I was catching up on my Orchid reading and I noticed you didn’t
receive many direct answers to your inquiry about your burnout
schedule. We’ve been casting the way you will be since about 1969. I
own an Aim kiln also but I also still use the same burnout oven and
Kerr long arm centrifuge my dad bought back then. I mostly use
Satincast investment and our burnout schedule is pretty much what you
noted except we usually don’t end quite as hot. An hour at 325, an
hour at 700, two hours at 1,200, and if we are casting sterling an
ending temp of 1,000. I think 200 degrees below the melting temp of
metal is an ok rule though I cast copper with the flask coming out
of the kiln at around 1,850 and hold a reduction flame on the copper
as late as possible.
If you want to read a really good series of step by step articles
about lost wax centrifugal casting my dad wrote a six piece series
for Rock and Gem magazine in 1975-76 that holds up perfectly well
today. If you have interest I’ll send you a photocopy.
Your idea of building a vacuum table sparked some memories. We’ve
probably enjoyed building equipment as much as making and selling
jewelry. We started hobby casting by vibrating the air out of flasks
with an electric vibrator (hand massager) clamped in a vice.
Actually did an OK job. We built our own vacuum table using a
compressor from an old refrigerator. I still use it today. It’s a
little slower than something professional and modern but it still
pulls 23inHg. Someday when the compressor gives up the ghost I’ll
buy the pump I’ve been eyeing in the Rio catalog, but it’s gone over
35 years and counting.
We built our first wax injection unit out of a large and a small can
separated by plaster with Nichrome wire wound around the inner can. A
"U" of copper pipe with a cone on one end and a plunger (handle was
from the choke of a '54 Chevy) did the injection work. As we got
into more production we eventually replaced it with a compressed air
injector but the home-made one got us started. We vulcanized outside
the shop in a toaster oven and compressed with a four bolt clamping
Our family history with jewelry goes back to the late 1800’s and
many times you just had to make your own equipment. My Grandfather
had Oklahoma watchmaker’s license number 0003. I still occasionally
use his home-made watch degausser and his ring welder.
Things haven’t always work perfectly. We fabricated a vacuum caster
out of box tubing, run off the same compressor as the vacuum table,
that worked - sort of - but was too slow to be effective. And the
experiments with vulcanizing in the oven at home made our 1972
Thanksgiving dinner late (we were all standing outside while the
house aired out).
Although jewelry and watch repair put food on the table, making
equipment has been just as fun. Thanks for your post jogging some