No Model Metal Casting

Metal casting in the sand requires a model to make a mold, which is usually an already existing object or a 3D print. After doing some tests with 3D printed objects, I was curious if I could skip the step of preparing a model and make a mold for casting directly on the sand. I had CNC milling technique in mind, but for the start, I tried hand engraving with a Dremel tool.

I pressed the sand in the box for casting, to fit two small models. With the first model I used the rounded tool, to get soft edges. Making the shape freehand was a bit difficult task, but didn't take a lot of time. The sand was not flying away as I was afraid it could do, and my other concern was what it does with the drill bits. With a model of this size, they were not damaged, but I would keep spare bits specifically for a project like this.

With the second shape, I used the simple twist bit, to get closer to the CNC effect (the idea is still not doing it manually).

In the metal workshop, I collected pieces of aluminum and cut them in smaller parts to fit a can for melting.

I heated the aluminum with a torch and carefully poured it into the molds. It is also possible to make a 2-part mold with tunnels for pouring metal, to have a more precise outcome.

When the metal cools down a bit, it is safe to take it out with plyers and put into the cold water. The pot is still very hot. The leftover metal in it can be used for another cast.

I used saw to separate the bottom part of a casted object (this is where the 2-part mold system works better!), but the round shape was not very easy for both the saw and the grinding machine, so I only minimized the edge of it. Then I used pads for polishing to make the surface more matt on the shiny areas, and a bit of sandpaper to fix some details of the casting. Of course, it is possible to do the opposite and give it a very shiny and polished look, but I liked the original roughness of it.

Here is the outcome, which can be developed into a more machine-controlled process.

I enjoyed working with the sand directly, without pre-making an object that I will probably not use again if I don't need another cast of it.