2
$\begingroup$

From Krulikowski (1997), the callout for several coplanar surfaces using the Profile symbol is done by using two surfaces to establish datum plane A-B and then tolerancing the remaining coplanar surfaces in reference to A-B.

Can other non-coplanar features reference this datum plane A-B as I would a normal datum? See below for example.

enter image description here

In the O-ring groove above (2.5 x 1.6), the callout on the left is for coplanarity. The callout on the right is for location and form, NOT coplanarity. I guess it would be obvious that it is not coplanar, but something about it looks off.

Is referencing datum A-B for non-coplanar features legal, illegal, or just plain bad notation? Or is it just a matter of preference?

Improve this question
$\endgroup$
0

2 Answers 2

Reset to default
1
$\begingroup$

This is fine, but not typical for cylindrical faces.

The Profile GD&T symbol describes a 3D tolerance zone around the face, and as such is typically used for complex surfaces where other symbols cannot be used. See https://www.gdandtbasics.com/profile-of-a-surface

Improve this answer
$\endgroup$
1
$\begingroup$

I think you need something inline with this:

enter image description here

Note that the datum A is identified by using an indicator under the callout. A-B could equally be used with the same meaning if you identify the two surfaces.

You can have more explanation in ASME 14.5:2018 figure 6-6.

Improve this answer
$\endgroup$
2
  • $\begingroup$ my answer is for planar surfaces $\endgroup$
    – Jean-François MAUREL
    Commented Sep 25, 2020 at 14:03
  • 1
    $\begingroup$ I modified my answer. The point is the datum. $\endgroup$
    – Jean-François MAUREL
    Commented Oct 8, 2020 at 17:10

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.