Improperly hung shafting, unbalanced pulleys, and crooked and badly constructed belts absorb an amount of the power used for manufacturing purposes that would probably, if known, astonish the most observant. When it is considered that this power is costly -costly not only in the first means for its utilization, as in the construction of a dam, flume, wheel, etc., when natural water power is employed, but eminently costly when the source of power itself is an item of continual expense, as in the employment of steam it will be conceded that the subject of saving the amount now wasted from imperfection in the means of its transmission, cannot be of merely slight interest. Too many of our shops and manufactories present a spectacle, anything but pleasant to the mechanical eye,in sprung shafting, cut boxes, inefficient belts, unbalanced pulleys, shafts of insufficient size, and a general lack of evidences of intelligent arrangement and proper management. Some, it is pleasant to say, are models in all these respects ; the manager allows no leaks to escape his observation ; from the source of the power to its ultimate delivery, every step and every means are carefully scanned and kept in perfect order. For such, any directions we may give, any advice we may offer, any suggestions we may make, are superfluous. We write the following for others. Before selecting the iron for a shaft, or for several lines with their counters, the machinist or millwright should take into consideration the weight each section of shaft is to sustain in the size of pulleys and strain of belts, the distance between points of support (boxes), the velocity of the shaft, and the nature of the machinery it is to drive. In all cases the iron for shafting should be chosen for its homogeneousness and perfection of rolling, seen by the finish of its surface. Each section should be handled carefully in transportation. As it comes from the mill it is usually straight, or nearly so, but teamsters and dealers in iron bars seem to suppose that no more care is necessary in handling a bar calculated for shafting purposes than in treating so much scrap iron. Frequently the lengths come crooked, bent, and sprung, to the Jiand of the machinist; they receive in transit no more consideration than the trunks of passengers on a railroad or steamboat at the hands of baggage smashers. It would be well for manufacturers of rolled iron for shafting, if they would follow the example of steel makers, or of Jones Laughlins, manufacturers of cold rolled iron at Pittsburgh, Pa., and pack their bars in boxes. It would be well not only for them,but for the workman who is to convert these bars into shafts. And here let us say a few words in favor oi a most meritorious improvement, that just referred to, en passant, the cold rolled shafting. Its first cost is greater than that of the best refined iron ordinarily used for shafting but it comes with a perfect finish, rolled to perfect size, without bend, kink, or spring, is ready at once to receive pulleys, and only requires centering and sufficient turning at the ends to give a shoulder for tHe couplings ; although if the, cpupling adapted for it and lllustrateOtT J$b, 20, Vol. X n, Scientific mebicak, be used, the end turning may be dispensed with if not the centering. But, passing from this style of nearly perfect shafting, let us look at the processes to be employed to produce proper sections where they must be turned. The first process is the straightening. To begin at the beginning, the shaft should be centered at the ends. It is evident this center must be found by the circumference. If the shaft is bent or straight, in either case the center should found and drilled, before any attempt to straighten the shaft is made. For this purpose the ends of the shaft should be squared. This is done preferably by the vise and file ; for if placed on temporary boxes in the lathe in order to use the side, or squaring-up tool, we do not know that the bearings of the shaft are true, and it cannot be placed upon centers until center holes are made, and this is our first object. Let the machinist take the shaft or bar to his vise, resting one end on the floor, and file by the trysquare until he has the end square with the longitudinal surface ; the center punch and dividers will give him the proper center. This, be it borne in mind, before any attempt at straightening is made. We are aware that a centering lathe is frequently used, and if used judiciously it is a valuable machine, even for crooked or sprung bars, but for those who have not this tool the plan above is sufficient. The center being found, drill by the hand or breast drill, if a lathe is not convenient, a hole of about one-eighth of an inch diameter at least half an inch deep ; then chamfer or flare the hole with a cone-shaped drill, milled on its face not a four-sided or three-sided tool, or a flat drill of two sides, but one circular to bear on every point at the same time. The shaft is now centered, and is to be straightened. To determine how much out of true it is, suspend it between the centers of a lathe and rotate it by hand ; no dog is required. If sprung in a long sweep,put a block of solid wood across the ways of the lathe, with a hook bolt projecting above it at the rear end, and use a wooden bar as lever, placing one end under the hook, and at the other end apply your weight. Any crook not too short can thus be straightened. If short crooks occur, not manageable in this way, do not strike the iron cold on an anvil, but heat it to a red, or nearly so, and then straighten, not by the direct blow of the sledge, which will indent the iron, but through the medium of a hollow " former," the reverse of the "fuller," so that the iron is not injured. We place great stress on this method of straightening kinks, as we know that not only is cold hammering injurious in indenting the iron, and injuring its texture, but that after these indentations are removed by the turning tool, if it goes so-deep, the crooks sometimes return, like curses, to vex the peace of mind of the ignorant or careless workman. Turning the shafting must be deferred to another time.
This article was originally published with the title "Shafting, Pulleys, and Belts"