ToolingU CNC

T-Slot Cutters

A T-shaped milling cutter that machines a portion of a T-shaped slot into a workpiece. T-slot cutters often resemble a toothed disk mounted on a narrow arm.

T-Slots

A T-shaped opening running the length of a machine worktable. T-slots allow operators to use workholding devices during machining processes.

Micrometer

A U-shaped measuring instrument with a threaded spindle that slowly advances toward a small anvil. A micrometer must be used to accurately measure the true diameter during and after a turning operation.

Tolerances

A blueprint specification indicating an unwanted but acceptable deviation from a given dimension. Tolerances state the allowable difference between a part and its intended design.

Four-Jaw Chuck

A chuck with four jaws that move independently of one another. A four-jaw chuck can hold a number of differently shaped workpieces.

Self-Centering Chuck

A chuck with jaws that open and close together. Self-centering chucks accurately position a workpiece along the centerline of the chuck.

Three-Jaw Chuck

A chuck with three jaws that move together. Three-jaw chucks automatically center a workpiece and can be set up quickly and easily.

Gears

A circular, toothed machine part that transfers power from one machine part to another with matching teeth. Gears control modern lathe speeds.

Carbide

A common cutting tool material developed by combining carbon with chromium, tungsten, titanium, or other alloying elements. Carbide is used in metal cutting tools for its hardness and wear resistance.

Cemented Carbide

A common cutting tool material that is pressed and sintered to make both indexable inserts and solid cutting tools. Cemented carbide provides a cutting edge that is very hard and wear resistant.

Twist Drill

A common drill characterized by helical flutes along its length and two cutting edges at the drill point. Twist drills commonly have an 118° or 135° tip.

Surface Grinding

A common grinding process that uses a rotating grinding wheel to wear away precise amounts of a flat workpiece surface. Surface grinding is often one part of a sequence of machining operations.

Center Head

A component of a combination set used for layout. Center heads allow machinists to find the center of round or cylindrical workpieces.

Protractor Head

A component of a combination set used for layout. Protractor heads allow machinists to mark or measure any size angle between 0 to 180 degrees.

Square Head

A component of a combination set used for layout. Square heads allow machinists to measure and scribe 45° and 90° angles.

Spindle

A component of a lathe's headstock that rotates the workpiece. The spindle can be mounted with a workholding device to support the workpiece.

Spindle Nose

A component of the spindle onto which the workholding device is mounted. The type of spindle nose on the lathe determines the appropriate workholding device to use.

Vise Jaw

A component on a vise that grips and holds the workpiece in place. A vise has one fixed jaw and one moveable jaw.

Jaw

A component on a vise that grips and holds the workpiece in place. Jaws of a vise used in a milling operation are adjustable.

Toolpost

A component that sits on the compound rest of the carriage assembly of a lathe. The toolpost contains a slot for positioning the toolholder and cutting tool.

Thread Stripping

A condition in which a screw has damaged threads as a result of overtightening. Thread stripping can occur when tightening a mill's drawbar manually.

Smearing

A condition that causes a tool to leave burrs on a workpiece when it is not properly lubricated during machining. Smearing causes a poor surface finish.

Power Feed Unit

A control unit that allows the table to move side to side automatically. The power feed unit is attached to the mill table and must first be set by an operator.

Flood Cooling

A cutting fluid delivery method that completely covers the workpiece and the cutting tool with cutting fluid. Flood cooling is the least commonly used fluid delivery system for manual machining.

Mist Cooling

A cutting fluid delivery method that uses a high-velocity stream of air to disperse a small cutting fluid over the cutting area. Mist cooling reduces the overall amount of cutting fluid needed in a cutting operation.

Between-Center Turning

A cutting operation in which the workpiece is supported on each end by a pair of centers. Between-center turning allows the cutting tool to make contact with the entire length of the workpiece.

Parting

A cutting operation performed on a lathe that uses a cutting tool to separate a finished part from the rest of the stock. Also known as cutting off, parting is an outer diameter operation.

Parting Off

A cutting operation performed on a lathe that uses a cutting tool to separate a finished part from the rest of the stock. Also known as cutting off, parting off is an outer diameter operation.

Cutoff

A cutting operation performed on a lathe that uses a cutting tool to separate a finished part from the rest of the stock. Also known as parting off, cutoff is an outer diameter operation.

Cutting Off

A cutting operation performed on a lathe that uses a cutting tool to separate a finished part from the rest of the stock. Also known as parting, cutting off is an outer diameter operation.

Interrupted Cutting

A cutting process in which the cutting edge of the tool comes into and out of contact with the workpiece surface. Interrupted cutting is also known as intermittent cutting.

Cutoff Tool

A cutting tool designed to separate a finished workpiece from the bar stock. A cutoff tool is usually a thin blade of high-speed steel.

Cuttoff Tool

A cutting tool designed to separate a finished workpiece from the bar stock. A cutoff tool is usually a thin blade of high-speed steel.

Form Tool

A cutting tool ground to a specific shape that is used to create that shape in a workpiece surface. Form tools used for grooving on the lathe are often square or V-shaped.

Form Tools

A cutting tool ground to a specific shape that is used to create that shape in a workpiece surface. Form tools used for grooving on the lathe are often square or V-shaped.

Coarse

A cutting tool pitch with less inserts, spaced farther apart. Coarse pitch face mills remove more material than a finer pitch face mills.

Fine

A cutting tool pitch with more inserts, spaced close together. Fine pitch face mills remove less material but produce a smoother surface finish than coarse pitch face mills.

Multi-Point Tool

A cutting tool that has more than one cutting edge. Multi-point tools include mills and drills.

Inserts

A cutting tool that has multiple usable cutting edges. Inserts are typically very hard and wear resistant.

Single-Point Tool

A cutting tool that has one single cutting edge. Single-point cutting tools are usually made of high-speed steel or carbide.

Multi-Point

A cutting tool that has two or more cutting edges. In holemaking, multi-point tools may also be known as multi-edge tools.

Conical Taper

A cylindrical feature that gradually changes from a larger diameter to a smaller diameter at a constant ratio. Conical tapers are machined on the lathe using a taper attachment or the tailstock positioned off-center.

Alignment Pins

A cylindrical metal fastener that secures a workpiece or workholding device into position. Alignment pins inserted in a worktable's T-slots can securely hold a vise.

Shank

A cylindrical part of a tool or device, such as a drill or a reamer. The shank of a center drill is short and wide.

Clamp Bolts

A cylindrically shaped, threaded device for fastening parts. Clamp bolts hold the mill head and other components securely in a rigid position until the bolts are loosened.

Tap

A cylindrically shaped, threaded device that either cuts or presses threads into the interior of a pre-drilled hole. A tap's external teeth match the internal threads it is designed to produce.

