Sorry dpb, I wrote my description before going to lunch and was simply
fried. After re-reading it I think it's confusing too so I'll start
over.

Let's say I have a 2"x4"x4' board with sides A (top), B (right), C
(bottom), D (left), E (front), F (back). I want to get C and D at 90
deg, and they're close to start with. I know that I will have snipe
affecting E & F based upon where I place my weight as the board passes
over the knives. My concern isn't so much E&F as C&B. C&B start close
to 90deg then gets closer to 0deg with ever pass that C stays where it
is. C always remains flat but the angle of C in relation to B moves in
to 0Degrees.

So, I have this nice flat surface (C) even though it's less than 90deg
in relation to B. I should be able to run C against the vertical fence
and make B = 90. Nope. As I run it, C and B edge closer to 0 as the
board begins turning into a long board with wedged D side .