While speaking of engine-making or other machine-making, the name " tools " includes every implement and machine, small and large, simple and complicated, which is used to produce or operate upon the pieces of machinery in course of progress. Through the name being used in such a general manner, a hammer in the hand of a smith is a tool, and a twenty-ton steam-hammer also is a tool. A centre-punch in a turner's pocket is a tool, and the lathe before him is a tool.

The tools now to be treated are indispensable to all engine and machine makers, whether producers of small work or large. Although a maker of small machinery may work for several years without resorting to moulding, casting, and forging, he will find it impossible to do without the machinery described in this chapter, if he is to profit in any monetary way whatever by engine or machine making. Very few of the tools now introduced are used for bending and pressing as in the forging processes, because nearly the whole of the implements to be mentioned are adapted to operate upon and alter the external forms of cold metals, without altering their internal shapes. When the internal arrangement of fibres is changed, the operation belongs to forging, strictly speaking, although the metal may be cold while the inside is being bent or otherwise modified.

To produce an orderly description of these instruments is difficult; therefore to effect an approach to a progressive and intelligible array of details that shall not be monotonous, but shall manifest as much variety of expression as the subject will admit, the tools are arranged into classes, and the tools of each class are separately described. The first division contains descriptions and processes belonging to marking, lining, and measuring tools; and the second division is devoted chiefly to implements and machinery for purposes of cutting. The intricacy and variety connected with the processes belonging to tools and tool-making requires a preliminary understanding of terms and names; because no reader can comprehend an author's description of a method or process, unless the author first tells what meanings he intends by the terms he uses. The terms employed in engineers' factories resemble the terms in all other factories in containing numerous words that do not convey a correct idea of the tools and processes to which the terms belong. Many tools of quite different appearances and uses have but one name given to them by workmen who know nothing more than their own routine of work. Numbers of technical names now in use were thus invented or applied by ignorant men, and are now freely used by scientific writers, to describe various things and processes, because shop and factory terms are familiar to those who use them. But these phrases are of little use and often perplexing to a careful student of names and definitions, because he has nothing definite to use as a key to the descriptions and details of processes which he reads. And because the "Mechanician" abounds with processes that are known only to engineers and other mechanicians, and also to enable the author to make himself understood, it is necessary that a few definitions be now introduced.

It will be noticed that the primary significations of each phrase are placed first, because they are the meanings which belonged to the terms before they were applied to engineering purposes; and, by comparing the primary meanings with those that follow, a student will be enabled to distinguish the appropriate phrases from those that are not so expressive as they should be.

To Anneal

To soften materials by means of slow baking. To soften iron and steel by making them red hot, and afterwards gradually cooling in cinders or charcoal. Also to soften copper and brass by heating and immediately cooling in water.

An Arbor

A piece of timber that was used as an axle in a machine. A piece of iron used for the same purpose is therefore termed an arbor, or arbre; and, in a rather inappropriate manner, arbor is the name given by watch-makers and lathe-makers to small spindles used in their work, although such spindles may be only a millimetre in diameter.

An Apparatus

A collection of implements or furniture that are in a condition of being ready for use. A finished tool. A finished machine. Also a number of machines that are complete and in order.

An Appliance

A means. An act of applying an implement or apparatus to use, but not the apparatus itself. A method of performing an operation, but not the tools that are employed.

An Arc

Any portion of a circle's circumference.

An Arm

In a piece of machinery, the arm is the thinner part which extends from the thicker. The arm of a crank-lever is the portion between the two bosses. Arms of machinery are both straight and crooked.

An Axis

A distance across an object. A diameter. Any line in any rod, lever, or shaft may be considered as an axis; and the principal axes are the mean major and the mean minor. The mean major axis of a shaft is a straight line through the centre of the shaft, and equal to its length; and the mean minor axis is the mean diameter of that across section of the shaft which is at right angles to the major axis, and also divides it into two equal lengths. Consequently, if the shaft is cylindrical, all its minor axes are of equal length; but, in a rectangular or rhomboidal shaft or bar, the minor axes are of different lengths, and the longest one is the length of the longest diagonal of the across section. In a crosshead, the major axis is the total length of the crosshead through the centre; and one of the minor axes is the length of the hole in the middle of the crosshead. The major axis of a wheel is usually termed the wheel's diameter; and the minor axis is the length of the wheel-boss; therefore, a wheel on a shaft rotates around the wheel's minor axis, while the shaft rotates around its major axis. The terms major and minor are preferred to longitudinal and transverse, because the transverse axis of a rod or shaft is merely the thickness of it, but the transverse axis of an ellipse is the greatest length of it.