This instructible has no photos, only drawings. This unit I Built in the late 70's for melting aluminum transmissions, bumpers and such.
The unit was about 4 ft square and 6 ft tall, would accept whole transmissions that that had been drained of oil, and automobile bumpers thru its 36" feed chute. the continuous flow of molten aluminum was poured into 1/2 ton molds.
The burner unit which is the main focus here can be scaled up or down for your particular needs. This size unit when burning uses about 7 gals used oil an hour, at 20,000 btu per lb, that's equivalent to 1.12 million btu an hr. much more than most garages need.
A 1.5" x 12" unit was placed in a barrel stove in a garage, it produced as if the barrel stove was running wide open, and burned thru in 5 mins because there was no fire brick. So be careful and have fire extinguishers handy, if you decide to build a unit like this.
Step 1: Continous flow Smelter
Step 2: Air input
The air is provided by a blower, I have used kirby vacuums, canister vacuums in 5, 10, and 20 gal size, and commercial vane blowers salvaged from scrap yards as the blower. The size will depend on the heat output you intend to produce. the Standard exhaust tubing unit will be totally useful using the 5-10 gal vacs. Always provide a divirsion valve for the air flow for smooth startups and when restricting to a reduced heat output.