Formula for spring rates (part II)

[Smokerbros@aol.com]

I wrote:

> I can't seem to find anyone local with a spring rate tester that I can use, 
>  and neither of my Carroll Smith books seems to have the formula for spring 
>  rate.  Anyone have it handy?

And I forgot a couple of things...  Is a spring with a pigtail (coil diameter 
gets smaller at one end) figured any differently?

What do you do with the portion that's ground flat on one end?  Start 
counting coils where it ends?

CHD