Radius Not Enough % of a Circle

We used a couple Sciencope OVM systems. Sadly, looks like they no longer make them. Although maybe that's not too surprising, there are lots of optical systems out there.
And to be honest I wasn't as happy with their "newer" system we purchased, it was never as crisp as the old crusty one that we totally wore out. 

Wow, I think I found my solution! Thanks guys. My results are within a couple thousandths from nominal. I'll make sure I double check my results with a comparator.

Here's what I did: for the size of the radius, I measured a normal autocircle (LEAST_SQR) and included a report comment "IF OUT OF TOLERANCE, CHECK WITH OPTICAL COMPARATOR." For the location of the radius (dimension not shown in my example), I measured it again as a "FIXED_RAD" autocircle.

I am currently in a position to simply ask the customer if reporting as a profile is acceptable.  That's usually what's functional.

I was taught something called the T-value method, and I'm curious to see what others think. If you have the model (or can correctly program the points using calculations) you take individual points on the radius instead of a circle. You then report the T-value for each point and use a variable to calculate the average. You then take the nominal radius size and add or subtract the average T-value deviation depending on whether your value is positive or negative and if your radius is an inside radius or outside. Of course if you have both positive AND negative deviation this doesn't work, but I generally don't run into that. Thoughts?

One of the things that I am thankful for is I am part of our DFM team. Short arc length radii are known issues with our team and we often will bounce this back to the customer and ask for profile of that surface or ask them to double whatever tolerance they have given on the print and tell them the issues of CMM measurement of a short arc length radius. Form, fit and function are easily explained to our customers in this manner.

What is T value anyway? Isn't it essentially the same as a polar radius? My interpretation if the help file is that T value is polar radius except it's reporting deviation from nominal instead of a radius value.

Deviation from nominal. 

Right. Relative to a coordinate system (datum system locking 6DOF) right? Cookea, I believe you're doing it the hard way. Look into PRAD (Polar Radius option)

T-Value is the amount of deviation from nominal along the vector of the feature I believe. I saw a post from Neil about it.

Quick Edit: Found post here at the bottom

https://nexus.hexagon.com/community/public/pc-dmis/f/pc-dmis-for-cmms/138169/convert-tp-to-profile

With a vector point, it's deviation along nominal vector (machine can't do anything else).  Not sure if it's nominal or actual vector with surface points, if I ever need to use T-value, I'll test first.