A Cast Aluminum Countershaft
For the Gingery Lathe
A couple of years ago (Winter 2003 I think) someone on the Yahoo Gingery Machines E-Mail List asked if the countershaft for the lathe could be made using castings instead of angle iron and bar stock. It took a while for me to get to it, but I figured out how to make one. This page will try to explain how I did it.
This picture shows the patterns required to make the countershaft. The handles are cast together with a runner between them. When casting the base place a 1"ø sprue about 1" from either end. For the handles, place a 1"ø sprue on the runner connecting the two handles. The main part of the countershaft requires more discussion though.
As I built the countershaft, the stop for the handles is built into the pattern. Also, the parting line is fairly complicated. In the drawing the red line is the parting line (and the vertical line on the left is actually sloped to the right):
The easiest way to make the mold is to use a follow board for making the cope:
Cut two notches in the board to let the stops extend below the parting line. Also, place a spacer between the flanges to keep the sides from being pressed together while ramming the cope. Ram up the cope, placing a sprue pin in about 1" from the top of the pattern. Vent the cope, rub in a molding board, and roll the cope onto its side. Remove the follow board and form the parting line, making sure the surface is smooth. Then roll the cope onto its top. Remove the sprue pin and place a short dowel in the hole. At this point I rapped the pattern to loosen it a little in the cope. This was to help it stay on the drag when the mold is opened.
Dust the parting line and ram up the drag. Vent and roll the mold. Run a small dowel through the sand in the cope and rap the pattern. This is another attempt to keep it on the drag. Open the mold and remove the pattern. Cut a runner in the sand in the drag from the sprue to the cavity. Clean up, close, and cast.
The centers for all the holes can be determined from the Gingery text. Since it's aluminum I used some stainless steel shoulder bolts instead of rivets. It also helped that I had these bolts on hand. Here are a few more pictures of the countershaft: