Turning and boring tapers . Figure 8. Action of work on centers. Having seen how tapers are made under the imag-inary conditions named, we must now consider the prac-tical questions involved, the most serious being the factthat the centers must enter a sufficient distance to sup- Turning and Boring Tapers. port the work, and that the work is carried in a crampedand constantly changing position owing to the offset, asshown in figure 8. It will be seen that the effective length of the bar,so far as our calculation is concerned, has been short-ened by the depth of the center on each end, and thed
Turning and boring tapers . Figure 8. Action of work on centers. Having seen how tapers are made under the imag-inary conditions named, we must now consider the prac-tical questions involved, the most serious being the factthat the centers must enter a sufficient distance to sup- Turning and Boring Tapers. port the work, and that the work is carried in a crampedand constantly changing position owing to the offset, asshown in figure 8. It will be seen that the effective length of the bar,so far as our calculation is concerned, has been short-ened by the depth of the center on each end, and thedepth of both must be deducted if we wish to get downas fine as possible. The longer the piece or bar, the less each center is li inch. Derry Uollard Co Figure 9. Taper bearing at ends only. deep, the effective length of bar is only reduced from24 to 23)4 inches—a change of nearly y|„- of an inch tothe foot; and the careful man will want to know whythe taper is not exactly as calculated. As a matter of fact, it is not wise to depend toomuch on calculations in this case, as at best they areonly a guide, and the practical man measures very care-fully with a gage, if he has one, or with calipers at twopoints a measured distance apart. The calculations areuseful in getting pretty near the right taper, but it issafer to measure after each cut and adjust the tail stockaccordingly. In fact, turning a taper just right or twojust alike in an ordinary lathe is not always easy to do. Turning and Boring Tapers. Where it is not necessary to have a fit the wholelength of the taper it is a rather common practice torelieve the taper in the center of either piece, as it ismuch easier to obtain a g^ood fit, free from shake, thanwhe
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