Dave, Is it possible to hollow the original model before making the
mold? If not try the following: There are burrs with only three
blades that do not get clogged very easily. Check out Rio Grande
Tool Catalog. I place an injected wax piece in a cup filled with ice
cubes and cool it before hollowing it. I place the piece back into
the cup when the wax starts to gum up. You will have to be careful
not to put too much pressure on the wax when it is chilled as it has
a tendency to get brittle. That brittleness is what allows you to
remove wax without gumming the burr. I assume you will cast the
hollow wax pattern then make a mold of it so you don’t have to
hollow each piece. Good luck Lee
There is a trick it’s called water soluble wax. used for making
cores for beads and other things such as dome rings,wolf heads, etc.
you can find it on page 179, item #3 in the lower left hand corner
of the page.In the ALPHA catalog, 2000/2001 issue #00. If you have
never heard of ALPHA Supply, Inc. They have offices in Seattle &
Bremerton, WA., & Mumbai, India. e-mail = two@alpha-supply.com —
Phone 1-800-257-4211 This water soluble wax is used as a preshaped
core, a carvable wax is applied to the outside with heat and spatula
, dip in wax pot or what ever you can get away with. I like the hard
carvable wax and pecks purple for fine details then soak in water
and you have a wax shell to cast. be sure it is thick enough to
allow the flow of your metal.and be sure to sprue it well. I do not
work for ALPHA, they are a company who started in this business
about four years after I did and I now buy from them on occasion. I
am a minor competitor doing Gem Shows Now.
Call or e-mail ALPHA they are nice people and will be happy to send
each and every one of you a catalog,it’s 273 Pages long.
Good luck Art Smith, Facet West, 149 Vernita Ln., Glide, Oregon
97443 Tell them I sent you Thanks Art
Hi Dave, For metal models, i have developed this trick. Make a normal
rubber mold.
Depending on the thickness of the master, take a rigid PVC sheet.
Typically, this ranges between 0.5 to 1.5 mm.Cut the top 2 to 3 mm of
a cheap tapered plastic ballpoint pen. Draw the outline of the master
with the pen touching so you get a border which is 2 to 3 mm bigger
than the periphery of the master. If the master is deep, then you may
have to draw another outline, still more enlarged, around it. Cut the
plastic sheet on this marking.
You now need only the cavity side. Place the cut sheet on top of the
cavity. Put this in the same metal frame the same way as the
original. Add sheets of unvulcanized rubber to make a new punch/male
side, with the plastic sheet in the middle.
Vulcanize.
If you have not used sparting powder or spray beyond the plastic,
cut the mold to expose the sheet. Remove the plastic sheet. You will
get a mold that you can get a thin wax piece from. Some trimming of
the wax will be necessary from the sides.
You can get a thicker article too with this process if the original
was too thin, by choosing the proper sheet.
You can try variations with a cloth or some flexible sheet for RTV
molds.
This process can be useful for using masters made from 2 1/2 D CAD
too.
Regards
Shishir Nevatia