Elements of machine construction and drawing Volume 1 ; or, Machine drawing, with some elements of descriptive and rational cinematics

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1874 Excerpt: ...in this table, the distance between the threads.----;--o n = number of threads per inch, the nearest whole number to--P w = width of the flat top and bottom, that is, of the outer and P inner edges of threads. = 5 o 2--least diameter of finished nuts and bolt-heads = perpendicular between opposite sides, or diameter of inscribed circle. 1 D + inch. 7t = long diameter of hexagonal nuts, or bolt-head = diameter of circumscribing circle.-i x 1.155 t = Do. of square nuts or bolt-heads. = I x 1.414 t = thickness of finished nut or bolt-head. = D--in. The threads are to be truncated as at Fig. 48, to give increased strength both to the thread and the bolt, and the angle abe is fixed at 60, that being much easier to verify than the English one of 55, besides'giving a more substantial thread. The following table presents a few examples, and the dimensions of only finished nuts and bolt-heads. All the dimensions are in inches and fractions of an inch. Essay on a System of Screw-Threads and Nuts. Example XXXIX. Endless Screws and Spiral Gear. Description.--An axis revolving in fixed supports, and having a screw thread cut upon its circumference, is an endless screw. Because such a screw makes no advance in the direction of its axis, it will advance or move any yielding piece on which its thread can act. One complete revolution of the screw will advance the point upon which it acts a distance equal to the pitch of the screw. If, then, the thread engages with a wheel whose teeth are so set as to be tangent to the thread, when in contact with it, the screw will give a slow rotation to the wheel. PI. XXXI., Figs. 1 and 2, shows such an arrangement. OO'K--O"K' is a wheel actuated by the screw HAB--B'L. In this case the screw thread is formed in the usual manner; ther...