Chip on the shoulder

[[SH...]]

I have a position for radius 16 it has MMC, for calculating the true position it calls for me a feature, I measure the diameter. What tolerance should I add for the diameter to calculate MMC, same as a radius position or its double??

is there is any option in calypso to measure the position of a radius without converting to diameter?
I have the curve but I don't have CAD model.

IMG20200616214824.jpg

[[Ro...]]

I posted the same question years ago on the old forum and was told by all the GD&T people that bonus for radii are to be doubled.
the 0.1tp won't change, but the bonus will.

[[SH...]]

This is what Iam expecting, now I can set my diameter tolerance -0.2 / +0.1.

[[Br...]]

The problem is that a radius tolerance is not what would be considered a size tolerance. Position can only be applied to features of size and the FCF for a position tolerance needs to be applied to a size tolerance. So where Y14.5 speaks of limits of size it refers to tolerances that control a feature of size. (e.g. Ø(diameter), or a width of two opposed planes.)

A radius tolerance controls the location of the surfaces within its own tolerance zone would have a crescent shape in cases like fillets.

The big problem is that a position tolerance requires an actual mating envelope to produce the axis or center plane of the feature. But on an open ended radius feature that doesn't have opposing point, it cannot contain the actual mating envelope. Even worse, at MMC you have a boundary at the virtual condition that the surfaces cannot violate, but a radius in some cases could move into infinity without ever violating the boundary.

You can double the radius tolerance and treat it like a size tolerance, but the drawing is wrong out the gate. CMMs tend to have a difficult time with small arcs depending on the form error. It is attempting to project some diameter off of a small portion of an arc and can output failures that do not actually reflect the design or function.