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Understanding Profile of A Line Report

Looking for clarification on how PC-DMIS reports the profile of a line values.

The part in question is a cylindrically symmetrical curve, with a cross section cutout listed as a profile of a line between point A<->point B. No datum structure on the control frame. Profile limit .060"

When getting a report trying to get a best-fit result, I usually expect the min and max values to be similar, and according to the online help https://docs.hexagonmi.com/pcdmis/2020.2/en/helpcenter/mergedProjects/core/geometric_tolerances/Profile_of_a_Line.htm
Setting min/max should find the smallest tolerance to fit all the points, but it shows -.016" to +.034" range.

The initial line of the report shows that it is only using .050" of the .060" tolerance but also is out of tolerance, not helping my confusion.

Taking the actual points reported and running them with the other softwares we have at our facility, I have more experience in and can get the even split of the deviations (-.023"<->+.019") or an overall lower profile (-.013"<->+.025") with another

So is there a simple answer to the following questions
1) is the profile good at the initial .050" reporting, even though it is listing it .004" over?
2) Is there a obvious reason that the min max in not having all the point inside the tolerance window.







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  • I think the term cylinder was misleading, the area that is called out for profile is just mirrored around the cylinder, the size of the cylinder is not tied to the profile control. Cereal bowl for a similar idea of the size of the bowl (while being tolerance'd else where) has no impact on the form of the profile callout, as long as the flow of "milk" from B<->A is the right slope.

    In the results being discussed, it says there is a lump outside that form, at pt5. however its should pt 1 (B) being at -.016 of its allowed -.030", if the tolerance zone was shifted (since there is no datum to control in nominal location) it should bring that max point ,.034" ,down at the cost of increasing the deviation on the min point. Other software's when I have used them would do that as part of the best fit option. The total spread might not decrease, depending on how that tolerance zone moves, but the part would be in tolerance.




  • Graphing your result may give you more insight.
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