notches are cut into the stringers using router
treads are individually positioned in stringers
Cut and Place the Stair Treads
Once the stair stringers have been created, cut the notches for the stair treads into the stringers with a hand-held router (Image 1). Each notch has to be cut to a precise size, angle and distance apart so that each stair is spaced properly and level. Cut the individual stair treads to precise dimensions with a mortise-and-tenon design. Once the treads and notches are all cut, individually position the treads in the stringer and tap into place (Image 2).