This started coming up on Dave T’s build thread. I also know John C happens to know a thing or too about casting metals. I have played with it and know others have also. But I wanted to get some ideas and understanding on casting pewter mainly but also other metals such as brass/bronze. Dan and I have also discussed this a bit. Its an interesting topic.
Here is where I would like to start the discussion. When I have played with lower temp metals mainly lead and pewter pouring into RTV mold or even aluminum molds (fishing weights and jigs). I find it very frustrating trying to get the metal to flow nicely to all parts of the mold. I have pre-heated, I have used talc, I have flamed my aluminum molds and all have helped but getting a consistent pour each and every time to all parts of a detail oriented mold is eluding me. I don’t have the money to go buy a centrifugal metal slinger for the few parts at a time that i would make them. Lost wax casting with centrifugal force seems the best way to accomplish what I want to do. But the slinger is expensive. I have watched videos on hand held sling casting and while flinging hot metal around and about my head and face seems fun I am wonder if their are other ways. I do believe i will try the sling casting as I have a near endless supply of bronze at my disposal and I can easily make RTV molds for pouring wax to latter make the plaster molds for sling casting. This would give me a reproducible product.
One idea I have thought about trying and would love input on is the idea of using low melt temp pewter in a high temp RTV mold in an oven that is set above the melt point of the metal and then adding a vacuum much like vacuum casting resin. I think a very simple oven could be fashioned out of a pressure cooker that then could be sealed and a vacuum applied. Instead of the pressure being explosive in a pressure cooker you would be having implosive pressure and not a lot would be required as long as the temp stays above the melt point of the metal you are using. Any thoughts or concerns on this idea.