Abstract: Error correction of measurements of workpieces taken using a coordinate positioning apparatus in which the workpiece is mounted on a bed of the apparatus and a workpiece sensing probe is moved relative to the bed into a position sensing relationship with each workpiece and a position reading taken, and in which means are provided for measuring at least a function of the acceleration of the probe relative to the bed, the method including, in any suitable order: measuring the workpiece; determining the repeatable measurement errors from a predetermined error function, look-up table or map; measuring at least a function of the acceleration and calculating the unrepeatable measurement errors as the workpiece is measured; and combining the repeatable and non repeatable errors in steps (b) and (c) to determine the total errors; and using the total errors determined in step (d) to correct the measurements of the workpiece.

Abstract: A method and apparatus are disclosed for providing a battery low voltage warning for a range of batteries having various initial voltages. When a battery is inserted into a battery holder its initial off-load voltage is measured using a microprocessor. The microprocessor selects a suitable voltage threshold, at which the battery is considered to be discharged, from a predetermined number of voltage thresholds. The initial off-load voltage of the battery is used by the microprocessor as a basis for selecting a suitable threshold. An LED warning or the like is used to indicate that the threshold is reached in use. A measurement probe is shown which uses such a method and apparatus.

Abstract: A touch probe (10,50) is disclosed comprising a probe body (12,52) housing first locating elements (23,58), a stylus holder (16,54) having second locating elements (24,57) which co-operate with the first locating elements to locate the stylus holder within the probe body, and a bias (36,68,86) to urge the first and second locating elements into contact, wherein an element (35,50,76,90) is provided to damp motion between the probe body and the stylus holder. The element may slow a relative movement between the locating elements perhaps by resisting the urging of the bias or absorb energy produced by a relative movement between the probe body and stylus holder. The element may be slidably or rotatably mounted with respect to one of the probe head and stylus holder.

Abstract: A pivot joint has a first structure comprising a ball mounted in a receptacle, wherein the location of the ball is held with respect to the receptacle, and a second structure mounted on and movable with respect to the ball, wherein the second structure has at least one bearing surface which defines its position with respect to the ball. The ball may be held in location by contact with the receptacle at at least two positions. At least one of the positions of contact may be adjustable.

Abstract: A scale for a scale reading apparatus has a scale track with scale marks which form an incremental scale. The scale also has a set of reference marks. The scale has at least one additional track and different combinations of markers in the at least one additional track have different functions, for example reference mark enablers and right and left limit switches.

Abstract: A device and method for detecting the presence or absence of an object which has repetitive motion are disclosed comprising, a receiver for receiving a signal from the object, and circuitry for determining the presence or absence of the object to be detected, wherein the circuitry records the signal from the receiver as a pattern of data during at least part of the repetitive motion of the object, compares the data with a previously recorded data pattern and, produces an output signal based on the comparison. The signal may be received during discrete time intervals, and may be light which can be transmitted with varying intensity. The circuitry may determine the value of signal received at a receiver and produce a binary value. The signal received at the receiver can be reflected from the object to be detected.

Abstract: A method of measuring an object on a coordinate positioning apparatus. A first object is placed on a coordinate positioning apparatus and measured with a workpiece contacting probe to create measurement data. The measurement data is collected at multiple stylus deflections or probe forces. For a plurality of points on the surface of the first object, the measurement data is extrapolated to that corresponding to zero stylus deflection or zero probe force. An error function or map is created from the measurement data and the extrapolated data. Subsequent objects are then measured using a known stylus deflection or known probe force and the error function or map is used to apply an error correction to these measurements.

Abstract: Interferometry apparatus which comprises a measurement light beam (2a, 2b) and a reference light beam (2c, 2d) which interact with each other to cause a spatial fringe pattern (24). An optical device (12) is provided which interacts with the spatial fringe pattern (24), such that light is spatially separated into different directions (30, 32, 34, 36). The intensity modulation in two or more directions of the spatially separated light is phase shifted. The optical device may comprise, for example, a diffractive device, a refractive device or a diffractive optical element.

Abstract: A metrology instrument, such as a probe, probe head, stylus or stylus arm, for mounting on a coordinate position apparatus. The metrology instrument is at least partially constructed from at least one sheet of thermally stable metallic material which is folded to form a three dimensional structure. The at least one sheet of thermally stable material is utilised in the metrology loop of the metrology instrument.

Abstract: A pivot joint has a first structure comprising a ball mounted in a receptacle, wherein the location of the ball is held with respect to the receptacle, and a second structure mounted on and movable with respect to the ball, wherein the second structure has at least one bearing surface which defines its position with respect to the ball. The ball may be held in location by contact with the receptacle at at least two positions. At least one of the positions of contact may be adjustable.

