tolerance and accuracy

Tolerance is the range within which a certain parameter must fall. For example, a hole must be drilled 35 mm in diameter, with a tolerance of +/- 1 mm. So the hole could be 34 mm to 36 mm and still be within specified tolerance.

Accuracy is usualy given in Per Cent. A hole of 35 mm with an accuracy of +/- 3% would mean that the hole could be 35 + (.03 x 35), or 35 - (.03 x 35), or 33.95 to 36.05 mm in diameter.
 
I agree on what Lancie says, but for me it would also mean:

I need a hole of 35 mm with a tolerance of 1 mm. So for any hole you make, it should be 34-36 mm

I have a drill, it is 35 mm and has an accuracy of +/- 3%, so a hole you make is expected to be within 33.95 - 36.05 mm (with a certain level of probability)
 
Pretty much the same as above but just another way to word it..

Tolerance is a given range of something that is exceptable...

Accuracy is a messurement of probable distribution of errors...

Well that what I was thought... o_O
 
Worth bearing in mind - Tolerance can also be stated as 35 mm +1, -0 .
This is useful for a hole in which a pivot pin is to be fiited . A 35mm pin with a tolerance of -1 , +0 will not be an interference fit. Using accuracy , 2 different sizes would be specifed to prevent seizing.
Paul
 

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