Abstract: A drawing compass has mounted on a projecting stub an internally screw-threaded clamping nut which is for clamping a pencil, ball-point pen, or the like in place in the stub. The nut is held captive on an external screw thread on the stub by stop means at the inner and outer ends of the external screw thread. The clamping nut is composed of plastics material sufficiently resilient to permit the nut, during assembly of the compass, to be moved past one of the stop means at an end of the external screw thread and sprung into operative engagement with the said thread. The stub may be die-cast and have an unthreaded outer portion having an inner end which is adjacent to the outer end of the external screw thread. The inner end constitutes the stop means for the clamping nut at outer end of said thread. The stub also has an unthreaded inner portion having an outer end which is adjacent to the inner end of the external screw thread.

Abstract: A drawing instrument comprises a pair of die-cast limbs pivotally connected together to form an assembly at the inner ends thereof. A bow top has an interior hole and fork limbs having inside faces embracing the assembly of the ends. A centralizing member is held between the inner ends of the pivoted die-cast limbs. The centralizing member includes an elongated pivot receiving hole and first and second keying poles. A first die-cast keying projection is integrally formed at the inner end of a first one of the pivoted die-cast limbs. A first arcuate slot is provided in the inner end of the first pivoted die-cast limb. A second die-cast keying projection is integrally formed at the inner end of the second one of the pivoted die-cast limbs. A second arcuate slot is disposed in the inner end of the second pivoted die-cast limb. The first and second die-cast keying projections engage the second and first arcuate slots, respectively.

Abstract: A drawing instrument comprises a pair of limbs pivoted together at their inner ends to form an assembly. A bow top has an interior hole and fork limbs embracing the assembly of the inner ends of the pivoted limbs. The fork limbs include pivot holes for receiving the pivot which connects the pivoted limbs to the bow top. A centralizing member is held between and is keyed to the inner ends of the pivoted limbs. A portion of the centralizing member projects upwardly into the interior hole of the bow top. The centralizing member includes an elongated pivot receiving hole. The centralizing member is effective to press against a side wall of the hole in the bow top to cause the bow top to turn and keep central upon any angular movement of one of the pivoted limbs with respect to the other pivoted limb.