Sand and Lost Wax casting with aluminum

First thing you need is a furnace to melt aluminum in... This diy example is really simple and cheap.. Where i've used ceramic fiber blanket in the base, sodium silicate and perlite can be used.... The top of the furnace is a stainless steel bowel lined with ceramic fiber blanket, then rigidized with silicon dioxide, a colloidal silicate.... I had an old photo copy stand that i use to lower & raise... It also swings to the side and locks in place for access to the crucible... Old disposable propane cylinders hold about 5# of aluminum, and are good for 4-6 melts...
Now for a few pics of said oven..

 

The burner is made from standard pipe fittings, and some 1/4 fittings... Here are a few different burners made from different size pipe and fittings.. I use different size wire welder tips for the propane orifice ..

 

Few more pics of the furnace and mold frames, also a finished casting of my skull ashtray....
Don't know why the pics are in a different order than the way i uploaded them?

 

Very cool!

 

There's a CZ in his tooth and 10mm black onyx in his eyes... on the back side i used contact cement to fix the leaves to the mold....

 

Very Nice!

 

Looking pretty slick.

 

Lost wax casting molds mostly use opened ended steel cylinders for the molds. The wax is attached to a rubber mold base which holds the cylinder and seals the bottom of the mold.. The mixed jewelry plaster is poured over the wax, filling the cylinder to the top... An hour later the base is pulled off, then its into the oven set on low.... If you're too aggressive on raising the temp, there's a steam explosion in the oven... Really bad if it's an original wax you've spent days making.....
Nowadays all my castings are gravity pour, no spin or vacuum casting... pouring aluminum is really a simple, low cost, backyard operation.... That's the biggest attraction for me, and I get a sense of accomplishment when i make something out of metal... any metal, cheap thrill i guess...

 

what's with this 5 minutes to edit crap... talk about something that needs fixing... at least for someone as slow as myself...

 

So the jewelry plaster hardens and the wax melts out in the oven?

 

The plaster mold goes into the oven when it's hard and still wet.... The wax begins to melt and flow out of the mold at about 160-170*f. The wax is caught in a ceramic saucer to save the floor of the oven... The temp needs to be kept under 200*f until most of the water is eliminated.. There is low pressure steam created at these lower temps that help eliminate most of the liquid wax... The temps still need to increase to 1200*f to completely burn out any wax that was absorbed by the plaster....
Sand casting molds can be cast as soon as the pattern is removed and the mold frame closed... By far the fastest way to cast metal with good detail....Lost wax allows casting of very thin cross sections and extra fine detail.... It's always a trade off of something...
I'll also post some pics of lost foam casting later... A process that involves pouring molten metal into a mold containing a foam form.... The foam doesn't need to be removed, molten metal is poured directly into the mold and burns it away... Most very intricate, large steel castings are done that way... They machine a steel mold to make the foam form.... All in all a very involved process.
What i do is just a hobby that helps pass the time, and keeps me from sitting on my ass, doing nothing...
I have so many interests that take up my time... I'll probably start a thread on vacuum forming before long.. I have a 24"x 24" vacuum former i designed and build, also a 12"x 12" former..
Another new idea always seems to be dragging me off in a new direction... At least it keeps me busy..
Mods,
Please try to change the 5 minute edit time.... I'm old and need more time to edit.... I hate seeing my stupid mistakes in print...

 

So your saying you can only edit your post for 5 minutes and then its locked down?

 

I think I increased it to 30 minutes. Let me know if it works.

 

Very cool skull!

 

Thanks for the explanation, mytwhyt. I've wondered how it worked, but never spent any time learning about it. Looks like it reproduced the leaves very well.

 

Gonna bump this old thread up a bit.. Here's a few rings and the handle I did for an old friends knife blade.. Then he had the nerve to leave this mortal realm with out picking it up.. The elephants are the links in a bracelet. One is cut in half to build the catch in.. I'm making up some new molds for sand casting... Raiders and The Golden Knights.. 6"x7" Plan on making them to fill an empty truck hitch receiver..
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That's pretty cool. I learned how to do lost wax casting in 8th grade shop class.