Hi, I've been thinking of buying a perforated flask vacuum casting
machine. I've vacuum cast with solid flask for many years. I'm
wondering if anyone here has gone from solid to preforated flask. I
often cast with only one item in a flask. Two and three items are
common as well. I cast mostly 14 and 18k gold, white and yellow.
acasionaly I cast 22 and 24k and sterling silver.
Is there an improvement in casting quality considering the small
batches I cast in?
Tom, I found that my one or two piece gold castings were equally good
either with a solid or a perforated flask. I stuck with the solid
just because my smallest perforated was still much, much bigger than
the solid flask I would use for one or two pieces. It was bugging me
how much more investment I was using, seemed like a waste for the
same results. Plus the indentation for the sprue from the base was
much bigger on the perf flask, so when I pour my relatively small
amount of gold, to cast my one or two pieces, I felt like it was too
much hole for too little metal. I worried that if I didn't hit the
sprue opening with the molten metal just right that it would spend
too much time spiraling down the cavernous sloping walls of the
indentation and cool more than I'd like.
My experience has been that the solid flask are not as good. More
air is sucked through more holes then only one at the bottom. Thus
more solid castings up and down the entire sprue.
I wrap the flasks in paper wrapping tape to hold the investment
until it sets. Then it can be pulled off or burnt out in the kiln..
I see the ONLY benefit is the burnout time lessened and sometimes (in
damp weather) a more complete burnout- or the grey cast is gone
earlier ! the major most important factor is to having a very good
sleeve around the flask- and you should go ahead and buy a couple of
sleeves or roll of sleeve making material at the beginning of your
investment into the new set-up. other than that you won't see any
major differences in the capacity the amount of metal to a flask of
"x" size can hold- Just sprue at the widest point with good wires of
the appropriate width for the pieces if you want to experiment a
small "tree" set up in a wider flask than you may have had before.
other than that no good advise!...I prefer a solid flask if using a
kiln, or direct casting methods for single items myself... rer
I hope this gives some insight. and this just the way I see it...
Solid wall flask for spin cast. the vacuum only does the first 1 to
2 ins. unless you use some type of webbing.
If you having surface issues from Craving wax. I would use pref.
If you using plastic with metal molds. again Pref. Flask..
If there is anything else just ask. Have a stullerific day
Andy "The Tool Guy" Kroungold