Steel square

The Steel Square is a tool that carpenters and other tradesmen use. It consists of a large arm and a smaller one running off it at 90 Degrees. It can consist of other metals like aluminum which is lighter rust resistant. The arms have various names such as tongue and blade. One of the arms is 2 inches wide and the other is 1.5 inches wide. The Square has numerous uses such as laying out common rafters, HiP Rafters, Stairs, Diagonal Scale and a board feet Scale. On the face side of the Square there are 24 numbers in increments of one inch. Under the number there is first a number carried out to 2 decimal points. i.e. Under 6 Inches there is 13.42. This is the diagonal measurement of a rafter with a rise of 6 inches and a run of 12". The same is true of the hip Rafter except the Hip Rafter is running at a 45 Degree angle to the Roof. The Hip measurement is rounded off to 18.00 inches. When laying out the common rafter 12 Inches is lined up on the edge of the rafter and the selected rise is lined up on the other arm. When laying out a hip rafter 17inches rather than 12 inches is used. It is actually 16.97 inches but insignificant unless the rafter is excessively long. Basically the readings on the steel Square are footnotes to Pythagoras who discovered the Pythagorean Theorem. Each rafter has a plumb cut and a seat cut which is the horizontal cut or the complimentary angle of the plumb cut. There is usually another plumb cut that runs at 90 Degrees to the seat cut on the plate of the wall that the rafter is attached to.