This is a great article on the history of machine tools and machine work. But it is also a history of the growth of early america and the United States. A Thank You needs to go, first to the author-unknown, to American Machinist for originally publishing this article, also to The Wayback Machine for archiving it, and to Pedro for finding it at The Wayback Machine and emailing me. My position here is that this article needs to be available for interested machinists and others to read, I don't think either of the other sites will be doing that. I gladly make it available while making no benefit from it -Note: The ads at the top of my pages are Angelfire's not mine. Enjoy, Pat McGuirk

Former link to the article at the American Machinist site. http://www.americanmachinist.com/library/features/aug96/lathes.html

Article was originally printed: American Machinist, August 1996

World War I was over and America, emerging from the conflict as the most powerful industrial nation on earth, boldly entered a new era. Production increased, but it wasn't matched by wage increases or price reductions. The result was a lag in buying power. Plant expansion slowed, and idle money went into stock speculation. The economy ballooned and, on "Black Thursday," Oct 29, 1929, finally burst.

The Great Depression gripped the world as no other plunge in the business cycle ever had. Total unemployment in the U.S. reached 12.8 million in 1933, just about 25% of the total labor force. In the manufacturing industries, the number of wage earners decreased from an average of 8.8 million in 1929 to a low of 6.1 million, the average for 1933. And total wages paid dropped from a high of $11.6 billion in 1929 to $5.3 billion in 1933.

The value of goods produced in America's factories, which had reached $70 billion in 1929, at the height of the "boom," plunged to $31.4 billion in 1933. Slowly, however, the nation began to recover, prodded by a succession of drastic economic and social measures, many of which are still being debated.

How long this downturn would have lasted, if it had been allowed to run its course, is unknown, for America's manufacturing capabilities were shortly to shift into high gear for production of military goods for World War II.

Despite the wild swings of the American economy in the period between the wars, the history of manufacturing is marked by the development of mass production first in the automotive and later in the aircraft industries, the evolution of appliances from luxuries to necessities, improvements in machine tools and cutting tools, and the introduction of new and better materials with which to manufacture consumer goods.

During the early 1920s, machine-tool builders competed fiercely with one another in bringing out machines of higher production capacity, especially for the auto industry. There were any number of crankshaft lathes, automatic lathes, camshaft grinders, and diesinking machines. But certain trends became discernable.

The methods of transmitting power to machine tools were constantly improving. Helical gears for connecting parallel shafts were used more and more to provide smooth transmission. Special steels and heat-treated gears were common, and hardened-and-ground gears were gaining favor where greater accuracy was required.

The use of motor drives and of ball bearings and a growing trend toward hydraulic instead of mechanical transmissions were the outstanding developments in machine tools of the 1920s. Centralized control became popular and, in several types of machines, it was possible to shift speeds instantly, without stopping the machines, through a combination brake-clutch.

By 1927, another definite trend became noticeable; a trend toward single-purpose equipment of the so-called manufacturing type and away from machines of a more universal nature. The design of these single-purpose machines was such that only a few key parts needed to be interchanged to make the machines adaptable to a wide variety of work. Like many other trends, this one was short-lived; by the early 1930s, it had been completely reversed.

One of the greatest advances of the late 1920s was in positive lubrication. In many machines, all important bearings were oiled from a central reservoir by means of force-feed pumps. Both the circulating system, in which a continuous flow of oil is provided to the bearing and back to the reservoir, and the intermittent system, which supplies a drop or two of oil at easily regulated intervals, were being used.

Gas and arc welding battled for supremacy, but the development of coated welding electrodes and of ac welding in the 1920s and 1930s started arc welding on its ascendancy. Heavily coated shielded electrodes were introduced on a commercial basis in 1929, and they revolutionized arc welding. The weld it produced was better than the steel it joined, and the higher currents speeded fabrication, gave greater penetration, and reduced welding costs. In the same year, an ac welder that would operate from single-phase power was introduced. These two developments, despite the onset of the Depression, launched the big growth of the arc-welding industry.

Other welding processes were also in use in this era. Carbon-arc welding, which had been virtually abandoned, was reintroduced as an automatic process around 1930. It was usually used on light-gage work where the edges of the joint could be flanged to make a weld without filler metal. And atomic-hydrogen welding also reappeared as an automatic process.

