the hand wheel on-the left side of the apron engaging the pinion with the rack on the bed. By means of plunger (4), the one-shot lubricating system forces oil to all bearings in the apron, the bottom slide and carriage ways and the cross feed bush. The construction of the 17"-24" Regal apron (figure 8) is similar to that of the 13"-15" but differs slightly in its operation. Lever (1) is moved down to engage the cross feed, and swings up past the stop (2) to engage the length feed. Lever (3) is the half-nut handle which can only be engaged when lever (1) is in neutral against the stop.
Lever (5) is the apron feed reverse which reverses the direction of feed without shifting the headstock feed reverse. Of course, the direction of the leadscrew rotation must still be set at the headstock. THE CARRIAGE THE FEED ROD The feed rod transmits the power from the quick change box to the apron. Most lathes of this type are not provided with separate feed rod, but use a splined leadscrew for both turning and chasing, thus the leadscrew is always in use. On Regal Lathes, a separate feed rod is provided to transmit the power for turning and facing.
FEED ROD SAFETY DEVICE All Regal Lathes, because of their extensive use in schools where they are operated by comparatively in- experienced persons, are equipped with a safety device, which releases when the load on the feed rod becomes too great for the machine. At a predetermined factor of safety, the spring-ball clutch releases the feed rod and automatically engages it again when the strain is released. Thus, if the carriage runs into the headstock, the balls will compress the spring and release the shaft and save the feed mechanism from breakage, but as soon as the feed is disengaged at the apron, the safety device engages again and resumes turning the feed rod.
THE LEADSCREW The leadscrew is used only for thread-cutting. The leadscrew slip gear (10, figure 3) has a sliding fit on the feed box end of the screw and can be engaged with, or disengaged from, the feed rod gear by a short sliding movement on the leadscrew. When not chasing threads., disengage the sliding gear so that the leadscrew does not revolve. On other lathes of this type, where splined leadscrews are used to drive the feed gears, the leadscrew is subjected to torsional strains at all times and soon becomes inaccurate. The key engaging the spline (keyway) in the leadscrew also burrs up the edges of the threads and the leadscrew acts as a tap, constantly wearing the half-nuts.
The leadscrew on a Regal Lathe remains accurate for the life of the machine as it is not subject to these conditions. The headstock end of the leadscrew runs in the leadscrew bush which is held in a bearing in the quick change .box by two screws. The leadscrew is held endwise between a shoulder and the adjusting nut with hardened thrust washers on each side of the bush. End play is eliminated with the adjusting nut. Care must be taken to keep the leadscrew free from end play or the threads will be spoiled when the lathe is reversed without backing the tool away from the work. All right-hand threads, and the majority of turning cuts on a lathe, are cut toward the headstock.
For this reason the Regal Lathes are equipped with left-hand threaded leadscrews. This also reduces the number of gears in mesh between the spindle and the leadscrew. The thrust of the leadscrew is taken at the feed box end of the screw, thus the leadscrew is in tension under this condition. The leadscrew takes a bearing in back box, but it takes no thrust at this point. The back box supports both the leadscrew and the feed rod on the tailstock end of the lathe. FIG. 9 – CARRIAGE ASSEMBLY The carriage (1) travels along the bed and is guided by an inverted V-way or shear in front and a flat way in back.
The movement of the carriage is by means of the gear train in the apron to which it is attached. The bearings (bed ways) are protected by shear wipers to prevent chips and dirt getting between the carriage and the bed. The carriage is gibbed to the bed both in front and back. The cross feed bush (2) forms the bearing for the cross feed screw, on the front end of which is a micrometer dial 3 and cross feed handle (4). The carriage clamp screw (5) is used to clamp the carriage to the bed for facing and cutting off operations. NOTE: Before engaging the longitudinal feed, be certain that the clamp screw is loose and that the carriage can be moved by hand.
The carriage is clamped to the bed when the lathe leaves the factory to prevent movement during transit. Lift the compound rest dirt guard over the cross feed screw and oil the screw (6). Oil the felt in the wipers. When working with cast iron, remove the wipers occasionally and clean them in kerosene. 11