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air bearing
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A device that, through the release of compressed air, lifts one part slightly off another so that the parts may glide past each other.
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axis member
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The moving part of a CMM that corresponds with an imaginary line formed by the Cartesian coordinate system.
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bearing
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A friction-reducing device that allows one moving part to glide past another moving part.
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bridge-type CMM
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A type of CMM with two vertical supports and a horizontal beam holding the probe. The bridge-type CMM is the most common type.
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calibration
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The comparison of a device with unknown accuracy to a device with a known, accurate standard to eliminate any variation in the device being checked.
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cantilever CMM
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A type of CMM with a single, moveable vertical support with a suspended horizontal arm that holds the probe. Cantilever CMMs provide easy access to the staging table.
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Cartesian coordinate system
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The system that describes the location of an object by numerically expressing its distance from a fixed position along three imaginary linear axes.
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CNC machine
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A machine controlled by a computer that runs special programs driven by numerical data. CNC machines are very rigid and are capable of fast cutting speeds.
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computer-aided design
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A method of designing two- and three-dimensional objects using computers and software.
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continuous analog scanning
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A method of gathering coordinates that requires that the stylus stay in constant contact with the part's surface.
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coordinate measuring machine
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A sophisticated measuring instrument with a flat, polished table and a suspended probe that measures parts in three-dimensional space.
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direct computer control
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Completely hands-free machine operation that is directed by a software program.
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encoder
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An opto-electronic device that detects the incremental lines on a scale to determine positioning. An encoder is also known as a reader head.
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feature recognition
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Software that, when given a small amount of data like a set of coordinates, can recognize the part in question.
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footprint
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The amount of physical floor space that a machine takes up in the shop.
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gantry-type CMM
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A type of CMM similar to the bridge type but much larger. Gantry CMMs can measure parts the size of a car.
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guide way
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The stationary part of a CMM that corresponds with an imaginary line formed by an axis in the Cartesian coordinate system.
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hard probe
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A solid contact probe consisting of a precision ball or tapered shape that is mounted to a shaft. Operators use hard probes to manually inspect the surface of a part.
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joystick control
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A vertical handle or lever that allows remote, but hands-on, operation of a machine.
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laser probe
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A measuring device that projects a narrow beam of light onto the part’s surface. A lens on the probe then reads the beam's position.
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linear axes
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Imaginary perpendicular lines that serve as reference points in the coordinate system.
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macro
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A single computer command that executes a series of commands or actions.
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manual control
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A control that requires complete hands-on operation.
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mechanical bearing
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A small, highly polished, metal ball that allows objects resting on it to flow smoothly and freely. Mechanical bearings are usually used in multiples.
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micron
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A measurement equal to one twenty-fifth of a thousandth of an inch (0.00004 inch).
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non-contact probe
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A type of probe that consists of a laser or scanning system that does not contact the part surface. Non-contact probes are used to inspect small, flexible parts.
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non-prismatic
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Surfaces or objects that generally do not have angles. Non-prismatic surfaces include a sphere or the contour body of an automobile.
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operating system
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The software on a computer that allows files to be created and organized, manages the interaction of different programs, holds data in memory, and performs other functions.
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opto-electronic device
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A mechanism that uses light to generate an electronic signal or that interprets light as an electronic signal.
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origin
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The fixed, central point in a coordinate system. The origin has a numerical value of zero.
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part program
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A string of software commands that tells a coordinate measuring machine how to inspect a part.
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pixel
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A small dot that, when alongside other dots, forms a cohesive image like a television picture.
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planar condition
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Geometric space that is two-dimensional or flat, such as a disk.
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plane
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An imaginary surface that is perfectly flat or level.
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polar coordinate system
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The system used to measure circular-planar or spherical objects from a common point of origin. The R-axis indicates the distance from the origin and the Θ-axis indicates the angle from the positive X-axis.
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portable CMM
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A type of CMM consisting of a moveable arm with multiple joints that holds a probe. Portable CMMs can be taken to the part for inspection.
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probe
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A device attached to the Z-axis ram that gathers measurement data from the workpiece.
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radial
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Projecting from a common origin or center point, as in the spokes of a wheel.
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reader head
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A common name for an encoder.
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resolution
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The smallest change in a measured value that the instrument can detect.
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reverse engineering
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A type of design in which a finished piece is examined to determine how it was made. The data collected allows the original to be reproduced.
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sample
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A representative part from a larger group.
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scale
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A series of fine lines that is located along the axis member of a CMM. When read by an encoder, the scale tells the CMM the axis coordinates.
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servomotor
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A small motor that can move machine components in very small, precise increments.
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software
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The programs and instructions that control the computer hardware functions and operations.
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spherical condition
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Geometric space that is three-dimensional or round, such as a ball.
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stitch-scanning
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A measurement method in which a series of individual points on a part are touched and their positions recorded. The CMM then estimates the surface location between these points.
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stylus
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A spherical portion of the probe that is mounted on the shaft and makes contact with the part. The stylus is usually a synthetic ruby.
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tolerance
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An unwanted but acceptable deviation from a given dimension. Tolerances indicate the allowable difference between a physical feature and its intended design.
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touch-trigger probe
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A type of contact probe that detects a feature on a part and generates an electronic signal to record its dimension. Touch-trigger probes are the most accurate and commonly used probes on the CMM.
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video probe
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A measuring device that takes a digital image of the part. The image is then broken up into tiny dots, which are measured and counted by the software.
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working plane
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A combination of two axes of the Cartesian coordinate system that together form a two-dimensional area.
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