As industry picked up its pace to meet the threat of another world war, two other processes came onto the scene; arc stud welding and capacitor-discharge spot welding of aircraft aluminum. By 1939, welding was "king," and just in time, for, during World War II, almost everything that was made of metal was welded.

Alloy steels had been used in the first two decades of the century for paring knives and cutlery; in the 1920s, they were used to make parts. By 1930, there were some 200 trade names for specific steels, and a typical automobile used more than 30 distinct types, all made to order. Chrome was added to steel for toughness, nickel for surface hardening, chrome-molybdenum for strength, chrome-vanadium for resiliency, and copper for resistance to corrosion.

Stainless steel, born of disputed parentage in Europe and reared in the cutlery trade of Sheffield, had its first significant impact in America in chemical-process equipment. By 1929, it was being used for automobile trim and, in the mid-1930s, its combination of strength and corrosion resistance was exploited in the construction of high-speed, streamlined passenger trains.

But is was a new steel-fabricating technique - continuous sheet-rolling - that gave impetus to the consumer-goods boom of the mid-1920s by providing the manufacturers of autos, appliances, and myriad other products with the quantity of consistently flat sheet steel that they needed to meet the growing demand for their products.

But steel had competition. After World War I, aluminum emerged from the cooking-utensil stage to challenge steel in industrial applications. Stronger and harder alloys and improved ways of heat treating them to enhance their qualities for specific uses were developed.

In the fall of 1928, word reached the U.S. of a new German cutting-tool material, a combination of tungsten carbide and cobalt. Tungsten carbide had long been known as a hard material, but it was weak and porous. What the Krupp Works discovered was that additions of cobalt would make tungsten carbide about half as strong as high-speed steel without impairing its sapphire-scratching hardness. Here was a material that was to have lasting impact on manufacturing techniques and on machine-tool design.

While Krupp was experimenting with tungsten carbide in Germany, General Electric was pursuing similar research in the U.S. Shortly after Krupp introduced its product, called Widia, at the Leipzig Fair in 1928, GE introduced its brand of tungsten carbide under the name Carboloy.

It wasn't long before machine tools specially designed to take advantage of the higher metal-removal rates of these new carbides appeared on the market. New lathes with spindle speeds of 900 rpm appeared, as did boring mills with 1,000-sfm cutting speeds.

Shortly after entering the Naval Academy in 1909, Donald W. Douglas saw a demonstration flight by the Wright brothers. From this grew an interest in aviation that led him to resign from the Naval Academy and enroll as a student at MIT. In 1914, he became MIT's first graduate in aeronautical engineering. As a graduate assistant at MIT, he helped build the first aircraft wind tunnel. In 1915, he became chief engineer of Glenn L. Martin Co. and helped design the Martin bomber, the first American designed plane built in World War I.

Douglas went to California in 1920 and organized Davis-Douglas Co. David Davis had placed an order for a single-engine plane for use in a transcontinental flight and, even though the flight was not completed, the Navy ordered $120,000 worth of the planes.

Under Douglas's leadership, Douglas Aircraft Co. (the name was changed in 1928) expanded rapidly, developing and building advanced military planes and civilian transport planes that, by the outbreak of World War II, served airline routes in 57 nations.

The American auto industry came into its own in the 1920s. It was America's best organized industry, and its plants were considered the last word in mass production and assembly techniques.

In 1920, Henry Ford, the leading automaker at the time, improved foundry practices by conveying molds to the metal-pouring station instead of carrying molten metal to stationary molds. The same year, Ford introduced continuous pouring of molten iron and produced gray-iron castings directly from ore. The first automatic production line for large-scale manufacture of a complex automotive assembly went into operation in 1921. This was the automatic frame line at A.O. Smith. It performed 552 separate operations in a ten-second cycle, and it was still operating in the 1960s.

Nickel plating made its debut on auto radiators and lamps in 1921, and chromium plating followed just a few years later.

Introduction of continuously rolled sheet steel in 1924 provided automakers as well as other metal-goods manufacturers with improved metal surfaces, lower cost, and better thickness and width control. From then on, steel gradually became the logical material for automobile exteriors.

Two other developments had major effect on auto exteriors from 1925 on: the introduction of chromium plating for auto parts and the use of synthetic, quick-drying pyroxylin finishes that were sprayed on and then baked. These Duco finishes replaced paints and varnish, cutting days from the total auto-production cycle.

