Lathe-Work (Paperback)

This historic book may have numerous typos, missing text or index. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. 1881. Not illustrated. Excerpt: ... CHAPTER XIII. DIVIDING APPARATUS. Its object and use--Dividing the lathe pulley--Numbers most useful for dividing purposes--Originating and making a division plate-- Drilling the holes--Index pegs of various kinds. Dividing apparatus is used on the lathe for many purposes, wheel-cutting being perhaps the most important, though also the most rare. Its chief uses on the foot lathe are to space out divisions on work which is turned, such as the bolt-holes of a cylinder cover, and for marking equidistant lines on cylinders which have to be made prismatic in shape, such as bolt-heads and nuts. In conjunction with the drilling or the upright spindle and overhead gear, which are described elsewhere, the dividing apparatus is used to hold the lathe mandrel while the driller or upright cutter is used in any of their numerous applications. The apparatus consists of a division plate drilled with a series of concentric circles of equidistant holes, bored either in the face of the pulley itself or in a ring attached to it, and an index which is a point arranged to fit into the holes, and so hold the pulley from revolving. The holes in the division plate are usually drilled in circles of numbers which afford the largest variety of useful divisions. For general purposes the numbers best suited are 360, 200, 96, and 84, if the number of rows is limited to four. When the number of rows is not so restricted, the holes in each of course are selected to afford the largest number of extra divisions, and in deciding these it is necessary to have due regard for the purposes for which the divisions will be used. Three hundred and sixty is a very desirable number to have, as it enables the degrees of a circle to be marked, besides giving a wide range of numbers. This large number cannot...