aerodark
Titanium
- Joined
- Feb 15, 2008
- Location
- Eugene OR USA
I think I have a fairly good handle on these three geometric tolerancing features. I often wonder why a true position tolerance is called out on a pair of round features on turned parts, where a runout or total runout callout would be better. Concentricity within one thou between the datum round feature and a second round feature would allow .002 indicator reading, yes? A true position of .001 between the same two surfaces would allow only .001? Is this the reason the true position callout is popular on round features, rather than a smaller concentricity callout. I think the total runout callout of .001 also limits the roundness of each feature, and their shared axis of rotation.