How do you set the stop when you know S.E.L?

OK guys what in tarnation is SEL?

 

For us newbies, SEL (segment edge length) is the measured length of the long edge of the trapezoid that makes up each segment you cut. For the purposes of simplicity, this edge determines the outside diameter of each ring. (Put away your slide rules boys, I have to keep it simple and limit the trigonometry or my brain gets all ‘splodey.)

 

Thanks Brett