Control Frames 2

[princed90]

Can someone explain what the differeces are between the two examples in the attachment?
I'm being told that there are no differences.
Also being told that the projection callout is incorrectly applied.

 

[pmarc]

Yes, there is no difference between the two - this is a special case when composite FCF (lower frame in your example) and multiple segment FCF (upper one) are equal in meaning.

Projected tolerance zone height is applied incorrectly only because there is a line separating P modifier and .070 value. It should not be there.

 

[Belanger]

One small addition. There is no difference ... as long as datum A intersects the features (usually A is perpendicular). But if for some reason datum A were parallel to the axis of the features, then there is a difference between the two callouts, since there would be two relationships to datum A: orientation and location.

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

http://www.gdtseminars.com

 

[princed90]

Thanks pmarc and Belanger.
Since there shouldn't be a line between the P and the .070 should there be a line between the .001 and the P?

 

[CheckerHater]

No line before, no line after.

Also, as projection tolerance essentially applies to part of the fastener (or gage) protruding above the surface of the part, you may consider using (M) modifier with .001 tolerance as well.

 

[pmarc]

Good point, J-P.
I should have mentioned that at the very beginning of my reply.