【转帖】do brackets mean no tolerance
 

do brackets mean no tolerance
can someone point me to a reference for the following:
(.xxx) means no tolerance
this is on a drawing and i referred to the block for tolerances.
i believe i am correct referring to the block but i can't find a reference that by putting a dimension into brackets or () this means no tolerances.
thanks for any help.
(xxx) is a reference dimension with no tolerance.
amse y14.5m-1994 paragraph 1.3.10 for definition and 1.7.6 for implementation. basically, a dimension that is repeated, derived, or in some way auxillary is a reference dimension. reference dimensions are identified by being placed within parentheses. ( ) they do not have a tolerence, nor do they govern production or inspection operations.
matt lorono
cad engineer/ecn analyst
silicon valley, ca
the parenthesis mean one of two things; either the same dimension is shown elsewhere on the print and is a hard dimension or it can be derived from other dimensions, inwhich case those dimensions are toleranced
powerhound, gdtp t-0419
production supervisor
inventor 2008
mastercam x2
smartcam 11.1
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this is sometimes confused with a secondary dim.
i have seen:
.123
(.2)
thinking primary and secondary.
it should be:
.123
[.2]
(numbers are examples only)
the () is for reserved for reference dims.
chris
solidworks 08 0.0/pdmworks 08
autocad 06
thank you for the reference and answers, i have never seen this before (learned something today)
peterjn,
my i ask your background, careerwise?
matt lorono
cad engineer/ecn analyst
silicon valley, ca
hi fcsuper,
my background is electrical & optical engineering.
i appreciate your help.
thanks again,
pete
pete,
it's good to know the background. if you are going to be more involved with mechanical drafting, i recommend either a workshop or a jc class that covers asme y14.5m-1994. best of luck!
matt lorono
cad engineer/ecn analyst
silicon valley, ca