Fig. 685.
Referring now to some of the details of construction of the lathe, the slide rest a, [Fig. 683], is bored to receive sockets d d, [Fig. 685], and is provided with caps, so that the sockets may be firmly gripped and held axially true one with the other. The socket-bores are taper, to receive the taper ends of the arbor x, and are provided with oil pockets at each end. There is a driving pulley on each side of the emery-wheel, and equal belt-speed is obtained as follows: Two belt driving drums m n are employed, and each belt passes over both, as in [Figs. 683] and [685], and down around the pulleys p. The diameter of the drum n is less than the diameter of the drum m by twice the thickness of the belt, thus equalizing inside and outside belt diameters, since they both pass over the pulley of the emery-arbor. The piece t is a guard to catch the water from the emery-wheels, and is hinged at the back so that the top is a lid that may be swung back out of the way when necessary.
Fig. 686.
Fig. 687.
The method of securing the emery-wheels is shown in [Fig. 686]. Two flanges z (made in halves) are let into the wheel, and clamp the wheel by means of the screws shown. The bore of these flanges z is larger than the diameter of pulleys p, so that the emery-wheels may be changed on the arbor without removing the pulley. [Fig. 687] represents an end view of the bearings b for the roll to revolve in, being provided with three pieces, the two side ones of which are adjustable by the set-screws, so as to facilitate setting the roll parallel with the bed of the lathe. The height is adjusted by means of screws k, k, which may also be used in grinding a roll of large diameter at the middle of its length, by occasionally raising the roll as the carriage c proceeds along the roll (the principle of this action is [hereafter] explained with reference to turning tapers on ordinary lathe work). When the wheels have traversed half the length of the roll, the screws k are operated to lower it again, it being found that the effect of a slight operating of the screws k is so small that the workman’s judgment may be relied upon to use them to give to a roll with practical accuracy any required degree of enlarged diameter at the middle of its length with sufficient accuracy for all practical purposes.