32mm System

 Screws for Wood Products

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: Bevel head (or flat head) and Pan head (or non-countersunk). Non-countersunk heads—where the head is fully exposed—encompass the largest variety. This style includes: oval, round, round washer, and pan/truss heads (binding head is occasionally referred to as binder head). Flat head designs mainly consist of flat, trim, self-sinking, 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.

Driver Type

Drive style—or drive recess as it is called—refers to the kind of tool you use to install (or remove) the screw.

Of the many that exist, the most common are: slotted, Phillips, combination (both slotted and Phillips), hex, hex socket, square, and spanner.

Pilot Hole

Think of a pilot hole as piloting the tip of the screw. It leads the screw in the desired direction.
Plus it reduces the chance of the screw splitting the board by clearing material away for the Minor Diameter of the screw.

The threads will cut into the wood fibers and grab hold. Softer woods do better with coarse thread, while fine thread screws can be very effective in hard woods.

Countersinking

Countersinking is done to allow a countersunk screw head to seat in the wood either flush or below flush. That way you don’t have any screw head exposed above the surface of the wood. This is done with a countersinking bit.

Countersinking can be useful if you’re wanting to hide the screw heads by filling with a wood filler or putty. Countersinking (done deep enough) will allow room to fill the holes, sand flush, and make the screw heads disappear.

Counterboring

This is done to give clearance for sinking a panhead screw for example, or even a hex bolt. It leaves a flat surface for the head of the screw or bolt to rest against.

This is common in pocket hole joinery. The pocket hole drill bit leaves a counterbored hole and a clearance hole in the leading board. The counterbored hole gives a good, flat surface for a pan head (or pan washer) screw to seat.