Cuting rubber mold assistance

I hope I can explain in my English this issue.

I have the model of a ring with a square “C” shape, about 10 mm wide
with 0.8 mm thick walls all over the shank, and ends on each side of
the mounting top, also with a connected groove between the channel
area of the “C”, something like a rectangular grooved frame bended
over the ring. I’ve already cut a mold, but the wax models sometimes
get broken, where the three walls of the frame meet, and I can’t
figure out how to cut the mold for easy release of this shape.

Thank you in advance.

but the wax models sometimes get broken, where the three walls of
the frame meet, 

Well, Quatah it’s pretty hard to visualize your model from you
descriptio n… First off,.8mm is awfully thin for any model to
survive the experience. And you probably have weak spots where it’s
breaking, which is why it’s breaking there~. There’s a way to get
wide rings without damagethat works pretty well, though. #1 problem
with bad molds is bad models, remember that.

Cut your mold and remove your model. Around the rubber that is the
core of your ring cut straight down all around the edge. On the
OUTSIDE of your mold, cut a pear-shaped area that has the core in the
middle of the space. Cut the two of them as neatly as you can until
your cuts meet. That’s hard to describe, probably hard to visualize.
What you are making is a flap on the outside, and when you pull on
the flap the core of the ring will pop out the side of the mold.
Shoot your wax, let it cool, and pull the flap which will remove the
core from the center of the wax. Then open your mold and the ring
will just pop out…

about 10 mm wide with 0.8 mm thick walls all over the shank, 

Seems a might thin to me. After mold and casting shrinkage, the
finished mounting will be 0.7 mm thick at best! If you have to do it
this thin your going to need wax designed for thin injections. You
might want to pull the mold while it’s quite warm. With out the
model to look at, it would be very difficult to know how to cut it.
It’s possible that it would need to be a multi piece mold. There are
examples of these types of molds in Murry Bovin’s, “Centrifugal or
lost wax Jewelry Casting” book. Respectfully I submit that you could
consider subcontracting a mold maker and take a good look at how
they did the job. Think of the job cost as an educational expense.

Regards, Kevin

Hey Guys thank you very much for your advise, it is clear that I need
to remake the master model with ticker walls!!! also I’ll try cutting
the core.

Gustavo Suarez
Argentina