Control the angle of a theoretical line between two holes relative to a mating part on assembly

[erik3000]

Please see the attached image.

The green part comes in with two holes which are controlled relative to each other. It mates to the blue part so that the big hole is some distance from datum A (loose tolerance), and the green part is clocked so that the angle of the red line relative to datum A is within a specific tolerance. The outline of the green part has no specific relation to the hole pattern. Once the desired position is achieved, they get clamped together and matched drilled and bolted together. The two holes shown then get used for additional mating parts. How would you call out the angle shown on the assembly drawing?

 

[3DDave]

I would use a position tolerance just as if the green part was welded in place and the holes were drilled afterwards. There are a variety of choices, but one part of the solution is that the angle of interest would be basic and based on [A]. I can't be more specific because there is insufficient detail about why the holes are to be located.

There's a rule that dimensions and tolerances apply only at the drawing level they are shown; duplicating them at a different level is not double-dimensioning.

 

[DeanD3W]

Does what I've shown in the attached file provide what you're after?

I hope this helps.

Best Regards,
Dean

http://www.validate-3d.com

 

[DeanD3W]

erik3000,
I just looked at this again and I see that I included a vertical basic dimension to the larger hole. Please disregard that. I didn't intend to leave that in the mark-up.

Best Regards,
Dean

 

[erik3000]

Dean,
Thanks for the pic. I think something like that will work if I understand it correctly. When you show datum D as secondary in the FCF for the small hole, does that mean the tertiary datum plane B "moves" with the large hole wherever it is located? If not, I think I am still missing something about how the small hole can have a tighter tolerance relative to B than the large hole.