It seems to me that the best way to learn about cutting rubber molds
is to look inside a lot of them that someone else has already cut.
Can you possibly locate anyone who casts from them in your area, and
ask to look at their molds? There is a lot to it, and we all have cut
molds badly and had to start over and make a new one and try again!
When I began to cast, I was sending my work out to Billanti in N.Y.
and so I got molds back from them, cut by professionals. What a great
tutorial in mold-cutting! My own early molds were mostly somewhat
flat, and so presented few cutting problems. I worked my way along
from there, and can now usually cut anything right the first time,
even though it is a more complex form. One hint: do a little drawing
of how the piece lies in the mold before you vulcanize it. This can
help you hit your marks as you open it up later. When I make mold
after mold all day, I sometimes forget which one is in there, and how
it is oriented! Of course you want your separation seams to be on
areas which are easy to clean up later, such as a smooth edge or rim,
if possible. Once your mold is in 2 pieces, make cuts as necessary to
pull waxes out of them without distortion. You may also need to make
extra vent cuts for air to get out of dead-end areas if they won’t
fill with wax.
Good luck, and don’t hesitate to remake a mold; the rubber isn’t
that expensive. It is worth it to end up with a great production
mold.
– M’lou Brubaker, Jeweler
14015 W. County Road 578
Goodland, MN 55742