Ok. We have all seen this. A print with a centerline call out that really only controls size and not location. Think of this as solid block with a U shape cut thru it. The entire U shape is severely tipped to 1 side. We almost have a this wall condition on side. The U itself has perfect size and form. . We are getting push back from another dept saying according to the print it is good to go! There is a note saying all undefined geometry is controlled at +/- .010 on the print and we also use an internal control that states +/-.10 on all undefined dimensions. This dept has never heard of that document for some reason. So I would say the shape itself needs to be within .010 of the C/L. Can everyone out there quote a standard that talks about undefined symmetry ? Y14.5 has nothing ( and I didn't expect it to ) . The drawing isn't referencing any other specs and it is an internal drawing so this is more of a dept vs. dept P!$$!NG match. I would like to win this war with a MOAB !
Ok. We have all seen this. A print with a centerline call out that really only controls size and not location. Think of this as solid block with a U shape cut thru it. The entire U shape is severely tipped to 1 side. We almost have a this wall condition on side. The U itself has perfect size and form. . We are getting push back from another dept saying according to the print it is good to go! There is a note saying all undefined geometry is controlled at +/- .010 on the print and we also use an internal control that states +/-.10 on all undefined dimensions. This dept has never heard of that document for some reason. So I would say the shape itself needs to be within .010 of the C/L. Can everyone out there quote a standard that talks about undefined symmetry ? Y14.5 has nothing ( and I didn't expect it to ) . The drawing isn't referencing any other specs and it is an internal drawing so this is more of a dept vs. dept P!$$!NG match. I would like to win this war with a MOAB !
You can usually reference an ISO DIN standard (or in Europe we do), there are separate tolerances for what kind of part it is, cast, machined etc. The only issue I have with using DIN standard tolerances is that they are very generous. I would guess there is an ASME equivalent but again it will probably have the same problem of being quite a large tolerance for what you do.
Unfortunately I don't have access to any at the moment so cannot provide you some values.
We always have an internal document like yourselves, or have it written on the drawing that all un-toleranced surfaces shall use these tolerances.
If you think a single ASME book (with examples!) is cause for a headache, you should definitely not take a look at the 50+ interlinked standard(s) that is ISO...
In ISO-land, the standards ISO 2768-1 and ISO 2768-2 defines general tolerances (for anything that is not explicitly toleranced on the print). Assuming the print says so...
No. Its a print for an Aluminum Extrusion DIE.. OK I take that back. There is a DATUM so you know which out side surfaces you are using to establish the C/L , ( the outside is stepped) but there isn't a FRC or anything else to verify the shape is actually on center other than out internal document about undefined Tol. being +/- .010 which the DIE shop seems to be making the claim they have never heard of.....
It's says right there in 2.3 Limits of size. feature of size is ONE CYLINDRICAL or SPHERICAL, or a SET OF TWO OPPOSED PARALLEL SURFACES. 2.2 explains with Datum Control, you have no Datums or starting points. So you have 0-Diminsional, POINT(SPHERE). 1D, LINE(CYLINDER). or 2D, PLANE. One Feature +/-.010. They go on to explain it as an envelope.
I'm sorry you do have Datum control, still doesn't change the definition of feature of size, the only thing it will change is location.
That's because everyone skips pages 1 and 2 in the GD&T book. That shows different books, more in detail, to relate to and nobody buys them, so they just start making up stuff and changing the rules to make bad parts good, or good parts bad.
