【转帖】ir concentricity

yang686526

tir & concentricity
does anyone know how to measure tir and concentricity using a video cmm.  
i am working with a micro-vu.  i was told that to find concentricity i first find the od, the id, and the distance between the two.  the distance should then be multiplied by 2.  is this correct?  can this be used to find tir?  thanks in advance.
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what is the dimensioning standard for the drawing and what is the callout that you are concerned with?
yes, you could take the distance between average centers as the radial mis-concentricity, and multiplying by two would tell you the diametral.
to find tir you  would also add the ovality (or in more precise terms, the maximum deviation of form from circular) of the checked diameter to the distance between centers as a vector sum.  i.e. the clocking of the maximum mis-circularity relative to the clocking of the mis-concentricity must be considered.