Since the initial tests of castings of individual parts went so well we decided to try casting assemblies of parts as a single piece. Right now there are a few assemblies of parts we are gluing together and we wanted to test casting them as a single piece. The process was the same as described before – only this time the molds were more complex.
Below you can see the mold for the Y carriage. Aluminum and wood pins were placed in the mold to provide removable mold pieces. To cast parts from the resulting mold the pins are inserted into the mold, which is then prepared and cast as described in the earlier post. When the cast material has hardened the pins are removed to remove the work piece. Wood pins provided aligned holes for screws, and channels in the finished parts for screwdrivers and other assembly tools to pass, and the Aluminum pins were machined where precise holes were required such as bearing or motor mount points. After it dries there is some slight flexing of the mold material so using solid shafts helps keep the holes aligned in the mold.
Preparing to make a complex mold
Below you can see one of the prototype Y and Z carriages using cast pieces. As before the white parts were cast plastic, and the black pieces were cut from ABS sheet plastic.
Cassius - Early prototype carriage using cast parts
Here is a slightly better view of the cast parts. The picture parts were from early attempts and there were a few visible casting defects, but the part functions fine.
Cassius - Close up of early prototype Y-Z carriages using cast parts
