Device for circumscribing circles and ellipses

摘要

A device for circumscribing selectively both circles and also ellipses of variable proportions includes a housing in which is rotatably mounted an armature. The armature is constrained to move on two axes disposed at right angles to one another, so as to enable elliptical shapes to be generated. One such axis is provided by a rectilinear channel in the base of the device, in which is engaged a follower operatively attached to the armature; the other axis is provided by a rectilinear slot formed through the cover of the device. A hub is engaged in the cover slot and is assembled with the armature; it can be moved to any selected position along a rectilinear axis of the armature without disassembly, and can be secured in position by tightening of a clamping mechanism. In one position the axes of rotation of the hub and the armature are aligned, to thereby cause the device to circumscribe a circle; in other positions the axes are offset, thereby conditioning the device for circumscribing ellipses.