I need to route a square approx. 1 inch by 5 inches by 1/8 inches deep in a
piece of 10 foot 1x8. I have never tried to do this before.

I have a porter cable 691 with a plunge base and I set the depth guage up
and tried to "free hand" it on a test piece of lumber. Well - let's just
say that free handing is out of the question.

How should I do this to get a "perfect" square? I kind of figure I need a
"4 sided edge guide". An edge guide won't work on all sides as it won't
extend long enough into the board for two of the sides.

I'm at a loss.

TIA
Eric