This may have been asked but a search netted me nothing. Is there a check box or something that I can modify that will correctly calculate the Cp and Cpk on a true position call out or other one sided call out. I hate that a hole with 3.0mm true position tolerance and an average measured TP of .3 gives me a bad Cpk.
Yup, knew that. Customer requirement. Maybe I should talk them into taking the capability of the axis deviation instead. The last place I worked at stopped reporting TP and just applied the tolerance to the axis. Might be time to talk to the boss here.
Yup, My boss from 12 years ago taught me about the box in a circle thing. Although I always used (TP*.7071)/2. Your way is faster. Thanks for the help Matt.
While you point about directionality makes it moot in this case, any idea why there isn't a unilateral option in DataPage like there is in MiniTab? Not too many things I measure use a true Unilateral tolerance but I am just curious.
If so try changing the distribution to half-normal to get a slightly better Cpk.
I running version 3.24, go to VIEW menu, VARIABLES, I use the FORM EDITOR.
Select your part from the list, then open the VARIABLE pull down and scroll to the TP variable(s) you need to change.
In the DISTRIBUTION pull down choose HALF NORMAL.
Make sure to hit Save All before closing the dialog box.
If HALF NORMAL doesn't give you a satisfactory Cpk try some of the other DISTRIBUTION options.
