【转帖】specification of tolerances

yang686526

specification of tolerances
hello all,
  i'm having a minor debate about whether or not to specify asme y14.5m-1994 on a print or not. there are no gd&t symbols on the print, but i have a default note that specifies the standard on all prints because i apply gd&t every time i can. it scares our manufacturing department though so occasionally, i'll spare myself the headache of protest and leave the symbols off if the part isn't critical. our manufacturing supervisor wants the note deleted on this one print in particular, probably because he feels like it will allow him more tolerance. my contention is that all prints should specify a standard to be checked by. if i leave the note out, does that means general rule #1 will not apply? is it illegal not to specify a standard or is it just bad practice...or does it really even matter when there are no symbols?
powerhound
production supervisor
inventor 11
mastercam x
smartcam 11.1
ssg, u.s. army
taji, iraq oif ii
find a job or post a job opening
even if it contains no gd&t, it should state to which standard it is to be interpreted.  asme y14.5 covers dimensioning and tolerancing in which gd&t does not have to be used.
indeed, it still relates to the first thiry pages of the standard that shows dimension practices and non-gdt tolerancing methods and interpretations.
i agree.
imo, people that do not want it on the dwgs, or used at all, are either lazy or ignorant.
i suggest having someone come in and give a demo on gd&t and setup some training.
chris
systems analyst, i.s.
solidworks 06 4.1/pdmworks 06
autocad 06
ewh,
  thanks for the input. i understand that gd&t still applies even in the absence of symbols, but our manufacturing department doesn't. this is why i want to leave the note on the print if for no other reason than to maintain consistency. i'm afraid if i remove the note from this print, then they'll want it removed from all prints.
powerhound
production supervisor
inventor 11
mastercam x
smartcam 11.1
ssg, u.s. army
taji, iraq oif ii
and once that happens, future drawings can be released no matter how poorly the parts are defined, and that will only cause more confusion.  i don't know your full situation, but i would tend to stand my ground.
keep it on and make sure that it states "this drawing complies with asme y14.5m -94 rather than referencing the standard.
dave d
well, it all started with an old print that the supervisor wanted re-drawn. it had a note that required a certain length of tubing to be straight enough to accept a rod along the entire length of the id of the tube. the rod is exactly 1mm smaller than the id of the tube so i added the callout of "straight within a diameter of 1mm" to the id, using gd&t symbology of course, and eliminated the note. he flipped out accusing me of adding stuff to the print that wasn't there. when i tried to explain to him that it was there, albeit in antiquated terms, he went into total denial and wanted any reference to gd&t removed from the print.
  so there you have it. on one hand, the print is pretty basic and it's probably not worth the fight for this print, but on the other hand, i don't want someone to get his foot in the door and start requesting all sorts of other stuff modified on a whim, just because he doesn't understand it.
powerhound
production supervisor
inventor 11
mastercam x
smartcam 11.1
ssg, u.s. army
taji, iraq oif ii
i had the same situation once.
i created a part dwg without and without gd&t. i asked purchasing to send them out separately for quotes. then 2 weaks later send them out again, but swap the prints to each vendor.
i asked for the prices. most of the parts that came back with the lesser $$ quotes had gd&t on the dwgs. (of course not all of them did, but most).
per ewh, stand your ground. i did and eventually won.
chris
systems analyst, i.s.
solidworks 06 4.1/pdmworks 06
autocad 06
the fact of the matter is that asme y14.5m-1994 is not a "gd&t" standard. it is a "dimensioning" standard that defines how to use feature control frames and datums. if you don't specify a standard the drawing can be interpreted anyway the fab shop wants. allways reference a standard if you intend to place dimensions on a drawing.
david
my next question is this: is there a standard that requires, or even recommends that a dimensioning standard be specified on a print? i know that will be the question when i approach our engineering manager with this.
powerhound
production supervisor
inventor 11
mastercam x
smartcam 11.1
ssg, u.s. army
taji, iraq oif ii