TP for stepped face

[Sa-Ro]

To define the stepped face (location), in what way datum A and B will support.

I think datum C alone will constrain the location and orientation within GT.

 

[Belanger]

ASME doesn't allow position to be used on a face (surface). They would have you use profile of a surface.
Or should I presume you're using ISO, which does allow position?

Or... are you using position to locate the "feature of size" span across two faces?

 

[mfgenggear]

I agree with Belanger
what needs o be there is perpendicular or parallel to -c-

 

[Sa-Ro]

ASME Y14.5:2018

Parallel to C and located from C

If we are using profile of surface, what way datum A and B will constrain.

Thank you.

 

[Burunduk]

If the flat faces need to be parallel to C and located from C, use profile of a surface with reference to C only. Make sure the leaders from the profile FCFs point to the surface and that the FCFs are not connected in any way to the extension lines or dimension lines of the basic dimensions.

The specification for the flat faces in your sketch does not reference A or B so I do not understand the question "what way datum A and B will constrain." They will not constrain any degrees of freedom for tolerances that do not reference them if this is what you are asking.

 

[Sa-Ro]

If datum A and B are specified as secondary and tertiary, how it will constrain.

 

[Burunduk]

If A and B are specified as secondary and tertiary in the profile of a surface FCFs they will do nothing. C as primary constrains 2 rotational DOF and one translational DOF required for the full definition of the flat faces' location and orientation.

 

[Sa-Ro]

Thank you.