How best to add GD&T to ensure symmetry

[RCor]

Hi!

I'm trying to dimension and add GD&T to this cross-section

to prevent the left and right from going asymmetrical like this (over-exaggerated)

I've tried several things (see below), but haven't found a good solution that is both correct and measurable by operators (with simple gauge(s) and or caliper).

(Note that I use the upmost dimension as reference since this is the dimension with the smallest tolerance on it)


Option 1 - makes no sense since centerline of referenced dimension moves along with centerline of reference

Option 2 - would make more sense, but not sure how this would be measurable

Option 3 - basically like option 1: centerline and position move together

Any tips or advice is very welcome!
Thank you in advance!

 

[jassco]

Hi, RCor:

So, your center line is perpendicular to the bottom face (datum feature A) and is located with an equal distance from centers of the two corner bend radii (datum feature B).

If you use a CMM machine, you can also use virtual sharps to establish the center line or center planes.

With datum A and B established, you can now assess profiles of "V" and their associated features.

As drawoh indicated, symmetry has been made obsolete per ASME Y14.5-2018. You will need to use profile to control the "Symmetry". For feature of sizes, one would use position to control symmetry.

Best regards,

Alex