Do I even need datums for this profile?
Do I even need datums for this profile?
(OP)
My intent is that the profile is good to itself along the designated length. I have added datums to help the inspectors, however, I'm thinking that I can achieve my intent with a profile FCF with no datums at all.
Comments?
Comments?





RE: Do I even need datums for this profile?
RE: Do I even need datums for this profile?
They are for the machining center to hold the part.
They are a process note, not a inspection note.
Sorry, I should have removed them for this question or clarifoed that.
RE: Do I even need datums for this profile?
Nothing in your drawing shows (with or without GD&T) how your profile is related to cylindrical features, which means geometry of your part is not defined yet.
I would also like to mention that GD&T is not created for the sole purpose of inspection, so just because you believe you provided enough information to the inspector, doesn’t mean your GD&T is correct.
RE: Do I even need datums for this profile?
The profile IS NOT related to any cylindrical features. It has to be good to itself.
Inspection dept asked for datums in order to inspect the profile. I gave them some datums to locate on. But that concerned me. I did not think it needed datums.
Back to my original question:
The right hand view does not actually need datums, does it? It could just be profile of .003?
RE: Do I even need datums for this profile?
Profile is evenly split on each side of the basic shape with the given callout. The nominal distance from the datums to the desired surfaces is zero. This leaves the profile half embedded into the datum simulator, which cannot happen, and is therefore not available for tolerance.
If you excused the wide surface from the profile tolerance and made it flat to .003, keeping datum reference A and ditching B, then you'd have something easier to measure, but without knowing what the part does, it's not possible to say if it's what you need.
RE: Do I even need datums for this profile?
If you remove all the datums and make the FCF profile of .003 (no datums), is that adequate if all one is concerned with is that the shape is good to itself along the noted length within profile of .003?
RE: Do I even need datums for this profile?
RE: Do I even need datums for this profile?
However, as CH (CheckerHater) noticed, from perspective of part's geometry completeness applying datumless profile callout means that nothing on this drawing controls orientational/locational relationship between the contour and the cylindrical features on both sides of the part, thus the drawing is incomplete.
RE: Do I even need datums for this profile?