Compasses for drawing concentric circles


  • Inventors: FENG ZHENG
  • Assignees: 冯正
  • Publication Date: December 10, 2014
  • Publication Number: CN-203995321-U


The utility model relates to a pair of compasses for drawing concentric circles. The pair of the compasses comprises a first support plate, a second support plate hinged to the top of the first support plate, an adjusting fixing plate arranged in the middle of the first support plate and the middle of the second support plate, and a circle drawing device arranged at the bottom of the second support plate. The first support plate is a telescopic rod, a first locking device is disposed on the hinge portion of the first support plate and the second support plate, the circle drawing device comprises a transverse plate, a sliding groove, a first drawing arm and a second drawing arm, the sliding groove is formed in the transverse plate in the length direction of the transverse plate, the first drawing arm and the second drawing arm are installed in the sliding groove through a second locking device, and the transverse plate is fixed to the bottom end of the second support plate. When the compasses are used, the distance between the two drawing arms is adjusted according to requirements, one drawing arm serves as a reference object, the radius of a circle is adjusted, a suction cup is attracted to a blackboard after adjustment, the other drawing arm moves around the first support plate for one turn to finish drawing of the concentric circles, time and labor are saved in the drawing process, and meanwhile deviations are reduced.




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