Comprehensive CNC Router Machine Glossary

A

Absolute Coordinates: The machine’s position is referenced to a fixed origin. Using the G90 command sets the controller to absolute coordinate mode, ensuring every movement is specified relative to the part’s starting point. G91 cancels this mode, switching the system to relative coordinates, where each movement is measured from the current tool position.

Absolute Move: In absolute mode, the tool is commanded to an exact coordinate in the machine’s frame. Relative Move follows the current tool position, adding the displacement value.

Accuracy: The difference between the expected measurement and the actual reading, critical for high‑precision machining.

Acetal (Delrin): A low‑friction, lightweight polymer that, when combined with PTFE, delivers excellent wear resistance and is commonly used for lead‑screw nuts on Tormach CNC mills.

Acme Screw: A standard lead‑screw design with a trapezoidal thread. While robust, its higher friction and backlash make it less suitable for precision CNC applications.

Active High/Low Logic: Refers to how a device interprets electrical signals. Active high logic considers a high voltage as a ‘signal on’, whereas active low logic does the opposite. Active high is also known as open‑collector logic.

Angular Contact Bearing: Engineered to handle heavy axial loads while maintaining radial load capacity. These bearings are ideal for supporting lead‑screws and precision spindle assemblies.

Annealing: A heat‑treating process that reduces hardness, making a material easier to machine while maintaining structural integrity.

Arbor: A versatile workholding device that expands its outer diameter to clamp the inner diameter of a workpiece. Often used in grinding and buffing operations.

ASE (Autodesk Standard Export): A file extension for 3DS Max ASCII export files, commonly used as a CAD interchange format.

ATC CNC Router: An automatic tool‑changer router used extensively in manufacturing for cutting, engraving, and drilling plastics, non‑ferrous metals, marine, kitchen cabinets, and signage.

Automatic Grinding Center: A specialized machine dedicated to grinding and sharpening tooling, ensuring consistent performance.

B

Back Driving: A phenomenon where a low‑friction lead‑screw reverses under load. Proper design and anti‑back‑driving devices are essential to prevent unintended table motion.

Back EMF (Electromotive Force): Generated when a stepper or servo motor slows, pushing current back into the power supply. Proper motor driver design prevents voltage spikes that could damage components.

Backlash Compensation: Software that accounts for mechanical play in lead‑screw or ball‑screw systems, ensuring the machine returns to the intended position after direction changes.

Backlash Eliminator: Mechanical additions—such as double‑nut assemblies with precision spacers—to reduce or eliminate backlash, especially on ACME lead‑screws.

Backplot: A CAM feature that visualizes the entire toolpath on the part drawing, enabling quick verification of the program before execution.

Ballscrew: A low‑friction, low‑backlash lead‑screw that incorporates rolling balls. Ideal for precision CNC applications where repeatability and speed are critical.

Ballscrew Mapping: An advanced calibration technique where the controller records positional errors along the screw’s length, automatically correcting them to enhance accuracy.

Bar Feeder: An automated system that continuously supplies bar stock to a lathe, eliminating manual loading and increasing throughput.

Bed Mill (Column Mill): A vertical CNC mill design where the spindle is mounted on a column that slides vertically, providing stability and efficient material removal.

Bellows: Protective sleeves that shield machine ways and lead‑screws from chips and coolant, prolonging component life.

Belt Drive: Used to transmit power from a motor to a spindle or axis. Timing belts and V belts are common types, and in some configurations they replace lead‑screws for simple linear motion.

Block: The smallest unit of a G‑code program—a single line that the machine can execute. Blocks are whitespace tolerant, enabling compact code.

Breakout Board: A hardware module that splits a single cable or protocol into multiple connections for wiring convenience.

C

CAD: Computer‑Aided Design software used to create precise part drawings and assemblies.

CAM (Computer‑Aided Manufacturing): Software that converts CAD geometry into machine‑readable G‑code, simplifying complex machining operations.

Canned Cycle: Predefined G‑code sequences that automate routine operations—such as drilling, boring, or tapping—reducing programming effort and minimizing errors.

Capacitor: An electronic component that smooths voltage fluctuations; electrolytic capacitors are common in DC power supplies for CNC machines.

Carbide: A hard, wear‑resistant material used for end mills, boring bars, and twist drills. Carbide tooling allows higher spindle speeds and feed rates than high‑speed steel.

Center Cutting: End mills designed with teeth that reach the center of the end face, enabling vertical plunging cuts.

Chip Auger / Chip Conveyor: Systems that manage and remove chips from the cutting zone, improving surface finish and reducing heat buildup.

Chip Breaker: A device that forces chips to curl or break before they can damage the tool or machine.

Chipload: The thickness of the chip produced per cutting edge. Calculated as Feedrate / (RPM × Number of cutting edges). Managing chipload optimizes cooling and tool life.

Chuck: A tool‑holding device that secures workpieces or tools by rotating them around an axis, commonly found on lathes and rotary tables.

Circular Interpolation: A motion strategy that approximates circular arcs using small linear segments, enabling smooth toolpaths.

Climb Milling: Cutting in the same direction as feed, reducing cutting force and improving surface finish. Backlash compensation is critical for consistent results.

Conventional Milling: The traditional approach where the cutter rotates against the feed direction, often resulting in higher tool wear.

Collet: A precision sleeve that holds cutting inserts or drill bits with a uniform radial force, offering high concentricity.

Constant Surface Speed (CSS): Maintains a consistent spindle speed (RPM) relative to the workpiece diameter, ensuring optimal cutting conditions across varying tool sizes.

