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Rubber molds.some pictures to look at of complex pieces

Hi, Here is a quick page I put together with some powder seperated
molds ( 4 part molds)and pictures of the waxes from those molds . The
pics are large so it may take a while to open up for those on a
telephone connection. This is for those who would like to see a small
example of what can be done this way. Daniel Grandi we do casting,
finishing and moldmaking for people in the trade

I saw your molds and they look great, especially if you didn’t need
to do any touchup. For the sleigh I noticed you cut the mold it in 4
parts (2 removable). Do you have any problem with them shifting out
of position during injection?

What about making molds of cluster ring with a narrow opening at the
bottom. How do you go about cutting the mold so the wax can be removed
without damage.

Hi Randall Brooks, These molds were not “cut”, They were powder
seperated. When we do complex
rings such as you described, we find ways of powder seperating the
molds around the basket area so that the rubber comes out of the
inside from between the wires as well as the top and bottom hole of
the ring. We use every area available to remove the rubber from inside
the ring. There are occasions were we have to cut spirals , but that
is rare. Sometimes, we may ask the designer to create a bigger hole
under the ring… if this hole is not visible fom the top and does not
detract from the design, then there should be no problem making the
model this way. We often recommend to designers to think ahead when
they initially design their pieces to think about the mold making
process before finalizing their model. If we can mold it, cast, and
finish it easier, then it will be less expensive to do your
production and you will get better and repeatable results. This is
where we are different from most casters… since I’m also a longtime
model maker and mold maker, I can usually give recommendations to
designers that will make their design work well. Best wishes, Daniel
Grandi We do casting, finishing in giold,silver,brass/bronze and
pewter for people in the trade.

   What about making molds of cluster ring with a narrow opening at
the bottom. How do you go about cutting the mold so the wax can be
removed without damage. 

Hi Randall, I have used two approaches successfully for the above

1: Make the master model in two parts, inject 2 waxes and solder
them together after cast; or put the two injected waxes together in
wax and cast them.

2: Make a 3 part mold (with a wedge shaped tab that removes the
rubber from the inside of the shank and the narrow opening of the
cluster setting). The hardest part is getting the rubber out of the
narrow cluster opening without ripping it (you’ll want to use a rubber
with excellent tear strength- like the Castaldo White or Gold label
vulcanizing rubber). If you can get the rubber out through the
opening (I find using a fine tweezers helpful in coaxing the rubber
out), then you can cut the plug of rubber you pulled through the
opening of the cluster into a “corkscrew spiral”. You have to be
careful to put the rubber plug back into the mold neatly before
injecting it. Now, inject the wax, pull the plug out of the mold
(from the outside, before you open the mold) the plug will ‘snake’ out
of the mold then spring back onto shape- allowing you to pull the core
out of the ring with out breaking the wax. This mold may not last
quite as long as a regular mold, as you are pulling on a thin piece of
rubber, and it can tear. I hope this helps… Kate Wolf I haven’t seen
the Louis Sanchez moldmaking video.