We all have built that 10 year old OOP kit that we find is missing a part or has a broken part. One option is to try and buy a replacement, if you can find
one. The other option is to cast a new one. I recently started one such kit and this is my solution.
Here is my problem. When I started to sand the tires, I discovered an air pocket. I figured I would fill it will super glue, but it was larger then I thought.
So I cast a new one.
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This is a 1970's era racing tire. As you can see the damage to the tire will make it unusable.
I used Alumilite Mold Maker for the mold. I also used their casting kit.
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I used a 2-piece mold. The first step is to make something to use as a mold box. I use a simple plastic container. If you make your own, make sure to seal
the corners so the rubber doesn't leak out. Mount the master in the center of your box.
I use rice that I pour into the mold box to give me an idea of how much Mold Maker to use. You then measure the rice and mix the Mold Maker. Since I made a 2
part mold, I only had to measure the bottom half.
In this case.... the rice is 50cc.
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Pour the Mold Maker into the mold box. Pour it into the corners and let it flow around the part. Use some kind of mold release on the bottom half, I coat it
with a thin coat of Vaseline, and pour the second part. You will need to make alignment areas to help align the mild halves. I use wood dowels set in the
rubber.
Once the rubber sets, pop the mold out of the box and this is what you should have. Cut out a pour hole on one edge. Clamp the two halves together and you're
ready to pour. Don't squeeze it too tight or you will deform the cast.
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A bit on mixing the resin. I use small cups like you see in the hospital. Mix the resin 1 to 1 and mix it to a uniform color. Work fast if you are using the fast setting type. You will only have a few minutes before it begins to set. Once mixed pour it into the mold. I sometimes use a pipette to put the resin in the mold.
The finished product:
Here is another example of casts that I made. These are 50's Roadster tires.
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I use the quick setting resin, but there are other kinds that can take up to 24 hour to set. I think the slow setting resin gives better detail as it has time to work itself into all the cracks and crevices. There are also different colors... I have used the clear, white and tan. The clear can be tinted to provide color.
While pricey the Mold Maker is good for perhaps 7 or 8 molds depending on their size.