when the four rows of holes, sixteen in number, for the doweland locating-pins I and J J were drilled. These holes were for locating the rack blanks, which had been previously milled to size, and the four holes in each drilled in a jig so that they were exact duplicates of each other. In drilling the holes in the casting it was strapped on an angle-plate, facing the spindle, which was in turn clamped to the extension plate on the millingmachine table, taking care to get the casting H fastened so that the tongue J was parallel with the table. The first row of holes was then drilled by first using a small centre-drill and spacing the holes by means of the dial on the feed-screw of the table, and then drilling them all in the same manner, repeating the operation until the four rows of holes for dowel- or locating-pins I I and JJ were drilled.

In the spacing of the holes, so as to get them in the relation to each other, as shown, great care was taken so as to have them coincide perfectly with those drilled in the racks, as these pins locate the blanks square on the fixture when in use. Sixty-four small pins were then cut off to the length shown, and rounded at one end; they were made of Stub wire and driven tightly into the holes drilled in the fixture, and an easy fit in the holes of the rack blanks.

The small clamps shown at K K, of which there were thirtytwo, were then made to the shape shown, by taking four bars, long enough to get eight out of each, and milling them to the shape required, after which they were cut into sections, which were the clamps shown. The clamps were then drilled for the screws L as shown, and sixteen fastened at each side of the fixture in the position required, so as to grip tightly the ends of the blanks and keep them flat and square on the fixture. The heads of all screws were case-hardened.

The various parts of the fixture were then assembled, and the fixture complete strapped on the milling machine table by means of bolts through the ends at II, and with the tongue S in the centre slot. The sixteen rack blanks were then located and fastened on the fixture by fixing them on the pins 1 I and J J and the clamps tightened as shown on the blanks M in the plan view of the fixture in Fig. 380. This figure shows the blanks partly

finished, the last one being off to show the pins for locating them. Two cutters of the pitch required were used, and the table of the miller raised so that the full cut would be taken. The feed was then put on, and the cut taken through the entire sixteen blanks, when the table was run back to the starting-point, moved over the required number of thousands, and the cut repeated, and so on, until the entire sixteen blanks were finished. They were then removed and another lot located and fastened in the same manner, and the operation of milling repeated.

This fixture overcomes the difficulties which are usually met with when milling one rack at a time, by holding it in the milling-vise. As when it is done in that manner it is necessary to mill all sides of the blank perfectly square with each other, in order to get them to lay flat while being cut, while by the use of this fixture, as shown, it is not necessary to be so particular, as the blanks are held by means of the clamp at either end, and located squarely and in line with each other by the pins shown. Another thing, the setting is easy to accomplish, as it entails no adjustment of the parts.

JIG FOR DRILLING SMALL THREAD DIES.

Some years ago I had a job of making one hundred small thread dies for screw-machine work. To have drilled them in

the regular way would have taken a great deal of time and made them very expensive, so I made the jig shown in Fig. 382 for the purpose.

First, I turned and finished a bar of steel to exactly the right size for the dies and then cut off the blanks, being particular to

The

get them all the same thickness and also to chamfer the corners. Fig. 381 shows the die blanks, which are 4-inch diameter. Fig. 382 shows two views of the jig, the top and a cross section. jig was made in the shape of a round box. B is a piece of round machine steel turned and finished as shown with a thread of 10pitch cut at F which was cut loose in order to work the jig rapidly. At the same time the seat for the blanks was turned out at Cso that they would just fit in without play. A hole was then bored through at D to give clearance when the drill came through and also to let the chips out. The jig proper A was a piece of round tool steel chucked and finished all over in the way shown. The centre hole was drilled at the same time, and a circle was struck to drill the other four holes by. heavily knurled to give the operator a good grip. reamed and slightly countersunk to allow the freely, when the work was carefully hardened and drawn, being then ready for work. The blanks were laid in at C, the cover A was screwed down, and the holes all drilled, and another die inserted, and so on with them all. It was surprising how quickly the dies were made by the use of this jig.

The outside was

All holes were drills to enter

CHAPTER XXII.

Special Tools, Fixtures, Devices, Arrangements, Contrivances, and Novel Methods for Metal Working.-Continued.

A MACHINE FOR TWISTING CORKSCREWS.

THE machine here shown was made for twisting wire corkscrews of the type shown in Fig. 383. The wire before the twisting is shown below the corkscrew. It is "looped" at one end and bent, while the other end is pointed. The cutting off of the length of wire and the pointing of one end are accomplished in

FIG. 383.

one operation by means of two simple tools in the monitor; the tool used for pointing being a "needle" box-tool, and the one for cutting off a "chopping-tool." The second operation on the wire lengths, that of bending and forming the "loop," is done by hand, with a simple bending fixture not of sufficient interest to show here.

The drawings, Figs. 384, 385, and 386, of the twisting-machine show its construction and little description will be necessary. The machine consists of, first, a body or main casting on which are four standards for bearings for two shafts. The pulley,

clutch, and small driving-gear require no explanation. The wire is clamped between two jaws H H, Fig. 384, the upper one of which is raised or lowered by the handle and two gears AA turning right and left screws. The mandrel or forming-spindle X is of tool steel finished to fit easily within the sleeve K, which in turn is fitted and keyed to turn with the slide, back and forth within the main spindle V by a key at D. A handle at Z fastened to the forming-mandrel by the set-screw W keeps the mandrel stationary, by a round-headed pin entering the back at Y, while the sleeve with the main spindle rotates and twists the

wire. This pin is located in the bracket T, with a spring at the back at S and a handle at R to allow of its being forced back when the mandrel-lever is to be turned.

When the machine is in use the work is located and clamped between the two jaws H II, with the pointed end lying in the slots L and M of the sleeve K and the spindle V respectively, and the handle of the forming-mandrel located and held by the pin T, Fig. 384. The clutch-lever is then pulled back and the spindle V and the sleeve K rotate while the forming-mandrel remains stationary, thus twisting the wire around the mandrel to the shape shown in the half-tone. The clutch-lever is then pulled out and the machine is stopped when Z is released and turned