Feed Handle

A device attached to a machine that controls the movement of a component. Feed handles, or handwheels, move the table side to side and forward and backward on a manual mill.

Graduated Rule

A device marked out on a tool for measuring distance. A graduated rule on the tailstock sleeve allows for controlled movement of a cutting tool in and out of contact with a workpiece.

Feeler Gage

A device of known thickness used to measure small distances. Feeler gages come in a range of sizes.

Manual Bench Tap

A device that aligns a hand tap with a hole for a hand tapping operation. Manual bench taps ensure the tap enters the hole straight.

Spindle Speed Selector

A device that controls spindle speed. The spindle speed selector is a dial located on the gearbox or headstock of an engine lathe that allows an operator to select and adjust the spindle's revolutions per minute.

Chuck

A device that holds a workpiece in place as it rotates on a lathe or other machine. The chuck commonly has two, three, or four jaws that can be adjusted to fit various workpieces.

Fasteners

A device that holds two or more objects together. A fastener can be a bolt or a screw as well as a button or a zipper.

Encoders

A device that translates mechanical motion into a digital signal. Encoders send locations to a numerical display panel on a lathe.

Workholding

A device used to hold and locate a workpiece. Workholding is used to keep the workpiece stationary on a mill.

Gibb

A device used to reduce side play in the mill table as it is moved from one direction to another. Gibbs are placed between the ways and the table.

Toolholder

A device used to rigidly hold a cutting tool in place. Toolholders may hold inserts or larger tools.

Steady Rest

A device used to support long rotating workpieces. Steady rests can support longer workpieces for high-pressure operations on the lathe, such as knurling.

Workholding Devices

A device used to support, locate, and hold a workpiece. Workholding secures the workpiece on the worktable in milling.

Chuck Key

A device used to tighten or loosen the bolts or cam-locks on a chuck. A chuck cannot be removed from a cam-lock spindle nose without the use of a chuck key.

Cutting Tool

A device with one or more edges used to create chips and remove material. Cutting tools are either single-point or multi-point tools.

Blueprint

A document containing all the instructions necessary to manufacture a part. A blueprint, or print, includes a part drawing, dimensions, and notes.

Print

A document containing all the instructions necessary to manufacture a part. A print, also known as a blueprint, includes a part drawing, dimensions, and notes.

Lathe Drift Pin

A fastener that locks a tool into the Morse taper of the tailstock sleeve of a lathe. The lathe drift pin also allows for easy tool removal.

Angle

A figure formed by the intersection of two lines. Angles are also used to measure distances around a circle.

Finishing

A final metal-cutting pass that emphasizes tight tolerances and a smooth surface finish. Finishing cuts often require faster speeds and a lighter depth of cut.

Finishing Cuts

A final pass of the cutting tool that emphasizes accuracy, tolerance, and surface finish. Finishing cuts often require faster speeds and a lighter depth of cut.

File

A flat metal cutting tool with a large number of very small teeth. Files wear away workpiece material through abrasion.

Face Mills

A flat mill cutter with multiple cutting teeth surrounding the bottom edge. The face mill is often used to remove a large amount of material to create flat surfaces.

Shoulder

A flat step or plane in between two surfaces. Shoulders within holes provide space for nuts and screws to sit below the top surface of a workpiece.

Workbench

A flat structure, similar to a table, that is used to perform manual cutting operations. Workbenches provide the surface and support for performing benchwork operations.

Faceplate

A flat, round workholding device often used to mount flat-bottomed workpieces. A faceplate is the most basic means of mounting a workpiece on the spindle of a lathe.

Layout Dye

A fluid that is brushed on a metal workpiece before operation. Layout dye allows the lines and features to be seen more clearly.

Cutting Forces

A force generated by the motion of the cutting tool and the resistance of a workpiece. In turning, the cutting forces are generated by the movement of the workpiece against the cutting tool.

Chasing

A form of threading. Chasing occurs to repair damaged threads.

Stainless Steel

A grouping of steels that contain large percentages of chromium, as well as nickel, manganese, and/or nitrogen. Stainless steels have very high hardness and corrosion resistance.

Feedwheel

A hand-cranked wheel that advances a cutting tool in and out of contact with a workpiece. The tailstock and carriage of a lathe each have a feedwheel.

Cross-Slide Handwheel

A hand-cranked wheel that moves the cross slide on a lathe back and forth, perpendicular to the workpiece. The cross-slide handwheel brings the cutting tool into and out of contact with the workpiece during turning.

Carriage Handwheel

A hand-cranked wheel that moves the lathe carriage back and forth along the ways, parallel to the workpiece. The carriage handwheel positions the cutting tool for turning operations.

Feed Handles

A handle attached to a machine that controls the movement of a component. Feed handles on the milling machine move the table side to side and back and forth.

Knee Crank

A handle used to raise and lower the knee and worktable on a milling machine. The knee crank features a micrometer dial that allows operators to adjust the feed rate incrementally.

Manual Feed Handwheel

A handwheel located on the front of the mill head that controls quill feed. The manual feed handwheel is used for very precise quill movements.

Bushing

A hardened steel tube that guides drills, reamers, and other cutting tools. Bushings ensure a cutting tool enters a drilled hole at the correct angle.

Drill Bushings

A hardened steel tube used to guide holemaking cutting tools such as drills and reamers. Drill bushings are used when a counterbore tool does not have a pilot.

Thread Plug Gage

A hardened, cylindrical 'Go/No Go' gage used to inspect the fit of threads in a hole. Thread plug gages are available in standardized sizes.

Pin Gage

A hardened, cylindrical gage used to inspect the size of a hole. Pin gages are available in standard diameters.

Center Holes

A hole drilled in the end of a workpiece to allow a center to be inserted into it. Center holes provide a location for a center to hold a workpiece.

Morse Taper

A hole in the sleeve of the tailstock that narrows to a point and holds tools or a center. A Morse taper allows for easy locking and removal.

Bore Gage

A hole inspection gage that makes three points of contact within the hole. Bore gages are handheld, variable instruments that provide very accurate readings of hole sizes.

Blind Hole

A hole that begins on one side of a workpiece and ends inside the workpiece. Blind holes do not extend through the entire thickness of a workpiece, so they only have one opening.

Through Hole

A hole that passes through the entire thickness of a workpiece. Through holes pass through two workpiece surfaces and have no bottom.

Through Holes

A hole that passes through the entire thickness of a workpiece. Through holes pass through two workpiece surfaces and have no bottom.

Fixture Plate

A large flat piece of stock clamped to the worktable. Fixture plates provide a flat surface for workholding without interference from the worktable's T-slots.

Turret

A lathe component that holds a number of cutting tools. The turret rotates to place tools in the cutting position.

