Scarfing photos by Ken Schott

A shop square was used to get all the panels staggered the exact same amount throughout the whole stack. The air brad gun was used to get the panels to all lay flat & tight. It is difficult to get the plywood to lay PERFECTLY flat. I used the brads and placed them barely hidden from the expected cut. The first panel was brad to the bench, then the next layer, next layer, and so on.

An aluminum angle was used to get a hard firm bench edge to work from. The stagger was a 10:1 ratio. Example: 3/8" (.375") ply @ 10:1 ratio=3.75" stagger. Notice the first panel must be staggered enough away from end of bench for the router bit to clear the bench.

I used a piece of 3/4" hardboard as the top fence to run the router on. You must have a firm straight edge here. Add up the total height from bench to upper fence; the stagger of upper fence is 10x height to get a 10:1 scarf. I got everything brad down so as not to move.
A little wax on the router bridge helps it glide easier over bench edge and top fence.