An example of a bar designed to remove a large amount of stock in a very short time is given in Fig. 8. The work shown at G is a steel boiler nozzle which is forged, and a 5-inch hole punch in it before it is machined by the vertical turret lathe. The finished hole is 8 inches in diameter and it was desired to remove the surplus stock as rapidly as possible. Accuracy in the diameter of the hole was not essential. The bar L is a steel forging which fits the turret face at M and is held to it by the screws N. The stem 0 is used to center the bar in the turret. Two rectangular holes are broached through the body of the bar, at right angles to each other, and these receive the high-speed steel cutters shown. It will be noted that these cutters are so proportioned that they remove the stock in a series of steps, each tool extending beyond the preceding one and also above it about 1/8 inch.

Fig. 8. Bar with Four Cutters set at Different Radii for removing Considerable Stock in One Cut.

The section taken at A - B shows the manner in which the tools extend beyond each other, and the lower view illustrates the cutting action of the tools. One end of the first tool G makes the first step, while the other end H makes the second. In like manner one end of the upper tool J makes the third step while the other end K takes out the remainder. The two screws P hold the first tool in place, while the other is secured by the screws Q. It will be noted that the work is held in jaws D and is supported on buttons at E; the height above the table is great enough to allow the end of the bar and the set-screws to go through far enough to finish the cut. Regarding the upkeep of these tools, attention is called to the fact that they may be pushed backward or forward to compensate for wear and distribute the cut. For roughing purposes requiring rapid removal of stock and rapid cutting, a bar of this sort has proved very successful, but it is not recommended for work requiring great accuracy.