Reply by Lee Barker

Clamp a straight edge (3/4” board) on your plywood, enough south of the liner so the cutter lands right on your line. Register the base of the router to the straightedge and you should be fine.

Cole, the reason you have problems with alignment is the cutter is not exactly parallel with the fence of the machine. If it is .01 inches off, when you turn the machine around to cut the mating surface, the two slots will be .02 out of parallel.

My Lamello is dead on parallel and my DeWalt is darn close. I never have problems with alignment.

Kindly,

Lee

-- "...in his brain, which is as dry as the remainder biscuit after a voyage, he hath strange places cramm'd with observation, the which he vents in mangled forms." --Shakespeare, "As You Like It"