|
Vacuum Chamber Plans, advice?(Resin)
QUESTION: I am wanting to make a vacuum chamber for casting resin (just a
small one for casting some 1/48 cockpit size stuff), and was wondering
if anyone has any advice, or knows of any plans for this contraption.
From an earlier thread, it looks like a cylinder is the way to go. Any
tips on materials to use,how much vacuum is needed,vacuum sources
etc., would be greatly appreciated.
ANSWER: You need a vacuum chamber for the mold rubber, not the resin. The
cheapest ready to go chamber would be a vacuum dessicator at about $120
along with a pump capable of pulling 28" Hg in 5 minutes or so. For
casting the resin a pressure pot with a cast lid (paint pots for HVLP
systems work well) capable of holding 60 psi and a compressor with a
tank at least as large as the pot. The pots run about $110. I do not
recommend you try to build either vessel yourself.
Bell Jar (the vessel only has to tolerate a fourteen psi differential) or a
paint pot will do.
You'll need to pull at least twenty-eight inches of Mercury.
You don't REALLY need a vacuum chamber for either. The secret is in the
design of the mold. I am just about to send in a manuscript to FSM on
vacuumless casting, though there is no guarantee they will accept it.
The biggest secret is to think like an air bubble when you design the
mold. How would you like to see passages to allow you to exist as resin
fills mold Sprue should enter mold cavity from bottom, not top, and
one vent tube is needed for every local high spot in cavity.
|
|
|
|
