Customs: Casting help/advice needed

Discussion in 'Creative General Discussion' started by Venksta, Feb 24, 2010.

  1. Venksta

    Venksta Render Project Creations TFW2005 Supporter

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    Hey guys. Looking for some help with casting. I just started, and am using my Energon axe as the first casting test. I made the rubber molds last week, using Smooth-On Mold Max 30. It seemed to turn out good. I tried casting, using Smooth Cast 325. Since its neutral color is a translucent amber color, a friend suggested it be great for the axes, especially with an orange dye.

    So I tried casting the axes, and its not turning out too well. I keep getting the top of the axes not filling up with the plastic, or sometimes the big sphere won't fill up. Plus, the casting has tons of microbubbles inside the plastic. The Smooth Cast 325 has about a 2 min potlife or something. So I mix Part A and B together for about 30 seconds before I start pouring. Anyways, any help or advice on how to fix these issues will help. Also, should I just invest in a Vacuum chamber? Especially for translucent parts?
     

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  2. TGping

    TGping Well-Known Member

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    Well, I think the only thing I can help you with is the bubbles. To prevent bubbles you need to vibrate the mold as its setting, so that means pounding the table or getting a small table specially made for shaking up the mold.

    Could you post some pics of the box yuo poured the mold into?
     
  3. QmTablit

    QmTablit Disguise: Check. Robot...

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    LOL From the thumbnail, I didn't realize those were tiny bubbles *strums ukulele*

    I thought it was a metal flake paint, like a clear pearl or something.
     
  4. amd098

    amd098 En taro Artanis!

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    i think the last picture is his original axe right?
     
  5. Venksta

    Venksta Render Project Creations TFW2005 Supporter

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    So a friend on Cybertron gave me some advice. I was able to get the top parts of the axe casted. Still have problems with the sphere not filling up, and micro bubbles inside the casting. The surface itself is smooth and free of bubbles. After doing some research, it seems for any clear or translucent parts, I'm going to need to get a vacuum chamber or a pressure pot. I'm probably going to go with the pressure pot, as its alot cheaper and it seems more people use that.

    I tried doing that. Not sure how the bubbles keep forming. The combined liquid, before pouring, is bubble free. The box for the mold is destroyed. I had some people look at the mold itself, and they said it was fine.



    Yeah, it does look a bit pearly, haha.

    The last picture is a casted axe. Its showing the bubbles inside the piece.
     
  6. amd098

    amd098 En taro Artanis!

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    huh i kinda like that bubbly look... but do the bubbles make it more fragile?
     
  7. Venksta

    Venksta Render Project Creations TFW2005 Supporter

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    No, these axes I casted so far are very strong. I tried to break them. Their kinda flexible. Very different from the resin you would expect from model kits. In order to break them, you'd have to be doing it on purpose, with a hammer or something, lol.
     
    Last edited: Feb 26, 2010
  8. amd098

    amd098 En taro Artanis!

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    are those for the axes you will be repro'ing and selling?
     
  9. Venksta

    Venksta Render Project Creations TFW2005 Supporter

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    Yup, once I get them right, I'll post info about selling them. I picked a pressure pot today. I need to remake the mold for the axe in the pressure pot, as the current molds won't work. So I should be able to do my first castings with the pressure pot on monday.
     
  10. TGping

    TGping Well-Known Member

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    Do keep us updated :) 
     
  11. DanHibiki

    DanHibiki Dan Couga Mellencamp

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    I would add a vent hole to the sphere. That is a very thin path for both air and resin to pass through. When your mold fills are you getting a good bloom at the top?
     
  12. aurascope

    aurascope Kitbash Resource Indexer

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    yes, I concur. it may need a vent hole.
     
  13. Venksta

    Venksta Render Project Creations TFW2005 Supporter

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    I did my first pressure cast this morning. One of the axes came out near perfect. No bubbles at all. I did get some castings where the sphere did not fill up. Might have to vent that. I'll decide after a couple more castings...
     
  14. C. Wallace

    C. Wallace Freelance Artist

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    It's all in your venting, pour holes and pressure. I have worked making molds and casting for over 15 years now and I can tell you from experience that venting a mold properly is key. Especially when not using pressure. However, with small transparent parts like this, I would ALWAYS advocate pressure casting.

    Keep in mind for things to be done properly, the mold that you are pressure casting with should also be made under pressure, or it will, over time, if not immediately, distort when subject to the pressure while casting parts with it.

    Pressure doesn't eliminate bubbles, it just shrinks them down to the point of where they cannot be seen...this pressure also causes the volume of the resin to decrease.

    With that said, your having issues because you left no reservoir for an overfill of resin near where your pouring into the mold. Also your mold does not seem to be keyed very thoroughly which can cause other problems, especially under pressure.

    What pressure are you casting at? What are you using as a pressure tank? How are you pressurizing said tank?

    For smaller molds like this, I would recommend Mold Max 40 it will decrease distortion and you will not have to make the molds as thick. ;) 
     
  15. Venksta

    Venksta Render Project Creations TFW2005 Supporter

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    Thanks for the tips! I was able to get the axes to cast properly a couple days ago with the pressure pot. Its a paint pressure pot. Its working good so far. After my first few tries, the axes are coming out great. Just have to play with the orange tint. :) 
     

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