Analysis of information sources in references of the Wikipedia article "Machine taper" in English language version.
As shown in Table 1, the well-established tapers for shanks and sockets now in use vary from 1⁄2 in. to 1 in. or more per ft., the tendency being to use a somewhat steeper taper for the larger than for the small sizes, perhaps because with small tapers, the liability to slip produced by the work is not so great and the "bite" of the taper when forced into the socket is sufficient to secure effective driving. In the larger sizes, tenons or tongues must be provided to aid in driving and in the still larger sizes keys of some form are needed, as, unless the angle of taper is very slight, the tenons are liable to be twisted off. When such auxiliary means of driving is provided the taper can be made steeper, giving the advantage that the parts can be more easily separated.
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