Quick-Change Gearbox

A lathe component that houses the gears that control the power transferred from the motor to the spindle. The quick-change gearbox allows the spindle speed and rotation to be adjusted quickly.

Tool Post

A lathe component that sits on the compound rest of the carriage assembly. The tool post contains a slot for mounting the toolholder and cutting tool.

Belt-Driven Lathes

A lathe that uses either one or more V-shaped belts to drive the spindle. A belt-driven lathe must be manually adjusted to adjust spindle speed.

Turret Lathe

A lathe with a mounted device that holds multiple cutting tools. The turret rotates to position a specific cutting tool into place.

Dividers

A layout tool with two sharp-pointed legs used for spacing distances and scribing circles. Dividers have a spring-loaded adjusting screw that allows operators to expand or contract the legs.

Precision Steel Square

A layout tool with two sides that form a 90° angle. Precision steel squares check the squareness of two surfaces to each other.

Cross Slide Feed Lever

A lever located on the carriage assembly that controls movement of the cross slide. The cross slide feed lever can be set to automatically feed the carriage toward or away from the chuck.

Aluminum

A lightweight, non-magnetic, metallic element that is silver-white in color. Aluminum has low hardness levels.

Speed Range

A limited set of possible speeds at which a machine is capable of running. Speed ranges for a manual mill include high and low range.

Tool Center

A line or point of a cylindrical tool that is equally distant from all other points located on the tool's circumference. Tool centers are located by subtracting the tool's radius from any point on its circumference.

Boring Tool

A long bar used to position a single-point tool for boring operations. Boring enlarges existing workpiece holes.

Drawbar

A long metal bar that is threaded through the spindle and pulls the toolholder into a seated position. Drawbars can be manual or powered.

Threads

A long, spiraling groove that may appear on the interior or exterior of a workpiece surface. Threads help fasteners, such as screws, grip material and hold components together.

Leadscrew

A long, threaded device that controls the precise movement of machine tool components. The leadscrew controls worktable movement on the mill.

Belts

A looped band of flexible material used to transfer power from one machine component to another. Belts power the spindle on old models of lathes.

Manual Mills

A machine controlled by an operator that uses a multi-point tool to remove metal from the surface of a workpiece. Manual mills are classified by the spindle orientation, as vertical or horizontal.

Motor

A machine that converts one form of energy, such as electricity, into mechanical energy or motion. The motor on a mill head powers a belt and pulley system, which then rotates the spindle.

Manual Mill

A machine that uses a rotating, multi-point cutting tool to remove material from a workpiece. Manual mills require an operator to control machine movements and adjust settings

Mills

A machine that uses a rotating, multi-point tool to remove material from a workpiece. Mills may also refer to cutting tools used on the mill.

Grinder

A machine that uses an abrasive to remove material from the surface of a workpiece. Grinders include surface grinders, centerless grinders, and cylindrical grinders.

Engraving Machine

A machine that uses cutting tools, lasers, or other methods to carve letters, numbers, and symbols into a workpiece surface. Engraving machines are computer numerically controlled.

Drill Press

A machine tool that can be used for a variety of hole-making operations. Drill presses create round holes in workpieces.

Lathe

A machine tool used to create cylindrical parts. A lathe holds a cylindrical workpiece on one or both ends while a cutting tool is gradually passed along or into the surface of the rotating part.

OD Grooving

A machining operation performed on the lathe that cuts a narrow channel into the exterior of a rotating cylindrical workpiece. Grooving can be an inner or outer diameter operation.

ID Grooving

A machining operation performed on the lathe that cuts a narrow channel into the interior hole of a cylindrical workpiece. Grooving can be an internal or outer diameter operation.

Grooving

A machining operation performed on the lathe that cuts a narrow channel into the surface of a rotating cylindrical workpiece. Grooving can be an inner or outer diameter operation.

Turning

A machining operation that rotates a cylindrical workpiece while a single-point tool is guided along the length of a part. Turning is performed on a lathe.

Metal Cutting

A machining process that uses a tool to remove metal from a workpiece in the form of chips. Metal cutting operations include milling, drilling, and turning.

Spray Bottle Method

A manual coolant-delivery method in which an operator uses a squeezable bottle to spray fluid on the cutting area. The spray bottle method is most often used with water-based cutting fluids.

Drip Method

A manual cutting fluid delivery method in which an operator uses a brush to apply fluid on the workpiece surface. The drip method is often used with oil-based cutting fluids.

Hand Tap

A manual cutting tool that cuts internal threads into a drilled hole. Hand taps are typically held and driven into a hole by a tap wrench.

Hand Reamer

A manual cutting tool that smooths or enlarges existing holes. Hand reamers have a straight shank and a square tang, or peg, that can be gripped with a tap wrench.

Milling Machine

A manual machine that uses various cutting tools to remove metal from the surface of a workpiece. Milling machines are also called mills.

Mill

A manual machine that uses various cutting tools to remove metal from the surface of a workpiece. Mills are also called milling machines.

Knee

A manual mill component that supports the saddle. Knees can also be used to adjust a mill's worktable to different heights.

Vertical Column And Knee Mill

A manual mill with a spindle that is perpendicular to the floor and machine worktable. Vertical column and knee mills, or milling machines, are more common than horizontal mills.

Vertical Column And Knee Milling Machine

A manual milling machine whose spindle is perpendicular to the floor and machine worktable. Vertical column and knee milling machines are more common than horizontal mills.

Tap Wrench

A manual tool that holds a hand tap's square end and allows a machinist to turn the hand tap. Tap wrenches can also be used with hand reamers.

Hardness

A material's ability to resist penetration, indentation, or scratching. Increased hardness tends to indicate a material is very strong and resistant to wear.

Properties

A measurable quality or attribute that describes how a material reacts to an impact or energy that attempts to stretch, compress, bend, dent, scratch, or break it. Properties that influence lathe speed selection include a material's hardness, brittleness, softness, and ductility.

Dimensions

A measurement of space, especially length, width, and height. Dimensions of a part are indicated on the blueprint.

Taper Ring Gage

A measuring device with an internal taper. Taper ring gages are used to determine taper angle of a cylindrical part in taper turning operations.

Dial Indicator

A measuring instrument used to indicate linear movement. Using a dial indicator is the best way to make sure a workpiece is properly aligned with the spindle.

Thread Gage

A measuring instrument used to inspect the threads of a part. Thread gages are made for either internal or external thread inspection.

Caliper Rule

A measuring instrument with a pair of expandable jaws on one end and a beam containing a marked scale of unit divisions. Caliper rules can measure both internal and external features.

Calipers

A measuring instrument with a pair of jaws on one end and a long beam containing a marked scale of unit divisions. Calipers can measure both internal and external features.

