For you gearheads out there.
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| Norman Rockwell |
WW2 Dossier and WW2 Records "In October 1943, three Luftwaffe engine specialists stood around a captured American radial engine at Rechlin — Germany's top flight-testing center. They expected to confirm what everyone in the Reich believed: American manufacturing was crude, sloppy, inferior to German precision.
"They removed the cowling. Nine cylinders, air-cooled, twelve hundred horsepower. And within minutes, something was wrong. Not with the engine — with everything they thought they knew about American industry. The machining was flawless. Every part fit without hand-filing. No shims. No adjustments. Then one of them checked the data plate riveted to the housing. The name stamped on it wasn't an aircraft manufacturer. "It was a car company from Indiana. "What the Rechlin engineers discovered inside that engine — and what it revealed about why Germany was already losing a war it didn't know it was losing — is one of the most quietly devastating engineering revelations of the entire conflict." . . ."When I was an EE in the 1980s (digital logic for graphics cards) the Germans were still doing this (fixing bad engineering designs on the manufacturing floor by very skilled labor). Our management talked with a German company and they decided to share some of their designs so they could be made by both companies. When our engineers saw the German designs we burst into laughter because it couldn't possibly be assembled in a US factory. They were using ECL logic and to avoid clock timing problems (setup and hold violations) they had the factory floor choose one of several circuit paths on the board with different delays presumably according to an oscilloscope measurement. Our board designs could be assembled from any parts with no testing and it was expected to run. This is not a matter of worker efficiency, it was a matter of engineering design effort. The designer was expected to work on a design so that it could use any parts that met the spec for that part. It was not that the parts were "identical" but instead that engineer specified the variation in parts sufficient to work with the design. Translating timing specs on digital chips into dimensional part specs, it's a bad engineer who specifies a part dimension as 0.500". That is an exactness that no factory can produce. Instead, a dimension is always given a range, for example 0.495" to 0.505" and the factory is expected to keep all parts in that range and the engineer was expected to verify that parts in that range would always work in the design. To make manufacturing easier, the engineer is expected to modify the design so that it can use parts with as wide a tolerance as possible (frequently what is available as a standard inexpensive part). That is what US tradition in engineering design is about not quite what this video describes. The tradition dates to the Revolutionary War and war of 1812 when firearms were more or less first specified to have interchangeable parts. To get this to happen you have two actors interacting, the engineering designer and the manufacturing engineer. The designer specifies the necessary tolerance and the manufacturer verifies that they are producing parts within that tolerance." Carl Brannen
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