Understanding Screw Heads
Screw type fasteners are manufactured with different head styles. Sometimes the style serves a functional purpose, and sometimes it's more decorative in nature. Understanding the differences will help you decide which style to choose.
There are two basic designs: countersunk and non-countersunk. Non-countersunk heads—where the head is fully exposed—encompass the largest variety. This style includes: binding, button, cheese, fillister, flange, hex, pan, round, socket and low socket, square and truss heads (binding head is occasionally referred to as binder head). Sometimes features are combined, as in the case of slotted hex, hex washer, slotted hex washer and round washer head designs.
Countersunk designs mainly consist of flat, oval and bugle heads. Unless the material is very soft, flat and oval heads require a countersunk hole. The advantage is that little or no part of the head protrudes beyond the surface of the material. If you are using flat heads screws in finish work, consider using a flat head screw cover (also known as a "beauty cap") to hide the head (not all drive styles will accept screw covers). Made of plastic, these caps are available in standard colors that match commonly used plastic laminates and wood. Bugle heads are commonly found in drywall screws, and the head design automatically compresses the drywall paper and gypsum as it is installed thus forming its own countersunk hole.
