 thumb|steel square the steel square is a tool that carpenters use. they use many tools to lay out a "square" or right-angle, many of which are made of steel, but the title steel square refers to a specific long-armed square that has additional uses for measurement, especially of angles, as well as simple right-angles. today the steel square is more commonly referred to as the framing square. it consists of a long arm and a shorter one, which meet at an angle of 90 degrees (a right angle). it can also be made of metals like aluminum, which is light and resistant to rust. the wider arm, two inches wide, is called the blade; the narrower arm, one and a half inches wide, the tongue. the square has many uses, including laying out common rafters, hip rafters and stairs. it has a diagonal scale, board foot scale and an octagonal scale. on the newer framing squares there are degree conversions for different pitches and fractional equivalents. carpenter's squares are very much like steel squares. == blade and tongue == in traditional timber frame joinery, mortises and tenons were typically two inches wide and two inches from the edge of the timber when working with softwoods, giving rise to the width of the blade. likewise, mortises and tenons were traditionally one and a half inches wide when working in hardwoods, explaining the width of the tongue. this allowed for quick layouts of mortise and tenon joints when working both hard and softwoods. == use in stair framing == thumb|right|250px|theoretical rise and run of stringer, placement of square, marking of tread and rise, dropping the stringer, abc=90Â°, total rise of stringer = 2r-t, total run of stringer = 2ab. stairs usually consist of three components. they are the stringer, the tread and the riser. the stringer is the structural member that carries the load of the staircase, the tread is the horizontal part that is stepped on, and the riser board is the vertical part which runs the width of the structure. there are many types of stairs: open, closed, fully housed, winding, and so on, to mention a few of them. laying out a staircase requires rudimentary math. there are numerous building codes to which staircases must conform. in an open area the designer can incorporate a more desirable staircase. in a confined area this becomes more challenging. in most staircases there is one more rise than there are treads. # the rise (vertical measurement), and the run (horizontal measurement). note that the stringer will rest partially on the horizontal surface. # this is a two-by-twelve piece of lumber. a framing square is placed on the lumber so that the desired rise and tread marks meet the edge of the board. the outl
Dimensional_instruments Woodworking_hand_tools Woodworking_measuring_instruments