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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 wait—I 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 wait—I want to go to McMaster-Carr.

  4. #44
    Thanks Richard. Lots of work done tonight on this little box. Hopefully I'll be duping some wax copies soon.

    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

    4th and final coat. Plaster bandages go on next.
    4thcoat.jpg

    One thing I see I already screwed up was, when I applied the 3rd layer, I should have siliconed some registration pegs for the mother mold. I'm not worried this time. These will be a simple one piece mother molds just to hold the silicone rigid for wax pouring. Live and learn.

    Mothermold. This is plaster bandage crap I found at a hobby lobby. 4"x15ft for 4bucks. Took a little over 1 roll. Cheap and this stuff kicks FAST.
    Mothermold.jpg

    I'll pull everything apart in about 12hrs or so. FINGERS CROSSED or I'm turning it into an ASHTRAY!
    Last edited by jagboy69; Yesterday at 08:32 AM.
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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.

  6. #46
    Quote Originally Posted by Zapins View Post


    Woah I just saw your post. What is that silicone stuff you are using? I need some of that for my eagle mold.
    Rebound 25 from reynolds. You are looking at the smallest kit they sell. 30bucks worth of silicone. For your eagle, buy 2 kits and the smallest bottle of thivex to go along with it. First coat mix 1:1, second coat I added a small bit of thivex and went up from there. This stuff will go on a vertical surface with thivex added. This is the cheaper way to go than pouring a box. Plus it's shore is 25 and flexible so it's supposed to be great for detail and even cavities like your birds mouth.

    Edit... Zap what are you using now for molding material????
    Last edited by jagboy69; Yesterday at 08:53 AM.
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  7. #47
    Mother mold is still a little damp. Gotta wait on the others. Here is the first one. Works like a CHAMP! IF the bottom comes out this well, I HOME FREE!
    The detail of that texture is AMAZING inside this silicone. So far this stuff is a winner.
    Lessons learned so far:
    Hot glue sticks to cheap dollar store wax paper like a BEAST and makes a great hold down for wax
    Rebound 25 does not stick to microcrystalline wax so no mold release needed
    Rebound does slightly stick to waxpaper, but if thick enough, peels off brilliantly.
    Will use wax paper again! Being able to rip it off the work surface is a big plus! No need for pulling and prying work off the table.


    lidmold.jpg
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  8. #48
    Senior Member Zapins's Avatar
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    I'm using High Strength Silicone RTV Mold Making Compound - Gallon - Yellow Fast Cure: http://www.ebay.com/itm/High-Strengt...kAAMXQAEFSHTFs

    It doesn't gel at all. I need to see if I can buy a thickening agent for the stuff I have so I won't need to buy totally new stuff. Maybe save a bit of cash.

    Can't wait for pics on the rest of the mold making process and the wax copies. I wanna see how it works out and the detail you will get.

    I might have to buy some of your stuff and some fiber glass which I've never used before.

  9. #49
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    I use Cab-O-Sil for thickening. It's cheap; it's available, and it works.

    R
    When I die, Heaven can wait—I want to go to McMaster-Carr.

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