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need information concerning metric drawing

thread174-288426

need information concerning metric drawing

need information concerning metric drawing

(OP)
My company is currently working on parts from German drawings. The following callout n25 H7 is used several times. I know the 25 is mm I know the H7 is class of fit. what I can't find out is what n means.
thanks

RE: need information concerning metric drawing

What feature is dimensioned that way? It could mean "Nabe" - like an diameter in an internal spline. (The H7 tells you that it is an internal feature, ISO fits use the capital letters for holes/internal features.)
 

RE: need information concerning metric drawing

Theonics- Your tolerance is a hole tolerance. Capital letters are for holes. H7 is position and quality.
In your case: 25H7 = 25mm -0, +21. Quality H7 can be achieved by reaming.That is -0.000mm, + 0.021mm.
My advise: If you are in the machining business - study DIN/ISO 286. Google it! You will need it.

Go here for more info: http://www.wisetool.com/fit.htm
Good luck.
 

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