Unilateral Profile Calculation

[[Da...]]

Could anyone help me with the actual calculation of a Unilateral Profile? I have a callout [0.1 U 0 - ABC] and the drawing authority wanted to change it to [0.2 U 0 - ABC], the change decreased the calculated actual by 0.1 and I need some help understanding how this is calculated since the deviations do not change.

[[Ma...]]

This can help

viewtopic.php?p=21541#p21541

But for ISO it is wrong for one sided

[[Da...]]

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Thanks for the reply. We understand what the callout means. We are looking for how the actual number reported is calculated. In this case we have a min deviation of -.075mm and a max deviation of -.175mm. The actual number reported when changing from [0.1 U 0 ABC] to [0.2 U 0 ABC] is .1 different. Why does the tolerance band play a role in the actual reported?

[[Ma...]]

Well, on drawings in this case you should have mention which side is used.
Then in profile callout you just write whole tolerance and select onesided. Or you can use bilaterall and to lower input you put ZERO or whole tolerance and pick from where it will count ( picture on button ).

Tolerance band play this role. When you have normal profile, then furthest point from middle of band is your profile number *2.
So when piece is same as model, then you get "0" profile.
On onesided you get "0" at middle of band - so piece same as model gets tolerance/2

[[Ja...]]

Like Martin said, the nominal is the center of the tolerance zone. If you increase the tolerance zone, the nominal, and deviation from that changes.

How Profile is calculated.pdf

[[Da...]]

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Thank you for the explanation. This PDF is perfect, much appreciated.