Technical CASTING, Made my own cast alloy nailhead valve covers

8/22/15 In the lost wax casting process the wax is melted and poured out of the mold thus forming a hollow cavity. Then the aluminum is poured into the mold.

 

I'm in the process of building a mini foundry and intend to use the "lost foam" method to cast some small decorative stuff. I'll let you guys know how it went

 

I know its an old thread, but its got some good info in it, thought I would add, I built a small forge and during my aluminum experimenting, have made a few neat smaller items, shift knobs etc.
Have been doing lost foam casting, make sure to make a clamshell for top to create head pressure for a tighter pour.
I have pictures of each step if somebody wants to see.

 

8/21/15 Burning styrofoam produces poisonous phosgene gas so make sure sure you have excellent ventillation.

 

Yeah....what 19Fordy said.....and go join "Alloyavenue.com"......that board will be a big help for you.

Roger

 

yes sir, my set up is out doors, smelting aluminum can also be explosive dangerous !

 

Phosgene gas has two chlorine atoms per molecule, Styrofoam is Polystyrene that contains no chlorine atoms. How do we get phosgene gas from decomposing polystyrene? It's not good to inhale the decomposition products but phosgene it ain't got.

 

They must have crossed it with PVC

Nice Thread,
just put together aluminum foundry in garage.
Using CNC router table to make lost foam forms.
Valve covers, valley covers, air cleaner covers are all pretty easy to model in solidworks.

We're trying to build supercharger intake and drive setup.
McMaster-Carr has castable refractory in 50 pound bags for $85 for anyone looking to build their own foundry.
Temperature limit was 3000 F. IIRC that's good enough for cast iron.

Hope to get this supercharger project done before the snow starts flying again.

Cudos to all the other builders on this list that grab the bull by the horns.

 

done a small amount of casting, lots of fun

 

You won't get phosgene from pvc either! The most common way to get phosgene poisoning in a home shop situation is from welding parts cleaned with brake cleaner, or burning certain refrigerants.
https://en.wikipedia.org/wiki/Phosgene
My first foundry try. It will need lots of finishing/machining, but I think it will be a handsome gauge cup when finished. Will also work as a clearance light for my truck project. (I cast a dozen)


"Yeah....what 19Fordy said.....and go join "Alloyavenue.com"......that board will be a big help for you."
I heartily agree with this. Lots of knowledge, from jewelry casting to production iron foundry.

 

"Man" I learn the coolest shit ever on this site !!!

 

I'd agree with that. It is correct that polystyrene fumes are nasty, and I will indeed be casting outdoors only, but I didn't think phosgene was the gas produced?
Thanks guys for the advice and caution anyhow.

 

Yep, and Wikipedia never has errors
http://jat.oxfordjournals.org/content/4/4/166.abstract

 

Freeman Pattern Supply out of Cleveland OH ( I think ) is supplier of tons of pattern supplies, including very expensive shrink rules.
As far as shrinkage rates, think about it 1/8" for iron PER FOOT , 1/4" PER FOOT for steel, it;s not a lot.
We have taken actual valve covers to mold with no shrink factor built in used the actual part to mold and pour and they turned out fine