A friend asked how to cut a dome ring mold. Here is a very rough approximation of his model. I made the ring just so I could make the mold. :-)
Sprue former on the right end of the picture, silver model on the left. Note that the dome is very hollow.
The video I am working on will demostrate how to cut this type of plug mold. It is good for very thin objects with large inside spaces that need to be removed from the wax.
Note that the plug has an outer ring that carries the impression of the inside of the ring shank. There is an 'S' shaped bar that fills the center of the plug.
This shows how the plug is pulled out of the mold. Note how the pink handle of the plug pulls on the 'S' shaped bar and finally the end of the bar pulls the plug out of the mold.
I know. It is really difficult to picture how this happens. I plan for the video to make it clear how to cut a mold like this.
Here is an image of the heat-cured silicone rubbers from Nicem (http://nicem.it) that I use for this mold. I prefer this rubber for this type mold because the shrinkage is the same across all the different rubbers from hard to supple.
