TECH: How to make a sand casting master in your basement

What is it for?

 

Geez, I missed this the first time around. Great thread!

 

It's one side of a horseshoe oil tank.
Some assembly required.

Needs more hand work, before it goes to the foundry.

 

I was doing home sand casting a few years ago for antique gas engine parts. I found a foundry supply out in Pa where I bought " green " Sand ( which was red) for the sand box. I have done some split patterns using wooden dowels. Have been thinking of doing a core to make a hollow part. Basically you make a pattern of the hollow in what you want to cast, make teh "core" out of sand pressing it together very tightly then putting it inot he sand mold. Pour the metal then knock out the sand when it's cool. Thats where freeze out plug holes come from.

Great thread!

Cheers!
Matt

 

PS: I have been using a tempering furnace I got at a auction but have seen where a really good furnace can be made from a old oil furnace. I usually use a mixture of aluminium scraps from a local machinist and alloy wheels. It seem to machine freely generally. Don't use beer cans, not much metal in em & when you try to machine it it gums up. Save them for shim stock!

 

I bought a complete casting set up from the estate of a retired high school shop teacher.

His heirs didn't know much about the equipment so I got lots of nice stuff but no instruction.

I have had the casting equipment (small foundry furnace, copes, drags, sand, etc.) for a couple of years now and havent developed the needed courage to actually melt some of the aluminum that also came with it.

Thanks for the posting, now I am all fired up to fire up the furnace.

 

Norm, is it a speedy melt or a Johnson furnace? those are fairly common school shop size set up. tt

 

The furnace that I bought from the estate is a home made natural gas fired unit. It appears to be made with a large pipe for the out side, about 2 feet in diameter. The inside (where the crucible goes) is a little less than a foot in diameter and about 16" high.

The lid is equiped with a spring loaded affair so that you don't have to heave the top off of a hot furnace.

The air supply is an old portable blower of some kind with a slide to control the air flow. It appears that the gas is just run wide open?

I'm planning to run the blower with a router speed control figuring that it would be easier to control the air flow.

Like I said I have the stuff but not much in the way of experiance or instruction.

I have been to a couple of casting demonstrations where they used the "lost foam" method. The pattern is made up of insulating foam board coated with drywall compound. The foam burns away when the aluminum is poured in, it kinda looks like a little volcano.

The problem with this method is that everything is a one off since the pattern is incinerated in the process.

 

Aluminum was the most fun time I had in shop class. I don't know how much useless crap I made. After I graduated I could go back and cast parts which was great until they finally shut down the metal shop.

 

Great job on the filter mount, i would love to have those on all my hot rods, if there for sale...
I designed and built a license plate, plaque when i was 16 for the Dune Riders Oragization, my Dad the Vice President. I made them up in Metal shop 50 years ago. Then we found a company back then to reproduce them for the members. My buddy was cleaning his Mom's garage and found one made of brass. Also found the reciept. We paid back then 3.00 dollars for the aluminum one's and 7.00 ea. for the Brass one's. Wow,,,,I would love to have some more of these made up, now that we have one for a master. Is there anyone out there that would consider making some up for us. Not many of us left, but im sure we could find ten or fifteen. Great job, was a fun project back in the day. Keep up the good work....Im finishing up my last Willys Coupe project, be hanging up the welding leeds...Ted McClure, gasserted@yahoo.com

 

Great job. Reminds me of the days I used to teach sand casting in my high school industrial arts classes. Now the class is history (2006) and all the equipment went in the dumpster. Today's students are missing out on a lot of cool stuff.

 

Excellent work.

My father used to do bronze artwork in the lost wax process. We played with the dense black wax as kids. So your project has me thinking...cast brackets on my COE bed would look really cool.

 

Nice tech jeff !

 

im quiet keen on makin some cast parts for my bikes as well as the coupe project, a guy round the corner from our house has a model A roadster with a v12 lincoln in it & he modifyed his intake manifold to take triple strombergs by casting his own carb bases and then fitting & welding em in place. He made the masters in a similar fashion to alchemy but he bought a bag of casting sand and used a large set of old clay garden pots to cast the moulds into, and smashed em to get them out afterwards, just got to make sure its pre heated & completely dry before ya pour, nobody wants an unfortunate smelting accident! i think aluminium melts around the 710 (celcius) degree mark not sure what that is in fairenhiet, but old aluminium truck rims make real good smelting material too

 

Subscribed.

 

When making a larger casting,a good rule to go by is aluminum shirnks 5/32 per foot when poured. Your pattern needs to be that much bigger to avoid any size problems. I did this for 35 years in a patternshop. Still doing patternwork at home. I have access to an aluminum foundry that is about 6 miles down the road. We did make some furnace's out of 55 gallon barrels cut in half. Lines them with firebrick. Used propane and an air compressor for the heat. You have to install these down low and at an angle to get the heat to be uniform. The cast iron ladles or melting pots would be the only item that would be hard to find. Ours were about 3/8 thick and approx.10" in diameter. Also stood about a foot tall. They sat in an iron ring with 3' handles welded on each side. We poured various sizes and amounts by hand. The largest castings we could pour weighed 500 pounds and would require 10 guys pouring out of eight ladles fired by 8 different furnaces.. We didn't pour all at once but did have to make sure we had fresh molten aluminum going in from start to finish. Castings were seat molds made for the foam tooling industry. Shop closed just this past July.

 

Hello, Happy Thanksgiving,
I realize this is an older post, but I am very interested in this process, you mentioned the part is oversized 102%, I know that when you are casting aluminum , cast iron etc there is some type of factor required that must be built in for "Shrinkage" do you know the formula? or in simple understandable terms how to calculate or compansate for that when building the master form? Thanks in advance Johne,
jehammer1952
johnescolano2@gmail.com

 

Hey, Johne;

Don't know a formula for shrinkage, but IIRC, there is a neat 3-sided drafting ruler that has different metal-shrinkage-%-lengths on each side, used for scaling when drafting the blueprint patterns. So when you're done, the mold pattern is too big to use, but after casting in 'whatever metal' you're using, shrinks to the correct size. When I 1st saw these, at a really good drafting supplies shop(which, AFAIK, is long out of business), I didn't know that I would need them in the future, so now I get to search for some myself... .

Marcus...

 

When I build parts they sometimes need to match up to another part. I need to make my pattern for casting at 102% (aluminum) of final size so the cast part will fit. No formula needed, other than making all dimensions 102% of final.

Measure the "other" part with a regular scale and make the pattern with your upsize scale.

An almost free way to make an oversize scale is put a regular scale on a copier glass and set the copy size to 102%. I laminated the oversize one for durability.