The fixture for turning the cam is simply a piece of scrap Aluminum round stock, with a tapped hole, offset from center, to fasten the cam blank to the fixture. A piece of round stock is turned with a "step", the smaller OD fits inside the cam blank, and the thick portion is just there to space the cam away from the fixture. All is held in place with a 1/4-20 SHCS and a washer. One of the extra tapped holes is from a previous cam, and the other is a "first try" at getting this cam profile correct. My first attempt resulted in a cam that did not have a very steep profile, (too round).
The cam, almost complete. Many steps are required to obtain the shape. First, the blank is turned, advancing the cross slide a little at a time, until the final radius for the bottom portion of the cam is reached. At this time, there is only an arc cut on the bottom of the cam.
Next, the carriage is locked (compound was locked previously). There can be no additional travel of teh cross feed at this point. The Cap Screw is loosened, and the cam is rotated counter-clockwise (same direction as the spindle rotation) for just a few degrees. The screw is tightened, and a small step will be taken off the cam. Actually, this step is so small that it blends in with the cam surface.
The cam is again rotated, another cut made, and the process repeated until the profile is cut. The lobe is then rounded with a file., and any slight "steps" are also taken out.
The timing gear needed some machining. It required boring, and turning down the hub. I chucked the gear in the 4-jaw using the SouthBend, and centered it using a Dial Test Indicator in the ID of the existing bore. The resulting bore and hub will then still be concentric with the teeth.
