Probably slightly off topic, but related to material removal. About 3 years ago I visited a factory that had a number of CNC mills, one of which was making some ally boxes for race car electronic enclosures and they were specified as machined from solid billet. The way that the material was removed for "pocketing" was that the machine was programmed to plunge drill a series of holes about 50mm deep with something like a 20/25mm drill, each hole slightly overlapping the next such that it left a series of islands standing and serrations round the edge. The finish milling then simply meant removing the islands and cleaning up the edges. Of course this was a commercial machine, through tool cooling etc., but the factory owner told me that it was by far the quickest and cheapest way to remove material. I realize that this method is probably well known, but I thought it was interesting. G.