I have a cylinder I'm measuring, (should be a profile in my opinion), that I'm measuring the beginning, middle and end of with 7 points each. This is only 100° of a cylinder. 0.5" long. It is parallel in Z to my a plane. Anyway, my concern is that when I report out each circle constructed least square from the cylinder hits, They are showing a z value of around 0.002" and some change. When I report the cylinder itself it is showing only 0.001" in Z. I report these out in legacy and get the same as well. Why am I 0.001" off. I'd think that the cylinder would be a centroid location which would be an average of the 3 circles used to make the cylinder. Am I missing something?
The nominal Z value for your cylinder is 0.0001 different than your circles (CYL1 = 0.3425, CIR25-1, CIR25-2 & CIR25-3 all = 0.03424). Taking that into account, you can see that the Geometric Tolerance command is reporting the worst end of the axis and correlates with CIR25-3.
I did see the difference in nominals after posting which I changed. But that didn't do anything. This still doesn't explain to me why the cylinder as a whole, with no projection, just measuring the whole cylinder (minus .002 from each end) has a true position by half of what each constructed circle is reading. It would make sense if my cylinder had a true postion of .004 (best case) or .0046 (worst case), or .0042 (average) or anywhere in between all of that. It doesn't make sense why it is 0.0021.
I did see the difference in nominals after posting which I changed. But that didn't do anything. This still doesn't explain to me why the cylinder as a whole, with no projection, just measuring the whole cylinder (minus .002 from each end) has a true position by half of what each constructed circle is reading. It would make sense if my cylinder had a true postion of .004 (best case) or .0046 (worst case), or .0042 (average) or anywhere in between all of that. It doesn't make sense why it is 0.0021.
