Customs: Need Advice-Molding and Casting

Discussion in 'Creative General Discussion' started by gaetz, Oct 17, 2010.

  1. gaetz

    gaetz Gaetz

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    First off, I've never made a molding before.

    Beyond the info i've gathered on how to make a two part mold. I"m curious has anyone used TAP Platinum Silcone to make a Two Part Mold? If so what do you think of the product? Is there anything else out there thats better? I'm intrested/willing to spend the extra money, if its going to allow me to create a better casting.

    In regards to the casting, has anyone used EasyCast Clear Casting Epoxy? I just dont' know enought to know if this epoxy (1-1 mix ratio) is the best way to go, or if another type of resin would be preferable.

    If anyone can help that would be great.

    Edit #1

    Also to put into consideration is the fact that I want the mold to beable to generate a minimum of 40 casting. Once more i'm not sure if that would be even possible or reasonable to do with the products i've listed above.

    I'm determined to make my army of seekers!
     
  2. Fishdirt

    Fishdirt Tin Toy Transformer

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    I'd avoid caulk silicone unless it's two part 100 percent. You lose details.

    Smooth on makes the least brittle plastics. Their tack line is similar to toy plastic THOUGH you can get liquid abs in fiberglass repair kits at a hardware store or dept store cheap. It works by evaporation of the liquifying element. Haven't tried it but heard good things.

    Overall you'll be ok with a smooth on pourable starter kit. Dick Blick has them at a good price. If treated right the molds can last 100+ castings for the OOmo.

    Eventually you'll want to invest in a vacuum chamber and a pressure pot. Vacuum chambers can easily be made from the food containers for vacuuming and a shop vac but pressure chambers should be bought because they are extremely dangerous when home made. If you hate life then you can make one at home but if you like living buy one.
     
  3. gaetz

    gaetz Gaetz

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    My particular intrest in the platinum silcone is because of there claim of Low viscosity (vacuum not required to de-air).

    Well Living is more of a requirement, less of an opition. In regards to the Vacuum Chamber, I would like to have one. However, i'm more intrested in installing a crucible into the vacuum chamber. That way I can play with vacuum metallization. However, not untill I have a well ventilated garage. No need to shorten' my life due to toxins.

    New Question, on top of everything else i've asked, does anyone know where either a vacuum and or pressure chamber can be purchased at a resonable price?
     
  4. Fishdirt

    Fishdirt Tin Toy Transformer

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    yes indeedy. Paint pressure pot can be bought at harbor freight for a very low price. You have to do some mods to it but it's a great deal all around. I plan on it soon. This is what I'd look for if they don't hit canada. Pressure paint pots.

    2-1/2 Gallon Pressure Paint Tank

    I have the mod instructions downloaded if you need them. I can't remember where I got them though.

    If you get the metal filled resin at smoothon I think you can electro plate the plastic. Avoid one hazard but if you go this route you better dispose of the liquids properly. Ebay has a ton of small kits for this.
     
  5. Fishdirt

    Fishdirt Tin Toy Transformer

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    Incidentally I am no expert on this stuff. I've worked in plastics for over 10 years and it was either injection or blow mold. I'm just passing along the intense research I went through.
     
  6. Bigbot3030

    Bigbot3030 Well-Known Member

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    Stick with smooth-on if your starting out. I havent' heard many good things about the TAP stuff, excpet it's cheap for a reason. but since I've never used it myself, I can't vouch one way or anouther about it.

    I'd find a starter kit here The Compleat Sculptor, Inc.

    I've used GI-1000 quite a bit and like it, but you have to de-gass it. If your serious about molding and casting, and want to do production runs, getting a vacuum chamber will save you time in the long run. You get better results, consistently, by doing it that way. Both molds and parts. By putting things into chambers, you can get the excess air out faster, which means your resins can kick faster, which means faster parts. it may not be a big deal for a couple pieces here and there, but if you want to make the qty's your talking about, you'll thank yourself later.

    but i'd recomemd getting some experience casting before you try and make production runs to sell or whatever. Less pressure on yourself, and you learn dos and don'ts better.

    Hope that helps and makes sense.

    Randy!
     
  7. Venksta

    Venksta Render Project Creations TFW2005 Supporter

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    Just my 2 cents (I don't consider my self an expert yet). I've been using Smooth On products for my Renderform stuff. For the molds, I'm using Mold Max 30. And for the resin, I'm using Smooth Cast 325 series. I don't have a vacuum chamber, but do have a pressure pot. What I do is cure my mold under pressure, for the 24 hours it needs to cure. From what I read, if you want to cast under pressure, than the molds need to be bubble free. Which can be done with a vacuum chamber, or a pressure pot. But from what I've seen, making my molds in the pressure pot has been fine. And saved me money from buying a vacuum chamber.