Abstract: A machine having a pair of spaced structures, a plurality of ball and socket joints spaced apart on each structure, and six struts interconnecting the structures. Each strut engages with a respective ball and socket joint on each of the structures, and defines a variable distance between the centers of the ball and socket joints to which the strut is connected. At least one of the ball and socket joints to which the strut is connected has a plurality of the struts connected thereto, the ball and socket joint having a socket on each respective strut, co-operating with a sphere, the sockets having three engagement elements biased into engagement with the sphere.

Abstract: A method of scanning is disclosed comprising, providing a scanning system (10) having a sample holder (14) and a relatively movable scanning device (18), performing a scan of at least a part of an object (22) located on the sample holder (14), establishing orientation of the sample holder and interpreting data from a scan using the orientation whereby, the orientation is established using data from the scan of the surface of the sample holder. The orientation may be established by defining a plane (56b) of the sample holder, which may be limited by boundaries (76a,76b).

Abstract: A stylus 12 for a workpiece contacting probe has a tip 14 which comprises a self-lubricating or low friction material, in order to inhibit debris generation or adhesive wear (pick up) as the tip scans a workpiece surface. Various materials are described, including composites having a solid state lubricant incorporated into a dimensionally stable microstructure. The tip 14 may be made entirely of such a composite, or may have a substrate 30 with a coating 32 of the self-lubricating or low friction material.

Abstract: A bearing arrangement for an articulatable support includes bearing assemblies. In one embodiment, the assemblies have a ball and aperture having sliding contact at discrete areas during relative rotation. In another embodiment, the sliding contact may be formed at a ball and a plastics (e.g. P.T.F.E. support). Resilient displacement of the bearing contact along a rotational axis is provided by planar spring supports and a rigid support is provided by supports.

Abstract: A measuring system for calibrating a machine in which a base (10) is attachable to a surface of the machine and a housing (20) is mountable on the base, wherein at least one surface of the base and at least one surface of the housing are each provided with a complementary part of a mounting device, such that when the two parts of the mounting device are connected together, the housing may be aligned in any of a plurality of predetermined directions. The base includes a lifting mechanism (64) which when lowered allows the complementary parts of the mounting device (93, 95) of the housing (20) and the base (10) to be in contact and when raised causes them to at least partly break contact with one another. The level of the base (10) may be adjusted using a system of members and tapered rollers.

Abstract: A method of determining the shape of a dental prosthesis is disclosed comprising, scanning at least a connecting portion of a preparation, wherein the preparation comprises a first anchor and a connecting portion connected thereto, forming a physical model on the connecting portion to produce a pontic, and scanning at least the pontic whereby the surface of the first anchor is also scanned during a scanning step whereby the scanning steps can be carried out in either order. The preparation may be scanned to provide data concerning relative locations of the first anchor and connecting portion, which may be used to align data obtained during the scanning steps. Also disclosed is a method of producing a model of a dental prosthesis and a method of manufacturing a dental prosthesis.

Abstract: Disclosed is a scanner for the scanning of articles comprising a scanning apparatus (10) having a scanning device (18) and a rotatable sample mount (14,420) whereby, the scanning device and mount are relatively displaceable along the rotary axis (48) of the mount, a receptacle (40,140,240,400) mounted on the sample mount, the receptacle being capable of securely accommodating an article (30), and an actuator (146,246) for linearly displacing the receptacle whereby, actuation of the actuator displaces the receptacle and any article secured thereto, with respect to the sample mount. The article may be elongate and the displacement by the actuator is along an axis defined by the elongate axis of the elongate article. Also disclosed is a method of scanning.

Abstract: A probe (10) for a machine tool has a switch (32) or other sensor for connecting its battery power supply in response to movement of the probe. In a preferred embodiment, the switch responds to rotation of the probe in the machine tool spindle. The switch (32) is responsive to linear accelerations, but is mounted in the probe so as to respond also to the rotation. A circuit is provided to discriminate between the rotation and linear movements.

Abstract: A method of error compensation for measurements taken using a co-ordinate positioning apparatus comprising an articulating probe head having a surface detecting device. The surface detecting device is rotated about at least one axis of the articulating probe head during measurement. The method comprises the steps of: determining the stiffness of the whole or part of the apparatus; determining one or more factors which relate to the load applied by the articulating probe head at any particular instant, and determining the measurement error at the surface sensing device caused by the load.

Abstract: A device for the axial and rotational movement of a sample is disclosed comprising a mount member for mounting the sample, which is rotatable about and movable along an axis, characterised in that the mount member has a helical screw thread which produces the movement along said axis simultaneously with the rotation. A sample may be scanned or machined whilst being axially and rotationally moved. The screw thread may be disengageable perphaps by relative movement of co-operating screw threads into and out of engagement with each other by a lever to allow movement of the mount member along the axis without rotation when desired. The screw thread on one of the members may be formed from a piece or layer of a deformable material, which deforms to form a mating screw thread upon being brought into engagement with the screw thread on the other member. Also desclosed is a method of scanning a sample.