The castings for the heads before machining were square all over except for the dovetailed and gib surfaces, which were roughly cast.

The first operation was accomplished on a large milling-machine by means of a supply fixture, and a large inserted toothmilling cutter handling ten castings at a time. This fixture is not illustrated.

For milling the dovetail and gib-way the jig Fig. 420 was used. This accommodated eight castings. The work is located

on a machined seat. PP are the side-locatings, L L the lugs for the side-fastening screws, and N the projection in which the endfastening screws are located. With this jig the vertical milling

attachment was used. First the dovetailed slideway was machined with an angular cutter, taking two cuts, one at each side; then the gib-way C was machined by substituting a suitable cutter for the angular one. As all the surfaces of the castings were perfectly square and to size, the milling in this operation was done very rapidly.

The milling of the inclined formed face D D of the castings was done by handling one casting at a time in the jig Figs. 421 and 422. The amount of material removed in this operation is indicated by the dotted lines. A large formed milling-cutter was used for this work.

Operation fourth was the drilling of all the holes in the head casting. This drilling was done before milling the keyway for the brass key, because the long central hole H H had to be perfectly straight and reamed to size.

Fig. 423 is a plan partly in section of the jig. It is of the box type with cast legs L on four sides. The work is located by

means of the dovetailed locator N N on a machined seat in the bottom of the jig, and is secured by means of a swinging strap, not shown, hinged at X and fastened at Z by a thumb-screw. The locator N N is of machine steel, fastened to the inside of the jig side by two dowels C. The bushings for drilling the long hole are removable. They are notched at the side for the knurled-head locating-pins R, which prevent them from turning or falling out. The hole H H is drilled from both ends, half way from each. When reaming, the two-drill bushings are replaced by others. One at the bottom fits the reamer, while the upper one fits the stem. In reaming this hole a shell reamer reversed is used, so that the cutting-end is upward and the hole is reamed from the bottom.

For milling the cross-slot or keyway, the jig shown in Fig. 424 was used. This was made to hold a number of castings at

once. The work is located and fastened positively and with ease, and its removal when finished is quickly accomplished. The clamp shown at the front end is so made as to allow of locating

it quickly by means of the small latch P which is hinged in the clamp at K. By simply pressing back the handle of this latch the clamp is released and may be

slid off.

By reverting to Fig. 419 the machining required for the small parts will be understood. First, we have the back-plate V. This is of machine steel and is first milled and squared all over, the milling of the formed edge to coincide with the formed face DD of the punch-head being done after the drilling of the four screwholes. Then we have the brass "key." This is cut from the bar and cleaned up to size. The drilling of the two holes K in the brass key and the four J in the backplate are all done in the one drilling-jig, Fig. 425. The jig is made to accommodate a plate at one end and a brass key at the other. The body casting is machined so as to leave locating-seats for the work and with a channel across

it for the piece O against which the work locates. The bushing-plate is fastened to the body by four flat-head screws.

SSSS are the plate-drill bushings and T T the key-drill bushings. MM are the jig legs cast on the body. Q and Rare two screws for fastening the work on and against the locating surfaces. The work is slipped in at the ends; then the screws are tightened and the holes are drilled.

The remaining piece shown in Fig. 419 is the gib. This has a pin which is grooved out at one side to coincide with the taperpoint of the gib-screw F. When the screw is tightened it forces the gib in and thus clamps the head in position on the perforating-machine. This gib is of machine steel and is milled to size in the miller-vise, an angular cutter being used to taper the edge. For drilling the hole for the pin L a simple little slip-jig is used.

The tools shown possess no novel features, nor are they of intricate construction. However, they are interesting and should prove suggestive for other work, as they illustrate how accurate repetition work may be done rapidly and cheaply if some thought is given to the devising of simple and inexpensive tools.

FACING AND COUNTERBORING LARGE SPIDER CASTINGS IN THE DRILL-PRESS.

In a shop where paint-mixing machines are built the writer came across a method of facing and counterboring large castings

in the drill-press which may prove suggestive to readers for the machining of other work in a like manner. An idea of the shape and size of the castings may be gained from Fig. 426, in which is

shown the nature of the work to be done. As will be seen, the casting has two hubs which are required to be bored to a finished diameter of five inches, then faced at A A, B B, C C, and D D respectively, and, lastly, counterbored at FF to a depth of one inch and a diameter of seven inches. It is at once obvious that the large drill-press which is equipped with a floor base is the proper machine for the work, and that it would be very difficult to do the work in any other machine.

The boring to a finish of the cored holes in the hubs presented no unusual difficulties; a large boring-bar of approved construction being used and the projecting end allowed to run in a bushing bolted to the floor base of the drill, to which the work was

strapped. To accomplish the facing of the four hub faces and the counterboring of the seat in an expeditious and accurate manner, however, required other means than those used for the boring. It was for this work that the special facing and counterboring tool illustrated in Fig. 427 was used.

As will be seen, the special tool consists of the regulation bar, turned taper at one end to fit the drill-press spindle, and rounded at the other to enter easily the supporting bushing on the base of the press. This bar has five holes let though it to accommodate the boring-head. The holes are indicated in the engravings by letters CDE and F respectively. Three holes are for the cutter-bar and the other two are tapped holes for the feed-screw

In the cutter-head, H is the bar, O the "goose-neck" cutting-tool, a seat for which is provided in the cutter-clamps M at