1. Clamp a guide to the square.

To make it easy to align the framing square on the stringer consistently, clamp a straight wood strip to the square. On the outer edges of the square, align the strip with the run dimension on one leg and the rise dimension on the other.

2. Find the crown.

Sight down the edge of the stringer stock to determine if it crowns. If it does, lay out the stringer so that the crown on the completed stair will face upward.

3. Lay out the first tread and the second riser.

Hold the square so that the leg with the tread dimension is closest to the end of the stringer stock but far enough from the end to allow for a riser below. Try to lay out the notches so that cutting them gets rid of knots and defects.

https://www.finehomebuilding.com/2013/10/15/lay-out-accurate-stair-stringers-with-this-custom-tool

By Andy Engel Issue 248 - Dec/Jan 2015