Step 16: Lost wax casting process
So, I did a little looking around and found a local trade Jeweler/Supplier/Instructor who could do the tricky casting, finishing and stone setting for me.
It cost me a little bit of a premium to have someone do all these steps, but it is probably worth it.
I used The Jewelers Warehouse in Silver Spring, MD.
I recommend taking a look at this great instructable on the lost wax casting process, which shows the process in detail.
Or'' take a look at this video:
Briefly the casting process happens as follows:
The ring is prepared for investing. Investing simply means to surround the wax with a hard substance, in which it will leave a hollow behind when melted. This then becomes the mold for casting the metal ring.
Before investing the ring a wax sprue, and button, is added to it.
The sprue is a thick wax wire which is attached to the base of the ring band, which will form the pipe for the metal to be poured into. The button is a wider piece of wax on the opposite end of the sprue which will form the basin to pour the molten metal in.
The button (with sprue and ring attached) is placed on a rubber diaphragm base, and a flask is attached to the base.
Investing media is mixed as a liquid and poured into the flask around the ring.
The flask is then placed on a vacuum table and the bubbles forced out of the investment media, as it is left to set.
Once the investment is set the rubber base is removed, and the flask is placed upside down in a burn out oven. This burns/melts out the wax from the investment. The wax ring is 'lost' during this process, leaving only a perfect hollow of itself in the investment, hence the name "lost wax casting".
The investment is then heated in the oven to a specific temperature. When it is hot enough it is placed in a centrifuge powered by a large spring. The metal of choice is then melted in a crucible next to the investment and the centrifuge released, pushing the liquid metal into all the hollows of the investment mold. Sometimes the centrifuge is skipped and the molten metal is poured into the mold on a vacuum table instead.
Once the metal has cooled very briefly the still hot investment is quenched in water causing it to fracture away from the metal. The remaining investment is either broken away using brushing, concussion/vibration, or dissolved away using chemicals. After which you are left with a metal cast of the original wax ring.