Abstract: A rotary gas bearing is described that comprises a first part rotatable relative to a second part. The first part comprises a support member and a first portion and a second portion attached to the support member. The first portion comprises a first bearing surface and the second portion comprising a second bearing surface. Both the first portion and the second portion are attached to the support member by screw thread connections. The second part may comprise complimentary bearing surfaces. Epoxy may be used to fix the first and/or second portions to the support member. A method of determining the bearing working gap by measuring gas flow through the bearing is also described.

Abstract: An apparatus for measuring a surface of a workpiece is described. The apparatus comprises a support, attachable to the moveable arm of a machine, such as a coordinate positioning machine, and rotatable about first and second axes of rotation, the axes driven by first and second motors respectively. The apparatus additionally comprises a surface sensing device for sensing the surface of a workpiece, rotatable about a third axis of rotation. This third axis of rotation is alignable with the first axis of rotation, and when aligned, rotation of the support relative to the surface sensing device is actuatable by the first motor. A method for using an apparatus for measuring a surface of a workpiece is also described.

Abstract: A method of calibrating a probe is disclosed said probe being mounted on a machine and having a stylus with a workpiece contacting tip, comprising calculating calibration information for the probe for a first orientation of the probe, and rotating the calibration information by an angle to obtain a probe calibration information for when the probe is oriented by that angle with respect to the first orientation. Also disclosed is a method of calibrating a probe during a measurement process. The calibration information may include a vector which relates probe head axes to machine axes; a calibration matrix; datum data; an inertial matrix. The stylus tip may be datumed at the orientation of the probe or inferred from datum information obtained at different orientations. The rotation step may be carried out by a software/computer program which may be stored on a controller for the machine.

Abstract: A tool shank (18;38;138) is described that comprises a spindle attachment portion (20) that is removably attachable to the rotatable spindle (12) of a machine tool (10), a shank body portion (21;121) which extends beyond the end of the spindle when the tool shank (18;38;138) is attached to the spindle (12) of a machine tool (10) and the first part (26;38;148) of a separable electrical coupling (22;132). The shank body portion comprises a feature (28;128) suitable for engagement with a tool change device (29) and the first part (26;38;148) of the separable electrical coupling (22;132) is located on the shank body portion (21;121) between the feature (28;128) and the spindle attachment portion (20). A machine tool (10), and a kit for retrofitting a machine tool (10), that comprise the second part (24;148) of the separable electrical coupling (22;132) are also described.

Abstract: A method of measuring an object using a surface sensing device mounted on a coordinate positioning apparatus. The method has the steps of measuring a single surface point of a feature of the object with the surface sensing device, moving the surface sensing device along a path around the feature at a fast speed, thereby taking measurements along the path, including at the surface point, determining the difference between the measurements of the surface point and using the difference determined to apply a correction to the object or subsequent objects having the same feature.

Abstract: Apparatus and method for making a metrological scale by electrochemical machining of a scale substrate using a tool having at least one feature. The method has the steps of passing an electrolyte solution between the tool and the scale substrate and forming an electrical connection between the scale substrate and the tool. Electrochemical dissolution of the scale substrate occurs adjacent to the feature of the tool to produce at least one scale marking. This is suitable for making linear, rotary and two dimensional scales.

Abstract: A method of measuring an artifact using a machine on which a measuring probe is mounted. The method has the following steps: determining the approximate position of one or more points on the surface of the artifact; using this approximate position to drive at least one of the probe and artifact to one or more desired relative positions of the probe and the surface and taking one or more surface measurements of said point on the surface of the artifact at said location, wherein there is no relative movement between the probe and the artifact whilst the one or more surface measurements are taken; and using data from the measurements to determine a position of the one or more points on the surface in which dynamic error is substantially reduced.

Abstract: On a machine tool, a program receives data from a scanning or analogue probe, measuring a feature of a workpiece. This data is combined with assumed machine position data during the scanning movement. This avoids having to break into the servo feedback loop to get actual measured machine position data. The assumed machine position data can be derived from a part program which controls the scanning movement. Several ways are described for compensating for errors between the assumed machine position values and the actual values.

Abstract: A contact sensing probe having a stylus which is vibrated longitudinally by a piezoelectric transducer. Contact with a workpiece is detected from damping of the vibration. The stylus is mounted to a probe body via parallel diaphragm springs. These cooperate with a counter mass to form a mechanical low pass filter, which isolates the stylus vibrations from influences caused by the mounting or handling of the probe body.

Abstract: A tool shank (18;38;138) is described that comprises a spindle attachment portion (20) that is removably attachable to the rotatable spindle (12) of a machine tool (10), a shank body portion (21;121) which extends beyond the end of the spindle when the tool shank (18;38;138) is attached to the spindle (12) of a machine tool (10) and the first part (26;38;148) of a separable electrical coupling (22;132). The shank body portion comprises a feature (28;128) suitable for engagement with a tool change device (29) and the first part (26;38;148) of the separable electrical coupling (22;132) is located on the shank body portion (21;121) between the feature (28;128) and the spindle attachment portion (20). A machine tool (10), and a kit for retrofitting a machine tool (10), that comprise the second part (24;148) of the separable electrical coupling (22;132) are also described.

