【转帖】rectangular tolerance zones

yang686526

rectangular tolerance zones
this thread was started so as not to hijack the "symmetrical" thread any more than it already has been.
regarding ringmans reference to fig 5-21 in the standard, i have no idea what you are trying to convey about rectangular tolerance zones by using this example. this is a perfect example of cylindrical tolerance zones and their application as well as composite tolerance frames and how coordinate tolerancing can't address it.
powerhound, gdtp t-0419
production supervisor
inventor 2008
mastercam x2
smartcam 11.1
ssg, u.s. army
taji, iraq oif ii
why is it that somehow if a fcf is on a print, it begins to border on overkill. god forbid there be 2 fcf's. i just don't get how you can have nothing but coordinate tolerancing (which is a mediocre system anyway) on a print, implied datums and all, notes slathered up one side and down the other to explain everything that gd&t could do with a symbol, fundamental rules, and/or general rules. is this really better? does the application of gd&t really push the envelope towards the undesirable end of the print spectrum?
powerhound, gdtp t-0419
production supervisor
inventor 2008
mastercam x2
smartcam 11.1
ssg, u.s. army
taji, iraq oif ii
powerhound,
   first of all thank you for your service to the u.s.a. as well as any veterans reading this post. with that said, i understand your rant concerning the lack of gd&t. this is my second year in the industry so i might not have developed the hindsight to make the following statement or rant if you will. it seems my company doesn't employ gd&t because of a desire for short-term gain and never learning from long-term loss. it is well-known a lot manufacturing is being sent overseas and the constant pressure to keep part cost lean. upper management fears the datum symbols, so displaying 2 fcfs would warrant public ridicule to shame one from stepping out of the coordinate zone. upper management is stellar when it comes to multiplying annual consumption x increased costs for accuracy. the short-term cost savings are great until your mrb queue becomes overflowing.
failure is a prerequisite of successful design
powerhound,
my thanks also to you and all the others involved in iraq and afghanistan.  our hearts and prayers go out to you.
powerhound, i think this got touched upon in a thread a few months back.  a number of posters seem to believe that adding gd&t often increases cost and so should be avoided except when tight tolerances etc are required.
quote:
asme y14.5m-1994
2.1.1.1 positional tolerance method.  preferably, tolerances on dimensions that locate features of size are specified by the positional tolerance method described in section 5.  in certain cases, such as locating irregular-shaped feature, the profile tolerancing method described in section 6 may be used.
i do believe there are applications for square zones when using positional but from my limited experience diametric is more common.
(last post should have been 'best i can'.)
kenat, probably the least qualified checker you'll ever meet...