Steel pens are another most prolific example of the result of the fly-press, they pass through the hands many times, and require to be submitted to the action of numerous dies, to five of which alone we shall advert. The blanks are cut by dies of the usual kind so as in general to produce a flat piece of the exterior form of fig. 960, page 944, the square mortise at the bottom of the slit is then punched through, the next process is usually to strike on the blanks the maker's name.

The slit is now cut by a thin chisel-like cutter, which makes an angular gap nearly through the steel, from that side of the metal intended to form the inner or concave part of the pen, and the net of curling up the pea into the channelled form, brings the angular sides of the groove into contact, rendering the slit almost invisible. The slit which is as yet only part way through the pen, is in general completed in the process of hardening, (see vol. i. page 249,) as the sudden transition into the cooling liquid, generally causes the little portion yet solid to crack through, or else the slit remains unfinished, until the moment the pen is pressed on the nail to open and examine its nibs.

Lariviere's perforated plates for strainers, lanterns, meat safes, colanders and numerous other articles, exhibit great delicacy and accuracy in the mode in which they are punched out; the tools are illustrated by the enlarged sections, fig. 961 overleaf. The punch consists of a plate of steel called the punch plate, which is in some cases pierced with only one single line of equidistant holes, that are countersunk on their upper extremities. Every hole is filled with a small cylindrical punch made of steel wire, the end of which is bumped up, or upset to form a head that fills the chamfer in the punch plate, so that the punch cannot be drawn out by the work in the ascent of the press. The bed punch or matrix has a number of equidistant holes corresponding most exactly with the punches. In this case the holes in the work are punched out one line at a time, and between each descent of the punches, the sheet of metal is shifted laterally by a screw slide, until it is in proper position to receive the adjoining line of holes.

At other times the tool instead of having only one line of punches, is wide and entirely covered with several lines, so as to punch some hundreds or even thousands of holes at one time. For circular plates the punches are sometimes arranged in one radial line, but more usually, the whole of the punches required for the fourth, sixth or eighth part of the circular disk are placed in the form of a sector, and the central hole having been first punched, is made to serve as the guide for the four, six, or eight positions, at which these beautiful tools are applied.

Many of the thin plates thus punched require to be strained like the head of a drum to keep the metal flat, in which case the metal is grasped between little clamps or vices around its four edges, and then stretched by appropriate screws and slides with which the apparatus is furnished, and the same mechanism prevents the metal from rising, and therefore fulfils the office of the puller-off commonly used with punches.

The construction of the tools above described, calls for the greatest degree of precision, the drill employed to pierce the punch and matrix is of the kind fig. 474, page 547, and of exceedingly small size in the finest perforated works, as it is said so many as six or seven hundred holes have been inserted in the length of six inches, which, considering the intervening spaces to be half as wide as the diameter of the holes, would make the latter of the minute size of only six thousandths of an inch diameter. Such finely perforated metal appears to offer nearly the transparency of muslin, and is a manifest proof of the great skill displayed in the construction of the instruments and in conducting the entire process.*

Punches Used In Fly Presses And Examples Of Their  200268

Mr. Julius Jeffery's Patent Respirator, or breath-warming apparatus, for persons having delicate lungs, presents another very neat example of punched works. Most persons will have had an opportunity of seeing, that the apparatus consists of about a dozen very thin plates of metal, punched out with several rows of large rectangular holes, leaving the metal like a delicate lattice. These lattices are severally wound round with fine wire and then assembled together between perforated covers. The exhalation of the breath amidst the interstices of the wires, warms the instrument, and the instrument in return, warms the air that is inhaled by the wearer.

To return to the operation of punching the lattices, it is to be observed these measure from center to center, half an inch in length and one fifth of an inch in breadth, the bed punch which is represented in fig. 962, is a piece of steel about 3/4 inch thick, having a central aperture, 3 1/2 inches long, and 18 hundredths of an inch wide, as the long bars of the lattices are two hundredths wide. Six transverse notches, one eighth of an inch deep and half an inch asunder, are then made across the bed with a circular saw three hundredths of an inch thick, the grooves are fitted with slips of hardened steel, after which, the whole is ground to a level surface. The punch is a plate of steel 3 1/2 inches wide and 18 thick, across which six notches about 1/4 inch deep, are also made with the circular saw at intervals of 1/2 inch.

• M. Marc Lariviere's patent was granted 28th Not. 1825, and is described in the Repertory of Patent Inventions, vol. iii. 3rd Series, page 182. Some other particulars are to be found in Gill's Technical Repository, vol. ix., 1826, page 375, translated from the Bibl. Univ., for Dec. 1824.

The press has a puller-off or stop much as usual, and at the back it has a long screw of five threads in the inch, the nut of which has two square pins exactly like the two exterior portions of the punch. The copper, which measures about one hundredth of an inch thick, is cut in long wide strips, and one row of holes having been punched, the piece is hooked on the two pins of the nut, and when the screw has moved once round under the governance of a spring catch, a second row of holes is punched exactly one fifth of an inch from the former, and so on. When five rows have been punched, the screw is moved two turns to leave a wide rib, and another series of five rows is punched, and so on alternately, and afterwards the lattices are separated through the wide ribs with a pair of shears. Some of the lattices of small respirators have only six rows in the long and four in the narrow direction, and others five rows by three, thus making three distinct sizes with the same tools, and all present a most beautiful regularity and slendcrness.*