    For my molds, I usually get an average of 50 good castings, before the mold starts to wear out. I found from my early attempts at casting, that spraying a release agent, before casting, on the molds, helps prolong the mold life.

    One thing to keep in mind, if you want to do high volume casting, is the demold time. For example, Smooth Cast 326 says it can be demolded after 60 minutes. The only problem is that the resin is still soft, so you risk deforming the shape when popping it out. I usually wait 2x the amount of time of the actual demold time, before taking the casting out. I find its a bit more firm, and has a less chance of deforming and bending.

    For molding under pressure, you also don't want quick curing resin. Smooth Cast 326 has a pot life of up to 10 minutes. That great thing about that is once in the pressure pot, it has more time to eliminate the bubbles. With a quicker resin, that might have a pot life of 3 minutes, there is less time to remove all bubbles. For me, this has made a bigger difference on certain parts I've made.
     
  8. Fishdirt

    Fishdirt Tin Toy Transformer

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    Totally awesome stuff.

    I'd like to add vacuum chamber castings are still prone to bubbles as they get caught in corners and such.

    I did read a small bit on pressure pot molds but it wasn't too in depth. So it's a definite replacement for vacuum pot degassing then? that will save me buckage.
     
  9. Venksta

    Venksta Render Project Creations TFW2005 Supporter

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    Actually, when casting in pressure as well, there is chances for bubbles to be trapped in that method as well. You basically have to take care of this issue when laying out your mold. Basically, look at where air might get trapped, and make sure there is a vent. Sometimes, you can not completely vent to the outside/topside of the mold. So just create enough of a "passageway", to help push the air/bubbles into, and the resin will fill up thanks to the pressure pot.
     
  10. Fishdirt

    Fishdirt Tin Toy Transformer

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    I thought pressure crushed the bubbles and vacuum sucked them out. I did read a translated japanese mold making article and never took into consideration the angles before then, very important info that is.
     
  11. Bigbot3030

    Bigbot3030 Well-Known Member

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    Yes and no. it will do that, but you have to have a place for the bubble to escape from. If it's an undercut, the air bubble can't "jump" around that and out. It's always wanting to go up and out, so sometimes I have to angle my parts so any large flat surface won't hold the bubble down.

    Randy!
     
  12. Darkov

    Darkov Well-Known Member

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    If you are REALLY interested in getting a vaccuum chamber. They are VERY simple to make. I made mine out of 14" PVC...I can send you a pic if you are interested.
    Also Harbor Freight has vaccuum pumps that are more than capable of de-airing rubber or vaccuum casting. Here is the one I have..
    Two Stage 3 CFM Air Vacuum Pump

    Hope that helps
     
  13. gaetz

    gaetz Gaetz

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    Thanks, Venksta, Bigbot3030, I appreciate the awsome info.

    I think I will play around with some of the cheap stuff before moving onto the large volume products.

    In your opinion is this a better Clear Epoxy
    EasyCast clear casting epoxy
    Pot life of 40 mins
    Cure time is 24 to 72

    I'm intrested in the clear epoxy over the other ones recomended for the following reasons. I want to do transparent parts, as well as doing a mulitiplitude of colour variations.

    Not so intrested in producing for the sake of selling. Its more of a serious goal/hobby to do in my spare time.


    Hi, Darkov, I really appreciate that if you can.
     
  14. Venksta

    Venksta Render Project Creations TFW2005 Supporter

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    If you want to make translucent stuff, go with the Smooth Cast 325 series. Its default look is a transparent amber color. Works great with any color tint. If your doing any "clear"(no color tint) castings, you'll have to go with something else. Otherwise, the 325 series is the best. You'll probably want to go with the 326, as that will give you enough time in the pressure pot to get rid of the bubbles. It has the 10 minute pot life, and 60 minute before demolding time.
     
  15. gaetz

    gaetz Gaetz

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    I have yet to get a vacuum chamber or presure pot.

    However, I am eager to start. I know this is only a stop messure, but I own a vibrating plate. Would that help to remove any air pockets before pouring the molding or cast materials?
     
  16. Bigbot3030

    Bigbot3030 Well-Known Member

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    i could see that helping with the casting more than the molding, but I don't think it could hurt it either.

    Randy!
     

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