Hand-held builder's square and string line device incorporating a laser

Abstract

A compact, low-cost, hand-held builder's tool for use in defining reference lines perpendicular and parallel to a specified surface. The tool comprises a housing that is generally small enough to fit conveniently in the user's hand and that includes a battery-powered laser for projecting a visible laser beam through an exit window in the housing over an extended range. An on-board alignment mechanism is provided within the housing for adjusting and setting the alignment of the laser beam in fixed disposition for establishing an accurate reference line. The housing has two generally parallel broad faces joined by a plurality of connecting faces extending substantially perpendicular to the broad faces. One of the broad faces and two of the perpendicular connecting faces taken together define three reference planes that are mutually perpendicular to one another within a margin sufficiently small that the tool has an accuracy suitable for use over an extended range of at least about 20 ft (about 6.1 m). A practical tool may even be made with an accuracy suitable for use over a range of about 60 ft (18.29 m) or more. The on-board alignment mechanism enables the laser beam to be aligned in accurate perpendicularity to one of the mutually perpendicular reference planes and in accurate parallelism to the other two reference planes. In this way the builder's tool may project a line of laser light that is perpendicular to or parallel to a working surface in contact with one of the three faces defining the reference planes to within at least about .+-.1/8 inch (.+-.3.175 mm) at 20 ft (i.e., at 6.10 m), and may be set to a further accuracy of at least .+-.1/8 inch (.+-.3.175 mm) at 60 ft (18.29 m). Particular examples of on-board screw-thread alignment mechanisms and cam-operated alignment mechanisms are disclosed.