GD&T question

[Smallsvillanova]

Can someone please help me understand this callout? I am told it is proper per ASME but am not familiar with how to evaluate and report said feature. Attached is a small snippet.

Any help is greatly appreciated.

[Mike Ruff]

NOTE: My explanation is assuming that datum A is the face these features are on!!

This is essentially 2 separate callouts. The Profile of a Surface dimension would control the size and orientation of the slots, relative to datum A, and needs to be held to within ±.25 per side (the orientation for this segment can be ignored though, because the orientation is held to a tighter tolerance by the True Position). The True Position callout to A does not control size, but it controls the locations of the slots relative to each other as well as the orientation of the slots to the datum (perpendicularity in this case).

[Smallsvillanova]

Mike Ruff Thank you for the reply sir. You would be correct about datum A. That is exactly what my colleague thought as well, he is just having a hard time finding it in the standard. Can that be evaluated as a "WF" and would that become +/- .5? since its +/-.25 per side?

Again, thank you. Your help is greatly appreciated

[Mike Ruff]

Correct, the size tolerance for the width/ length of the slots is essentially ±.5, but personally, I would use points on all sides of the slots and a profile dimension, and maybe construct a WF for the true positions

[Smallsvillanova]

Mike Ruff out of curiosity why would you do it that way?

[DungT]

The way I see it is both are feature relating control, 10 slots to each other. The term "Boundary" is used in an application where it's necessary to control the boundary of an irregular feature of size, slots in this case

Profile controls size, form, slot orientation and location.
TP controls location of slot median point only.

I would level to A, best fit rotation and origin if applicable, then profile form+location and then TP from the same coordinate...just my 2 cents

[Smallsvillanova]

The way I see it is both are feature relating control, 10 slots to each other. The term "Boundary" is used in an application where it's necessary to control the boundary of an irregular feature of size, slots in this case

Profile controls size, form, slot orientation and location.
TP controls location of slot median point only.

I would level to A, best fit rotation and origin if applicable, then profile form+location and then TP from the same coordinate...just my 2 cents

Why does the TP only control the median points? I am still quite green and am just wondering as this is not a normal call out for us. profile is usually not something our customers request on slots

[DungT]

Your sketch shows TP|0.25|A and I thought TP|Ø.25|A…Now it makes no sense (?)
Anyway, as far as I know PC_DMIS does not include orientation of the slot when do TP, only to center point.