This invention relates to tools for use in stairway construction and is more particularly concerned with an improved tool for laying out stairway stringers and methods of using the same.
In one of the most commonly used procedures for constructing stairway stringers, the distance is measured between a preselected pair of points corresponding to the head and foot of a stairway, and then a stringer is laid out on a workpiece (usually a straight section of board) by successively positioning a carpenter's square along an edge of the board to mark off the individual steps of the stringer. Once a number of steps spanning the measured distance has been marked off, the board is cut along the marked steps to yield the stringer.
Because the carpenter's square must be consistently positioned with great precision to ensure that the individual steps are uniformly defined when a stringer is laid out, the construction of stringers in accordance with the foregoing procedure is tedious, time-consuming and expensive. This procedure also suffers a further disadvantage in that there is no simple way for the carpenter to determine from the measured distance whether a whole number of steps with given tread and rise dimensions will fit precisely between the preselected end points of the stairway. Consequently, in practice, many carpenters will actually fix the end points (such as by constructing landings or laying footings) without knowing whether the distance between them is suitable to accommodate a uniform stairway. It is only when they lay out a stringer that they discover the selected end points are unsuitable. In many such cases, because it would be unreasonably expensive to alter the fixed end points, the stringers are modified at one or both ends to fit between those points. Such modifications are highly undesirable, however, because the resulting non-uniformity among the individual steps can cause users of the finished stairway to stumble, thus presenting a risk of serious injury.