Cutting Tools Worked by Hand and Machine by Robert Henry Smith, 1882

This book does not pretend to be a descriptive treatise on tools. It does not enumerate all the cutting tools in use, nor does it explain all the details of construction of the machines referred to in it. To do so, indeed, would require very much larger space than is at our disposal, and, for other reasons, would be beyond the aim of the book. Such a descriptive treatise unfortunately does not at present exist in the English language.

Meanwhile, Hart's "Werkzeugmaschinen" published in Leipzig, is the best collection of detailed descriptions of machine tools for wood and metals; while Hartig's “Versuche ueber die Leistungen der Werkzeugmaschinen" is still the only book to which one can refer for trustworthy information regarding the horse-power required to drive these machines. The former is chiefly a collection of beautifully-executed illustrations, showing all the details to scale, and, indeed, having all leading dimensions in millimeters marked on in figures. But, having been published in 1870, it is already much out of date. Before that time there were to be found in the German workshops numerous examples of the machines made by the best tool-makers of France, England, and America, and the constructive' details of these were studied eagerly, and copied with an exactitude sometimes disconcerting to the original designers.

Since then, great advances have been made in England and America; perhaps great advances have been made in England and America, perhaps more especially in the former country. Hence, although a fairly complete technical description of hand and machine cutting tools, bringing the various manufactures really up to date, would be of the greatest interest and utility, yet the rapid progress of design in this direction would ensure its soon falling out of date, unless it were being continually revised. This object is carried out on a necessarily small scale in Shelley's "Workshop Appliances," which, so far as it goes, is a very useful book. Holtzapffel's "Mechanical Manipulation and Turning" is too ancient to be of great utility to modern artisans or manufacturers.

Hartig's work supplies very valuable data from which to judge of the requisite power to drive tools. Unfortunately, he seems to have been led away by the idea that the cutting force varies in simple proportion to the depth of shaving. This idea is wholly erroneous. It seems first to have received definite expression in certain mathematical papers published in the appendix to the later editions of Holtzapffel's works. These papers are singularly apt illustrations of the extremely vicious results of the attempts occasionally made by mathematicians to interpret Nature by algebraic formulas alone, without the aid of experiment. The author fully believes that mathematical theory is the only ultimate possible way of perfectly describing fully-developed scientific knowledge, but it is worse than useless for anyone to dabble in mathematical theory before becoming thoroughly and intimately acquainted with all the facts of the subjects obtainable by experiment and observation. In consequence of the above error, Hartig has divided the work done in each of his experiments by the volume of material cut away, and thus obtains what he calls a "constant," but what is in reality a most delusive variable.

The aim of this work is educational, and at the same time it is intended as an attempt, at least, to begin the elevation of the art of tool-making from its present entirely empirical to a more scientific position. It has, however, been found possible to make only brief and general references to the principles of strength and stiffness that ought to govern the proportioning of the various parts of machine tools. So far as the author knows, no attempt has yet been made to apply methods of exact calculation to the design of the leading dimensions of this class of machines.