Abstract: A method of measuring an artefact 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 artefact; using this approximate position to drive at least one of the probe and artefact 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 artefact at said location, wherein there is no relative movement between the probe and the artefact 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: A method of measuring an object with a coordinate positioning apparatus, comprises the following steps: placing the object within the working volume of the coordinate positioning apparatus; measuring the object with a workpiece contacting probe to create measurement data of the object, the measurement data being collected at multiple probe forces; for at least one location on the surface of the object, determining a function or look up table relating the measurement error data to the probe force; for said at least one location on the surface of the object, using the function or look up table to determine the measurement data corresponding to zero probe force; and outputting the measurement data corresponding to zero probe force as the measurement of the object.

Abstract: Re-orientation of a stylus 30 or measurement probe 12 can be accomplished by engaging a part of the stylus or probe with a fixed part 50 and moving the probe in a spherical path centred at the engagement. The engagement 50 is spaced from the stylus tip 34 and avoids bending of the stylus during re-orientation. The re-orientation can take place into a plurality of e.g. repeatable rest positions by virtue of a kinematic array (e.g. balls 122 and rollers 120 FIG. 2).

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 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: A method of manufacturing a fixed denture (18,58) is disclosed comprising, identifying the surface of a tooth preparation (110), relating the identified surface to a near net shape version of the denture (120), and altering the near net shape version (130) to produce a denture having an inner profile which substantially replicates the surface of the tooth preparation (140). The inner profile may include an offset (36). The surface of the tooth may be identified by digitising the surface. The near net shape can be altered by machining. The near net shape version may be a pre-formed sintered ceramic shell (20) which may comprise one of a plurality of standard tooth shapes (40) from which the most appropriate shape is chosen or an individually produced tooth shape (42). The fixed denture may be for example a coping (18), bridge (58), implant support abutment.

Abstract: A method of measuring an object with a coordinate positioning apparatus, comprises the following steps: placing the object within the working volume of the coordinate positioning apparatus; measuring the object with a workpiece contacting probe to create measurement data of the object, the measurement data being collected at multiple probe forces; for at least one location on the surface of the object, determining a function or look up table relating the measurement error data to the probe force; for said at least one location on the surface of the object, using the function or look up table to determine the measurement data corresponding to zero probe force; and outputting the measurement data corresponding to zero probe force as the measurement of the object.

Abstract: On a machine tool, a program 12 receives data from a scanning or analogue probe P, measuring a feature of a workpiece W. This data is combined with assumed machine position data during the scanning movement. This avoids having to break into the servo feedback loop 24 to get actual measured machine position data. The assumed machine position data can be derived from a part program 20 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 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: Re-orientation of a stylus 30 or measurement probe 12 can be accomplished by engaging a part of the stylus or probe with a fixed part 50 and moving the probe in a spherical path centred at the engagement. The engagement 50 is spaced from the stylus tip 34 and avoids bending of the stylus during re-orientation. The re-orientation can take place into a plurality of e.g. repeatable rest positions by virtue of a kinematic array (e.g. balls 122 and rollers 120 FIG. 2).

Abstract: A method of inspecting an artefact using a non contact measurement mounted on a coordinate measuring apparatus. An artefact is measured first with a contact probe (28) and then with a non contact probe (32). An error map or function is generated (34) which corresponds to the difference between the measurements taken with the contact and non-contact probes. This error map or function may be used to calibrate the probe. Alternatively subsequent artefact may be measured with the non contact probe (36) and the error map or function used to correct the measurements (38).

Abstract: A measurement probe (5) which comprises a housing (16) for mounting on an arm (6) of a coordinate positioning apparatus (2) and a stylus (10) mounted on a stylus support member (28). The stylus (10) and the stylus support member (28) are deflectable with respect to the housing (16). A first transducer system (40–48) measures movement of the stylus support member (28) relative to the arm (6) of the coordinate positioning apparatus (2). A second transducer system (38) measures movement of the stylus tip (12) relative to the stylus supporting member (28). A measurement of total stylus deflection is achieved by combining data from the first and second transducer systems.

