4 Datum Pads different heights

[[Ro...]]

Part I am working on has 4 datum pads, for Datum A, at two different heights. A1 and A2 are at one height, A3 and A4 at the other. What would be the best way to construct this?

I thought maybe a symmetry would work, making a plane using A1 and A2, with another using A3 and A4.

I also had the idea of using an offset plane. Using the same plane of A1 and A2, as I did for the symmetry, then used that along with A3 and A4 to make the offset plane.

Both seem to work, in simulation, when choosing datums for the position of a hole. I just was curious as to which one would be the best method. 

[[Ma...]]

Would be better to use RPS, but you can use one symmetry point from A1-A2 or A3-A4 and use stepped plane.

New GD&T available?

[[DW...]]

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 Are you sure these are not datum targets for a fixture?

[[Ro...]]

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This is for a vehicle, and the 4 pads are where this part gets mated to another part on the vehicle. This is why, in my brain, I was thinking symmetry, from a functional standpoint, made sense. 

Edited April 30

[[Ke...]]

I *believe* what I did last time I encountered this situation was to:

• Scan each pad, and create a Geometry Best Fit Alignment from them
• Create Maximum Coordinates for each Datum Pad (relative to the Geometry Best Fit Alignment)
• Offset two of those Maximum Coordinates by the nominal distance to the other two 
• Create a Plane, using the two Maximum Coordinates & two Offset Points

 

[[Cr...]]

I've had a few parts with this scenario. I used an RPS alignment. I measured the two pads at the same height as planes/recalled them into one plane/recalled the one plane as a point. Next, I measured the other two pads as planes and recalled them into points.  I then plugged them into the RPS alignment along with my datum B and C features.

[[Al...]]

If you would like to use a singular point, you could use a an "offset point". The offset would be the distance between the elements. Once you have all of the elements on the same plane, then you can select all four points and use a fitting plane.