Abstract: A method for planning the trajectory of an apparatus, such as an articulating probe head, mounted on a coordinate positioning apparatus, such as a CMM. It is determined whether for a given trajectory, the angular velocity or acceleration of the apparatus about a rotational axis of the apparatus will exceed a predetermined threshold. If so, parameters are adjusted so that the angular velocity or acceleration do not exceed the threshold.

Abstract: A surface sensing device for use in position determining apparatus has an elongate stylus (74) with a tip (82) for scanning the surface of a workpiece to be measured. Lateral displacements of the stylus tip are detected by a light beam which passes along the stylus from a light source (66) to a retroreflector (78). This reflects the beam back via a beamsplitter (70) to a position sensitive detector (76). The stylus is mounted for longitudinal displacement on a carriage (72). The longitudinal displacement is measured by another light beam projected by the beamsplitter (70) onto a second position sensitive detector (84).

Abstract: The present invention relates to an apparatus for the manufacture of a metrological scale comprises a scale substrate (18), at least one laser (20) for producing scale markings on the scale substrate (18), a sensor (30) to detect the depth of the scale markings produced on the scale substrate (18), and a feedback system which uses data from the sensor (30) to adjust parameters of the system to produce scale markings with the desired depth.

Abstract: A method and apparatus for measuring a surface using a surface sensing device mounted on a scanning head on a member of a coordinate positioning apparatus. The coordinate positioning apparatus may be operated to produce relative movement between the scanning head and the surface profile and the scanning head includes a drive for producing rotational movement of the surface sensing probe about one or more axis. A desired measurement profile on the surface which the surface sensing device will track and the desired motion of the orientation of the surface sensing device as the surface' sensing device follows the measurement profile are defined. This data is used to derive the required path of the relative motion between the member of the coordinate positioning apparatus and the surface, such that the surface sensing device prescribes a trajectory along the measurement profile.

Abstract: Apparatus for a co-ordinate positioning machine is described that comprises an articulating probe head for supporting a measurement probe. The articulating probe head comprises at least one electric motor. Heating means are provided for generating heat in the articulating probe head. The heating means may be the motors or discrete heating elements. Temperature sensing means, such as one or more temperature sensors, is also provided for determining the temperature at the articulating probe head. The apparatus allows the temperature of the articulating probe head to be controlled.

Abstract: A measurement system has a surface sensing device mounted on an articulating probe head, which in turn is mounted on a coordinate positioning apparatus. The surface sensing device is moved relative to a surface by driving at least one of the coordinate positioning apparatus and probe head in at least one axis to scan the surface. The surface sensing device measures its distance from the surface and the probe head is driven to rotate the surface sensing device about at least one axis in order to control the relative position of the surface sensing device from the surface to within a predetermined range in real time.

Abstract: A rotary drive mechanism is disclosed comprising a housing (10), a first motor (12) having a first rotor (38) and a first stator (32) connected to the housing and a second motor (50) having a second rotor (52) and a second stator (54) connected to the housing characterised in that the second motor is mechanically independent of the first motor whereby acceleration torques of the first motor are at least partially inertia balanced by the second motor. The balancing may be effected by equal and opposite rotation of the second motor. Control means may be provided to provide the second motor with a current which is proportional to that supplied to the first motor. Also disclosed is a positioning device and a probe having the rotary drive mechanism.

Abstract: On a machine tool, a program receives data from a scanning or analogue probe, measuring a feature of a workpiece. This data is combined with assumed machine position data during the scanning movement. This avoids having to break into the servo feedback loop to get actual measured machine position data. The assumed machine position data can be derived from a part program which controls the scanning movement. Several ways are described for compensating for errors between the assumed machine position values and the actual values.

Abstract: A machine tool control method is disclosed employing a machine tool for carrying out a work producing process having a cutting implement for machining a workpiece according to the process, the cutting implement comprising a first part having a shank and a second part having a cutting surface and, optionally a tool holder, a sensor device provided on the second part of the cutting implement for sensing at least one condition of the process, and a machine controller, the method comprising: operating the machine under the control of the machine controller to cause a process to commence, sensing at least one condition of the process, and adapting controller or sensor based cutting parameters during the process in accordance with the sensed condition. The cutting implement may be changeable during the process. The process can be a single cutting operation. Sensor based parameters can be adapted independently of the machine controller.

Abstract: A method of measuring an object using a surface sensing device mounted on a coordinate positioning apparatus. The method has the steps of measuring a single surface point of a feature of the object with the surface sensing device, moving the surface sensing device along a path around the feature at a fast speed, thereby taking measurements along the path, including at the surface point, determining the difference between the measurements of the surface point and using the difference determined to apply a correction to the object or subsequent objects having the same feature.