I have two questions;
1. Is the cutting mainly done by the XY table movement and the tool rotation is principally to present the tool at the required rake angle to the line of movement at each location on the path?
2. I am not familiar with Linux nor LinuxCNC, but I notice that you use a HAL file for the control. Is that because LinuxCNC does not use Gcode (I thought it did) or does a HAL file have advantages over Gcode?

I have been thinking of making a rotary broach but this is a much better approach for general work because you do not need a new broach for each size and shape of hole. A small and large boring bar is all you need for any size and shape. Now I'll have to write some Gcode, although a search of the net might turn up a wheel already invented by another.
Nice work BTW.

PS. I just realised that I'll have to add a rotary encoder to my spindle before I can follow your example. I have been meaning to do that for a while now, this is just the motivation needed.