Heavy investments were made in new machine tools and other production equipment for the auto industry in late 1926 and early 1927. Buick was running three parallel assembly lines at Flint to produce 1,300 cars in a nine-hour day. Beginning with the bare frame, the complete car emerged at the lower end 1 1/4 hours later without having left the line.

Henry Ford's Model T, introduced in 1908, had outlived its popularity and, when Ford announced in 1926 that it would be discontinued, he had no replacement in mind.

After building just over 15-million Model T cars, Ford halted its production in May 1927 and, just six months later, introduced the Model A. To do it, the company spent nearly $10 million for the purchase of 4,500 new machine tools and alteration of 15,000 more. Preparing to make the new rear axle alone necessitated construction of an entire group of machine tools. Some 160 gear-generating machines were completely rebuilt, at $3,000 each, to produce two gears for the new rear-axle assembly.

By 1931, the auto industry's motto was "anything that can be sold can be built." While the manufacture and sale of cars declined somewhat during the lean Depression years, improvements in construction continued.

The expenses of retooling eliminated the early possibility of radical changes, but many refinements were made. Chevrolet, in 1930, began making valves by extruding and grinding rather than by drop forging, turning, and grinding. The material was a high-silicon steel with chromium added.

The trend to automatic drive was definitely established. By 1931, free-wheeling was available on some makes of cars and, by the close of the decade, Fluid Drive and Hydromatic drives had appeared. The gearshift lever was taken from the floor and put first on the dashboard and then on the steering column. Ford introduced a new V-8 model ($460-$650) to replace the Model A in 1932 and became the first company to use a cast alloy-steel crankshaft in place of a forging. This was also the year that auto production hit its lowest level since 1918. Auto production also declined sharply in 1938, slipping 40% from the previous year.

At the close of World War I, there was a great surplus of airplanes and aircraft equipment and thousands of young Americans who knew how to fly, but there was no place in the country's economy that could absorb the fledgling aviation industry. Between the two wars, aircraft production was relatively insignificant, compared with the production of the auto, machinery, railroad, appliance, or other major industries.

More spectacular than any other development in this period was that of design, as wood gave way to metal and box-like wings gave way to internally braced thick wings with metal skin.

The Liberty engine was the standard of the day, but new ones came along rapidly. Pratt & Whitney Aircraft developed first the 450-hp, air-cooled, radial Wasp and then the 550-hp Hornet. The latter was used to power the famous Martin bomber that made aviation history in 1927 as the first military plane to carry a load greater than its own weight.

But 1927 will be better remembered for Charles A. Lindbergh's solo flight across the Atlantic. His Spirit of St. Louis was powered by a Wright Whirlwind, an engine design previously proven in years of airmail service.

In 1930, huge transport planes carrying 20 to 40 people were introduced on domestic and overseas airlines. Speeds of 125 mph were common, and there was talk of 200-mph planes. But this was the last "big news" from the aircraft industry for a few years.

As the industry suffered through the Depression, it took advantage of the slow times to simplify the design and construction of aircraft engines and to develop the tools and fixtures it would need to achieve interchangeable manufacture and lower costs.

In the following year, 1934, aircraft construction started upward again. On the drawing boards that year was what turned out to be the Douglas DC-3, the Model T of the aviation industry. It first flew in December, 1935 and, by the time production ended in 1945, some 13,000 had been built.

Starting in 1936, the aircraft industry began to receive large orders for military aircraft, and 1937 turned out to be the best year ever for aircraft and aircraft-engine production, much of it for military export.

Serious practitioners never thought that the American system would or could ever be as orderly and as controlled when applied to the manufacture and assembly of discrete parts, often in small batches, as it already was in such continuous-process industries as chemical and petroleum processing.

Until recently, that is. Since the Depression years and the great war that brought them to an end, a number of developments in tools, in materials, in machining and forming processes, in inspection and controls give hope that we may eventually achieve a true manufacturing system.

As the American system moved into this most recent stage in its development, before manufacturing people could give thought to making improvements in the system, there was a more urgent matter. World War II had to be fought and won.

During most of the Depression years, there had been neither the will nor the way to improve manufacturing facilities. When the American Machinist Inventory was taken in 1940, only 28% of the machine tools in use were less than 10 years old. Five years later, in the 1945 Inventory, that figure had gone to 62% - the greatest change ever recorded in such a short period in any developed country for which data exists.

