A timber connector is any device used to increase the strength and rigidity of bolted lap joints between heavy timbers. For example, the split ring (fig. 1-27) is embedded in a circular groove. These grooves are cut with a special bit in the faces of the timbers that are to be joined. Split rings come in diameters of 2 1/2 and 4 inches. The 2 1/2-inch ring requires a 1/2-inch bolt, and the 4-inch ring uses a 3/4-inch bolt.

Shear plates are shown in figure 1-28. These connectors are intended for wood-to-steel connections, as shown in view B. But when used in pairs, they may

be used for wood-to-wood connections (view C). When making a wood-to-wood connection, the fabricator first cuts a depression into the face of each of the wood members. These depressions are cut to the same depth as the shear plates. Then a shear plate is set into each of the depressions so that the back face of the shear plate is flush with the face of the wood members. Finally, the wood members are slid into place and bolted together. Because the faces are flush, the members easily slide into position, which reduces the labor necessary to make the connection. Shear plates are available in 2 5/8- and 4-inch diameters.

For special applications, toothed rings and spike grids are sometimes used. The toothed ring connector

(fig. 1-29) functions in much the same manner as the split ring but can be embedded without the necessity of cutting grooves in the members. The toothed ring is embedded by the pressure provided from tightening a high-tensile strength bolt, as shown in figure 1-30. The hole for this bolt is drilled slightly larger than the bolt diameter so that the bolt may be extracted after the toothed ring is embedded. The spike grid is used as shown in figure 1-31. A spike grid may be flat (for joining flat surfaces), single-curved (for joining a flat and a curved surface), or double-curved (for joining two curved surfaces). A spike grid is embedded in the same manner as a toothed ring.