The proper angle of the jaws to the centre line of the jaws may be determined as follows:—The most desirable angle is that which will enable the wrench to operate the nut with the least amount of wrench-motion, an object that is of great importance in cases where an opening has to be provided to admit the wrench to the nut, it being desirable to leave this opening as small as possible so as to impair the solidity of the work as little as practicable. For a hexagon nut this angle may be shown to be one of 15°, as in [Fig. 444].
Fig. 445.
Fig. 446.
Fig. 447.