Datum not at origin

[[Am...]]

So im trying to figure out why my datum planes are not closer to 0 for the origin they are controlling. I have datum B as the Z origin but Datum B shows as .009" on the actual. Datum C is the X origin and it is .013" from 0. I can't see anything obvious happening that would cause this I know they are never at 0 but this just seems a bit too far off. If the part is just off from the model I would expect the other features to be not in the right place and not the location of the plane that is setting the origin.

[[To...]]

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When viewing the X, Y or Z values of the features, they are based on the origin of the feature, i.e. lower left corner of plane, which may or may not be where the datum is. For example, using 3 planes, top, front and right side. If we use the top plane as our spatial and Z origin, the feature will show this plane a Z 0 and have an A1 and A2 of 0.

If we use the front plane as our planar and Y origin, the actual Y value will probably not be 0. If you look at A1 X/Y, it will probably be zero as it is free to rotate about Z but the A2 Z/Y will probably have some tilt. Since the Y value is based at the lower left hand corner, it will likely not be 0 because of the tilt. However, where the 2 planes intersect, creates a line and that line is Y 0 and be the X axis.

When we look at the right side plane, you will likely see that X is not at 0 and the A1 and A2 will both have some tilt to them. Since all of the rotation controls are locked up by the top and front planes, no rotation is allowed. Again, if we look at the X and Y values of this plane, they will not be at 0 due to these tilts. However, where these 2 planes intersect, creates a line and where this line intersects the first line line is X0, Y0 and Z0. But it is not the Y axis. The Y axis is perpendicular to the first line, at X0/Y0.

To test this, create an intersection construction of the 3 planes and you will see the nominals and actuals are 0.

Another example. Let's say we're using a plane on top of a round part as our spatial and an OD cylinder as our X/Y origin. The plane will be at Z0 and the A1 and A2 will be zero. When you look at the cylinder, the A1 and A2 values will probably not be 0 because they will have some tilt to them. You will also see that the origin is not at 0 because the origin of the cylinder will be at the bottom, or most negative point of the cylinder and being affected by the tilt. However where the axis of the cylinder pierces the top plane will be at 0. Test using an intersection of the plane and cylinder.

If we reversed the roles of these 2 features and used the cylinder for our spatial and X/Y origin the top plane as our Z origin, you'd see the cylinder would be at X0/Y0 and the A1 and A2 would be 0. However, the plane would probably not be at Z0 and the A1 and A2 would not be at zero because the plane would not be perfectly perpendicular to the OD. Remember. the origin of the plane is at the lower left corner, not at the center. Again, this can be tested with an intersection construction, showing where the axis of the cylinder pierces the plane is X0/Y0/Z0.....

[[Ro...]]

Your A1 is over a half degree off, that would be the first place i'd start looking.
It is possible that your part is really that bad.
I'll bet your sigma & form are way out as well.