Motorized telescope Lens Caps

One requirement for my amateur astronomy hobby is to control the observatory and telescope equipment completely remotely, eliminating a 300-foot walk out to the observatory. Motorized lens caps for the telescope and guide scope are needed for fully remote operation.

I needed to machine splines on ¼" brass shafts to mate with motors that could be controlled remotely. These are the finished splines.

To machine the splines, I removed the three-jaw chuck from the lathe and installed it on a rotary table attachment for the milling machine. I used a regular end mill to cut the spline. After each cut, I rotated the shaft 45° and made the next cut. Eight cuts, and the spline was finished.

Here's a close-up of the splines. The shafts are ¼" round brass stock. The angle between faces of each cut is 90°. Some angles appear more acute, but this is an illusion caused by the camera angle. A square-end mill can cut only 90° angles.