Dual purpose transparent set square - has slot enabling forty five degree square to be used for thirty degree angles and vice=versa

摘要

A transparent set square for drawing office use etc. of the usual 30 [deg.] triangular shape, has a slot cut across it so that it can be used as the other type of set square. Thus a 30 [deg] set square has a slot made at an angle of 45 [deg] to one of the sides forming the right angle. Conversely, the 45 [deg] set square has a slot at an angle of 60 [deg] to one of the sides forming the right angle. All the edges are stepped so as to ensure a clean line as the drawing instrument is moved along it.