John T. Parsons (October 11, 1913April 18, 2007) pioneered numerical control (NC) for

machine tool A machine tool is a machine for handling or machining metal or other rigid materials, usually by cutting, boring, grinding, shearing, or other forms of deformations. Machine tools employ some sort of tool that does the cutting or shaping. All ...

s in the 1940s. These developments were done in collaboration with his Chief Engineer and Vice President of Engineering,

Frank L. Stulen Frank Lem Stulen (January 22, 1921 – June 25, 2010) graduated from Carnegie Mellon University (then Carnegie Tech) in 1942 with a degree in aeronautical engineering. After graduation, Stulen served in the U.S. Army Corps of Engineers and in the ...

, who Parsons hired when he was head of the Rotary Wing Branch of the Propeller Lab at

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, in April 1946. Together, they were the first to use computer methods to solve machining problems, in particular, the accurate interpolation of the curves describing helicopter rotor blades. In 1946, "computer" still meant a punched-card operated calculation machine. In 1948, Parsons' company, "Parsons Corporation" of

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, was awarded a contract to make the challenging tapered wings for military aircraft; they won the contract because they developed the computer support to do the difficult three-dimensional interpolation for the complex shapes, as well as the 800 steps long production cycle for the wing manufacturing. IBM was one of the subcontractors, as was

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, which took care of the servomechanisms. The latter lab boosted the developments of numerical control machining in the following decades, by developing reliable servo control in 1952 and the

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(''Automatic Programmed Tool'') programming language for NC machines. It was only after the servos were also steered by computers that real "numerical control" was realised. The initial developments of Parsons and Stulen were only about the ''calculations'', and not the control: the results of the calculations were given to human operators that turned the wheels on the machine tool to generate the desired tool paths. Parsons, however, quickly saw the potential of connecting computers to the machine motors. On January 14, 1958, he received a

patent A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an enabling disclosure of the invention."A ...

for a ''Motor Controlled Apparatus for Positioning Machine Tool'' (patent number 2,820,187, filed on May 5, 1952). The initial developments of NC machines, however, had been so expensive that Parsons was fired from his own company because the funding of the MIT developments was too much for the company. Parsons was reinstated as president of the company after royalties on the patent had generated significant amounts of money. ( Bendix Corporation was an initial licensee of the patent, in 1955, and eventually bought all the rights to it.) In 1985, Parsons and Stulen received the

National Medal of Technology The National Medal of Technology and Innovation (formerly the National Medal of Technology) is an honor granted by the President of the United States to American inventors and innovators who have made significant contributions to the development ...

. In 1988 he received an honorary Doctor of Engineering degree from the

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. In 1993, Parsons (but not Stulen) was inducted into the

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for inventing numerical control. Parsons died on April 18, 2007 at the Grand Traverse Pavilions. He was 93. He had six children.

References

{{DEFAULTSORT:Parsons, John T. 1913 births 2007 deaths National Medal of Technology recipients People from Detroit