Abstract: A flexible coupling for torque transmission having a plurality of helical beams extending between the coupling ends, the helical beams having beam cross-sectional dimensions selected to provide equal stresses in operation at the inner and outer diameters of the beams, irrespective of direction of rotation and being of a ratio of depth to thickness to provide for substantially simultaneous failure in the buckling and elastic modes when rotated in a direction opposite the direction of beam spiral, whereby the load capacity of the coupling is independent of the direction of coupling rotation.

Abstract: Attachment of an orthodontic appliance by direct bonding to a tooth utilizing a composite base with a porous tooth-abutting face and various methods for making the device, such as casting as a unitary structure, or forming the composite base by rolling a mesh, in strip form, so as to form flats on at least one surface of the mesh where the mesh is to be in contact with a solid base portion, then bonding the mesh to the base. In the latter embodiment, the metal base is a metal foil to which the appliance is attached and the mesh and foil form a composite strip, from which individual composite pads are formed.

Abstract: Sheet material is fastened to a base by means of a tape which is extended along the sheet material. Staples are periodically and automatically driven through the sheet material into the base so as to enclose the tape, thereby fastening the tape and the sheet material to the base. The tape is in the form of a continuous strip.