Cylinder callout question

[[Th...]]

When I'm working with cylinders callout, there are two options: tol the feature with ref lengths or tol the feature as recorded center line. When do I pick one over the other?

Why does picking Base alignment (A,B,C) and picking individual datum resulted in different result on position callout?

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[[SH...]]

Answer to first question: P button is for projected tolerance zone it is also used for ASME evaluation ,. Outer tangential evaluation.the other button is used for ISO evaluation in other words LSQ evaluation. If you are working with ASME you have to use P button but you have to down the axis inside the feature or you can directly change the evaluation by clicking the feature.

In calypso as a default use LSQ evaluation for BA, you might activated ISO 5459 settings in CMM settings.so it is all about evaluation, you can verify it by clicking the feature.