Telescope Gage

A measuring instrument with a spring-loaded device used to check the inner diameter of a part. Telescope gages are then measured with a micrometer to get the proper value.

Caliper

A measuring instrument with two pairs of jaws on one end and a long beam containing a marked scale of unit divisions. One pair of jaws measures external features; the other pair measures internal features.

Micrometer Stop

A mechanical device attached to the ways of a lathe and mounted in front of or behind the carriage. The micrometer stop limits the travel of the carriage assembly and prevents it from hitting the chuck.

Cast Iron

A metal consisting of iron, over 2.11% carbon, and 1 to 3% silicon. Cast iron offers heat resistance and compressive strength.

Power Feed

A method of advancing a workpiece into a machine automatically. Power feed is controlled by an on-off lever on the apron of the saddle on the lathe.

Dovetail Cutters

A mill cutter used to cut a dovetail angle into a workpiece. Dovetail cutters can produce angled slots.

Horizontal Column And Knee Mill

A mill with a spindle that is parallel to the ground and machine worktable. Horizontal column and knee mills, or milling machines, are less common than vertical mills.

Shell Mill

A milling cutter with solid, nonindexable cutting edges around its entire periphery. A shell mill's cutting edges are often helical, similar to an end mill.

Column And Knee Milling Machine

A milling machine whose spindle is mounted in the column, and whose worktable rests on an adjustable knee. Column and knee milling machines are the most common type of manual mill.

Horizontal Column And Knee Milling Machine

A milling machine with a spindle that is parallel to the ground and machine worktable. Horizontal column and knee milling machines are less common than vertical column and knee milling machines.

Slotting

A milling operation that cuts a long, rectangular channel into the surface of a workpiece. Slotting uses a circular disk-like cutter.

Face Milling

A milling operation that produces a flat workpiece surface using a face mill cutter. Face milling is primarily used on the top workpiece surface.

T-Slotting

A milling operation that uses a T-shaped milling cutter to cut a channel shaped like an inverted T into a workpiece. T-slotting is often used to machine worktables.

Slab Milling

A milling operation that uses a cylindrical cutter on an axis parallel to the worktable to create a flat surface. Slab milling is performed on horizontal mills.

Form Milling

A milling operation that uses a mill with a unique shape to create that shape into the workpiece. Form milling is often used to machine gears and other parts requiring specially contoured shapes.

End Milling

A milling operation that uses a narrow mill to create slots, pockets, and contours in a workpiece. End milling may cut with both the bottom and sides of the cutting tool.

Straddle Milling

A milling operation that uses two parallel cutters attached to the mill arbor to create two identical, parallel, vertical workpiece features. Straddle milling is performed on the horizontal mill.

Manual Milling

A milling operation where machine movements are controlled by an operator. Manual milling is most commonly performed on the vertical column and knee mill.

Combination Set

A multi-faceted measuring device that allows operators to lay out any size angle. A combination set consists of a protractor head, square head, and center head on a steel rule.

Drill

A multi-point cutting tool used to create a round hole in a workpiece surface. Drills are common tools for holemaking operations on the lathe.

Reamer

A multi-point, or multi-edge, cutting tool with straight cutting edges, used to enlarge or smooth holes that have been previously drilled. Reamers may have straight or helical flutes.

Slots

A narrow channel cut into the surface of a workpiece. Slots can be machined by end milling or face milling operations, depending on the width.

End Mill

A narrow cutting tool that can be used to machine grooves, slots, pockets, and contours into workpieces. End mills have one or more flutes.

Half-Side Cutters

A narrow, wheel-shaped milling cutter that has teeth on one side of its periphery. Half-side milling cutters are used on horizontal mills to create vertical workpiece features.

Full-Side Cutters

A narrow, wheel-shaped milling cutter with teeth on both sides of its periphery. Full-side milling cutters are used on horizontal mills to create vertical workpiece features.

Diamond

A naturally occurring mineral, the hardest known substance. Diamond is used as a cutting tool material for very hard workpieces.

Feed Ratio

A numerical expression representing proportion that uses two numbers separated by a colon. The feed ratio on a lathe indicates whether its cross slide feedwheel dial measures a radial or a diametrical value.

Micrometer Adjustment Nut

A nut located on a threaded rod that is used to determine spindle depth. Micrometer adjustment nuts are numbered in thousandths of an inch or hundredths of a millimeter.

Locknut

A nut that is used to keep the micrometer adjustment nut from moving out of position. The locknut is located below the micrometer adjustment nut.

Precision-Ground Parallels

A pair of metal support blocks that machinists use to position a workpiece to the desired working height in a vise. Parallels are made using highly accurate precision grinding processes to ensure both blocks have equal thickness.

Parallels

A pair of vertical metal supports that are used to position the workpiece to the desired working height in the vise. Parallels are positioned directly within the vise jaws.

Symmetrical

A part that can be divided by a line into two equal halves, with identical features that are equal distances from the dividing line. Symmetrical part sides appear as mirror images of each other.

Scriber

A pen-like layout tool. Scribers create fine lines on the surface of a workpiece.

Chips

A piece of metal that is removed form a workpiece during cutting or grinding. Chips are tiny curls, shards, fragments, shavings, or particles of metal.

Drive Plate

A plate that is mounted to the spindle to provide the turning force during machining a workpiece between centers. The drive plate contains a lathe dog with which the workpiece is clamped.

Indicator Pin

A point on the end of the dial indicator. Indicator pins run across two or more surfaces to measure differences in distance.

Centers

A pointed cylindrical device that mounts in the headstock and tailstock to support a workpiece at one or both ends. Center are inserted into holes drilled into the ends of a workpiece.

Center

A pointed device that mounts in the headstock and tailstock and supports a workpiece at one or both ends. Centers are inserted into holes drilled into the ends of a workpiece.

Squares

A precision measuring instrument with two straight edges that meet at a right angle. Squares are commonly used in milling layout and setup.

Chamfer

A process that adds a small, angled surface on the end of a shaft, around the opening of a hole, or along an edge. Chamfering removes the sharp edge and helps remove burrs.

Step

A raised or lowered flat surface in a series of workpiece surfaces. Steps on a workpiece can be created by face milling and end milling.

Apron

A rectangular plate mounted to the saddle. The apron holds the carriage handwheel and cross-slide handwheel.

Keyways

A rectangular slot or groove that is machined down the length of a hole. Keyways make up the specific design of a keyhole.

Carbide Inserts

A replaceable cutting edge made of hard carbide material that has multiple cutting edges. Milling cutters often use carbide inserts as cutting teeth.

Cutting Inserts

A replaceable cutting tool with a geometric shape that has multiple cutting surfaces. Cutting inserts can be repositioned when a cutting edge has worn down since only one edge is used at a time.

