| 摘要 |
<p>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 and which 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, and which clamping nut is of plastics material sufficiently resilient to permit the nut, during assembly of the compass, to be moved past 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 the inner end of which is adjacent to the outer end of the external screw thread whereby to constitute the stop means at the outer end of said thread for the clamping nut, and have an unthreaded inner portion the outer end of which is adjacent to the inner end of the external screw thread whereby to constitute the stop means at the inner end of said thread for said nut. .</p> |
