Re: Tolerance in text

["Gene Kim-Eng" <techwr -at- genek -dot- com>]

Having spent some 15 years in naval and aerospace design during the
70's and 80's, I can attest to the fact that there are design standards for
both military and civilian shipbuilding that spell out in no uncertain terms
allowable dimensional tolerances.  US military blueprints, for example,
use ASME Y14.100-200, other industries apply ANSI, ISO, DIN,
JIS or other standards.  All it takes is a single note stating that drawings
are prepared "in accordance with" a standard to automatically apply all
of its tolerance requirements to every dimension in the drawing, "unless
otherwise specified" (and in such cases the standard will specify *how*
you are supposed to otherwise specify).  You certainly cannot take a
dimension from someone else's email and "imply" a tolerance such as
"25 mm actually means 25 mm + 0.49 mm / - 0.50 mm" without knowing
what drafting standard is in use, or you end up with incidents like
Challenger or Hubble.

Gene Kim-Eng


----- Original Message ----- 
From: "Geoff Lane" <geoff -at- gjctech -dot- co -dot- uk>