The hairspring stud 6 has an annular groove 12 provided therearound. The side face 14 of the groove 12 is perpendicular to the stud axis and the side face 13 thereof is frusto-conical. Stud 6 is inserted in a guiding slot having side faces 8 lying on resilient arms 9 of a stud holder. The edges 10 and 11 of faces 8 are rectilinear and evenly beveled. Stud 6 urges arms 9 slightly away from one another in a direction perpendicular to the stud axis. Arms 9 are consequently bent so that they exert a clamping action on stud 6 through edge 11 engaging the frusto-conical stud face 13, thereby exerting forces on stud 6 having components along the stud axis, which cause the stud plane face 14 to be pressed on the coplanar side faces 20 of arms 9 while simultaneously ensuring stud 6 to be perpendicular to the stud holder.
A balance spring support which is blanked out or stamped to a shape such as to embrace at least two faces of the outer end of the balance spring. A bond is used for securing said outer end of the balance spring to at least one of said faces. The support is detachable from the rest of the movement.
A hairspring and collet assembly for timepieces in which the collet has a base having an opening and a stud integral from the base in a direction parallel to the axis of the opening. The hairspring comprises an inner turn ending in a bend. The stud occupies a portion of the base extending between the opening and the periphery of the base. The non-deformed portion of the inner turn of the hairspring is secured to the stud and the bend extends freely away from the stud about the opening.
A mechanical timepiece movement has a mainspring serving as a power source, a wheel train rotated by a rotational force produced by the mainspring for driving a display, and an escapement and speed control apparatus for controlling rotation of the wheel train and having a balance with hairspring, an escape wheel and pinion and a pallet fork. A stud holder is rotatably mounted with respect to a central axis of the balance with hairspring and a hairspring holder is attached to the stud holder to undergo movement in a direction orthogonal to the central axis of the balance with hairspring. A hairspring has a central portion fixed to the balance with hairspring and an outer portion fixed to the hairspring holder. The hairspring is adjustable by pivoting the hairspring holder.
