Specification of tolerances
Specification of tolerances
(OP)
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?
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





RE: Specification of tolerances
RE: Specification of tolerances
RE: Specification of tolerances
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
ctopher's home (updated 10-27-06)
RE: Specification of tolerances
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
RE: Specification of tolerances
RE: Specification of tolerances
Dave D
RE: Specification of tolerances
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
RE: Specification of tolerances
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
ctopher's home (updated 10-27-06)
RE: Specification of tolerances
David
RE: Specification of tolerances
Powerhound
Production Supervisor
Inventor 11
Mastercam X
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Specification of tolerances
RE: Specification of tolerances
There is a lot of other stuff in Y14.5 other than GD&T so just because you don't have any feature control frames etc doesn't mean 14.5 doesn't apply.
Also as Aardvarkdw says you should really say to what standard your drawing is to allow interpretation.
Firstly because there are differences between the various international standards.
Secondly because if you don't specify any standard then you'd have to add hordes of notes about things like 'edges drawn at 90 degrees are assumed to be 90 within general drawing tol' etc and all the other 'standard conventions' we take as read, even so far as probably defining what angle of projection is used and what it means etc for it to be 'unambiguous'.
This doesn't just go for 14.5. For instance while not compulsory and not apparently standard practice the asme thread standard does recommend that it be referenced on drawings calling out threads.
In my opinion, and training, if you’re using a standard to help define something you should reference that standard (directly or sometimes indirectly as applicable), even if it seems obvious to you.
RE: Specification of tolerances
Jim Sykes, P.Eng, GDTP-S
Profile Services
CAD-Documentation-GD&T-Product Development
www.profileservices.ca
RE: Specification of tolerances