Topics include, Machine Tools & Tooling, Precision Measuring, Materials and their Properties, Electrical discussions related to machine tools, setups, fixtures and jigs and other general discussion related to amateur machining.
I do not know where i was but they had several different types of step drills. A common one is used to drill a countersink for socket head cap screws. They are able to origionate and complete the hole. If you are using a drill to counterbore an existing hole then you do not want the pilot to cut at all so it will have no side relief. They had other bits that were stepped and meant to drill precise holes. You drill a pilot hole in location and then the center bit (a little bigger than the pilot hole) keeps the larger bit on center and with on wobble. or cutting an out of round hole. I have a few or these and they do produce a really nice hole.