I plan on sticking with Plat/Co alloy for casting.
Peter is correct in that you should stick with Pt/Ird to cast
with a torch. If you sprue correctly you can almost eliminate
most problems. Using one alloy gives you a lot more control of
your metal, you can take the button mill it out and fab with it,
re-cast and not be concern with mixing up metals. You can recast
and fab until its gone unlike re-casting gold alloys.
What I am interested in is your thoughts on burnout cycles and
flask temperatures when casting.
With the Supra you will have to use the following burnout
350 F 2 hours
500 F 2 hours
750 F 1 hour
Increase temp about 400 F per hour to 1650 F and hold for 1
hour to harden investment.
Lower the flask temp to 850 F for thicker items and 1000 F to
1100 F for thinner pieces. Hold the casting temp for a minimum of
1 hour before casting.
And any tips on the melt,
It is very important to melt the metal as quickly as possible. I
use 65 lbs. for the oxygen and 5 lbs. for propane. The flame
must be an oxidizing flame. Crank up the torch get a very hot
casting and quenching?
After the flask is cast you should let the flask set for at
least 20 minutes. If you do not it will thermally shock the
metal making it brittle. The investment is hard to get off the
castings. You can water blast, it will take about 10 to 15
minutes. Then remove most by hand then use Hydrofluoric acid
<>> should be taken. Gessewien will be supplying a
milder investment remover that you should look into.
Is there anything we should continue to send out?
I would send out customer jobs and one of a kind items then
practice with stock items to give you the experience of casting
before you start putting yourself under the pressure to produce a
Edward J. Friedman
The Buehn Company