reynolds sold it to me with the rebound25. Good salesman I tell ya.

    You guys probably already know about this guy, but if ya dig through his blog, he has tons of mold up photos using rebound 25. He's into saving architecture details... gargoyles and stuff from NY. http://www.urbansculptures.com
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  3. #43
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    If I were going to make a multi-piece silicone mold, I would probably make the bottom in two pieces, divided across the box. I figure I could bend those molds enough to slip them off the feet.

    I would cut the feet off.

    Richard
    When I die, Heaven can waitóI want to go to McMaster-Carr.

  4. #44
    Thanks Richard. I'll be updating this post tonight as I go along.

    Feet cut off!
    cutofflegs.jpg

    Hot glued pieces to wax paper. I had to setup in the kitchen. Too cold in the garage tonight.
    start.jpg

    1st coat. No turning back now. I skipped the mold release. It's wax. NO WAY this stuff will stick. (I HOPE)
    Rebound 25 temp is about 70degrees. This stuff is THICK! Chinese chip brushes are NOT the thing to use to push this stuff. They shed worse than a cat!
    1stcoat.jpg

    2nd coat with just a couple of drops of thivex. I'll make the 3rd coat a little more thicker.
    2ndcoat.jpg

    3rd coat
    3rdcoat.jpg
    Last edited by jagboy69; Today at 04:22 AM.
    Visit me: WWW.HandcraftedLanterns.com
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  5. #45
    Senior Member Zapins's Avatar
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    Well you could cast it in 1 block. Then just use a razor to cut a rectangular piece out on the bottom of the box using each leg as one of the corners where you cut between. You'd need to make the rubber mold with the opening to the box face down. Then mound some clay or lego bricks up inside the box to reduce the amount of silicone you need. Just beware of air bubbles inside. Maybe drill a small hole inside the box to let air escape as it fills.

    For spruing just make a J shape and put the box at the curved bottom end. The long shaft of the J will provide enough pressure to force the metal up and into the box. Just make sure the top of the J is about 9 inches tall. You want the top of the pouring cone to be about 3-4 inches above the highest point of the box otherwise the metal might freeze before it fills the object in thin complicated castings.

    I don't think you'll need to make a mold of the box unless you want to make many copies or want the mold making practice. It should come out on the first try with everdure.

    ***Edit***

    Woah I just saw your post. What is that silicone stuff you are using? I need some of that for my eagle mold.

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