Between those two simple figures lay the production miracle that made World War II a different kind of war from its predecessor and that was responsible for the outcome of that war. There can be no doubt that, without this production miracle, the war would have had a different set of victors.

In an effort to tighten the neutrality laws, the laws of 1935 and 1937 prohibited the shipment of anything to countries involved in war or the loan of money - even by private citizens. The 1937 law did not prohibit the purchase of armaments in the U.S. by countries that were not at war and, in 1938 and 1939, British and French purchasing commissions began to place major orders.

With the fall of France in May, 1940, Britain took over the French orders and rapidly began using up its sterling reserves to meet the cash requirements. By that time, for example, orders for 10,000 planes had been placed in the U.S. by Britain and France, but deliveries were about 250 planes a month.

Following the fall of France, President Roosevelt established on May 28, 1940, the National Defense Advisory Commission (NDAC) with William Knudsen as director of industrial production. There was nothing to direct. The first new defense appropriations the following month were for about $400 million, but the pace quickened, and another, larger appropriations bill passed a few days later. In that month of June, 1940, the Army and Navy let contracts for $825 million, followed in July by another $1,137 million.

Another new type of procurement was possible under the 1939 Neutrality Act. In September 1940, Packard Motor Car Co., Rolls Royce, the U.S. War Dept., and the British Ministry of Munitions signed a four-way contract in which Packard was to build a plant and produce 9,000 Rolls Royce Merlin engines, one-third for the U.S. Army Air Corps and two-thirds for the Royal Air Force. The contract had originally been intended for Ford, but, after Edsel, Ford and Charles E. Sorenson had negotiated it, Henry Ford's isolationism caused a withdrawal.

In the closing days of 1940, Roosevelt took to the airwaves in one of his "fireside chats" to call on the nation to abandon the pose of neutrality and to provide every aid to Britain short of actual combat. "We must be the great arsenal of democracy," Roosevelt said, creating a phrase that was to be the touchstone for the years ahead.

The act to achieve this was called, in a masterful Roosevelt touch, "lend-lease" although, in the years that followed, more than $50 billion in direct aid was supplied to 38 countries, about two-thirds of it to Britain.

Chaos already existed in the procurement offices. Now it was rapidly compounded. The Office of Production Management was created on top of the NDAC, and then the War Production Board was created on top of the OPM. Within weeks, the auto industry had agreed to cut passenger-car production by 80%. That reduction was voluntary. The next one, which eliminated another 5.3%, was a directive. Terminal quotas were set, and the last passenger cars for the duration were produced on Feb. 10, 1942.

Similar shutdowns were made in other metal products. The typewriter industry was converted to war production. But it was discovered that a war can be fought without passenger cars but not without typewriters, and L.C. Smith had to convert from guns back to typewriters.

Knudsen had envisioned that the auto industry would serve as subcontractors to the aircraft builders, but it soon developed that the tiny aircraft industry lacked the sheer numbers of production managers to manage the levels to which output had to grow. So the Army designated Chrysler as a prime contractor to build Martin designs, General Motors to build North American, and Ford to build Consolidated Aircraft.

The targets for aircraft output were big numbers, and the President kept raising them. Although Roosevelt talked publicly of 50,000 planes a year, the actual quota had been set at 28,600 planes for 1942. After the Japanese attack on Pearl Harbor, Roosevelt raised that to 45,000. A year later, he raised it again to 100,000.

Quotas were just as unrealistic for some other items. At a time when the Army possessed 500 tanks, many without armament, the quota was being set at 45,000 tanks a year. Chrysler had gotten an early start with a contract to construct the Chrysler Tank Arsenal, but it was plagued with delays, like most parts of the program. About the only thing that came naturally for the auto industry was the production of jeeps and some 2.5-million trucks.

The basic problem, of course, was machine tools. Machine-tool shipments had dropped to $22 million in 1932. In 1938, they were only $145 million, almost half of which was for export (two-thirds that year went to Russia and Japan).

After the fall of France, Britain tried to take over the French machine-tool orders in the U.S., and the first of many priority battles took place. By this time, the Army, realizing with a shock how great its machine-tool problems were, demanded a ban on machine-tool exports to Britain.

This was eventually resolved so that Britain got most of the machines it needed. When OPM was formed, the tools-allocation operation moved, with the same people, to the new organization and was granted increased authority to make allocations.

