I may be ignorant or just palin stupid, but I have a drawing that shows  unless stated a tolerance of +/- 0.05mm. I understand this to be if a size is 100.00 nominal the top size is 100.05, bottom size 99.95. I am having a bit of an argument with a contractor on this. It is one of his drawings. He claims the top size should be 100.025 bottom size 99.975.

Who is right? Thanks.

I may be ignorant or just palin stupid, but I have a drawing that shows  unless stated a tolerance of +/- 0.05mm. I understand this to be if a size is 100.00 nominal the top size is 100.05, bottom size 99.95. I am having a bit of an argument with a contractor on this. It is one of his drawings. He claims the top size should be 100.025 bottom size 99.975.

Who is right? Thanks.

You are correct. See page 15 of "An Introduction to Error Analysis", John R. Taylor. Rule for stating Uncertainties.

ISBN available from here...

http://www.chapters.indigo.ca/books/An-Introduction-To-Error-Analysis-John-R-Taylor/9780935702750-item.html?ref=Search+Books%3a+%2527error+analysis+taylor%2527

Thanks Will. I also found this, attached.

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