The title of the present chapter, may at the first glance, only appear to possess a very scanty relation to the tools used in mechanical manipulation, as the ostensible purpose of a punch may be considered to be only that of making a round or square hole in any thin substance. But it frequently happens that the small piece or disk so removed by the punch, is the particular object sought, and some of the very numerous objects thus made with punches, assume a very great importance in the manufacturing and commercial world, as will perhaps be admitted when a few of these are referred to in the course of the present chapter.

The general character of a punch, is that of a steel instrument the end of which is of precisely the form of the substance to be removed by the punch, and which instrument is forcibly driven through the material by the blow of a hammer. When the subject is entertained in a moderately extended sense, it will be seen that much variety exists in the forms of the punches themselves, and also in the modes by which the power whereby they are actuated is applied.

So far as relates to the actual edges of the punches by which the materials are severed, they may be classed under two principal divisions, namely duplex punches, and single punches. The duplex punches have rectangular edges and are used in pairs, often just the same as in shears for metal. The single punches have sometimes rectangular but generally more acute edges, the one side being mostly perpendicular.

The single punches require a firm support of wood, lead, tin, copper, or some yielding material, into which the edge of the punch may penetrate without injury, when it has passed through the material to be punched. Consequently many of the tools the author has ventured to consider as single punches, might be classed with chisels, and many of the duplex punches might be classed with shears, analogies which it is not worth while either to pursue or refute.

following classification has been attempted, as that best calculated to throw into something like order, the miscellaneous instruments that will be more or less fully described in this chapter, namely,

Section I.

Punches used without guides.

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II

Punches used with simple guides.

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III.

Punches used in fly presses, and miscellaneous examples of their products.

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IV.

Punching machinery used by engineers.

It is proposed in all the sections to commence with those punches having the thinnest edges, and which are used for the softest materials.

It would be hardly admitted, that a carpenter's chisel driven by a mallet through a piece of card could be considered as a punch, still the circular punch used with a mallet on a block of lead, for cutting out circular disks of cards for gun-wadding, is indisputably a punch, and yet scarcely more than a chisel bent round into a hoop. The gun-punch is formed as in fig. 938, overleaf, and is turned conical without and cylindrical within, or rather a little larger at the top that the waddings may freely ascend, and make their way out at the top through the aperture; when however annular punches exceed about 2 inches in diameter, it is found a stronger and better method, to make them as steel rings, attached to iron stems or centers spread out at the ends to fill the rings, as in fig. 939, but holes are then required to push out the disks that stick into the punch, as shown by the section beneath the figure 939.

The punch used in cutting out wafers for letters is nearly similar, it being formed as a thin cylindrical tube of steel, fitted to the end of a perforated brass cone having at the top two branches for the cross handle, by which it is pressed through several of the farinaceous sheets, and as the wafers accumulate in the punch they escape at the top. Confectioners use similar cutters in making lozenges, and frequently the thin steel cutter is fixed to a straight perforated handle of wood. The lozenges are cut out singly and with a twist of the hand.

When the disk is the object required, the punch is always chamfered exteriorly, as then the edge of the disk is left square and the external or wasted part is bruised or bent; but the punch is made cylindrical without, and conical within, when the annulus or external substance is required to have a keen edge. And when pieces such as washers, or those having central holes, are required in card or leather, the punches are sometimes constructed in two parts as shown separated in fig. 940, the inner being made to fit the buter punch, and their edges to fall on one plane; so that one blow effects the two incisions, and the punches may then be separated for the removal of the work should it stick fast between the two parts of the instrument.

Punches of irregular and arbitrary forms, used for cutting out paper, the leaves for artificial flowers, the figured pieces of cloth for uniforms and similar things, are made precisely after the manner of fig. 938, and also of fig. 939, except that they are forged in the solid, or without the loose ring. These irregular punches are however much more tedious to make, than the circular, which admit of being fashioned in the lathe.

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Figured punches of much larger dimensions, have been of late used for cutting out the variously formed papers used in making envelopes for letters. The punch or cutter is sometimes made in one piece, as a ring an inch to an inch and a half deep, or else in several pieces screwed around a central plate of iron, and when the punch is sharp it is readily forced through three to five hundred thicknesses of paper, by the slow descent of the screw press in which it is worked. Army clothiers use similar instruments for cutting out the leather for shoes and various other parts of military clothing, and several of these punching or cutting tools are often grouped together.

Proceeding to the punches used for metal, those having the thinnest edges are known as hollow punches; they are turned of various diameters from about 1/4 to 2 inches, and of the section fig. 941, they are always used on a block of lead, and sometimes for two or three thicknesses at a time of tinned iron, copper, or zinc. Punches 942, smaller than 1/4 inch, are generally solid, quite flat at the end, and are also used on a block of lead, which although it gives a momentary support, yields and receives into its surface the little piece of metal punched out by the tool.

Fig. 914, represents the punch used by smiths for red-hot iron, the tool is solid and quite flat at the end, and whether it is round, square, or oblong in its section, as for producing the holes represented, it is parallel for a short distance, then gradually enlarged, and afterwards hollowed for the hazle rod by which it is surrounded to constitute the handle (see foot note, page 202, vol. i.). Various practical remarks on the application of the smith's punches are given on pages 215 - 217 of vol. i., it will be thence seen that the smith's punch is frequently used along with a bottom or bed tool known in this case as a bolster, and which has a hole exactly of the same area as the section of the punch itself.

Punches when used in combination with bolsters, are clearly similar in their action to the shears with rectangular edges, as will be seen on comparing figs. 943 and 944, the only difference being that the straight blade of the shears, is to be considered as bent round into a solid circle for a circular punch, or converted into a square, rectangle, or other figure as the case may be; but every part of the punch should meet its counterpart or the bolster in lateral contact, the same as formerly explained in reference to shears. This supposes the tools to be accurately made and correctly held by the smith, but which is somewhat difficult, because, the bolster, the work, and the punch, are all three simply built up loosely upon the anvil, and the eye can render but little judgment of their relative positions, the punch is consequently apt to be misdirected so as to catch against the bolster and damage both tools. The mode sometimes used to avoid this inconvenience is represented in fig. 915, in which a guide is introduced to direct the punch, but agreeably to the proposed arrangement, this figure will be more fully explained in the next section, when some other tools of a lighter description have been spoken of.

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Previously however to concluding this present section, attention is requested to fig. 946, which shows a punch used by harp-makers and others, in cutting long mortises in sheet metal. The punch is parallel in thickness, and has in the center a square point from which proceed several steps, this punch is used with a bolster having a narrow slit, as long as the width of the punch. A small hole is first drilled in the center of the intended mortise, the first blow on the punch converts this into a square, the next cuts out two little pieces extending the hole into a short mortise, and each successive blow cuts out a little piece from each end, thereby extending the mortise if needful to the full width of the punch. From the graduated action, the method entails but little risk of breaking the punch or bulging the metal, even if it should have but little width. Sometimes, to make the punch act less energetically at the commencement of its work, the steps at the point are made smaller both in height and width; the serrated edge then becomes curved instead of angular, as shown.