GB1080068A - Improvements in or relating to balance spring collets for watches - Google Patents

Abstract

1,080,068. Watches. VIROLA S. A. March 18, 1966 [March 19, 1965; April 23, 1965], No. 12100/66. Heading G3T. [Also in Division F2] A process for making a balance spring collet assembly comprises the steps of positioning the balance spring 1, filling the space defined by the first one and a half coils of the spring with a liquid, metal adhering, plastics material, allowing the plastics material to set to form the collet 3 having the shape of the coils, and securing the collet on a balance staff. Pins 4 locate the spring centrally on a work plate 2 and an opening is formed in the collet by moulding the collet around a pin 5, which is subsequently removed. The collet is made of Aralotite, (Registered Trade Mark) acetate resin or acrylic resin and may contain metallic powders or be surface metallized to render it electrically conductive. The collet is light in weight compared with the spring, but if necessary, a balancing hole may be formed in the collet. Instead of fixing the collet directly on the balance staff, a tightening canon (10), Fig. 4 (not shown), made of polyethylene or nylon may be inserted in the collet. When the balance staff is introduced into the central hole of the canon, the canon expands radially, thereby gripping the collet. A plastics washer (8), Fig. 5 (not shown), may be glued or force fitted to one end of the canon, or washers (7, 8) Fig. 8 (not shown) may be fitted at both ends of the canon, thereby enclosing the collet. Alternatively, a washer (11), Fig. 9 (not shown), may be formed integrally at one end of the canon and a further washer (7), Fig. 10 (not shown), may be attached to the other end of the canon. The purposes of the washers are firstly to stabilize the spring and secondly to adjust the position of the spring on the balance staff, however, the latter may be effected by forming a shoulder (9a), Fig. 7 (not shown), on the balance staff (9).