I did this at TechShop Menlo Park. http://www.techshop.com
I'll let you into a secret for the magic, alchemical process of melting and pouring metal for numerous types of casting (sand casting, lost wax casting, investment casting, etc.) Pure molten fun!
Please read instructables on safety gear for casting, proper casting tools and how to operate a casting furnace before you get to this one. Do not attempt to do this alone, without proper tools or without thorough understanding of their use.
Step 1: Load aluminum scraps into the crucible
Find some aluminum scraps. Cut them down to pieces on the vertical bandsaw with the course aluminum blade. Make sure to wear safety goggles. The crucible is made of either clay graphite like the one we used or silicon carbide to withstand temperature.
Step 2: Position molds
Place molds on either sand or refractory brick so accidental spillage of molten metal doesn't interfere with the tar ground underneath.
Step 3: Ignite
Load the crucible into the furnace, I like to give it a base such as a refractory brick. You can use a variety of ways to ignite the fire such as a match or a sparking tool. I prefer a map gas torch to give myself as much space as possible.
Step 4: Introduce air
By turning on the motor and opening the air vent lid introduce air making the fire spin around the crucible making it heat evenly.
Step 5: Put the lid onto the furnace
Place the lid onto the furnace as shown in picture. Now be patient and observe the molten metal through the peephole on top of the lid. Don't hover and look directly above it, it will burn your face. Peek from the side.
Step 6: Get crucible out
Shut the motor and fire off and get the lid off the same way you put it on. Using proper crucible grabbers pull it out of the furnace and place it in the crucible pick up ring over some sand.
Step 7: Scoop impurities
Impurities will collect at the surface of molten metal. Scoop them off with a steal spoon.