The Who and the History of Geometric Dimensioning & Tolerancing
The Beginning: What we now call Geometric Dimensioning & Tolerancing, or "GD&T" started near the beginning of World War II. Stanley Parker developed the concept of "True Position" and also, reportedly the first use of round tolerance zones for round holes while he worked in a torpedo factory in Scotland. He realized that parts that had been rejected based on measurement results were actually functional, so as developed tolerancing practices to more effectively address functional requirements of mechanical parts, he was credited with creating the first elements of GD&T.
Development of GD&T Standards: GD&T standards started as military standards, such as US Army 30-1-7, dated April 15th, 1946, and then Mil-Std-8, dated December 30th, 1949, then the ASME (American Society of Mechanical Engineers) was the publisher for ASA (American Standards Association) Y14.5-1957. Subsequent Y14.5 standards have been released as USASI (United...
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Dean Watts
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Dean Watts is a mechanical engineer who has been providing Geometric Dimensioning & Tolerancing (GD&T) training, and coaching for the over 20 years. Dean is a registered PE in the State of Washington and certified as a Senior Level GD&T Professional by the American Society of Mechanical Engineers (ASME) (GDTP S-0295). He is also a former member of the ASME standards development committees Y14.5 Dimensioning and Tolerancing, Y14.8 Castings Forgings and Molded Parts, and he is the Chair of the ASME Y14.45 Measurement Data Reporting committee. He started his career with 3 years of full time experience in production machining, precision Sheetmetal, and TIG welding. He is also a retired U.S. Coast Guard Reserve officer, and former U.S. Navy Submarine Warfare Officer.
