Abstract: A workpiece holding assembly (20) comprises a magnetic chuck (22), and first and second separate sets of workrests for engaging with the outer circumferential surface of an annular workpiece (40, 60). The workrests are configurable such that when the outer circumferential surface of the workpiece (40, 60) is ground with the chuck Urotating in one direction, the outer circumferential surface is only urged in contact with the first set (26, 28) of workrests, and when an inner circumferential surface of said workpiece is ground with the direction of rotation of the chuck reversed, the outer circumferential surface is only urged in contact with the second set (30, 32) of workrests. Grinding methods using such a workpiece holding assembly are also described.

Abstract: A machine tool is provided which comprises a machine base; a first support provided on a first rotational machine axis, the first rotational axis being mounted on the base in a fixed position relative to the base; a second support provided on a second rotational machine axis, the second rotational axis being mounted on the base in a fixed position relative to the base, wherein the axis of rotation of the second rotational axis is parallel to and spaced laterally from the axis of rotation of the first rotational axis. A mount is carried by a support arm on the second support, with the support arm being moveable relative to the second support about a rotary axis.

Abstract: A machine tool is provided which comprises a machine base; a first support provided on a first rotational machine axis, the first rotational axis being mounted on the base in a fixed position relative to the base; a second support provided on a second rotational machine axis, the second rotational axis being mounted on the base in a fixed position relative to the base, wherein the axis of rotation of the second rotational axis is parallel to and spaced laterally from the axis of rotation of the first rotational axis. A mount is carried by a support arm on the second support, with the support arm being moveable relative to the second support about a rotary axis.

Abstract: A method of bonding a thin semiconductor film onto a rectangular substrate is disclosed. The method makes it possible to exfoliate rectangular semiconductor films from a round precursor semiconductor wafer, thereby providing for efficient tiling of the substrate with semiconductor film. The method includes the steps of creating a damage zone in the precursor wafer by ion implantation of the wafer, removing a portion of the wafer to formed a raised portion, bonding the raised portion of the wafer to the substrate, and exfoliating the bonded raised portion.

Abstract: A method of polishing a semiconductor layer formed on a transparent substrate is described, the method including measuring the thickness of the semiconductor from the substrate side of the semiconductor layer simultaneously with the polishing, and using the thickness measurement to modify the polishing.

Abstract: In a rotary cutter block each blade (14) is clamped in an inwardly divergent recess (12) by a wedge (16). The wedges (16) may be clamped simultaneously against their associated blades (14) by application of high pressure grease at any of one or more grease nipples (52, 54) which actuates by hydraulic plungers (22) in the bases of the wedge recesses (12). The angle of the wedges (16) is such as to provide a taper-lock between the wedges (16), the blades (14) and the recesses (12), which means that after depressurization the cutterblock can be stored or moved from one machine spindle to another without slackening of the wedges. The invention is of considerable advantage in reducing the amount of setting-up time involved in setting and grinding the blades of a rotary cutter head, since one pressurization is sufficient to tighten all the wedges simultaneously and to the same degree.