huangyhg

general drawing tolerances
i am interested in finding out if the field is moving away from using a general, or boiler-plate tolerance block on a drawing format or if most organizations are continuing to use it. any opinions would be appreciated.
i can't speak for automotive, but for mechanical and aerospace...we still have it and will be using it for several more years.
chris
solidworks/pdmworks 08 3.1
autocad 06/08
we have a boiler plate block on drawing format, in the us (asme y14.5m-1994 compliant(ish)) scientific instrumentation/metrology tools. doesn't work as well for metric .
people relying on mbd may be doing differently.
kenat, probably the least qualified checker you'll ever meet...
we definitely have a general tolerance block so that we don't have to specify a tolerance for every dimension...just those that need to be a bit tighter or looser...can't imagine eliminating it any time soon.
same as above.
when the people fear their government, there is tyranny; when the government fears the people, there is liberty.fff"> - thomas jefferson

brakemeister,
usually, tolerance blocks on drawings state that a certain number of decimal places indicate the tolerance. asme y14.5m-1994 states that you do not apply trailing decimals to your metric dimensions.
most of my drawings are metric. i can use our tolerance block, or i can follow asme y14.5m-1994. i follow asme y14.5m-1994.
going through each and every dimension on my drawings and adding or ensuring there is a tolerance easily adds around five minutes time to each and every drawing i generate. i think i have wound up with better drawings.
jhg
in the uk we just had a single general tolerance, it didn't vary with decimals as most drawings were metric. this meant that as with drawoh we added direct tolerances to a lot of dimensions, we also usually showed limits rather than +-.
kenat, probably the least qualified checker you'll ever meet...
my view on "standard" tolerances may be found here:
good memory mint.
kenat, probably the least qualified checker you'll ever meet...
yes, good find. i forgot about that thread.
chris
solidworks/pdmworks 08 3.1
autocad 06/08
the isn't a movement away from title block tols as far as i can tell either. however, there is just starting to be a move towards relying on the models themselves without drawings. however, even is such cases, tolerances are still required to be stated in the documentation of the model, and place .xxx tolerances is still a comment practice.
btw, even if metric is employed, title block tols can still be used. there's no law saying you can't. just make a note of this variation from the standard in your own company's drafting standards. it is acceptable within asme y14.100 paragraph 1.2 to not use particilar sections of the asme standards as long as you are clear as to what differences you have when this happens.
matt lorono
cad engineer/ecn analyst
silicon valley, ca

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