Newbie- Inspection question

[LeeinFl]

Hi, I'm new at this forum stuff but I thought I'd give it a try . I've always believed a round part could not be checked accurately for roundness solely with a set of standard mikes. My question is, I have a steel ring 26" in diameter. Can I check it's roundness just using a standard set of mikes? I thank you in advance for any replies.

[easymike29]

The short answer is no.

Gene

[tyler774]

Hi Lee

I think the best you could do with a micrometer is get a rough guesstamate of the rings roundness, ( max. - min. dia. )/2. This sort of thing is what CMM's are great at by the way.

From an old out of date CSA GD&T standard, ( don't imagine this stuff changes too often ),: " The roundness tolerance refers to the width of an annular tolerance zone, bounded by two concentric circles in the same plane, within which the periphery of the feature in that plane shall lie. The roundness tolerance must be half the size tolerance except for parts subject to a "restrained specification". "

Hope this helps.

Tyler

[easymike29]

http://local.wasp.uwa.edu.au/~pbourk...etry/reuleaux/

Note the last sentence

Gene