I have a bore that is Datum B. It has a perpendicularity callout to Datum A, which is a flat surface. So, I have to measure it as a cylinder. I have another bore that has a circular runout callout to AB. So do I have to measure B again as a circle? Because I would have to assign that as another datum to build the feature control frame. But if I just use B as a cylinder, then wouldn't it be measuring total runout and give me a different result than circular runout?
Ok, here's my next question. I have a part that looks kinda like my drawing below. It has two cylinders, one Datum B and the other Datum C. It wants the circular runout of C to B. I get that I have to measure B as a cylinder, but how about C? Do I measure that as a circle, cylinder, or both, since I also need the perpendicularity of it? I measured C as 3 circles and constructed a cylinder out of them because I also wanted to see the diameter at multiple levels since it's so tall. I measured the circular runout of that constructed cylinder and it was at 0.118, which is out of tolerance. The total runout was exactly the same. I measured the circular runout of each of the 3 circles, and the worst one was 0.118, same as the circular and total runout of C as a cylinder. Was I wrong to measure C like that? Should I have just done a measured cylinder and not a constructed one? Sorry if that's a lot to ask, I'm just trying to figure out if this part is good or bad.
Edit: Yes, I know the tolerence for that total runout is wrong per my drawing, but it's the deviation that I'm looking at.
Ok, here's my next question. I have a part that looks kinda like my drawing below. It has two cylinders, one Datum B and the other Datum C. It wants the circular runout of C to B. I get that I have to measure B as a cylinder, but how about C? Do I measure that as a circle, cylinder, or both, since I also need the perpendicularity of it? I measured C as 3 circles and constructed a cylinder out of them because I also wanted to see the diameter at multiple levels since it's so tall. I measured the circular runout of that constructed cylinder and it was at 0.118, which is out of tolerance. The total runout was exactly the same. I measured the circular runout of each of the 3 circles, and the worst one was 0.118, same as the circular and total runout of C as a cylinder. Was I wrong to measure C like that? Should I have just done a measured cylinder and not a constructed one? Sorry if that's a lot to ask, I'm just trying to figure out if this part is good or bad.
Edit: Yes, I know the tolerence for that total runout is wrong per my drawing, but it's the deviation that I'm looking at.
Your user profile says that you are running 2017 so will have to measure it as several circles - enough to give a good representation of the full extent of the surface and with a high enough point density to capture the form error. Evaluate circular runout for each one and look for the worst value out of all of them to determine pass/fail. For the perpendicularity, construct a BFRE cylinder from the hits of all of your circles.
XactMeasure & Legacy Dimensioning are unable to extract circular cross sections from cylinders. That is why, when you dimension circular runout of the cylinder, it gives you the same number as total runout - it's looking at all of the hits combined rather than each cross-section independently.
