Fun With Smelting (long)

[Jim L.]

I had a little fun the other day with the forge. I've been collecting scraps, chunks and junk implements of aluminum for a few years now with the plan to melt it down and cast something useful.

One drawback was what to use as a crucible. I decided on the cut off bottom of a steel compressed gas cylinder ("E" size) with a removable wire handle added.

My forge is a verticle hybrid feeder using both charcoal and parafin with forced air. Since it gets steel to non-mag in no time, I thought it would do the trick.

At first I was beginning to think I was mistaken. I'd gone through almost half my fuel with little more to show for it than smoke from the crucible.

Then it hit me, I had a brain cramp and forgot to put a grid between the combustion chamber and the fuel making the fire choke.

Well, after fixing the problem and refiring the forge, it got plenty hot. It was kinda' fun watching those old tank regulators, pistons and VBS chunks just melt right on down. Now I have to teach myself sand casting.

I wonder what the alloy was?

Thanks for reading y"all.

Jim L.

 

[Jim L.]

Speaking of alloys, I noticed a lot of the brass that couldn't be removed from the regulators was badly eroded. Could the missing material have alloyed to the aluminum?

I wonder what properties the resulting alloy would hold? Any help would be appreciated.

Thanks,

Jim L.

 

[xdshooter]

Jim,
I toyed around with lost wax casting pewter about 10 years ago. I think its easier to do than sand, but your parts are limited. The hard part is making the part you want in wax, but once that is done, the rest of the process is easy. Basically, build a box that will withstand an oven, suspend the wax part inside the box, fill the box with plaster. After the plaster has dried, flip the box over, melt out the wax, and get ready to pour. Just like sand casting, you have to make that little "stacks" for filling and air venting, but once the plaster is broken away, you get EXACTLY what you had in wax, no chance of "cave ins" that the sand may create.

As far as the brass alloyed into aluminum, IIRC it will just make it more ductile, but will result in a lower strength. There are some aluminum alloys that have higher strengths, but it is all relative, as you know aluminum isn't the strongest material to start with.

Have fun and post some pics once you get a finished part.

 

[Jim L.]

Thanks, XD. I hadn't thought of doing lost wax with plaster. I use aluminum stock for making guards and it gets hard to find some of the appropriate thickness without holes or some other kind of machining that dictates a shape that wasn't quite what I wanted.

As far as material strength, I would of thought the aluminum had more overall strength than pewter (hard for me to find). I was also planning on adding some aluminum "welding" rods to the mix I would other wise use to "solder" Al parts together.

It has a much lower melting point but is much harder. I've got to be real careful when filing or sanding this stuff as more Al will be removed than the solder. It'll be fun to see if I can pull off that alloy.

The plaster casting with lost wax makes me think I can cast a metric buttload of finished parts and blanks in one pouring. That whiring squeeking soud you're hearing is the cogs and gears between my ears comming up to speed.

Any other help/ideas will be greatly appriciated. Thanks again!

Jim L.