Making a rubber mold for investment casting

[pelletman]

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

[steamin10]

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.