I see that it is very difficult for the touched points hits the highest peaks that define the functional diameter. I think the measurement of a hole diameter with few points and maximum inscribed cylinder is ok for not precise measurements or parts with low form deviations. But, in these cases...
Underspec,
Do you use some data filtering or outlier elimination resource in the CMM software to avoid the influence of bad points? I ask that, because the minimum circunscribed and the maximum inscribed features are very sensitive to individual points - the diameter is directlly affected...
I found some information about it! There will be a new revision of ASME Y14.5M in 200X. Changes include Assembly and new tolerance representation (harmonization with ISO standards)
http://www.mel.nist.gov/msid/pe.htm (see objective 6)
Ademir
Hello dingy2
Thanks for the discussion! Yes, this is a very good way to control a hole diameter. But with this procedure it is not possible to calculate a Cpk index. An alternative is measure the hole in a CMM, but I see several problems in these traditional measurement procedures...
Due to rule #1 a size tolerance controls also the cylindricity. But a cylindricity tolerance alone does not control the size. A hole could have a very low cylindricity error and a very big diameter error (imagine a perfect cylinder with another diameter). The tolerance zone for the cylindricity...
Thanks your reply dingy2! I agree with you that the cylindricity must be inside the diameter tolerance (if the Rule 1 is specified), but the cylindricity alone controls only the form deviation, not the diameter. Do you mean a cylindricity control plus an average diameter control?
I see that...
I know that due to Rule #1 the maximum inscribed cylinder measured in a hole must be bigger (at least equal) than the MMC diameter. I know also that each measured distance between two opposite points must be smaller (at the most equal) than the LMC diameter.
The question is: has anyone...
Further to Drawoh's reply, the circularity error is the radial distance between two concentric circles. That takes to a interesting fact: if your part was fabricated with an oval shape, then the maximum circularity error is half of the diameter tolerance !!!
For another shapes is possible a...
I think the best way to find the temperature stabilization time is certainly to do a little test, measuring the part several times until the measurement results are stable.
I recommend also to compare the measurement results of the last measurement with the first one, after correcting the...