Screws are supplied with slotted, Phillips, Torx® or Allen heads for screwdrivers or with hex heads for wrenches. Most of the screws used on cars and trucks are sheet metal, hexagon or pan type. Occasionally, you'll find a self-tapping sheet metal screw, with slots in the end to form a cutting edge. These types cut their own threads when turned into a hole.
The size of a screw is designated as 8–32, 10–32 or 1⁄4 –32. The first number indicates the size of the thread at the root or minor diameter (the diameter of the screw measured from the bottom of the threads on each side) and the second number indicates the number of threads per inch.
| Fig. 2: Common screw and bolt head types
|
| Fig. 3: Screw and bolt measurement terms
|
