Nail shanks are made smooth or deformed. The deformed shanks is usually spiral (or helical) or ringed.
Spiral nails provide greater withdrawal resistance than smooth shanks nails and are particularly effective in resisting shock loads. Some typical applications are for: flooring underlay, panelling, gusset plates, soffits, siding, and roofing.
Ring-threaded nails also have high with-drawal resistance created by the keying action of displaced wood fibres against the nail grooves. Applications include fastening for gypsum wallboard, plywood underlay for flooring, and sheathing.
The shape of the point affects the tendency of the wood to split when a nail is used close to an end of edge because the shape dictates whether the nail acts like a wedge or like a punch. The sharper the point, the higher the holding power due to wedging of wood fibres against the fastener, the easier it is to drive the nail, but the greater the tendency of the nail to split the wood.
The most widely used nail point is the diamond which is a good compromise between ease of driving, minimization of splitting, and holding power.
Figure 5.3: Shanks and Points