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Unilateral profile Geotol vs Legacy

I recently changed employers, and went from a 3rd party inspection company using PCDmis 2014 to a manufacturing company using the latest and greatest (2023.1 currently). At my previous employer we also only used legacy dimensions, unless datum shift was involved, and even then we only used it if the dimensions were out of spec without datum shift. I have a unilateral profile, and I'm trying to use the report to tell the machinists where they need to make their adjustments, but I'm getting some confusing max/min results when reporting using Geotol. See the photo below (I hope this is the best way to attach a photo here)

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With my deviation here only being allowed to be negative from the nominal, I'm a bit confused as to why Geotol lists a positive number for my max. Today this profile is good, but yesterday it was bad, and I was struggling with my explanation as where they needed to move. I finally just got the t values of the points that were out and used that deviation to tell them what to adjust. Can someone help me understand this? 

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  • Thank you again for that link Neil. When I got some time to dig into the document a little bit further, it all finally started to come together. For that U0 profile, it shifted the nominal line to be the center of my minus tolerance, instead of reporting the deviation from the CAD model. So in this case (For U0 only), the deviation from the CAD model is actually the max value PLUS the abs(min value) in the minus direction. This definitely makes it a bit more difficult to use those numbers to communicate deviation from the model nominal to the shop floor when the tolerance is uneven, although U0 is still not bad now that I understand it a bit more. Sometimes I guess my brain just needs some time to chew on things. Anyway, thanks again, I think I finally get it.

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