Perpendicularity to two datums

[[Ri...]]

I can't figure out why I can't set a 2d Line to be perpendicular to a surface using two datums.
The selection for Parallel or Perpendicular is grayed out.
See images.

Any help is appreciated.
Calypso v2019 latest rev level.

Datums M, C, A-B.jpgPer_M to C_A_B not working.JPG

[[Ja...]]

How could your tolerance zone be perpendicular to C and A-B simultaneously?

[img]https://res.cloudinary.com/engineering- ... t8tvai.jpg[/img]
Ignore the part in blue there, this was the first image I could find from y14.5.

[[Ri...]]

It wouldn't be a 2d Line either way. It should be a 3d Line.

[[Ri...]]

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Datum M is perpendicular to Datum C
Datum M is perpendicular to Datum A-B
I don't see why it can't.

[[Ri...]]

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A 3D Line did not make a difference.

[[Ja...]]

Here's another thread on the topic: viewtopic.php?t=10632&hilit=perpendicularity+two+datums

The tolerance zone will be perfectly perpendicular to the actual feature C. If its then perfectly perpendicular to the actual feature A-B it will no longer be perfectly perpendicular to the actual feature C, unless your part is perfect. But in this instance the tolerance zone could be perpendicular to C and parallel to A-B.

[[Ri...]]

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I assume it's trying to control the Perpendicularity from A-B in the X-Y Plane. I tried Parallel Cylinder but that didn't work.

What about if you measured Circles at the Top and Bottom of each Cylinder and then Recalled the Center-Points into a Plane? It seems to work in principle in Simulation.

Thoughts?

[[Ma...]]

I think that lines should not work in this cas, but planes should.

Create 3d line from recalled cylinders/circles to obtain angle. Then use formulas for new theoretical plane, where you use angle in same axis to get that parallel with 3d line.

[[Er...]]

I think this goes back to the can, may, must rule. If the datums were set up as lines both could be applied.

[[Ri...]]

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I will give that a try.

[[Je...]]

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Erik has hit the nail on the head. This falls on Can-May-Must rule. Since the primary datum controls all DOF that the secondary would (and then 1 additional), the secondary datums controls are ignored. Once the "check box" is ticked in order of priority, they are no longer relevant from datums further down the list.

In order to evaluate -M- to Datum -C- and the -A-B- line (3d line btw; 2d = measured, 3d = constructed) they would need to be separate characteristics. If a print shows this tolerance in a single perpendicularity requirement, I would send this back to the designer for review.