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Mold cutting


#1

Hi to all you mold cutters, I may be preaching to the choir. I
recently saw a Castaldo poster showing the use of a church key to
help in the cutting of a mold. It made me think there may be some
mold cutters that are not aware of a tool Gesswein sells. It
consists of two arms hinged to a base. The opposite ends of the
arms have hinged toothed jaws. One edge of the mold is placed into
a set of jaws and the jaws are clamped tight against the mold. The
other mold edge is clamped in the second set of jaws. There are
long screw that are threaded through the arms and fixed to the base.
Once the mold is clamped the screws are turned which causes the
jaws to move apart thereby pulling the mold edges in opposite
direction. The screws are turned to pull the mold open as it is
cut. This tool greatly simplifies the cutting of molds. You do not
have to hold the hot mold in your hand or worry about the knife
slipping and cutting yourself. The tool is shown on page 104 of the
current Gesswein catalog. I have no connection to Gesswein or the
tool manufacturer. Lee


#2
It made me think there may be some mold cutters that are not aware
of a tool Gesswein sells. 

Lee, in my humble opinion, that mold cutting jig of Gesswein’s
(other sell it too, I think), is kinda overkill, and frankly, I like
my simple setup better. I just screwed an ordinary 25 cent can
opener to the flat portion of an extra bench pin (that fits my GRS
bench pin holder). The point on the can opener points away from the
pin surface, which is mounted upside down in the holder, so the point
is down. The point projects about a half inch in front of the end
of the wood. It’s sharp as sold, but i sharpened it a bit more.
it’s easy to then use that hook to grab a bit of the mold and pull
the portion of the mold on your side, away. though you do have to
hold the mold, I frankly like this better than that jig, because it’s
so fast to reposition the mold from one angle to another, and pull the
rubber just where needed. And my jig takes a lot less space to store
than that complex one. Plus it’s really cheap and quick to make.
Another comment, I let my molds cool to the point where they’re not
more than lukewarm, before I cut them. I find that cutting the molds
while still too hot leads to warpage of the rubber, and a mold that
won’t be as easy to keep shut when injecting.

peter


#3
   Hi to all you mold cutters, I may be preaching to the choir.  I
recently saw a Castaldo poster showing the use of a church key to
help in the cutting of a mold.  

For those on Orchid too young to remember the dark ages before
pop-top cans and for those outside the U.S.: A church key is American
slang for the old-fashioned beer can opener which hooked over the
edge of the can and punched out a triangular hole in the top.

They are ALSO good for mold cutting, if you can still find one. A
steel shoe horn, if flattened and screwed to benchtop, also works.

David Barzilay, Lord of the Rings


#4

Peter, I totally agree with you. The mold cutting devices seem
cumbersome and I have never felt the need for one.

In addition to the church key I use an ordinary spring loaded clamp
found at any hardware store that is fixed to my bench with a C
clamp. I start the mold cutting process with the church key and move
over to the spring loaded clamp after the locks have been completed.

Sure mold cutting this way can result in cut fingers but the
likelihood of that diminishes with experience. How many of us can
look at our hands at any given time and not find a cut, scab or scar
anyhow.

John Sholl
Littleton, Colorado


#5

I have to agree with Peter here. I tried one of the mold cutting
tools and found that it just is not as efficient or a versatile as a
good old can opener. I personally use the end of a rat tail file that
has been bent at a 90degree angle and sharpened. I just clamp it in
my bench vise and set the best angle to cut the mold. In defense of
the afore-mentioned mold cutting tool I did find it to be less stress
on the hands. For those without a lot of hand strength that find
holding the molds open while cutting a difficult and cramping process
the mold holder may be the way to go. Not for me. I gave mine away.
Frank Goss


#6

I have one of these tools (came with the myriad of shop geegaws I
got when I bought out that casting shop). Along with it, I also got
the video that shows how to use it, and the casting shop owners gave
me some lessons on mold cutting too, using the mold holder device. I
love the thing! It makes mold cutting almost simple, at least for
this novice. I position a bright light above the device so I can
clearly see exactly where I should be cutting, and I turn it around
as I work so that the side of the mold I’m cutting faces toward me. I
can’t imagine cutting molds any other way. I’m sure there are other
ways, but for now at least, I won’t be trying them.

–Kathy Johnson
Feathered Gems Jewelry
http://www.featheredgems.com


#7

Hi Gang,

A church key is American slang for the old-fashioned beer can
opener which hooked over the edge of the can and punched out a
triangular hole in the top.

This is kinda of silly, but in the interest of accuracy regarding
beer cn openers, there seems to be some confusion.

When I grew up in the midwest (Iowa), a long time ago, there where 2
kinds of openers for getting at the golden liquid. One was a sort
of an elongated hour glass shape wire contraption for removing the
caps from bottles. A bottle opener. Since it resembled a key, if you
had an imagination, & it was larger than most house keys, it was
given the name ‘Chruch Key’.

Then when things got modern & brewers started using cans for beer
the ‘can opener’ came around. The 1st cans though had a funnel
shaped top that was still closed with a ‘bottle’ cap & the ‘church
key’ would work. Soon the brewers figured out how to use flat top
cans & the ‘chruch key’ wouldn’t work & the pointed can opener was
invented.

Naturally, someone also invented a new name for the can opener. It
resembled a wrench need to adjust some of the carburaters on the
early cars. Needless to say the pointed can opener got the name
’carburater wrench’.

For you youngsters (bg) out there, a carburater was used to
control the gas & air mixture going into the engine.

Dave


#8

Lee and Peter,

My solution for cutting molds is halfway between yours. I use a
spring clamp (originally for woodworking) modified to have sharp
serrated teeth. I’ve also seen a heavy duty car jumper cable clamp
used. A piece of chain provides an adjustable length anchor. It
clamps to the back of mold with more security than just a hook but
without the extra arms and et cetera every where. Concerning mold
temperature… the hot ones DO warp, are not fun to cut, and you
can’t pull a wax til they cool down anyways.

Jeff Demand
CadCam Modeling Solutions
http://www.aztec-net.com/~jdemand


#9

Hi, Dave; There must be a lot of “regional” in those names, which is
probably the cause of the confusion – I (from Oklahoma) never heard
of a “carburetor key”; it was always called a “church key” in my neck
of the woods. And the first one you mentioned (“hour glass shape”) ,
as being called a “church key”, was just a “pop bottle opener”. And,
yes, I (now being 74) have been around during the era of both of
these tools.

Margaret
@Margaret_Malm2,
in Utah’s colorful Dixie