In 1941, Roosevelt began urging that machine tools be worked around the clock and that industry go on a three-shift, seven-day week. Actually, the shortage of skilled people was such that, by early 1942, many machine-tool plants were working 12-hr shifts-in many cases for six straight days-followed by two days off, and then another six straight days.

By the end of 1942, the worst of the problem was over, and it was soon easy to get any machine tool needed except for a brief flurry of shortages again in 1944, the result of unexpected new programs for large artillery shells.

When it was over, the nation was jubilant but exhausted. And, for the machine-tool industry, there was a giant hangover ahead; some 300,000 machine tools were about to be declared surplus and dumped on the market.

What may be the shortest memory for important lessons in the history of government was demonstrated at the end of World War II. Even though the critical role of the machine tool in national defense had just been learned under the most convincing possible conditions, the government appeared, during the next five years, to be intent not only on destroying military capacity but also on destroying the machine-tool industry needed to rebuild that capacity in an emergency. When the Korean War started in June, 1950, it seemed at first to be a quick "police action" that would be over before Christmas. Then China entered on the North Korean side, and the situation changed drastically.

Two things made this situation different from 1941. One was that there was no clear vision of the scope of the effort that would be required. The other was that there had been no advance buildup. In 1941, two years of accelerating orders from Britain and France had caused a major increase in the capacity of the industry. By contrast, in 1950, the industry was still in the doldrums produced by the surplus machines thrown on the market in the postwar years.

The new Ford with the help of Ernest R. Breech, who came in to run the company under young Henry Ford, began a clean sweep through management and procedures. Many of the new people came from General Motors. Del S. Harder, the new head of manufacturing, had been at Fisher Body and then president of E. W. Bliss, while John Dykstra, his assistant, had spent the last 13 years as manufacturing manager at Oldsmobile.

In 1946, these two men started to transform Ford production methods. Groping for a word to describe what he was seeking, Harder, reviewing plans for a new plant, said, "Let's see some more mechanical handling between these transfer machines. Give us some more of that automatic business . . . some more of that automation." The word he used stuck with his staff, and the company soon had an Automation Dept. devoted to making equipment operate at its maximum rate (which usually can't be done without automatic loading and unloading) and to making work safer by eliminating hand loading of presses.

When American Machinist made the first report on the work of this department on Oct. 21, 1948, it had been in operation for 18 months and had approved more than 500 devices, costing $3 million, that were expected to increase production by 20% and to eliminate 1,000 jobs.

Most of that early work was on presses and included (1) sheet feeders; (2) extractors, turnover, stackers, and loaders for blanks; (3) unloaders, turnovers, and loaders for drawn stampings; (4) applicators for drawing compounds; (5) scrap removers; and (6) finished-part counters and baggers. Next, the department turned its attention to a new engine plant to be built in Cleveland. In that plant was an impressive degree of automation in the machining of the engine block, "automation" meaning mechanical handling of the blocks in, out, and between machines.

Today, of course, automation is generally accepted as meaning the automatic operation or control of a process, equipment, or a system.

A system. That has become the goal of manufacturing engineers in recent years. The people in the process industries-chemicals, petroleum, food, and the like-have been using continuous processes in their manufacturing for decades. But, in the metalworking industries, you make individual parts, and then you put these parts together, usually by hand, to make products. This is called the manufacture of discrete parts.

The kind of automation that Harder was seeking was used at about the same time by The Timken Company at its bearing plant in Bucyrus, Ohio. The investment for equipment in the Bucyrus plant was about 2 times the then normal level for a bearing plant, the output per worker was about four times the normal level, and the plant opening was accompanied by a 15% drop in the price of the bearings produced.

Continuous automatic production lines did not start with the word "automation." The first one, in the modern sense, was probably installed by A.O. Smith in Milwaukee in 1920, with a plant built to produce automobile frames. This plant was so soundly designed that it continued to operate for more than 40 years, finally being closed because unit bodies eliminated the kind of frame the plant could build. Another approach to automation is to combine operations into a single machine instead of providing mechanical handling between machines. This was done at the Morris automobile plant in Coventry, England, in 1924. A collection of standard machines were attached to a continuous, 181-ft long bed to perform 53 operations on engine blocks. The machine had a total of 81 electric motors.

In 1929, Graham-Paige installed in its cylinder department a system of operations that included automatic jigs and fixtures with transfer bars to move work from machine to machine; all the basic elements of the modern transfer machine were present.

