Adjustable compass device

Claim 1

An adjustable compass device for making circles and parts of circles of variable diameter, said adjustable compass comprising an annular slide member having an inner circular surface and an outer circular surface, said slide member having a circular slot formed in its inner surface; mounting means for rotatably mounting the slide member for free rotation about its axis; a guide rod having spaced opposite first and second ends, said guide rod having an axial bore formed in its first end and a projection extending from its second end into the slot of the slide member; a tube-like frame having spaced opposite first and second ends, said frame accommodating the first end of the guide rod in the area of the first end of said frame; a track guide having guide means for accommodating a marking device, said track guide being affixed to the second end of said tube-like frame and having an internally threaded bore; and a screw member having spaced opposite first and second ends, the first end being accommodated in the second end of the frame and threadedly coupled in said track guide and the second end being in the slot of the slide member whereby the guide rod, the frame, the track guide and the screw member function as a variable length diameter of the slide member freely rotatable about the axis of said slide member for marking a circle or part of a circle of any diameter smaller than that of said slide member.