In [Fig. 2276] let s represent a shaft and f a feather, required by the drawing to be permanently fixed therein. The drawing will not, in ordinary shop practice, give any instructions as to how the feather is to be fastened; hence the mechanic usually exercises his own judgment about the matter, or is governed by the practice of the shop. If left to his own judgment he may determine to so fix it that it may be locked on all four sides, as in [Fig. 2277], or he may simply set it in as in the similar views shown in [Fig. 2278].
Fig. 2277.
Fig. 2278.
The method shown in [Fig. 2277] is the most secure and best job; but, on the other hand, it is the most difficult and costly. The difficulty consists in filing the parallel part above the surface of the shaft to a line that shall be quite even with the surface of the shaft. This difficulty may be overcome by leaving the sides parallel, and making the length a equal to the length of the acting part of the key, and the bottom b as much longer as may be required to get the required amount of dovetail on the feather ends.
