Another instance of my programmer and I butting heads. First off, I want to ask... Is an alignment needed to measure the concentricity of 2 circles? If so, can a proper alignment be made with paint on the plane that we are leveling the part to? He says that even with paint (very uneven paint) on the part, the concentricity will be accurate. Again, be gentle.
I suggest you run a test; measure with and without paint and with and without circles (cylinders). I suspect the difference you see is within the repeatability of the machine.
Really?
From the Wilcox Site - Mathematical Definitions of Dimensions
3.0 CONCENTRICITY The first feature must be a sphere (3d concentricity) or a slot, cylinder, cone, or circle (2d concentricity). The second feature is used as a datum feature and must be a cylinder, cone, line, or circle. If there is no datum, the origin and z vector of the current active alignment are used for the datum.
if the first feature is a slot, cylinder, cone, or circle, the perpendicular distance from the centroid of the feature to the datum feature's axis is calculated. The 2d concentricity is twice this value.
If the first feature is a sphere, the 3d concentricity is calculated as twice the 3d distance of the sphere's centroid from the datum centroid (or active alignment origin if there is no datum). End of Defintion.
So then PC-DMIS defines Concentricity not as opposing medians points. So if you need to report Concentricity per ASME Y14.5-1994, DO NOT use the canned dimensional icon. Figure another way to measure and report.
Twice times the 2d or 3d distance creates the feature zone. Sounds like POSITION.
That's why you can use features with an odd number of hits. NOT OPPOSING MEDIAN POINTS.
I suggest you run a test; measure with and without paint and with and without circles (cylinders). I suspect the difference you see is within the repeatability of the machine.
Really?
From the Wilcox Site - Mathematical Definitions of Dimensions
3.0 CONCENTRICITY The first feature must be a sphere (3d concentricity) or a slot, cylinder, cone, or circle (2d concentricity). The second feature is used as a datum feature and must be a cylinder, cone, line, or circle. If there is no datum, the origin and z vector of the current active alignment are used for the datum.
if the first feature is a slot, cylinder, cone, or circle, the perpendicular distance from the centroid of the feature to the datum feature's axis is calculated. The 2d concentricity is twice this value.
If the first feature is a sphere, the 3d concentricity is calculated as twice the 3d distance of the sphere's centroid from the datum centroid (or active alignment origin if there is no datum). End of Defintion.
So then PC-DMIS defines Concentricity not as opposing medians points. So if you need to report Concentricity per ASME Y14.5-1994, DO NOT use the canned dimensional icon. Figure another way to measure and report.
Twice times the 2d or 3d distance creates the feature zone. Sounds like POSITION.
That's why you can use features with an odd number of hits. NOT OPPOSING MEDIAN POINTS.
