Thanks Helter, Spec The part I am being asked to inspect is not actually flat, but a 2" section of 16.00" radius on a smaller part. I do not get the greatest results checking such a short chord length of a large radius, especially when their finish is not that great. I think I will ask them to find someone with an optical system or a scanning CMM.
Leigh, I understand flatness, thank you. I agree with you completely, simply playing devils advocate here. The question was regarding your "visibly deviant" statement. If a part had a warp on one corner and an inspector simply did not see it, the part would be inspected incorrectly. Another inspector may see it, resulting in differing results. Is this just a matter of separating the men from the boys or is there something in the spec that specifies how much of the surface needs to be inspected? It seems like the spec should try to limit judgement in as many cases as possible, limiting the head butting we have all over the industry. Perhaps even specifying that profile tolerances need to be checked by scanning or optics.