Timepiece sub-assembly including a component made of micromachinable material including an attachment area with a peripheral contact surface, and a shell element deformable between two shapes, one contracted and one expanded, arranged to hold the attachment area inside a housing with at least one degree of freedom, and which includes a complementary contact surface arranged, in its contracted shape, to exert a clamping force on the contact surface and to securely immobilise the attachment area in all directions, the shell element including a first element and a second element that are movable with respect to each other in its expanded shape, each including a complementary contact surface, and including clamping means for holding the first and second elements clamped together in its contracted shape.

A magnetic device for centring a shaft on a predetermined axis in a clockwork movement includes at least one first magnetic bearing provided with a magnet to exert an attractive force on a first ferromagnetic end pivot of the shaft. The first magnetic bearing includes a central part made of soft ferromagnetic material mounted between the magnet and the first end pivot of the shaft. The central part is positioned centrally in a washer made of non-magnetic material so as to centre the magnetic field flux generated by the permanent magnet through the central part in order to magnetically attract the first end pivot of the shaft on the predetermined axis. The diameter of the central part can be identical to, or 0 to 20% less than, or 0 to 20% greater than, the diameter of the first end pivot.

A magnetic device for centring a shaft on a predetermined axis in a clockwork movement includes at least one first magnetic bearing provided with a magnet to exert an attractive force on a first ferromagnetic end pivot of the shaft. The first magnetic bearing includes a central part made of soft ferromagnetic material mounted between the magnet and the first end pivot of the shaft. The central part is positioned centrally in a washer made of non-magnetic material so as to centre the magnetic field flux generated by the permanent magnet through the central part in order to magnetically attract the first end pivot of the shaft on the predetermined axis. The diameter of the central part can be identical to, or 0 to 20% less than, or 0 to 20% greater than, the diameter of the first end pivot.

A method for manufacturing a hole jewel, including forming a precursor from a mixture of at least one powder material with a binder; pressing the precursor, with upper lower dies, to form a green body of the future hole jewel including a blind cavity having a height between a height of the green body and a height of the future hole jewel, the cavity being provided with upper and lower portions respectively including blanks of a through hole and of a functional element of the future hole jewel; sintering the green body to form a body of the future hole jewel; machining the body, including a first sub-step of shaping a top of the body, during which a height of the upper portion is configured in readiness for an opening in the through hole blank for connecting the functional element to the upper surface, and a second sub-step of shaping a base of the body to form a lower surface of the hole jewel for connecting the functional element to to the lower surface.

A polycrystalline ceramic solely formed based on alumina, on chromium oxide and on magnesium oxide, where the polycrystalline ceramic contains between 0.8% and 1.2% of chromium oxide by total weight of the polycrystalline ceramic and between 0.03% and 0.09% of magnesium oxide by total weight of the polycrystalline ceramic, making it possible to obtain a red ceramic with a toughness (K.sub.c) at least equal to 2.8 MPa.Math.m.sup.1/2.

A timepiece oscillator includes a sprung balance assembly including a balance with a rim, which is returned by a balance spring and pivoted with respect to a structure, on a first side by a torsion wire, fixed by an anchoring element to the structure, and on a second side, opposite to the first side, by a contactless magnetic pivot. The balance includes a first pole embedded with the balance and the torsion wire, this first pole having a symmetry with respect to the axis of the sprung balance assembly, and cooperating with a second pole included in the structure, for the magnetic suspension of the first pole, and to exert on the distal end of the torsion wire, opposite to this anchoring element, a magnetic force for tensioning the torsion wire.

A timepiece oscillator includes a sprung balance assembly including a balance with a rim, which is returned by a balance spring and pivoted with respect to a structure, on a first side by a torsion wire, fixed by an anchoring element to the structure, and on a second side, opposite to the first side, by a contactless magnetic pivot. The balance includes a first pole embedded with the balance and the torsion wire, this first pole having a symmetry with respect to the axis of the sprung balance assembly, and cooperating with a second pole included in the structure, for the magnetic suspension of the first pole, and to exert on the distal end of the torsion wire, opposite to this anchoring element, a magnetic force for tensioning the torsion wire.

A method for orienting a timepiece component including ferromagnetic material, where, on both ends of this component, two magnetic fields each attract it onto a pole piece, with an unbalance in the intensity of these fields around this component, in order to create a differential in the forces thereon and to press one of these ends onto a contact surface of one of the pole pieces, and to hold the other end at a distance from the other pole piece. A magnetic pivot includes such a component with two ends. It includes a guide device with surfaces of two pole pieces each generating a magnetic field attracting one of these ends, the magnetic forces exerted on the two ends being of different intensity, in order to attract only one end into contact with only one of these pole piece surfaces.

A method for manufacturing a flexible strip, including forming a plate of the required thickness with one or more micromachinable substrate wafers; affixing, on either side of the plate, an upper mask with an upper window and a lower mask with a lower window, of identical geometry; etching the plate, at least to mid-thickness, from the upper side of each upper etching window, and from the side of each lower etching window; removing the upper mask and the lower mask, to delimit a flexible strip having a height equal to the thickness of the plate, and whose edges are as-etched. A flexible strip made of micromachinable material, including, between two parallel upper and lower surfaces, two peripheral, tapered and reverse-tapered edge surfaces, for a flexible pivot, a resonator, a movement or a watch.

A method for manufacturing a flexible strip, including forming a plate of the required thickness with one or more micromachinable substrate wafers; affixing, on either side of the plate, an upper mask with an upper window and a lower mask with a lower window, of identical geometry; etching the plate, at least to mid-thickness, from the upper side of each upper etching window, and from the side of each lower etching window; removing the upper mask and the lower mask, to delimit a flexible strip having a height equal to the thickness of the plate, and whose edges are as-etched. A flexible strip made of micromachinable material, including, between two parallel upper and lower surfaces, two peripheral, tapered and reverse-tapered edge surfaces, for a flexible pivot, a resonator, a movement or a watch.