Edge Finder

A rod shaped tool used to find the exact edge of a part along the X and/or Y axis. Edge finders are commonly used in milling to locate part zero.

Rotary Bases

A rotating base on the bottom of the vise. Rotary bases can position the workpiece at a variety of angles to the X and Y axes.

Burrs

A rough, sharp edge remaining on a part after a cutting process. Burrs pose an injury risk and interfere with the fitting of parts.

Gear

A round or cylindrical mechanical component with teeth that transmits power. Gears mesh with one another and can alter the speed, torque, or direction of mechanical energy.

Adjusting Screw

A screw that gradually moves a machine component with each turn. The adjusting screw on the manual mill head allows the operator to align the head in the X axis.

Depth Factor

A set of constant fractions used to determine the proper depth for common countersink angles. The depth factor for the angle multiplied by the fastener head diameter determines the depth.

Gearbox

A set of gears located in the lathe headstock. The gearbox can be adjusted to change the spindle speed.

Parameters

A set of measurable factors or characteristics that define the scope of an operation. Parameters of a milling operation include workpiece tolerances and properties.

Ways

A set of parallel tracks along which a machine component moves. The ways allow the carriage and tailstock to move along the bed of the lathe.

Quick-Change Tooling

A set of toolholders that uses a master toolholder with a series of rapid, interchangeable toolholders. Quick-change tooling increases the speed of production, but operators must check alignment after changing tools.

Pulley System

A setup on a machine consisting of two round, fixed pulleys. A pulley system features one pulley that powers and moves a belt, which in turn moves the other pulley.

Quill

A shaft that moves the spindle in and out of the mill head. The quill feed handle controls the quill's main vertical movements.

Center Hole

A shallow hole used to locate other holemaking operations. Center holes are created with center drills.

Dowel Pin

A short, cylindrical rod. Dowel pins are fitted tightly into holes to prevent motion or slipping.

Rules

A simple measuring instrument consisting of a long, thin metal strip with a marked scale of unit divisions. Rules come in many sizes and forms and can be rigid or flexible.

Steel Rule

A simple measuring instrument consisting of a long, thin metal strip with a marked scale of unit divisions. Steel rules can be rigid or flexible.

Approach Distance

A small distance that the cutting tool travels before engaging the workpiece. The approach distance is added for safety reasons.

Nib

A small protrusion or burr on a workpiece surface. Nibs form when a machinist aligns the cutting tool below the spindle centerline when setting up an engine lathe for operation.

Vernier

A small, movable, graduated scale used for measuring a fractional division of the fixed scale. Vernier scales appear on both manual calipers and micrometers.

Three-Dimensional

A space that has length, width, and depth. Three-dimensional space can be represented by the Cartesian coordinate system.

Taper Attachment

A specialized lathe attachment that includes an angled guide bar and shoe used to machine a taper on a cylindrical part. A taper attachment is clamped to the lathe saddle and connects to the cross slide to guide its movement during taper turning.

Variable Speed Control

A speed control on the mill with a high and low speed range. Speeds can be set to any speed within the high and low speed range.

Flute

A spiraling groove or recess around the periphery of a cutter that allows for chip flow away from the cut. Flutes also facilitate the flow of cutting fluid.

Collet

A split-sleeve device that expands or contracts to hold a cutting tool or workpiece in place as it rotates. Collets are designed to hold specific dimensions.

Tang

A square extension on the end of a reamer. Tangs allow reamers to be secured in tap wrenches.

Flutes

A straight or helical recessed feature on the periphery of a cutter. Flutes allow chips to flow away from the cut.

Tapping Fluid

A substance used to cool and lubricate the cutting tool and workpiece in a tapping operation. Tapping fluid is typically oil-based.

Coolant

A substance used to cool or lubricate a metal cutting process. Coolants can be oil- or water-based liquids, gases, or pastes.

Lubricant

A substance used to reduce friction between components or objects. Machinist use lubricant to lengthen tool life and prevent marring of a workpiece surface.

Known Surface

A surface that can be used to take accurate measurements. A surface becomes known after it is machined to a definite measurement.

Power Feed Engagement Crank

A switch that sets the quill feed to run automatically. The power feed engagement crank turns the power feed on, while the quill feed selector adjusts automated feed rates.

Cartesian Coordinate System

A system that describes the location of an object by numerically expressing its distance from a fixed position along three linear axes, which are perpendicular to each other. Cartesian coordinates are used to direct machine tool movements.

Engraving Pen

A thin hand tool that carves letters, numbers, and symbols into a workpiece surface. Engraving pens are generally pneumatic tools.

Stamps

A thin metal tool that has a raised mirror image of a letter, number, or symbol at one end. Stamps generally come in sets, so any desired combination of markings can be impressed into a workpiece surface.

Shim

A thin or tapered material used to support a workpiece. Shims may also be used to prevent damage to a workpiece surface when touching off with the cutting tool.

Unified Threads

A thread set to a measurement standard based on inches. Unified threads conform to specifications of the American Society of Mechanical Engineers (ASME) and the American National Standards Institute (ANSI), both of which set standards in the United States.

Threading Tool

A tool designed to cut threads into the interior or exterior of a workpiece. Threading tools can be used to make fasteners like bolts or screws.

Chamfer Tool

A tool that creates an angled surface which eliminates a sharp corner on a workpiece. Chamfer tools are available in a range of angles.

Tap Extractor

A tool that grabs the flutes of a broken tap to remove it from inside a hole. Tap extractors are held and turned by a tap wrench.

Pneumatic Tools

A tool that is powered by the motion and control of compressed air or gas. Pneumatic tools include engraving pens and screwdrivers.

File Card

A tool that machinists use to manually remove chips from a hand file. File cards prevent chips caught in a hand file from scratching a workpiece surface.

Center Punch

A tool used to mark small, sharp points along layout lines. Center punches create small indentations that indicate the centers of holes when preparing for drilling operations.

Tailstock

A toolholder and mount opposite from the headstock. The tailstock can hold holemaking tools or a center and moves parallel to the workpiece.

Carriage

A toolholder on a lathe that brings a cutting tool in and out of contact with a workpiece by moving it perpendicularly and parallel to the workpiece. The carriage moves along the ways.

End Mill Toolholder

A toolholder that holds an end mill in place with a setscrew. End mill toolholders hold tools with more rigidity than collet-type toolholders.

Tool Blocks

A toolholder that is kept with the tool already mounted on it. Tool blocks are considered quick-change tooling, because operators can easily change them in and out of a lathe's toolpost.

Adjustable Boring Head

A toolholder used in boring operations that require a hole diameter larger than that of the tool. An adjustable boring head can be set to bore differently sized hole diameters.

