Surface Finishes 1

I have a drawing that specifies a surface finish of "12.5s". I have heard of Ra, Rms, etc. but I have not heard of the "s" designation. Can anyone tell me where I can learn more about this? I've looked all over and cannot find anything.

Thanks

 

[gdodd]

I suggest your S may be a Z ie Rz which is defined as the difference between the mean of the five highest peaks and the five lowest peaks taken in a vertical direction along a measured trace.

"S" is usually defineed as the length of measurement over which a roughness trace is taken.

Hope this helps