My Iron-Melting Furnace

I want to do stuff like this...


And look at how small is the setup he is using! I might just play with this sooner than I thought...

I was just thinking of making stock to machine... he made a part that just needs finishing for use!
 
I am assuming that is pewter or other low melting point metal. Aluminum is not too bad. When you get to brass, the radiant heat is impressive. The crucible is orange and it will ignite wood a foot away. I'm ascared of iron!
 
wachuko said:
I want to do stuff like this...


And look at how small is the setup he is using! I might just play with this sooner than I thought...

I was just thinking of making stock to machine... he made a part that just needs finishing for use!
Click to expand...
I suspect rwm is correct, that is probably a pewter-type metal.

I won't deceive anyone, metal casting can be difficult.
The sand he is using looks like petroleum-based greensand, often called by the trademarke name "Petrobond".

You have to maintain petrobond, and add a bit of alcohol to it from time to time.
I started with Petrobond, and had trouble with maintaining it, since it gets too dry, and you can ruin it if you add too much oil (some say add 90% alcohol only).

I gave up on petrobond, and tried greensand, which is a water-based sand and clay molding mixture.
The surface finish with greensand was terrible.
Greensand also has to be maintained, and mixed in a machine called a "muller".

I tried sand (commercial foundry sand called OK85), bound with sodium silicate, hardened with CO2, and that worked pretty well.

Then I discovered resin-bound sand, which is what I use with the OK85 now, and it is a mix-on-demand product.
You have to wear a commercial chemical-rated respirator when mixing resin-bound sand, and it is not reusable.
For iron work, resin-bound sand with a sprayed-on ceramic slurry produces commercial grade casting results, assuming you have your sprue/runners/gates/risers correct.

I have tried low temperature non-lead material, similar to lead-free solder, and I could not get the mold to fill completely.
I don't recommend low temperature metals.

I tried Zamak, since it has a lower melting point than aluminum, and was not pleased with how that material drilled (the metal melts in front of the drill bit).

The metal that most backyard casters use is alloy 356 aluminum, which is designed for casting.
Aluminum that does not make good castings is extruded aluminum, and aluminum cans.
Aluminum alloy auto rims seem to be a good alloy to cast, but those can be troublesome to cut up, and many are painted, which may have to be removed prior to melting.

Melting 356 aluminum is easy, and no more difficult than melting zamak (a propane burner can be used).
Finding good mold sand, and making a good mold is not easy.
It is the sand molding that really limits most backyard casting folks.

This fellow is rather outspoken, perhaps too outspoken for some, but he tells it like it is.
And I respect his opinion because he makes commercial-grade aluminum castings.
I basically agree with everything he says in this video, and I also have John Campbell's casting book.

 
I would be shocked if he really did that casting in a home foundry. It has no detectable porosity and the machined surfaces are perfect. It is obviously heat treated to machine like that. Try machining your raw aluminum castings and you will never get that finish.
 
rwm said:
I am assuming that is pewter or other low melting point metal. Aluminum is not too bad. When you get to brass, the radiant heat is impressive. The crucible is orange and it will ignite wood a foot away. I'm ascared of iron!
Click to expand...
Melting aluminum is quite a mild mannered affair.
It melts easily with a simple propane burner, and pours at 1,350 F.

Melting brass/bronze is a lot hotter than aluminum.
I forget the pour temperature of bronze, but perhaps between 1,900 F and 2,100 F.

As the temperature goes up, the problem is radiant heat, in the form of infrared radiation.
This is why you wear heavy leathers, and have a heat shield on the pouring shank.

There is also a tremendous amount of heat that comes out of a hot furnace when the lid is open.
Most lids open sideways, but some flip backwards.
The backwards lids put their hot surface facing you directly, and that gets REALLY HOT.

I had melted a bit of brass and bronze before I attempted to melt gray iron, and recall being terrified of the iron temperatures, to the point where my hands would be shaking during the lift and pour sequence.

The charging tongs and skimmer have to have long handles with iron, because the will start to overheat your glove in seconds.
I am going to add a heat shield to my skimmer handle to help with that.

My daughter was using a video camera 10 feet away during an iron pour, and as I was pouring, I noticed her camera was starting to smell like melting plastic. The infrared will be absorbed by any dark surface, or really most non-reflective surfaces.

It took me about 6 iron pours before I could relax and not get nervous before an iron pour.
Now iron pours for me are almost as routine as aluminum pours, but as I mentioned, use a lot of heat shield and protective leather with iron, and so it is a matter of being prepared and having the right equipment.

Pouring iron is sort of like driving on the expressway at 80 mph.
The first time you do it, it seems very dangerous, but if you do it every day, it becomes routine, and you become good at it, and can do it with relative safety.

.
 
rwm said:
I would be shocked if he really did that casting in a home foundry. It has no detectable porosity and the machined surfaces are perfect. It is obviously heat treated to machine like that. Try machining your raw aluminum castings and you will never get that finish.
Click to expand...
He basically operates a professional foundry on a small scale.
Check out this casting.



or these runway light housings


Olfoundryman is what I call one of the BOB's, ie: Best of the Best with aluminum castings.
.
 
Last edited:
I stand corrected! Yes I know who he is. That is amazing work, and really not hobby level.
 
I found a short bio on olfoundryman, and his casting success is not accident.
He was a metalurist, worked in foudries, and ran his own commercial foundry, so he has a lot of depth, and that shows in his work.

He also uses professional materials such as the mold coating, release agent, degassing agent, etc., and that makes the difference between a rough casting and a professional grade casting.

He is very aware of the need to be careful not to entrain air and other things into the casting.

I don't agree with everything he says, but I agree with about 95% of it.
He has a ton of experience.

.
 
You must log in or register to reply here.
Back
Top