The part illustrated in [Fig. 35] is an automobile transmission shaft. In this particular case, cylindrical, tapering and spherical surfaces are turned. The upper view shows, diagrammatically, the arrangement of the tools and work for the first operation. After the shaft is “spotted” at A for the steadyrest, the straight part C and the collar B are sized with tools S and R which are mounted on the left-hand carriage. A concave groove is then cut in collar B by tool R, after which spherical end D is formed by a special attachment mounted on the right-hand carriage. This attachment is the same, in principle, as the regular taper-turning attachment, the substitution of a circular templet T for the straight kind used on taper work being the only practical difference.
After the surfaces mentioned have been finished on a number of pieces, the work is reversed and the tools changed as shown by the lower view. The first step in the second operation is to turn the body E of the shaft with the tool T on the left-hand carriage. The taper F and the straight part G are then finished, which completes the turning. It will be noted that in setting up the machine for this second operation, it is arranged for taper turning by simply replacing the circular templet with the straight one shown. When this taper attachment is not in use, the swiveling arm M, which is attached to a bracket, is swung out of the way.
The method of driving this shaft is worthy of note. A dog having two driving arms each of which bears against a pin N that passes through a hole in the spindle is used. As the ends of this pin, against which the dog bears, are beveled in opposite directions, the pin turns in its hole when the dog makes contact with it and automatically adjusts itself against the two driving members of the dog. The advantage of driving by a two-tailed dog, as most mechanics know, is in equalizing the tendency to spring slender parts while they are being turned.
Fig. 36. Axle End turned in One Traverse of the Five Tools shown
In [Fig. 36] another turning operation on a lathe of this type is shown, the work in this case being a rear axle for a motor truck. The turning of this part is a good example of that class of work where the rapid removal of metal is the important feature. As the engraving shows, the stock, prior to turning, is 31/2 inches in diameter and it is reduced to a minimum diameter of 11/16 inch. This metal is turned off with one traverse of the carriage or by one passage of the five tools, and the weight of the chips removed from each end of the axle is approximately 12 pounds. The time required for the actual turning is about 9 minutes, while the total time for the operation, which includes placing the heavy piece in the machine, turning, and removing the work from the lathe, is 12 minutes. The axle revolves, while being turned, at 110 revolutions per minute and a feed equivalent to 1 inch of tool travel to 60 revolutions of the work is used. It will be noticed that the taper attachment is also employed on this part, the taper being turned by the second tool from the left. As the axle is equipped with roller bearings, it was found desirable to finish the bearing part by a separate operation; therefore, in the operation shown the axle is simply roughed down rather close to the finished dimensions, leaving enough material for a light finishing cut.
Fig. 37. Lathe Knurling Tool having Three Pairs of Knurls—Coarse, Medium and Fine