The crucible steel, being lower in percentage of harmful impurities, can safely have a much higher percentage of carbon and yet be less liable to crack than the open-hearth material.

After all, the real essential for successfully doing work of this kind is brains; it is necessary to discriminate between the dies of different sizes and shapes, also to judge correctly of other conditions, and then act accordingly.

CHAPTER XI

HIGH-SPEED STEEL, DROP, AND HYDRAULIC FORGED CUTTING TOOLS, DROP-PRESS PRACTISE, AND HARDENING DROP-DIES

What is Good Judgment

A GREAT deal is heard of good judgment, and the man who possesses this quality commands a high salary. Often a machine-tool establishment which has secured such a man, depends almost entirely on his "good judgment" for better results, and it is often considered that with this he can overcome the lack of organization, cost system, or even of plant equip

ment.

A manager with good judgment is extremely valuable, but he must have the tools with which to work. If he does not obtain them a man of less ability, with better organization and with better equipment, will outdistance him. The same applies to the man in the shop-the mechanic. A good mechanic, to produce the best work quickly, must have good tools with which to work. If he is not given these, a less efficient man with better tools can produce better results.

Good judgment, as I see it, is the application of knowledge gained by experience. This is derived partly by direct observation, familiarity with the accomplishments of others, and partly from statistics compiled by others, which have been digested and the valuable points retained. If the manager is really a man of "good judgment" he will provide himself with the organization and the system which will furnish him with correct information. If the manager's works superintendent is a man of "good judgment" he will insist upon an

equipment of machines and tools which will allow of his mechanics producing good work rapidly.

High-Speed Steel and Tool-Holders

An important item in machine-shop organization and management is the speed of cutting tools and the use of cutting tool-holders. The speed of the tool is limited by the frictional heating of the tool, and its consequent softening by drawing its temper, so that for wrought-iron and mild steel the limits were from 10 to 30 feet per minute. Some increase was made on the introduction of a self-hardening steel in which higher speeds were attained. But these tools were rapidly broken down in wear or were abraided out of shape. Within the past ten years there have been introduced various brands of high-speed steel, cutting three, four, and in some cases even six times faster than the best tool-steels of the recent past, and also possessing a remarkable durability. In some cases the tools are heated to a dull red in the operation of cutting, while the chips are nearly as hot. This steel will stand long, severe, and continuous usage without regrinding, and this, together with the increased strength, effects a great saving in time and labor, otherwise wasted in removing, grinding, and replacing the tool. Deeper and wider cuts can also be taken with this steel, and this, together with the high-speed results in removing a far greater weight of metal per minute with a consequent considerable cheapening in the cost of production.

Speeds of from 75 to 100 feet per minute upon medium hard-steel have been attained in ordinary work, while roughing cuts have been made at the rate of 140 feet per minute on cast iron with 8 inch feed and 38 inch deep.

Though the cost of high-speed steel is considerably greater than that of common tool-steels, the difference in cost is more than covered by its labor-saving qualities and reliability. The best steel I know of for high-speed cutting costs about seventy-five cents per pound, and—for machine-cutting tool purposes at least-is not forged into solid tools, as in the oldfashioned way, but the cutting portions are forged and ground,

then inserted in a tool-holder and held by a simple plunger and locking stud, as illustrated and described farther on in this chapter.

Combination Tool-Holders and Their Use

The high cost per pound of the high-speed steels and the large waste of this valuable material by individual users and forgers of bar stock, where cutting-tools are forged from the bar, has brought about a truly wonderful demand for an efficient substitute for expensive forged tools-a substitute which shall possess all the best qualities of the bar-forged tools without their waste, uncertain heat treatment methods, and prohibitive expense. This substitute I believe-after careful personal investigation and use of various tool-holders-is secured in the combination tool-holder manufactured by the O. K. Tool Holder Company, of Shelton, Conn., as it is the only one I have ever seen and used which compares in efficiency and strength with the best high-speed tools forged complete from bar stock.

Though experiments have been conducted by almost all users of high-speed steel to determine the best shop-practise for treating it, the results of these experiments as a whole seem to have given us a general shop rule for treating a high-speed steel-tool: "Heat it to a white heat and quench it." But this, in my opinion, has its shortcomings, because a variation of 50 degrees Fahrenheit cannot be determined by the eye, but such variation is very important, especially in the tempering of these steels.

The results of poorly treated tools are: A decrease in shop production for the manufacturer, who allows it inside his establishment; dissatisfaction and poor work on the part of the machinist who uses it; an increase in the bill to the buyer of the shop's products, and the entire result a waste of energy and capital.

Therefore, I argue, the fact that perfectly finished, uniformly treated, and gauranteed efficient high-speed cuttingtools can be purchased direct from specialist makers, makes