Using the 85/15% math I came up with the following dimensions for a 3" start cube.
Dia. #1=2.55, Depth=.45
Dia. #2=1.785, depth=.315 more than the 1st step. .765" total from the face
Dia. #3=1.2495, depth=.220 more than 2nd step. .985" from the face
Dia #4=.8755, depth=.1545 more than 3rd step. 1.1395" from face
you can go on and on, till there is no meat left. just gets soo tiny, its hard to machine that small. Does this sound right?
The 1st square is 3"
2nd square is 2.1"
3rd is 1.47"
4th is 1.03"
Somebody double check my math please.