Offset Turning

A turning operation on a lathe in which the workpiece centerline axis is not continuously aligned with the Z axis. Offset turning operations include taper turning.

Axial Runout

A type of alignment describing the workpiece when one end is concentric and the other is not. A part with axial runout is eccentric.

Radial Alignment

A type of alignment describing whether or not the workpiece is concentric to the centerline of the lathe spindle. If a workpiece runs true, it has a proper radial alignment.

Hand Tapping

A type of benchwork operation that involves manually cutting an internal thread. Hand tapping is performed without the use of a machine tool.

Engraving

A type of benchwork operation that involves manually cutting thin lines into a metal workpiece to create letters, numbers, and symbols. Engraving is often used to create identification numbers on parts.

Chamfering

A type of benchwork operation that involves manually removing a sharp corner or edge from a workpiece by creating an angled surface. Chamfering generally turns a 90° angle into a 45° angle.

Hand Reaming

A type of benchwork operation that involves manually removing small amounts of workpiece material to enlarge an existing hole. Hand reaming is performed on holes that require tight tolerances.

Filing

A type of benchwork operation that involves manually removing small amounts of workpiece material with a tool that has small, sharp teeth. Filing can smooth workpiece surfaces, remove sharp edges, and add a chamfer.

Hex Bolt

A type of bolt that has a head with six sides. Hex bolts are used to tighten drawbars.

Dead Center

A type of center designed that is solid in construction with no moving parts. Dead centers must be lubricated with cutting fluid during each use.

Live Center

A type of center designed with bearings so that the point of the center rotates with the workpiece. Live centers require only monthly lubrication.

Independent Chuck

A type of chuck with jaws that can each move separately. Independent chucks can grip irregularly shaped workpieces during lathe operations.

Cutting Fluid

A type of coolant used to cool or lubricate a metal cutting process. Cutting fluids are typically oil- or water-based liquids.

Brazed-Tipped Cutting Tools

A type of cutting tool made of inexpensive material with a tip made of more expensive material formed onto the cutting end. The brazed tip may be made of carbide, high-speed steel, cubic boron nitride, or diamond.

Powered Drawbars

A type of drawbar that automatically pulls the toolholder into a secure position. Powered drawbars are typically controlled by a switch mounted on the machine.

Center Drill

A type of drill with a wide shank and a 60° angle tip. The center drill is used to start a hole to ensure that the hole is machined in the right location.

Center Drills

A type of drill with a wide shank and a 60° angle tip. The center drill is used to start a hole to ensure that the hole is machined in the right location.

Cam Locks

A type of fastener used to secure a chuck to a cam-lock spindle nose. A cam lock contains a base that a chuck key can attach to and turn the cam, which latches the cam-lock in place.

Dead Blow Hammer

A type of hammer that gives a solid blow to different materials without damaging their surfaces. Dead blow hammers can be made of plastic, rubber, brass, or lead.

Ball Peen Hammer

A type of hammer with a round end and a flat end used to tap the prick punch into the workpiece. Ball peen hammers are also known as machinists' hammers.

Adjustable Hand Reamer

A type of hand reamer that expands and contracts slightly to sizes within a small range. Adjustable reamers are often used for oddly sized holes.

Expansion Reamer

A type of hand reamer that expands slightly with a screw. Expansion reamers only expand and do not contract; the diameter expansion is permanent.

Helical-Fluted Hand Reamer

A type of hand reamer with spiral-shaped flutes. Helical-fluted hand reamers are often used to ream holes with keyways or interruptions.

Straight-Fluted Hand Reamer

A type of hand reamer with straight flutes. Straight-fluted reamers are the most common types of hand reamers.

Bottoming Tap

A type of hand tap that has 1 to 1 1/2 tapered threads. Bottoming taps are the last tap used when hand tapping blind holes.

Plug Tap

A type of hand tap that has 3 to 5 tapered threads. Plug taps are often used after taper taps but before bottoming taps when hand tapping blind holes.

Taper Tap

A type of hand tap that has 8 to 10 tapered threads. Taper taps are the first tap used when hand tapping blind holes, and they are also often used to tap through holes.

Height Gage

A type of measuring instrument with a precision finished base, a perpendicular beam, and an indicator. A height gage can be used in conjunction with a planer gage to align a cutting tool to a lathe spindle.

Conventional Milling

A type of milling that feeds the workpiece against the cutting tool rotation. Conventional milling creates chips that become gradually wider during the cut.

Climb Milling

A type of milling that feeds the workpiece in the same direction as the cutting tool rotation. Climb milling creates chips that become gradually narrower during the cut.

Analog Measurement

A type of readout that uses dials with scales inscribed on them to display dimensions on the lathe. Analog measurement is less precise than digital readout.

Set Screw

A type of screw with a rounded or cone-shaped end designed to fit into a matching recess. A set screw is used to expand an expansion reamer.

Setscrew

A type of screw, often with no head, used to hold a device in place relative to other components. Setscrews are used with end mill toolholders.

Cam-Lock Spindle Nose

A type of spindle nose in which the workholding device is held in place with cam-locks around its perimeter. Cam-lock spindle noses are often used on high-powered machines.

Short Taper Spindle Nose

A type of spindle nose in which the workholding device is held in place with fasteners around its perimeter. Short taper spindle noses are often used on high-powered machines.

Threaded Spindle Noses

A type of spindle nose that is screwed onto the spindle. Threaded spindle noses are often used on small lathes.

Carbon Tool Steel

A type of steel designed with improved wear resistance, toughness, and strength. Hand reamers are commonly made of carbon tool steel.

T-Handle Tap Wrench

A type of tap wrench that is shaped like a "T" and often used to hold smaller-diameter taps. T-handle tap wrenches require more force to manually rotate than other tap wrenches.

Straight-Handle Tap Wrench

A type of tap wrench with a long, straight handle that usually holds large-diameter taps. Straight-handle tap wrenches are easier to turn because they provide a machinist with more leverage than other tap wrenches.

Pipe Tap

A type of tapered tap that adds an internal thread to a pipe or tube. Pipe taps create tapered threads that improve the sealing capabilities of a tapped hole.

Tailstock Indexer

A type of toolholder mounted in the tailstock of a lathe. A tailstock indexer holds up to six different cutting tools at a time.

Drill Chuck

A type of toolholder that tightens to grip holemaking tools on the mill. Drill chucks allow for quick installation and removal of various tools.

Station Toolholder

A type of toolholder, also called a 4-position toolholder, that allows the mounting of four different tools at once on a lathe. These tools can then be selected by the lathe operator as required.

4-Position Toolholder

A type of toolholder, also called a station toolholder, that allows the mounting of four different tools at once on a lathe. These tools can then be selected by the lathe operator as required.

