This is the first rewarding step to building your roto cast machine. The first steps are to drill holes in preparation for the threaded rods. You will need to drill a series of 4 holes on the 18x18 inch 1x1 frame, and 2 holes in the 16x16 inch frame. All the holes for the 18x18 frame should be drilled in the exact centers of each side. The holes for the 14x14 frame should be drilled in the center of the top and bottom sides.
Once you have the holes drilled, you can then put the threaded rod to use. We will be putting a rod through the top (the 3.5 inch 5/16 rod) and bottom (the 4.5 inch 5/16 rod) of both frames. (refer to schematic) The rods will need to be fastened incredibly well to certain parts of the frames to allow for secure rotation. Additionally, other parts will remain loose. For the loose parts, it is still necessary to put a washer and nut on either side of the hole to ensure that the motion of the machine is not thrown terribly off swagger. I used a stop nut on the ends of the rods, and regular nuts on the inside of the rods.
After you have the rods secured, you will then need to attach the gear. To do this you will need to clamp the flat metal piece across the gear, and mount it on the gear using the two of the mounting holes. From there, you will then need to drill a 5/16 inch hole in the very center of the metal plate for the rod to go through. After that is completed, secure it to the rod with a regular nut on the inside, and a stop nut on the outside. Then place epoxy over the nuts, to ensure the gear can not become loose.