help me measure it, how would u dimension it

hi all
i got a measuring/construction/engineer/noob problem.
i have this small 40 degree, 2 degree conical thing, that is supposed to have a diameter 6.86mm where it is as smallest, and its supposed to be centered in the casted hole(D), and perpendicular to the plane(A)
i dont know how to measure it, since its a very small surface, and its also not cylindrical, its conical with a 2degree angle.
so i have to measure it as a cone. and then construct a circle using cone feature, but the results are very unsure.

the matching part has the exact same feature, except its internal, and it should run free over the tap thingy.
how can i measure it
or how would u else dimension it, so that the matching part fits.
ty all, thanks for ur feedback

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Charles.Hilton over 2 years ago

The only realistic way to report our that radius is to report it out as a profile. I've seen some companies create specs that if a radius has less than 60, 45, 30 degrees of arc, you are allowed to report it out as linear/surface profile.

In your case, the perpendicularity is applied to the diameter, which means the axis of the feature had to be perpendicular to A, which is will be next to impossible to report out in a repeatable fashion. The position callout to D (assuming that is the larger diameter) will also fall victim to the same issue. So your best bet is to get approval to report it out as Surface Profile of 0.05 to Datum A to Datum D or perhaps just to Datum D, depending on what is more critical. My guess to Datum D only, if you are measuring D as a Cylinder getting as much coverage of it as possible.

This dimension is a classic example of design engineers not designing for quality.
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