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Centrifugal casting question

I recently moved and set up my studio again in the new smaller
garage. Anyway, in the course of bolting my Spincaster down , gave
it a spin to see if it pulled the table off the wall to which I
just had bolted it to. I noticed that when letting the thing go to
spin that the arm hits the rubber stop with quite a whack! I
wonder if this could have caused some of my problems with pits etc.
as it seems this would knock some plaster loose? When you guys let
your spin arm go during casting do you let it go slowly and gently
or just let it fly and smack the stop? Dave

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I let mine fly but I don’t have a stop for it to smack against.

I always let it fly and never had porosity problems. A lot of
times, the porosity is due to the temp of the metal. You can’t
overheat, or underheat it. Their is a very fine line between too
much and too little. You’ll need to experiement to get the right
amount of heating for your applications. I’ve been casting with my
good ole centrifugal caster for about 15 years.


Sounds like you are releasing the arm with the flask parallel to
it. The flask should be brought ninety degrees to the arm prior
to release. J in Kodiak

Hi Dave,

Let the arm fly! The cast is accomplished in about the first 1/20
of a second. I’m assuming you are using a broken arm caster. For
all intents and purposes the mold is filled at the time the broken
arm completes the 90 degree spin to straighten it out. The rest
of the ‘spin’ is holding the metal in place while it hardens. Be
sure to balance the arm for the ring size. Broken investment is
no problem if you are using a ‘hard’ investment, provided that the
sprue former is kept clean. Most of the ‘crap’ comes from dirty


                                  Skip Meister
                                NRA Endowment and

Dave, Be sure if you’re trying the centrifuge to balance it up
with a dummy flask to keep it in balance. When a "broken-arm"
casting machine is in the start up position the part with the
crucible and cradle should be all the way “bent” at least 90
degrees. If not, that little bit of play will cause quite a
whiplash in your crucible full of metal and will affect your
casting results. All the power in a wind-up centrifuge is in the
first couple of revs…don’t slow it down! J.A.