Re: German airfield flak defences

Guy Alcala wrote:

[40 mm Bofors flak] (the USA had to re-design it completely to
make it suitable for mass production).


What design changes, specifically?  AFAIK the main US design changes, at
least for the standard (air-cooled) version, involved doinga new set of
drawings using US measurement standards, screw threads etc. Was there any
substantive re-design to better suit it to mass production?

The changes were majorily involved in the re-drawing. The original drawings were astonishingly uncertain regarding mating of parts. The design was not worked-out for production lines, but more in the style of small-batch manufacturing. Many measurements lacked reasonable tolerance specifications, which made it impossible to exchange parts manufactured at different batches oder plants. Often there were remarks like "to be matched at assembly" or "bored together at assembly" or "to be applied as needed", which led to a large amount of manual work in manufacturing as well as more difficult repair.

The US designers replaced these positions by defined measurements and tolerances, and changed some parts in order to make them easier to machine or assemble. This was done without changing the characteristics or appearance of the weapon (except of imperializing screw threads etc.). Chrysler Corp. boasted itself to have reduced manufacturing expense significantly and made 40 machine tools superfluous by these changes.

Regards

Joachim
.

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