LinuxCNC Rigid Tapping Encoder Mount??

I finally got my mill running and it would be a good idea to add an encoder to the spindle to use the rigid tapping feature in LinuxCNC.  I really like Jon Elson’s method of putting Photo-eyes ‘in’ his Bridgeport head to monitor the speed & position of the bull gear, but that seems like a lot of work making a rabbit and taking the lid off (you have to lift a heavy motor).  I suppose if (or when) I need to take apart the mill head, I can look at doing that. Anyway, I plan on installing a small differential encoder and decided to make the following fixtures to mount my encoder on the top of the mill.

Also, since I haven’t made anything since I got the mill tuned better, I need to make CHIPS!