A combination square for usage with a grooved blade, comprising: a straight component having a first straight edge and a second straight edge perpendicular to the first straight edge; an angled component having a third straight edge and an angled edge; a marked scale comprising degrees; a marker, wherein the square is configured to allow indication by the marker of angles on the scale; a slot configured to allow accommodating the blade; and a locking screw configured to allow clamping the combination square onto the blade at a desired position along the blade; wherein the angled component is rotatably connected to the straight component; and the square is further configured to allow measuring a center of a circle coupled to the second straight edge and the angled edge at a second end of range of motion of the rotation by the straight component relative to the angled component.