The Lathe to CNC

The lathe has been called the mother of machine tools because it can make the parts, including the screws, of other machines, including other lathes.

Turning

In a lathe the workpiece rotates and a cutting tool removes material to produce round shapes: shafts, pins, bowls, table legs, bolts. Ancient Egyptian bow lathes spun wood back and forth with a strap. Medieval pole lathes used a treadle and a springy sapling. Wood turners still use foot-powered and electric lathes.

Maudslay and precision

Around 1800 Henry Maudslay in London built an all-metal lathe with a slide rest and a lead screw geared to the spindle, so the tool advanced exactly the same distance each revolution. It could cut accurate, repeatable screw threads. Maudslay's workshop trained machinists who spread precision engineering through Britain. Standardised threads followed, and with them interchangeable parts.

Numerical control

After World War II, the U.S. Air Force needed complex aircraft parts. John T. Parsons proposed controlling a machine's motion with numbers, and in 1952 MIT's Servomechanisms Laboratory demonstrated a numerically controlled milling machine run from punched tape. Computers replaced tape, and CNC became the standard in machine shops worldwide.

The CNC machinist

A CNC machine still needs a skilled operator: choosing tools, setting work and tool offsets, proving a program at reduced speed, listening to the cut, adjusting feeds and speeds, and measuring the finished part. The CNC Machining program teaches manual machining first, then CNC turning and milling, CAM programming and inspection. Credentials: NIMS Machining, Haas, Mastercam.