Fig. 289 is a method used to prevent wide boards such as signboards, wide and shaped pediments, etc., from casting or warping. It iscalled dovetail keying. Beyond calling attention to the fact that the angles at the edges of the keys, where they are bevelled, should be at or about 75 degrees, nothing further need be said, as the drawing is self-explanatory. Angle dovetail keying is shown at Figs. 290 and 291.

Fig. 290. - Dovetail Key.

Fig. 291. - Dovetail Keying on the Angle.