this waste of energy and capital on the part of users of such tools inexcusable.

Economy in Use of Tool-Holders

On many operations of die-work a tool capable of removing stock at high-speed with corresponding heavy cuts is very

desirable. Formerly solid-forged tools were necessary, but modern practise demands the more economical tool-holder. A very efficient type is shown in Figs. 297 and 298. As will be seen, this holder is a radical departure from the old style

holder. The holder itself is made from a tough grade of steel designed to stand the shock and strains of heavy cuts. The cutting-points are hydraulic and drop-forged from high-speed steel, and are made exact duplicates of the solid-forged toolcutting ends, having a large body of metal to soak up the frictional heat generated by the chip.

Each tool is provided with a round shank fitting the receiving-end of the holder and is prevented from turning by contact of the plunger at the flat back of the tool, which in turn is forced ahead by the tapered face of the locking-stud. This method of locking gives practically solid backing to the

FIG. 300.-Plan of trimming die showing utility of high-speed steel cutting points.

tool, there being no possible chance of the point slipping away from the work.

One commendable feature of this holder is the entire absence of set screws, the lock, consisting as it does of a loose plunger, stud, and nut, can be instantly removed if occasion requires. Fig. 297 shows the method of shanking die-blocks with this tool. The head of the planer is first set over to the required angle on the side of the shank, and with the crosshead feed successive cuts are taken downward to the required depth, thus leaving no angular corner to remove with short light cuts. At the right is shown the tool used to undercut the side and base of shank. By this method very

close estimates on time may be made by ascertaining the number of pounds of stock to be removed, as the number of cuts may be figured to a certainty-half an inch in width being the average cut.

In Fig. 298 is shown a tool used for finishing side and base cuts on a block for a heading-die, this block being entirely finished with a standard shaper set of these tool points.

Fig. 299 shows a trimming-die, and well illustrates the utility of some of these shapes, the No. 27 tool being suitable for finishing the entire face, both right and left. For rough

ing work the Nos. 9, 12, 5, 6, 11R, 11L, 104, and 10L are suitable. All have been found excellent for their particular purpose or operation. It is to be noted that there are no side projections to this holder, which makes it especially good for trimming die-work. In Fig. 301 is shown an assortment of tools and holders made in several sizes. With an assortment of these standard shapes the machinist, die-maker, or tool-maker is enabled to do his work rapidly and accurately. In visiting one large die-sinking establishment recently, nearly 100 of these holders were seen in use on various parts of die-work and in maintaining tools for such work, having made a place for themselves by their great adaptability to all conditions and

their durability. Four of our leading machine-tool builders. send sets of these tools as part of the regular equipment of their new machines.

Forging the High-Speed Steel-Cutting Points

The most distinctive feature about these cutting-tools is that, instead of being forged complete from bar stock used as it comes from the mill, each cutting-point is forged to shape between dies in a hydraulic press, the most desirable conditions being attained in the finished product.

When we consider the most essential conditions necessary to high-speed steel-cutting efficiency, we find that the processes involved in the production of these cutting-tools are such as to insure the accomplishment of these most essential conditions.

The first is rigidity. In order to obtain the best results there should be absolutely no spring in the tool away from the work. Too much importance cannot be attached to this feature, as it is a principal that is very important in obtaining the maximum results at the minimum of expense and labor from machine tools. Cutting-tools of the solid forged type were heretofore considered necessary to accomplish this rigidity, as all machine-tool builders aim to build their machine more powerful than the cutting-tools used in it.

Secondly: there must be sufficient body of metal forged in the cutting-points to rapidly soak up the heat generated by the friction of the chip against the cutting-edge. This friction on cast-iron work fuses the metal to the top of the cutting-point. On steel, however, where the chips have more of a sliding action, the top face of the tool becomes worn away, in some cases to a depth of inch, as shown in Fig. 303, but this wear takes place well back from the cutting-edge. This condition seems peculiar, but is explained by the fact that at the angle of shear, the stock is crumpled and crushed and adheres to the tool, thus protecting the edge, and the sliding action that curls the chip starts at a point back of