Flatten kerfs for fine-fitting splines

If you cut kerfs using an alternating top bevel (ATB) blade, V-shaped notches will show at the bottom of the kerfs. To fix this problem, cut a piece of scrap slightly thinner than the kerf. Place its edge down on adhesive-backed sandpaper and cut a strip the same width as the scrap. Use this sanding block to flatten the kerf bottoms.