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CMM or OGP -actual local size

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greenimi

Mechanical
Nov 30, 2011
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Easy question:

What is the CMM"s way to report the actual local size per ASME Y14.5, for a pin for example?
(.500±.010 pin measured on the CMM).

As far as I know, for a pin, the outer tangential and min circumscribed algorithms should be the same, but that is only taking care of the envelope requirement, MMC boundary, doesn't it?


(a minimum circumscribed cylinder would be an example of an outer tangential feature for a nominally cylindrical pin)

How the LMC boundary is verified/reported on the CMM? Otherwise stated there is such as "inner tangential" algorithm for a pin?

LSQ algorithm is not accurate either as cannot identify if the pin is bigger in EACH CROSS SECTION than the minimum size requirements.

How to know/ which algorithm if the pin is not smaller than .495 in some cross sections?

In my brain:

The theory is clear: "The actual local size of an individual feature at each cross section shall be within the specified tolerance of size."

The reality/ how to measure: not so much.....


 
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