Jewellery development - Sand casting

Sand casting our badges- We used the 3D printed model as a master pattern for our sand casting moulds. We had decided to cast in brass as it was cheaper than silver. However we encounter a number of problems. It was difficult to calculate the amount of brass lemel needed, this was because the nylon of the 3D printed model has a different specific gravity to wax and it was not possible to find out the SP of the nylon. The second problem was medal flow within the sand mould, we try positioning the master model in various ways but without success. The third problem was that brass cools very quickly and the cold sand mould hindered this even more. The fouth problem was that brass generally doesn't like to flow very well in it's molten state and given we were just pouring the medal into the mould we had to rely on gravity to pull the medal down into the mould. We also tried with pewter. This yielded better results, however still not at a good enough standard. Our solution was to invest the two 3D printed models and cast them using the centrifugal casting machine. We had also decided to have our design laser cut in perspex.