How to Manufacture Metal Screws

Unlike bolts, which have threads that are carefully turned with SAE or metric thread dies, sheet metal and steel wood screws are quickly stamped and turned from a piece of steel wire in two steps. The metal screw threads don't have to mate to a matching nut, like the threads in a bolt. They only have to grip a piece of sheet metal or soft wood. For this reason, the threads on metal screws are larger, more aggressive and wider apart than threads on bolts.

Steel wire stock
Screw-cutting die
Screw-cutting lathe
Head-stamping machine
Hacksaw, or metal cutters
Safety goggles

Instructions

- 1
  Straighten out a small section of the steel wire. Cut the wire into short pieces the length of the desired screws
- 2
  Insert the screw blank into the head-stamping machine, and stamp the head design into the screw. Head designs include pan, flat, hex, Phillips, slotted and combo slotted designs.
- 3
  Insert the headed screw blank into the screw lathe. Mount the appropriate thread-cutting die into the lathe, and set up the lathe gearing proportional the properly integrated movement ratio. The rotation of the lathe is geared to the movement of the screw-cutting die. When the screw blank turns, the die cuts the threads into the screw and travels the length of the screw in a single, smooth motion. Each type of screw requires a different die and gearing ratio.
- 4
  Put on your safety goggles, turn on the screw-cutting lathe and allow the lathe to turn the screw. The machine does all the work once it's set up properly. When the screw is cut, remove it and insert another screw blank. Repeat the process for as many screws as you need.

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