AS shown in the attachment where would the X and Y origin be derived from along the cylinder
, at the middle (orange circle), where the cylinder starts at the face (blue circle) or at the projection/pierce point of [A] (red circle)?
If you project the cylinder to intersect with A, then the origin would be the red circle, otherwise the origin would be roughly the orange circle(center of feature) if you are just measuring/aligning.
Assuming datum B's axis is pointing along Z, then X and Y will be same at any point along that axis - so it doesn't matter. PC-DMIS will calculate the cylinder's axis direction from all of the hits and fit a cylinder to them. If you level ZPLUS to that cylinder and origin X & Y, any point along the axis will be X=0, Y=0. The THEO and ACTL co-ordinates displayed for the cylinder in PC-DMIS will vary depending on how you've measured it.
Measured cylinders - X,Y,Z are an average of all the hits so it will be the centroid.
Auto-Features - X,Y,Z are at the start point of the cylinder, which is dependent on which end of the cylinder you click when selecting from the CAD model.
The issue I am having is that I measure the
cylinder with sample hits on it's face so my X & Y origin comes from the intersection of the measured axis and the plane creates from the sample hits (blue circle). My supplier measures 2 circles on and creates a midpoint for his origin (orange circle) and in this case it makes the difference between OK and NOK on a True Position to [A|B|C] to other features. So after all that my question is.....from what point along the axis of cylinder would my origin be placed, orange, blue or red circle?
It's not the origin point that's the problem, it's using sample hits. If you use 3 sample points (or a sample feature), then that will over-ride the measured vector of the cylinder - it will take it's vector from the sample plane instead.
