Cleating. A cleat is a piece of material fastened across the width of a board to prevent its warping; if the surface is composed of several pieces, the cleat is also designed to hold them together. It may be applied to the back of the pieces, as shown by Fig. 275, or across the ends, as shown by Fig. 276. As the grain of the cleat is at right angles to that of the surface to which it is fastened, and since wood shrinks and swells more across the grain than with it, there is likely to be some movement of one on the other, and the fastenings used to secure the cleat should be of such a nature as to allow it. Otherwise, the edges of the board will be rigidly held, and shrinkage will result in the formation of large cracks, by the splitting of the board somewhere near the center. Screws are undoubtedly the best fastenings, as they will yield, to some degree, without becoming loosened. Nails frequently answer every purpose, and dowels are sometimes used. Glue is unserviceable. When it is used alone the cleats soon drop off; and when used with other fastenings it either gives way entirely, or breaks at intervals, causing local cracks.

Fig.275

Fig.27 6

225. Side-cleating, Fig. 275, is the more effective of the two methods, because the cleat may be larger and, for this reason, the fastenings be applied to better advantage. But when exposed to view, side cleats are unsightly, and are often objectionable because they increase the thickness of the piece as a whole. The proportions of the cleat may vary with the duty expected of it. Other things being equal, a deeper cleat like A will be more effective than B. It is more difficult, however, to put screws or other fastenings through A than through B; either may be fastened by screws inserted from the face of the board.

226. End cleats are neat in appearance, and, when decided warping tendencies are not to be overcome, do good service. To supplement the fastenings a narrow tongue may be formed on the board to fit a corresponding groove in the cleat, as shown in connection with B, Fig. 276.

227. If only one surface of a cleated board is to be made use of, - a drawing board, for example, - the strain on the cleat may be lessened by a succession of saw cuts on the lower side, extending the length of the board, as shown by Fig. 277. By this means the warping tendency of a seven-eighths-inch board may be reduced to that of a quarter-inch or even a one-eighth-inch board.

Joints for uniting Pieces at Right Angles.