File:Pratt & Whitney ASM.jpg

Summary
Automatic screw machine or also known as an automatic turret lathe. Mechanical analog programmed machine tool to make parts from stock. The machine above is a Pratt & Whitney Screw machine an early automatic turret lathe. The slowly rotating drums and disks below are programed analog fashion to preformed repeated machining.

Starting at the left the first drum handles automatically feeding stock to the machine's collet.

The disk controls the 'T' shaped thing that moves the drive belts forward and reverse from the two idler pulleys to the drive pulley in the center.

The next disk controls the right and left tools that shape the outside of the work. the left side of the disk controls the tool on the far side of the machine while the right side of the disk controls the tool on this side of the machine. Special tool bits are ground to make the outside shape in one pass, and the far side tool usually is the cut off tool.

The next drum controls the tool turret's depth of cut. Up to six operations. The turret holds drills, taps, dies, knurling tools etc. the things on the spoked wheel indexes the turret.

When each rotation finishes, ie the cut off tool cuts off the part the stock is automatically fed and clamped for the next part.

Machines like this were the backbone of the Industrial Revolution until replaced by computer controlled machines starting in the 1960s.