Stair layout square with adjustable rake bar

DETAILED DESCRIPTION The present invention is directed to a stair layout square having two flat planar blades, one long and one short, disposed at right angles to one another and a rake bar movably connected to each of the blades for being positioned at a distal location on one blade corresponding to a predetermined rise distance and at a distal location on the other blade corresponding to a predetermined run distance.
The rake bar has a flat contacting surface perpendicular to the plane of the blades and facing toward the intersection of the blades.
Upon being secured in position on each blade, the rake bar contact surface is engageable with the side edge surface of a stringer to bring the outer edges of the blades in proper alignment for making rise and run lines on the stringer.
Markings may be made successively for each step without taking further readings or readjusting the settings.
This square provides for movement of the rake bar over a range of distance values corresponding to distances desired for staircases, typically a six- to eight-inch rise distance and a ten- to twelve-inch run distance.
Movement capability is provided by means of an elongated slot in each blade, parallel to the outer edge of the blade and extending over the selected distance range, with the bar being movably connected to the blade at the slot so as to be movable inward and outward with respect to the blade intersection.
The bar also has a slot near each end to enable connecting bolts which ride in slots in the blades to move together and apart upon moving toward and away from the blade intersection.
Scale markings along the outer edges of the blades indicate distance locations within the desired ranges.
It is therefore an object of this invention to provide a square for laying out step-supporting stringers wherein contact of a portion of the square engaging the stringer is obtained over a large area.
Another object is to provide a stair layout square that is simple to use and compact in size.
Still another object is to provide a layout square which, once adjusted to reflect predetermined rise and run distances, may then be used for the entire length of a stringer without further adjustments or readings being taken