Abstract: Re-orientation of a stylus (30) or measurement probe (12) can be accomplished by engaging a part of the stylus or probe with a fixed part (50) and moving the probe in a spherical path centred at the engagement. The engagement (50) is spaced from the stylus tip (34) and avoids bending of the stylus during re-orientation. The re-orientation can take place into a plurality of e.g. repeatable rest positions by virtue of a kinematic array (e.g. balls (122) and rollers (120) FIG. 2).

Abstract: A probe 8 comprises a housing 10 and a member 20 movable with respect to the housing onto which a stylus 12 may be mounted such that movement of the stylus results in movement of the member and a primary transducer 50, 52 for measuring movement of the member relative to the housing. The member may be located in a precisely defined rest position 22, 24 with respect to the housing, putting the probe in a mechanical datum position. For a combined transducer probe, this enables the primary transducer 52, 54 to be locked while enabling use of a secondary transducer 70. The primary transducer outputs can be datumed while in this mechanical datum position. Drive 40, 50, 60 or bias 26 means in one axis secure the member in its rest position in all axes.

Abstract: A method of inspecting a series of workpieces using a coordinate measuring apparatus, comprising the steps of: measuring a calibrated artefact on a coordinate measuring apparatus at a fast speed 28; generating an error map corresponding to the difference between the calibrated artefact and the measured artefact 30; measuring subsequent workpieces at the same fast speed 34 and correcting the measurements of the subsequent workpieces using the error map 36. The artefact may be one of the workpieces.

Abstract: A method of calibrating an analogue probe (10) having a stylus (12) with a workpiece-contacting tip (14) or a non-contact probe (26). A calibration artefact such as a calibration sphere (16) is mounted on a coordinate measuring machine (CMM) (18). The probe (10,26) is mounted on an arm (8) of the CMM and the probe is moved along a path whilst continually scanning the surface of the calibration artefact such that the probe is exercised throughout its working range. For an analogue probe (10) having a workpiece-contacting stylus (12), the path is such that the deflection of the stylus varies along the path. For a non-contact probe (26) the path is such that there is variation of the radial distance between the path and the calibration artefact. The probe path may comprise a path parallel to a chord of the calibration sphere or a curved, e.g. a sinusoidal, path.

Abstract: A method of inspecting an artefact using a non contact measurement mounted on a coordinate measuring apparatus. An artefact is measured first with a contact probe (28) and then with a non contact probe (32). An error map or function is generated (34) which corresponds to the difference between the measurements taken with the contact and non-contact probes. This error map or function may be used to calibrate the probe. Alternatively subsequent artefact may be measured with the non contact probe (36) and the error map or function used to correct the measurements (38).

Abstract: A measurement probe (5) which comprises a housing (16) for mounting on an arm (6) of a coordinate positioning apparatus (2) and a stylus (10) mounted on a stylus support member (28). The stylus (10) and the stylus support member (28) are deflectable with respect to the housing (16). A first transducer system (40-48) measures movement of the stylus support member (28) relative to the arm (6) of the coordinate positioning apparatus (2). A second transducer system (38) measures movement of the stylus tip (12) relative to the stylus supporting member (28). A measurement of total stylus deflection is achieved by combining data from the first and second transducer systems.

Abstract: Re-orientation of a stylus (30) or measurement probe (12) can be accomplished by engaging a part of the stylus or probe with a fixed part (50) and moving the probe in a spherical path centred at the engagement. The engagement (50) is spaced from the stylus tip (34) and avoids bending of the stylus during re-orientation. The re-orientation can take place into a plurality of e.g. repeatable rest positions by virtue of a kinematic array (e.g. balls (122) and rollers (120) FIG. 2).

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.