My shop would have been state of the art in 1953. Used a Fritz-Werner vertical milling machine for the patterns and body roughing. I made quite a few different sized fly cutters and hand ground the cutting tools. The brass stuff you could do on a bench mill but rigidity counts. No substitue for pounds of cast iron and horsepower in the cutting tool. Especially with the wider cuts. Any tool chatter at all ruins the effect of the light patterns. That's something you can't see in the pics. As you walk by those guys they keep looking at you or changing shapes; the reflections crawl in geometric patterns that are almost unrelated to the ones that are cut in the metal. Kind of surprised others aren't already in this. 200 years ago 'engine turning' was a respectable hobby for refined gentlemen, although usually on a much smaller scale. For the patterns to work you have to control the depth of cut to about .002" (.05mm) All of them within that amount. Thanx for all the attaboys. Dave

Dave,
As a former machinist, your work looks great. Today a cnc mill would make things easier. In the older days, it was a matter of skill to hand crank a mill to get even cuts that would create the optical reflections you are getting. The cutter had to be sharp and fed at the right speed on a solid machine. Sometimes you have to put drag on the axis to get past chatter. This is a good example of old skills meeting a modern application. Way to go!

Don