Bilateral even and uneven distribution

[[Ni...]]

We are discussing a potential print change for a part to change from a .006 profile with even distribution to a .008 uneven with .005.

So with that, why would doing this change the result? shouldn't the result stay the same since the deviation from 0 stayed the same? Is calypso moving the "Zero" to account for the shift? I am trying to explain why this would be the case to the MFG Engineers before the change is pushed through and I would like to give the best answer


thanks nick

[[Th...]]

You could think of it like that. ASME calculates profile with the formula T+2g, where T is the total tolerance width and g is the shortest distance between your measured points and a tolerance boundary (if your surface is conforming) or the point furthest out of tolerance. You have a tolerance of .008, and with the unequal disposition of the profile tolerance allowing .003 minus material, the .0001 measured point is closest to a boundary. The value of g is negative for conforming points and positive for nonconforming points. Your surface is conforming, so g is -.0031.

Filling out the variables, you have an equation of .008+2(-.0031). This becomes .008-.0062, for a final value of .0018. I'm guessing there's some rounding on the displayed values, which accounts for the difference between Calypso and my result.