[Ri...] Posted March 19, 2024 Share Posted March 19, 2024 All, Just wondering how everyone would treat a measurement of a diameter of an arc on a part (180° available). Keep in mind that this diameter is also a datum. Would you attempt to constrain it, or not? Link to comment https://qualityforum.zeiss.com/topic/6002-arc-diameter/ Share on other sites More sharing options...
[Ma...] Posted March 19, 2024 Share Posted March 19, 2024 It depends. I would take a few points to get stable results. If you know how it's machined and its flaws, then you can decide if it's plausible to constrain radius. Link to comment https://qualityforum.zeiss.com/topic/6002-arc-diameter/#findComment-22780 Share on other sites More sharing options...
[Ri...] Posted March 19, 2024 Author Share Posted March 19, 2024 Please sign in to view this quote. The problem lies in the fact that constraining is a huge "grey" area. It's a machined surface, and while the diameter fits closer to nominal with a constraint, the form error constrained is really bad which leads me to believe it's not a good constraint. I'm not a fan of the "make it good" philosophy. Link to comment https://qualityforum.zeiss.com/topic/6002-arc-diameter/#findComment-22782 Share on other sites More sharing options...
[Er...] Posted March 19, 2024 Share Posted March 19, 2024 When dealing with form error on a radius like this, I would start with a diameter using a few points. Then create a curve and scan it and evaluate it back to itself. If you don't have Curve, I would use profile points and see how much it deviates and where. This would give you an idea of how true the radius was machined and where the flaws are. This exercise helps me determine if the part is relieving from being machine versus machined with flaws. Link to comment https://qualityforum.zeiss.com/topic/6002-arc-diameter/#findComment-22784 Share on other sites More sharing options...
[Ri...] Posted March 19, 2024 Author Share Posted March 19, 2024 Please sign in to view this quote. Has to be a Cylinder. It's a Datum, and I'm trying my best to follow y14.5 - lol. I've done some crazy stuff before in the past with Free-Form, and Circles to create an axis line, but those were extreme cases where the diameter was huge, and there wasn't much surface left. Not feeling good about a constraint on this one. Link to comment https://qualityforum.zeiss.com/topic/6002-arc-diameter/#findComment-22786 Share on other sites More sharing options...
[Da...] Posted March 19, 2024 Share Posted March 19, 2024 I really don't like constraining radii in general. We have some crazy circle sections and partial spheres that we run and I've never felt comfortable using constraints. Pump it full of points, throw in some single points to cover the start and stop gaps. Link to comment https://qualityforum.zeiss.com/topic/6002-arc-diameter/#findComment-22788 Share on other sites More sharing options...
[Ri...] Posted March 19, 2024 Author Share Posted March 19, 2024 Please sign in to view this quote. Yeah. I'm with you. Constraints are a huge grey area. I feel good about the data, but I always like to ask others and get their input. You guys/gals are all great, and I value any and all input. Thank you. Link to comment https://qualityforum.zeiss.com/topic/6002-arc-diameter/#findComment-22790 Share on other sites More sharing options...
[Cl...] Posted March 19, 2024 Share Posted March 19, 2024 Years ago, we had Zeiss write us a program. It was an ID sphere. It was probably a .125" Ø <180° and a datum. They ended up probing single points on the sphere, recalling that partial sphere into a full sphere and constraining XY&Z. Seemed to work well enough. Link to comment https://qualityforum.zeiss.com/topic/6002-arc-diameter/#findComment-22792 Share on other sites More sharing options...
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