Metal Casting

As a side project to my surfboard, I made a metal foundry in order to pursue the possibility of casting a metal impeller and diffuser for my board. I made the foundry based on a design made by "The King of Random," on YouTube. In order to cast the impeller, I 3D printed a PLA plastic impeller with low infill and cast it in plaster in order to attempt lost-PLA metal casting.

Aluminum

I cut up a broken aluminum pipe derived from my neighbor's party tent business. I used a reciprocating saw and hammer to make pieces that could fit into my crucible.

Crucible + Tongs

I bought a clay graphite crucible to melt the aluminum and tongs to remove the crucible from the foundry. I then made my own pair of tongs to use when pouring the metal

Ingots

To make the ingots, I poured the molten aluminum into an old muffin pan.

To build the foundry, I used a metal bucket, plaster, sand, chicken wire, metal pipe, and paint can

Step 1

I started by laying out a frame made of chicken wire inside a metal bucket to give the plaster more strength. I also cut a metal pipe and installed it in the bucket to provide a hole for the burner.

Step 2

I made a 50/50 mix of plaster and sand to act as the walls and lid of the foundry. I poured this into my metal bucket and used a paint can to create a cavity for the crucible and burner.

Step 3

I peeled out the paint can and cleaned up the plaster. I also made the propane burner which would heat the foundry.

Step 4

Once everything was tested, I heated the crucible slowly until it was red hot, and then let it cool slowly to temper it. I then loaded up the crucible with aluminum and made my first metal ingots!

Lost Wax/PLA Casting

I first attempted to mold and make a wax model of my impeller which was unacceptable. Due to this failure, I switched to a 3D-printed impeller which I cast in plaster and then heated in a fire to melt out the PLA. This left behind a cavity in the shape of the impeller. I poured the molten aluminum from my foundry into the molded cavity to create an aluminum impeller.

On the left is the wax diffuser. On the right is the 3D printed diffuser

Wax Impeller

Silicon Mold of Diffuser

PLA Impeller Casting