Beginner casting, which crucible size is best?

I am a novice jeweler. I bought a used casting machine that is
originally for dental casting. 

H.J. If you have a brand name… do a search for it and see if you
can find the mfg. If not… Rio Grande carries several different
crucibles and the rubber sprue bases. If you can find a crucible
that is close, you can modify it A LITTLE with a Mizzy wheel…
You’ll be white when finished so use ventilation…best done
outdoors if possible…makes a heck of a mess. I had an OLD Lucas
caster for many years and always had to modify new crucibles.

In 35 years of casting, I have never found a sprue base that makes
the metal flow like I want it to. Right after removing the base from
the flask, I always take a thin spatula I have had forever and I
taper that indentation to suit myself. Starting at the cavity hole,
I like a little area with 90 degree walls… about 3 to 4 mm
high… about the size of a dime or nickle in diameter, (depending
on the flask size) then I make the sides smooth and to look like a
funnel out to the bottom of the flask. This lets a nice button seal
off the flask…the 90 degree area gives some depth to the button.
This maintains heat in the button, keeping it molten just a little
longer…allowing the casting to “drink” as it cools. This stops a
lot of porosity and gives a better all around casting.

I suggest only Acetylene for melting silver… I always had problems
trying Propane. Make sure the tank is in date and safe along with
the hose & torch. Its… “Just your life” ;-).

If Its CNC We Do It
DeArmond Tool

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