Universal triangle

A universal triangle implement comprising in combination, a right triangle and a circular disk rotatably supported on said triangle, said triangle and said circular disk each including various measurement and drafting aid means, said triangle comprising a semi-circular notch forming a seat to rotatbly receive said disk, a groove formed in the periphery of said disk, a tongue projecting from the periphery of the notch and sidably engaging said groove, a removable wire extending around said groove whereby said disk is retained in said notch and can freely rotate with respect to the triangle, lock means extending from the triangle into the groove for locking the disk in a desired place with respect to the triangle, and means for adjusting the tension in said wire to control the ease of rotation of the disk with respect to the triangle.