GB728974A - Improvements in drawing compasses - Google Patents

Abstract

728,974. Drawing-compasses. AKTIEBOLAGET PIAB. Nov. 13, 1952, No. 28677/52. Class 97 (3). In a compass for describing circles which comprises a guide rod 1 on which a holder 15 for a centre point- 16 is slidable and within which a slide beam 2 carrying the holder 23 for the pencil point 24 is displaceable, the centre point holder 15 being pivoted to a compass by 14 which is also pivoted to a handle 13 pivotally carrying a second compass leg 11 that is pivoted to an attachment 3 on the guide rod, the centre point 16 is displaceable in its holder 15 by a depressing member, guided in the handle 13, through the intermediary of a pressure transferring member arranged in the compass leg 14. As shown, the depressing member comprises a rod 34 movable in the handle 13 by a knob 33 and abutting the pressure transferring member which is a rod 36 accommodated in the compass leg 14 and abutting the centre point 15. This latter has shoulders 28, 29 in the path of a stop pin 19 on which is threaded a nut 21 to hold the holder 15 in adjusted position on rod 1, and a shoulder 27 which abuts the periphery of rod 1, Fig. 5. When the ports have been adjusted from the position of Fig. 4 for drawing larger circles to the position of Fig. 1 for drawing small circles, the centre point comes adjacent a squared face of rod 1 and is free to move in its holder by depressing knob 33. Balls or springs may be interposed between the rods 34 and 36 and between the latter and the centre point 15. The pencil holder 23 is held on the slide beam by a screw and nut arrangement, the holder and the beam having interengaging teeth whereby the holder may be disposed at any angle to the beam. The pencil 24 is held in the holder by jaws 40 on an adjustable sleeve.