slot/width/symmetry Position

[[Jo...]]

I have a part with The Datum being centerline of part width. It then has various smaller widths(outside) and slots(inside) with position using modifier. All features are open ended with no length. I've searched the forum and still need help walking thru this.:
1. How do I establish the Datum feature, use symmetry plane, or symmetry ?
2. Same method on feature for position ?

I really don't understand the symmetry plane logic with 4 points. I feel like symmetry would give a better midplane position, but it doesn't account for functional width.

[[Ri...]]

If the slot is deep enough go with the Symmetry Plane, if it isn't then Symmetry Point will work just fine.

[[Jo...]]

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ok, I need grade school explanation. Symmetry plane would be the median(avg) of two plane features. If they were tapered, top to bottom, the median plane would still be near perfect vector. If you use the special geometry symmetry plane, it only uses 4 points. My concern is the median plane does not indicate if either plane used for construction violates the position independently, and functional width modifier is not accounted for.(think profile tolerance zone). Can I use slot feature ? I think I could use a formula for tolerance based on dimensioned width for the modifier, but still not satisfied with method of position. Position to me means worst case along that plane, being position, form, or vector.

[[Ri...]]

The Special Geometry Symmetry Plane can be scanned or single-point probed. It creates a feature of size that is one Plane - all of the points measured on the two opposing surfaces form an axis, and you can get the true mating envelope use the OTE if needed.

The Construction - Symmetry creates a symmetrical bisection between the two features. On two 2d features it's pretty straight forward. On two 3d features you are constructing two feature axis independently, and creating the symmetry between those two axis.

[[Ri...]]

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As for your question regarding the slot feature, I do this a lot for some measurements, but you cannot measure a slot that is open-ended.