Facing and Turning to a Diameter: Taking a Cut You Can Predict

Two cuts do nearly all the work on a lathe. FACING cuts across the end to make a flat square face and set the length datum; TURNING runs along the work to make a diameter. Everything else is a variation on those two. What separates a machinist from someone holding a tool against spinning metal is that the cut is PREDICTED. You decide the finished size, work out what the dial must read, take a trial cut, measure, correct once, and go to size. Creeping up on a dimension by guesswork wastes the metal and still misses. The single fact that catches every beginner is that the cross-slide removes twice what it reads, because the work is round and the tool cuts the far side away as well.