Such machines had developed much further, of course, by the time Ford built the Cleveland engine plant and tied the separate transfer machines together in a continuous system.

Numerical control as a concept developed in the mind of John Parsons as a way to produce integrally stiffened skins for aircraft, and this led to a series of Air Force research projects at the Massachusetts Institute of Technology, beginning in 1949.

The initial planning-and-study phase was followed by the construction of an experimental milling machine at the Servomechanisms Laboratory at MIT.

A 28-in., Cincinnati Hydro-Tel vertical-spindle contour milling machine was the starting point. It was extensively modified; all of the table, cross-slide, and head drives and controls were removed, and three variable-speed hydraulic transmissions were installed and connected to leadscrews. Each transmission would produce, through gearing and leadscrew, a 0.0005-in. motion of the table, head, or cross-slide for each electrical pulse received from the director. A feedback system was provided to make sure the machine was doing what it was told. A synchronous motor geared to each motion generated a voltage in response to movement; this was sent back to the director and compared with the original command voltage.

By 1951, the system had been assembled, and application studies were begun. By 1953, enough data had been assembled to indicate the practical possibilities that could be developed.

General Electric began working on a control system for a much simpler problem; the two-axis positioning of work on the table of a Wiedemann turret punch press. The first machine, developed in Philadelphia, used an electronic counter and a photoelectric scanner to measure length of motion by counting the number of ruled lines on a glass scale that passed under the scanner as the table moved. Later, GE's Specialty Control Dept., in Waynesboro, Va., took a different approach, using the same type of self-synchronous motors that were being used at MIT. The machine was fed data by punched cards, each card carrying data for the X and Y location and turret position for one press stroke. Giddings & Lewis, working on the same aircraft skin-milling problem that had inspired Parson, put on the market in 1955 a system called Numericord. It used magnetic tape to control the machine in up to five axes simultaneously. Before that, it had been necessary to calculate the decimal information, punch that in a paper tape, and process that data in a computer, which converted the digital information to phase-modulated, time-coordinated command signals recorded on the magnetic tape. A three-year research project at MIT sponsored by G & L led to the development, and the "director" had been developed in cooperation with GE.

Later that same year, Bendix Aviation Corp. demonstrated a control system the company had developed to operate a milling machine producing three-dimensional cams for a Bendix division in South Bend. Bendix had purchased the patent rights that originated in the MIT research project. New impetus was given to NC development when the Air Force placed orders for 100 new NC contour-milling machines. Four companies were to build the machines: Cincinnati Milling, Giddings & Lewis, Kearney & Trecker, and Morey Machinery. Five companies were to build the controls: Bendix Aviation, Cincinnati Milling, General Electric, Giddings & Lewis, and Electronic Control Systems Inc.

The first approach to automatic toolchange was to include the tool coding in the program and have numbered preset tools in a rack, which was connected to the control so the machine would not run unless the proper tool was missing from the rack (and presumably in the spindle) while all other tools were in the rack. Barnes Drill Co. had such a machine by 1957. Barnes built a drilling machine with four parallel horizontal drilling spindles. These moved on vertical ways to bring the desired spindle into position, and only that spindle would then feed.

In 1958, Hughes Aircraft and Kearney & Trecker announced the joint development of a flexible automatic line in use at the Hughes plant in El Segundo, Calif. The line contained three machines, one each for milling, drilling (and tapping), and boring. The three machines were tied together by handling equipment, and the whole system was under tape control.

The drilling and tapping machine in the Hughes line provided tool change by a 20-position drum mounted in front of the spindle. The drum was rotated to bring the proper hole in front of the spindle and the spindle then advanced through the drum, collecting the drill or tap in that position. The control system for the Hughes line was called a Digitape and had been developed at Hughes Aircraft. The entire line was called the Milwaukee-Matic Model I.

The Milwaukee-Matic Model II, which came later that year, made everything that had come before look tentative and fumbling. The Model II was a horizontal-spindle machine with the work mounted on an indexing table so that four sides could be machined. A rotary drum on the side of the machine held 30 tools. The tools were coded on the tool shank so that they could be placed at random in the drum. The desired tool was collected from the drum in one end of a unique double-ended arm. At the moment of toolchange, the other end of the arm would grip the tool in the spindle, remove it, index 180°, and insert the new new tool in the spindle. A complete tool-change took 8.5 sec. The NC multifunction machine, or machining center, was born.

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