Cool vid! Thanks for posting.
But can somebody explain the rig? I get the index block, and the index gear, but the wire or whatever it is rigged across it I've never seen before. Admittedly I've only seen gear cutting on the mill, vertical and horizontal. Is the wire wrapped around the index arbor to rotate in place as the carriage moves? So this is so the cutter just has to be cut at a straight angle and ends up with the involuted cut by traversing through? Is this how this did it back in the day or did he come up with this?