I had the idea in mind for a sand casting project for quite awhile. Now I am happy to present the first tries and results of my casting project. The first casts were a big success. I learned a lot about the behavior of the mould and could make some adjustments. The only major change was an additional riser that prevented a sink mark at the top.
The sand molds consist of a mixture of silica sand and sodium silicate. The two materials are chemically exposed to the addition of CO2 and produce extremely hard sand molds. For this I designed a simple system to fill the mold boxes with CO2. I used glass fiber rods for the necessary sprue holes, as well as vents, which could be inserted in the 3D-printed master form.