seat for the rubber washer let in at D D, and the hole at B bored and tapped to fit the threaded hub, part 1. The other set of jaws is used for holding part 2 after being machined all over, when the taper hole for the key J is being let in at S, Fig. 231, which shows the work located within the jaws and the hole drilled at S. This hole, after being centred in the usual manner, is reamed to the required taper by means of a "floating" reamer of the usual type. For turning the washer-seat at D D, in part 2, the special eccentric box-tool shown in Fig. 233 was used, which is of an interesting construction. A is a holder or frame, made of cast-iron, which a shank portion at B turned to fit the hole in the turret. C is an eccentric bushing located within the holder by the setscrew H; G the cutting-tool; F the lever by which it is manipulated. The depth of cut is regulated by adjusting the lever stop screw J, which is let into the projecting lug K as shown in the end view of the tool. In using this fixture, after the tool G has been entered into the cored hole in the work the required distance, the lever F is raised slowly until it rests against the stopscrew J, which determines the proper depth of cut, then it is dropped and the tool backed out. A novel drill-jig was designed for use in boring the six inclined air-draught holes leading into the combining-chamber F in part 2 of the gas-cock. The jig is shown in plan and in sectional elevation in Fig. 234, with the work in place. As is shown, these six holes are required to be drilled at an angle with the axis of the casting, and also to be equidistant, and an interesting design is the result. A is the body casting of the jig, which is machined on the base at D, and also on both sides of the projection B, to an angle Y with the base, as shown. The indexing-device X and the locating-stud for the work are of tool steel, hardened and ground. There are six equally spaced notches in the index-plate which coincide in shape with the end H of the index-pin R and locate the work for the six different holes. The drill-bushing Pis located as shown in the swing-lid J, which is hinged within the two sides K K of the body casting A by means of the pipe L. A hole O in the lid allows clearance for the work when located in the jig; all that is necessary for removal being to swing the bushing-lid J back and unscrew the work off the locating-stud. CHAPTER XIV. The Construction and Use of Boring Fixtures and Similar Tools. THE DRILL-PRESS AND BORING FIXTURES. ONE of the things that make the large drill-press a valuable machine tool is its adaptability for performing accurate operations in the production of interchangeable parts by the use of simple and often inexpensive fixtures. In fact, I do not hesitate to state that it runs the turret-lathe a close second for the place of the most rapid and economical producer in the shop. Now aside from the adaptability of the drill-press for jigdrilling, there is any quantity and variety of work requiring to be bored which can be handled to good advantage on this machine; and in this chapter, among other things, I will devote considerable space to describing and illustrating types for boring-fixtures which were designed to be used on the drill-press and have worked well in practice, and their presentation will prove suggestive for others. The practical points for the designing and construction of the fixtures will assist the tool-maker in the attainment of the desired results with ease, and dispense with much unnecessary labor and expense. BORING AND FACING FIXTURE FOR "SEXTIT" CASTINGS. The casting shown in sketch Fig. 235 has six radiating cylin ders, each with a cored hole through it. It was necessary to bore and finish the holes in line with the central hole E, and the opposite holes in line with each other. The jig shown in Figs. 236, 237, and 238 was made for the job. The centre hole was first bored and counterbored, and the front faced at D. It was then driven on to an arbor and the back faced at F. The jig consists of an angle casting with a boss, faced on the back at H and I respectively, also a back extension on the top. After being planed on the bottom and dovetailed for the bushing-plate K, bosses H and L were faced and the top was planed and dovetailed for the upper bushing-plate J. It was also dovetailed on the side for the index-pin bracket W, and the hole bored for the clamping-stud 0. The two bushing-plates K and J, of machine steel, were fitted. tightly into the dovetailed channels, located in line with each other, and fastened. The centres of the holes for the bushings U and were located by setting the casting on its side on a surface-plate and striking a line from the centre of the hole for the stud O to the plate J and K with the help of a Brown & Sharpe height-gauge. The centre in the opposite direction, the distance from the face of the boss H to the centre of the bushings U and V was also marked. The plates J and K were then W N X Front of Jig-Without the Work V FIG. 237. driven out and the holes were bored and the two bushings U and V were made and forced in. their respective positions. The plates were then returned to The index-plate N and clamping-stud O are in one piece. It was a mild-steel forging. equidistant square notches. ing, was then fitted to drive tightly into the dovetailed channel in the side of the angle-plate. The hole for pin X was then bored. The plate had on its periphery six The pin was made of tool steel, the end fitting the square notches in the index-plate, and slightly rounded to enter the notches easily. A stiff helical spring V was made and also a |