yang686526

iso 406
i am reading iso 10110 on how to prepare optical drawings. it says that drawings must be dimensioned and toleranced as per the iso 406 standard. it looks like i am going to have to buy a copy.
i have heard weird things about iso gd&t. is anyone here familiar with it? is the standard reasonably self-contained, or am i going to have to look for other stuff in addition to it, as with iso 10110?
jhg
almost all iso standards contain a "normative references" section up front, listing other iso standards that are "...indespensible for the application of this document."
almost always the first one listed is a glossary document.
seems like a scheme to sell more standards.
mintjulep,
that was part of the weirdness i was hearing about.
i paid my thirty bucks. iso 406 is a simplified version of asme y14.5m-1994, chapter_2. it allows the specification of dimensions on assembled parts. it says nothing about geometry. the asme standard allows the iso tolerance symbols like h6 and f7 on metric dimensions.
it appears that there is an iso 129 out there somewhere, on techical drawings -- dimensioning -- general principles...
all in all, it makes an excellent case for the asme standard.
jhg
it would be contrary to standard practice for the standards boards to standardise on a standard set of standards.
the iso standards for drafting & dimensioning are fragmented into individual documents to cover each sub-topic. it makes it extremely expensive to amass the entire set of relevant standards. asme is far better, though it also has some fragmentation (i.e. y14.41, the casting & forging standard, the gage & fixture standard, ...)
iso's gd&t has a number of other idiosyncracies as well. it allows you to use an axis line as a datum feature. it indicates the mathematical mean of the surface as the datum surface (great for cmms, lousy for traditional inspection methods).
the best explanation of the differences between asme & iso for gd&t is that asme is based on the physical reality whereas iso is based in the mathematical theory.
jim sykes, p.eng, gdtp-s
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cad-documentation-gd&t-product development
in the uk when they went to the iso they replaced bs 308 which was a single document with bs8888.
bs8888 essentially is a list of all the relevant (or in some cases not so relevant) isos, bs, ens etc.
when we got our full copy with all the listed docs it filled 3-4 ring binders (the 2.5" ones if i recall) and was so awkward to use and had so much irrelevant stuff that if probably got used less, and hence was less useful than, the old 308.
i don't know how much it was but it wasn't cheap.