Making a rubber mold for investment casting

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Making a rubber mold for investment casting

Post by pelletman » Sun Apr 18, 2010 10:56 pm

Hello everyone,

I have some old bike parts I want to reproduce and I'd like to make my own molds. To make up for shrinkage / polishing etc I understand I need to be 5% larger than the original piece. I am wondering if there is a product that I can coat the original part with and then pour the mold to give it the larger size. Thanks for your help. Dave

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Re: Making a rubber mold for investment casting

Post by steamin10 » Sat Apr 24, 2010 10:11 am

I use the brown investment wax to dip the small part in. It gives a smooth coat if you learn to rotate the part around by hand. It is removed with a photo light or heat lamp, and the wax will just melt away. Its drawback is it will fill in detail, and give roundy corners that must be touched up, but a set of clay carving tools or just about any pokey-shaped thing can give lines and depressions a bit more definition. I use a $3 set of Chinee sculpting tools.
Big Dave, former Millwright, Electrician, Environmental conditioning, and back yard Fixxit guy. Now retired, persuing boats, trains, and broken relics.
We have enough youth, how about a fountain of Smart. My computer beat me at chess, but not kickboxing
It is not getting caught in the rain, its learning to dance in it. People saying good morning, should have to prove it.

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