Angle Vise

A type of vise that can position the workpiece at an angle. Angle vises can be adjusted from zero to 90 degrees.

Grade

A type or category of cutting tool material specified for a particular use. Grades indicate different types of cemented carbides used in milling.

Speed Change Handwheel

A variable speed control handle that allows the operator to adjust spindle speed. The speed change handwheel on a mill adjusts spindle speeds incrementally within two speed ranges: high or low.

Face Mill

A wide, round milling cutter that contains multiple cutting teeth and is often used to remove large amounts of material. Face mills cut with their face and periphery.

Planer Gage

A work aid consisting of two right-triangle metal blocks fastened together. A planer gage allows users to measure dimensions of parallel surfaces within a range by sliding one block onto another.

Lathe Dog

A workholding device that clamps onto the workpiece and transmits rotary motion from the spindle of a lathe to the workpiece. The lathe dog allows a workpiece to be mounted between centers.

Vise

A workholding device with two jaws that grip and hold a workpiece in place. Vises are often used to hold workpieces on the mill.

Soft

Able to be easily scratched, indented or penetrated by another material. Soft materials are characterized by their lack of hardness.

Hard

Able to resist scratching, indentation, or penetration. Hard workpiece materials are usually more difficult to machine, and they generate more heat during machining than soft materials.

Setup

All the necessary preparation that occurs on a machine before an operation can be executed. Setup includes preparing machines, tools, and materials.

Axial

Along or parallel to the workpiece axis. Axial depth of cut is controlled by the carriage-feed handwheel.

Precision Machinist Square

An L-shaped tool that a machine operator can use to align square or linear workpieces. Precision machinist squares are less exact than indicators.

Jump Off

An abrupt, but slight, off-center shift of the edge finder pin. Jump off indicates that an edge finder has located a workpiece edge.

Guide Bar

An adjustable steel rod on a taper attachment. The guide bar sets the taper angle for taper turning.

Graduated Dial

An analog device that measures linear movement. Graduated dials are numbered collars attached to handwheels on the lathe that record and measure movement and positioning.

Graduated Dials

An analog device that measures linear movement. Graduated dials are numbered collars attached to handwheels on the lathe that record and measure movement and positioning.

Scale Dial

An analog device that measures linear movement. Scale dials are numbered collars attached to the feed handles and knee crank on manual mills.

Operator

An employee who runs a machine. Operators are trained to safely set up, run, and maintain their particular machine.

Pockets

An enclosed recess machined into a workpiece surface. Most pockets are square or rectangular with rounded corners.

Glass Scale Encoders

An encoder that uses light sensors to detect movement. Glass scale encoders are the most accurate encoders because they are not subject to backlash.

Belt

An endless loop of material used to transmit motion between two or more pulleys. Belts on a milling machine motor should only be repositioned with the spindle turned off.

Axes

An imaginary straight line that is used to measure the location of an object in three-dimensional space. Axes in the Cartesian coordinate system include the X, Y, and Z axes.

Roughing Cuts

An initial pass of the cutting tool that emphasizes heavy metal removal rates, high feed rates, and a heavy depth of cut. Roughing cuts are made prior to finishing operations.

Center Gage

An instrument that checks the angle of a cutting tool to a workpiece. Center gages help ensure the cutting tool is perpendicular to the workpiece for threading operations on a lathe.

Facing

An operation performed on a lathe that feeds a cutting tool across an end of a cylindrical workpiece to create a flat surface. Facing is an outer diameter operation.

Countersinking

An operation that cuts a conical surface into a hole. Countersinking allows the head of a screw with a matching conical angle to rest flush with the workpiece surface.

Scale Dials

Analog device that measures linear movement. Scale dials are numbered collars attached to the feed handles and crank on manual mills.

Benchwork Operations

Any additional process performed on a workpiece before or after it is machined. Benchwork operations are generally manual, such as hand tapping and hand reaming.

Off-Center

Any location on a part that deviates from the part's centerline. Off-center turning requires an independent chuck rather than a self-centering chuck.

Workpiece

Any part that is being machined, formed, or otherwise worked on. Workpieces are turned on a lathe.

Automated

Any system, machine, tool, or device that does not require human intervention. Automated engraving machines are often used for engraving complex symbols and high volume production.

Tooling

Assorted cutting tools used in various manufacturing processes. Tooling used in milling includes face mills, end mills, and holemaking tools.

Brazed

Bonded together using heat. Brazed tools have a cutting edge made of more expensive material bonded to a less expensive material.

Cubic Boron Nitride

CBN. A type of cutting tool material that has hardness second only to diamond. Cubic boron nitride tools are very effective at machining most steels and cast irons, but they are also very expensive.

Computer Numerical Control

CNC. A combination of software and hardware that directs the operation of a machine. Computer numerical control uses mathematical data to direct machine movements.

Ductile

Characterized by the ability to be drawn, stretched, or formed without breaking. Ductility is generally present in the absence of strength.

Conical

Cone-shaped. Conical workpiece features gradually change from a larger diameter to a smaller diameter.

Stop Rods

Control devices used to limit the travel of the table automated by the power feed unit. The stop rods are located on the front of the mill table.

Heat Treatment

Controlled heating and cooling processes used to change the structure of a material and alter its physical and mechanical properties. Heat treating is often used to adjust a material's hardness.

Setting Zero

Creating a known location on a machine. Setting zero establishes a reference point by setting the readout to 0 in each axis.

Center Drilling

Cutting a wide center hole into the end of a workpiece using a special center drill bit. Center drilling can create a hole that can be used by a center to support the workpiece or can act as a pilot hole for drilling operations.

Teeth

Cutting edges on the perimeter of a circular tool. Teeth perform the cutting action while flutes clear chips.

Digital Readout

DRO. A type of readout that uses an encoder attached to a machine that transfers information to a digital display. Digital readout is capable of very precise measurements.

DRO

Digital readout. A type of readout that uses an encoder attached to a machine that transfers information to a digital display. Digital readout is capable of very precise measurements.

Scribing

Drawing fine lines or features on a workpiece surface during layout. Scribing is done with a fine pen-like, hard-pointed tool.

Electrical Discharge Machining

EDM. A nontraditional machining process that erodes unwanted material from a workpiece using a rapid series of electrical sparks. Electrical discharge machining can be used to remove a tap that has broken inside a hole.

Tapered

Gradually decreasing in size from one end of the object to the other. Tapered taps create a conical shape at the bottom of a hole to fit screws.

High-Speed Steel

HSS. A common cutting tool material that is relatively inexpensive and offers excellent toughness. High-speed steel tools are often heat treated and coated.

Concentric

Having a common center or sharing the same axis with another object. Concentric objects are generally circular or cylindrical.

Run True

Having a common center or sharing the same axis with another object. If a workpiece runs true, it shares a centerline with the lathe spindle.

