Non-diametric location of slot

[[Ca...]]

Hey all,

I'm struggling to make Calypso measure something that SHOULD be really easy....

One of the dimensions on my part is a non-diametric location of a slot, back to only two datums. The slot is offset from its second datum, the origin. My issue is my result aren't corresponding with a simple height gage check. I think it's due to there being no rotational control of the slot, which is only about .010 inches in length. The "slot" really just looks like a hole with severe roundness issues. I'm probing the slot with a Symmetry Point Feature, it's just too small for anything else. I've adjusted the location Characteristic so that it's "Shape of Zone" displays deviation in "Z" only. I can't post a drawing, but I've attached an image of something similar. Any suggestions on how to constrain this ONLY using the Datums is great appreciated.

Thanks!!!

Slot FCF.png

[[Je...]]

You can't use just -AB- to constrain this to a single point location as the feature itself creates a portion of the alignment. The feature being controlled will need to have a length due to the nature of this requirement so you must use a Symmetry Plane with as much of the geometry measured as possible. The plane then sets the "orientation" to -B-. Otherwise the alignment is free to rotate until the reported value is optimal. "It can't be wrong" as the coordinate system is free to rotate until the symmetry point is at the optimal location.

[[Ca...]]

Thanks Jeff,

I'll give this another go Monday. Again, the flats on the slot are about 10 thou, so I'm not sure how stable that'll be for rotation control.

[[Ca...]]

Jeffrey, (Or anyone...)

Would you encourage constraining this symmetry plane to it's nominal vector for stability?

Also,

Could anyone suggest a secondary method to verify this?

[[Cl...]]

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You could go old school and use a surface plate, height master, a test indicator, and a little math.

[[Ri...]]

I would create an alignment to the center of the slot location per the B/P.
Then use three symmetry points, one at the left, middle and right.
You can control the location of the symmetry points based on the length of the slot (measure the length first).
If either location is OOT, then the slot is OOT.

[[Ni...]]

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Wouldn't this need a third datum to constrain it properly?
The whole part could be diagonal and it will still be constrained to A and B.
Since there is no third datum, calypso should be taking the skew off your base alignment(Planar rotation) and that could explain why its not matching up with your height gage.

You could be using the top plane for Planar Rotation to skew the alignment in calypso but you sit the part on the bottom plane to measure in the height gage. If both planes are not parallel to each other, then that could explain why your results don't match up.

This part should be simple to check on a vision system.

But try using the same plane for planar rotation that you use to sit the part when using it on the height gage. That way you should be getting similar results on both methods.

Also, if you're saying the slot is too small for anything else except symmetry points, then you might be using two different styluses. Make sure both have been qualified recently. If one is qualified recently and the other was qualified 3 weeks ago, that could also affect the results.