Constant Velocity Mode: Keeps the machine’s velocity steady during arc moves, improving surface finish and reducing vibration.

Contouring: Simultaneous movement of two or more axes to produce smooth curves and complex surfaces.

Contour Turning: The lathe equivalent of contouring, creating continuous, smooth profiles on rotating workpieces.

Conversational CNC: A programming paradigm that allows operators to control CNC machines via intuitive menus, eliminating the need for manual G‑code entry.

Coolant: Cutting fluid that cools, lubricates, and flushes chips from the cutting zone, extending tool life and improving surface finish.

Counterbore: A machining operation that enlarges a hole’s head to accommodate a bolt head or screw head.

Counterweight: A device that balances the mass of a vertical axis, enabling faster Z‑axis acceleration and reducing vibration.

Cutting Force: The mechanical load exerted by the tool on the workpiece. Excessive cutting force can cause deflection, chatter, or tool breakage.

Datum: An imaginary reference point, line, or plane used as a basis for measurements and alignment.

Delrin: A trademark for acetal resin, prized for its low friction and dimensional stability.

Deflection: The unintended movement of a workpiece or tool due to insufficient rigidity, leading to dimensional inaccuracies.

Digital Differential Analyzer (DDA): A computational algorithm that approximates smooth paths by discretizing motion into small steps, widely used in CNC control.

Digitizer: Equipment that captures the three‑dimensional geometry of a physical object, generating CAD models for reverse engineering.

DNC (Distributed Numerical Control): A networked approach that allows multiple CNC machines to receive programs from a central server, improving workflow efficiency.

DOC (Depth of Cut): The vertical amount of material removed in one pass. Larger DOC requires more power and may necessitate slower spindle speeds.

Dongle: A USB key that authenticates licensed CAD/CAM software, preventing unauthorized use.

Dovetail Ways: Precision rails that guide the machine axes, enabling smooth linear motion similar to dovetail joints in woodworking.

Drill Bushing: A hardened steel sleeve that supports the drill bit’s tip, ensuring accurate hole placement and reducing wear.

Drip Feed: A method of loading a G‑code program incrementally into a CNC controller’s memory, useful for large programs.

Drive or Driver: An electronic circuit that regulates power delivery from the supply to a motor, ensuring precise control.

DRO (Digital Read‑Out): A display that shows real‑time axis positions, providing operators with instant feedback.

Dry Machining: Cutting without coolant, relying on compressed air to remove chips. Suitable for materials that can tolerate high surface temperatures.

Duplex Bearing: A pair of angular contact bearings mounted together, offering improved load capacity and stability.

Dwell: A pause in the toolpath that can leave a visible mark; careful programming minimizes dwell to preserve surface finish.

DXF File: A widely supported vector file format used for CAD drawings and CNC programs.

E

Edge Finder: A sensor or switch that detects the precise edge of a workpiece along the X or Y axis, aiding in accurate tool positioning.

E‑stop / Emergency Stop: A safety device that immediately cuts power to the spindle and drives, halting all machine motion.

F

Feed: The rate at which the tool or workpiece moves relative to each other, typically expressed in units per minute.

Feed Hold: A machine function that pauses the current operation, allowing the operator to adjust or inspect the toolpath.

Feed Override: A control that allows the operator to increase or decrease the programmed feed rate without editing G‑code.

Feedrate: The actual speed of the tool or workpiece movement, usually set by the operator or calculated by the controller.

Finishing Pass: The final, shallow cut that refines the surface and improves dimensional accuracy.

Fixture: Equipment that holds and positions a workpiece, ensuring repeatable machining operations.

Flood Coolant: High‑volume coolant delivery that flushes chips and cools the tool, enhancing surface finish and tool life.

Flutes: Cutting edges on a tool; the number of flutes affects chip evacuation and surface finish.

Flycutter (Single‑Point Cutter): A cutting tool with a single edge, ideal for creating high‑quality surfaces and complex profiles.

Following Error: The discrepancy between the commanded position and the actual position, detected via feedback systems.

Follow Turning: A multi‑tool lathe operation that sequentially applies two tools to a workpiece, effectively doubling material removal per pass.

G

G12 / G13 (Circular Pocket Milling): G‑code commands that define clockwise (G12) or counter‑clockwise (G13) pocket milling, allowing selection between climb and conventional strategies.

Gang Tooling: A setup on lathes where multiple cutters are mounted on a cross‑slide, enabling quick tool changes without a turret.

Gantry Mill: A bridge‑type mill where the Z‑axis travels along a horizontal beam, often used for large routers and plasma cutters.

Gas Spring: A pneumatic device used as a counterweight to improve Z‑axis performance.

G‑Code: The standard programming language for CNC machines, directing tool paths, speeds, and operations.

Geometric Dimensioning & Tolerancing (GD&T): A system of conventions that clearly defines geometry and tolerances, essential for consistent manufacturing and inspection.

H

Handwheels: Manual controls that allow operators to move axes in precise increments, often connected to a manual pulse generator.

Hardness: A material property indicating resistance to plastic deformation, guiding tool selection and cutting parameters.

Harmonic Drive: A gear train with minimal backlash, ideal for transmitting precise motion from motors to machine axes.

Heat Treatment: Controlled heating and cooling processes that alter a material’s mechanical properties.

High‑Speed Machining (HSM): A technique that leverages rapid acceleration, high spindle speeds, and aggressive feeds to achieve faster cycles and finer finishes.

High‑Speed Steel (HSS): A steel alloy capable of withstanding high cutting temperatures, commonly used for conventional tooling.