GD&T (Perpendicularity/Surface profile)

[mechy20]

Does it make sense to call out a perpendicularity and surface profile for the same feature w.r.t the same datum? Doesnt one serve to tighten/negate the other?

If my understanding is right, if I have a 3d curved surface whose every point must be located within parallel planes (tolerance zone) to a datum, I would choose to use profile of a surface.

If however my surface is flat and perpendicular to a datum, I can choose to call out one or the other right?

Thanks in advance....

 

[reidh]

You are correct about the flat surface, either would be acceptable on the drawing.

Reidh

 

[KENAT]

A question like this may be better in the Drafting Standards, GD&T & Tolerance Analysis forum forum1103

As to an answer, I believe there could be circumstances where it may be appropriate to put both. For instance if you had a situation where perpendicularity to the datum was more important than the profile of the surface to itself.

 

[drawoh]

mechy20,

A profile tolerance applied to a flat surface controls perpendicularity, among other things. If your perpendicularity requirement is tighter than that of the profile tolerance, then you need a perpendularity tolerance as well.

Check out the GD&T forum.

JHG