Routing V-Grooves in Tongue-and-Groove
To produce identical chamfers on matching edges of tongue-and-groove stock, I use an extra piece of stock with a nailed-on router fence, as shown in the sketch. Both the tongued and the grooved edges can be pushed flush to the jig, ensuring a balanced V-groove in the finished work and eliminating the extra setup that would be required with a shaper or a tablesaw. You could adapt the idea to a router table just as easily.
W.A. Ward, Underhill, Vt.
Fine Woodworking Magazine, February 1984 No. 50