Vac casting on inexpensive set up

Hello Rodger Greene, We have found that we get even better
results using the tyvac vacuum liner in a standard flask … much
better than a perforated flask… the reason is that on the small
table top machines, the vac pumps are not very strong and when
you use a perforated flask you have to insert it into a chamber
which requires more vac draw. What the liner does is allow you to
cast standard flasks on a simple flat plate caster without having
to have a chamber. This gives you a better and faster draw(using
the liner only).The cost of standard flasks is very low in
comparison to perforated.There are a number of different tyvac
liners that range all the way up to a 5" dia x 8 " high flask. A
perforated flask also requires more oven space due to the flange
than a standard flask. A typical example of lost oven space…
in my smaller electric kiln , i can fit 4 perforated 4x6 flasks
… but i can fit 6 4x6 standard flasks in the same space. In my
40 flask(4x7’s)oven, the figure is 30 perforated flasks versus
40 standard flask… Thats a big increase in productivity. The
flanges on a perforated flask have been known to warp due to
repeated heating and quenching in water and once this happens,
theydon’t work as well and are not repaireable. Exhaustive tests
were run on these vacuum liners and the net result is that they
are superior and end up saving the caster money as far as oven
space, increased casting quality and the fact that these liners
have a raised border that is 2 " higher than the flask. This is
designed into the product for the investing cycle and stops your
investment from spilling over the flask and also helps to keep
the machine cleaner. The machines that allow you to cast standard
flasks are even cheaper than the perforated variety. sincerely,
Daniel Grandi http://www.racecarjewelry.com