Fig. 81. Automatic Wheel and Pinion Cutters.
Wheels are cut in two ways, on automatic wheel cutters as just described and on engines containing parallel spindles for the cutters, carried in a yoke which rises and falls, so that it clears the work while the carriage is returning to the starting point on each trip and engages it on the outward trip. The cutters are about three inches in diameter and rapidly driven; the first is a saw, the second a roughing cutter, and the third a finishing cutter. The carriage is driven by a rack and pinion operated by a crank in the hands of the workman and streams of soda water are used on the cutters and work to carry away the heat, as brass expands rapidly under heat, and if the stack were cut dry the cut would get deeper as the cutting proceeded, owing to the expansion of the brass, and hence the finished wheel would not be round when cold, if many teeth were being cut. The stacks of wheels are about four inches in length and the slide thus travels about twenty inches in order to clear the three arbors and engage with the shifter for the index. The last wheel of the stack has a very large burr formed by the cutters as they leave the brass and this wheel is removed from the stack when the arbor is taken out and placed aside to have the burrs removed by rubbing on emery paper.
Fig. 82. Wheel Cutting Engine.
This is one of the few instances in which automatic machinery has been unable to displace hand labor, as the work is done so quickly that the time of the attendant would be nearly all taken up in placing and removing the stacks, and so the feeding is done by him as well. About 35,000 wheels per day can be thus cut by one man, with girls to stack the blanks on the arbors, and an automatic feed would not release the man from attendance on the machine, so that the majority of clock wheels are cut to-day as they were forty years ago. Still, some of the factories are adding an automatic feed to the carriage in the belief that the increased evenness of feed will give a more accurately cut wheel, a proposition which the men most vigorously deny. Such a machine, they say, to be truly automatic, must take its stacks of wheels from a magazine and discharge the work when done, so that one attendant could look after a number of machines. This would result in economy, as well as accuracy, but has not been done owing to the great variations in sizes of wheels and numbers of teeth required in clock work.
[Figure 82] shows one of these machines, a photograph of which was taken especially for us by the courtesy of the Seth Thomas Clock Company at their factory in Thomaston, Conn.
About every ten years some factory decides to try stamping out the teeth of wheels at the same time they are being blanked; this can, of course, be done by simply using a more expensive punch and die, and at first it looks very attractive; but it is soon found that the cost of keeping up such expensive dies makes the wheels cost more than if regularly cut and for reasons of economy the return is made to the older and better looking cut wheels.