Abstract: A nominally cylindrical surface of a workpiece is sensed by a stylus displaceable radially of an axis of rotation of the surface relative to a support column defining a reference datum so that the stylus follows the cylindrical surface at a given height along the surface. Relative rotation of the workpiece and the stylus about the axis of rotation of the surface is effected and the displacement of the stylus used to determine information relating to the radial form of the surface at that height. These measurements are represented at different heights along the surface so as to determine its cylindrical form. The displacement of the stylus from a given position on the surface at each height before and after rotation of the stylus and workpiece through 180° are measured and the resulting measurements used to compensate for any error or deviation in the reference datum.

Abstract: A low vacuum wound drainage system comprising a high vacuum bottle having an on/off switch to allow/prevent release of the vacuum from the bottle, and a connector for connection of a wound drainage line such that a vacuum path is provided between the bottle and the wound drainage line when the on/off switch is in the on position. The wound drainage line is adapted to be detachably connected to the vacuum bottle via the connector to apply suction at a patient end of the line and includes a regulating valve incorporated in the detachable wound drainage line, the valve acting to continuously regulate the vacuum in the line, when the line is attached to the bottle, to provide a reduced vacuum at the patient end of the line. Also a wound drainage line including a regulating valve for use with a high vacuum bottle.

Abstract: A portable metrological instrument for measuring surface finish parameters has a main housing which sits on a workbench. A slidable arm can be extended or retracted over the bench so as to move a stylus over a workpiece. The stylus is fitted to a gauge mounted to the end of the arm. The mounting includes a vertically movable slider which incorporates a mechanism for lifting the stylus away from the workpiece and lowering it back. The operation of the instrument is controlled by modular software which can be reprogrammed using an external device, and the machine is operated by a control panel on the housing or by an identical control panel on a remote controller. The gauge includes an inductive sensor, and the associated circuit includes automatically adjustable error canceling devices. The control system uses the sensed position of the arm to estimate the speed of the motor which drives the arm, avoiding the need for a shaft encoder on the motor.

Abstract: An orthopaedic bone cement mixing device comprising a mixing bowl (1) and a lid (3), said lid (3) having a handle (4) extending outwardly therefrom. A mixing paddle (7) comprising a shaft (8) and vanes (9) extending outwardly therefrom extends into the bowl (1) from the lid (3) and is anchored in a groove (10) running around the base (2) of the bowl. A step-up gear mechanism (5, 11) is provided between the paddle (7) and the lid (3) such that, as the handle (4) is rotated the lid (3) rotates, causing the paddle (7) to rotate around the bowl (1). The drive wheel (5) of the gear mechanism is also caused to rotate and drives the driven wheel (11) which causes the shaft (8) of the paddle (7) to rotate about its own axis as the paddle (7) moves around the bowl (1).

Abstract: In the alignment of successive masks relative to a photo-sensitive substrate in the manufacture of multi-layers respective fiducial marks on the substrate and on each mask are brought into the correct relative position for exposure of the substrate, without introducing the inaccuracy resulting from the superimposition of successive photographic images of the mask fiducial marks on the substrate. In one method the mask and substrate fiducial marks are arranged to be out of register with each other when the mask and substrate are correctly aligned, the two sets of fiducial marks being brought into register by an optical beam displacing arrangement.

Abstract: In the alignment of successive masks relative to a photo-sensitive substrate in the manufacture of multilayers respective fiducial marks on the substrate and on each mask are brought into the correct relative position for exposure of the substrate, without introducing the inaccuracy resulting from the superimposition of successive photographic images of the mask fiducial marks on the substrate. In one method the mask and substrate fiducial marks are arranged to be out of register with each other when the mask and substrate are correctly aligned, the two sets of fiducial marks being brought into register by an optical beam displacing arrangement.