Indexable

Having multiple cutting edges that can be repositioned to reveal a fresh cutting edge. Indexable inserts on a face mill can be rotated to a different cutting edge once the original edge has been worn or damaged.

Inner Diameter

ID. Cutting operations that take place on the interior surface of a workpiece. Drilling, reaming, and boring are all inner diameter operations on a lathe.

Internal Diameter

ID. The inner surface of a hole or cylindrical feature. Internal diameter operations on the lathe include drilling, reaming, and boring.

Linear

In a straight line along a single axis. Linear workpieces can be aligned on a mill worktable using a precision machinist square.

ID

Inner diameter. Cutting operations that take place on the interior surface of a workpiece. Drilling, reaming, and boring are all inner diameter operations on a lathe.

Concave

Inwardly curved in shape. Improper cutting tool alignment during parting off can result in the bottom surface of a part becoming concave.

Length-To-Diameter Ratio

L/D ratio. A numerical value comparing the length of a cylindrical tool or workpiece to its diameter. Higher length-to-diameter ratios offer less rigidity; 4 to 1 is typically the maximum ratio for standard cutting tool steels.

Referencing

Locating a tool, workpiece, or machine component in a known position. Referencing is used to measure and create part features in manual milling operation.

Cylindrical

Long and circular in shape. Cylindrical objects can be hollow or solid.

Perpendicular

Meeting at a 90° angle. Cross-slide movement is perpendicular to the spindle axis.

Eccentric

Not having a common center. Eccentric rotating components do not share the same centerline, or axis.

Outer Diameter

OD. Cutting that takes place on the outer surface of a workpiece. Outer diameter operations include turning, facing, and parting off.

Outside Diameter

OD. The outer surface of a cylindrical workpiece or feature. Outside diameter operations on the lathe include turning and parting off.

Pitch

On a thread, the distance between a point on an individual thread to the corresponding point on the next thread. Pitches range from coarse, with few teeth, to fine, with many teeth.

OD

Outer diameter. Cutting that takes place on the outer surface of a workpiece. Outer diameter operations on a lathe include turning, facing, and parting off.

Convex

Outwardly curved in shape. Improper cutting tool alignment during parting off can result in the bottom surface of a part becoming convex.

Personal Protective Equipment

PPE. Any of the various articles of clothing or safeguarding devices that operators are required to wear to ensure their safety. Personal protective equipment includes safety glasses and ear plugs.

Radial

Perpendicular to the workpiece axis. Radial depth of cut is controlled by the cross-slide feed dial.

Bar Stock

Raw material purchased from metal manufacturers in the form of long bars. Bar stock may be round, square, or hexagonal.

Stock

Raw material that is used to make manufactured parts. Stock is available in standard shapes such as long bars, plates, or sheet.

Rpm

Revolutions per minute. A unit of measurement that indicates the number of revolutions a machine component makes in one minute. Revolutions per minute measures rotation from the center of a tool or spindle.

Hexagonal

Six-sided. Hexagonal workpieces can be held by self-centering and independent chucks.

X Axis

The Cartesian axis describing cutting tool motion toward and away from the spindle centerline. The X axis is perpendicular to the spindle centerline on a lathe.

Y Axis

The Cartesian axis describing in and out movement. On the mill, the Y axis represents coordinate positions along the shortest distance parallel to the worktable.

C Axis

The Cartesian axis describing motion around the Z axis. The C axis describes the rotation of the spindle on a lathe.

Z Axis

The Cartesian axis describing the location of the spindle centerline. The Z axis is always parallel to the spindle on a lathe.

Strength

The ability of a material to resist forces that attempt to break or deform it. Increased strength in materials can make them more difficult to machine.

Tolerance

The acceptable variation from a specified dimension. Tolerances indicate the allowable difference between a physical feature and its intended design.

Alignment

The accurate positioning of parts in a mechanical system in relation to one another. Alignment on a lathe requires the workpiece and spindle to share a common centerline.

Step-Over

The amount of a face mill cutter's diameter that is engaged in a cut. Step-over should be no more than 75% of the cutter's diameter.

Depth Of Cut

The amount of material removed by one pass of the cutting tool. Depth of cut measures how far the cutting tool penetrates the surface of the workpiece during a cut.

Flex

The amount that a part bends due to pressure from the cutting tool. A smaller diameter part will flex less often if the tool is fed away from the chuck.

Flexing

The amount that a part bends due to pressure from the cutting tool. Flexing is less drastic on smaller diameter parts if the tool is fed away from the chuck.

Arbor

The bar attached to the spindle of a horizontal milling machine. The arbor holds the milling cutter for different types of milling processes.

Saddle

The base of the lathe carriage assembly. The saddle rides along the ways to reposition the carriage assembly.

Bed

The base of the lathe. Beds provide a foundation for various machine tools.

Circumference

The boundary or perimeter around a circle. As circumference of a cylindrical workpiece decreases during a turning operation, the cutting speed also decreases, while the spindle speed remains constant.

Cutting Variables

The changeable aspects of a given metal cutting operation. Cutting variables for lathe operations include speed, feed, and depth of cut.

Carriage Assembly

The combination of components that make up the carriage. The carriage assembly includes the saddle, cross slide, compound rest, tool post, and cutting tool.

Gear Ratio

The combination of different gears for the transfer of power. Shifting power from one gear to a differently sized gear will change the amount of power being transferred.

Headstock

The component of the lathe that holds the motor, gearbox, and spindle. The headstock powers the lathe.

Rigidity

The condition of a workpiece, machine, or machine setup characterized as still and immoveable. Rigid components are fixed securely in place.

Hi-Neutral-Lo Lever

The control that puts the motor in gear. The hi-neutral-lo lever, located on the right side of the mill head, is tied to the operation of the forward-reverse switch.

Surface Finish

The degree of smoothness of a part's surface after it has been manufactured. Surface finish is the result of the surface roughness, waviness, and flaws remaining on the part.

Specifications

The design parameters that set the limits of acceptable deviation for a part's intended application. Specifications are also called specs.

Chatter

The development of surface imperfections on a workpiece caused by cutting tool vibration. Chatter occurs if the machine does not have sufficient rigidity or if the cutting tool is applied in an incorrect manner.

Toolholders

The device used to rigidly hold a cutting tool in place. Toolholders may hold inserts or larger tools.

Diameter

The distance between two opposing points on the edge of a circle passing through the center. The diameter divides the face of a cylindrical workpiece into two equal halves.

Major Diameter

The distance from crest to crest of an external thread or from root to root of an internal thread. Major diameter is also called thread diameter.

Thread Diameter

The distance from crest to crest of an external thread or from root to root of an internal thread. Thread diameter is also called major diameter.

Minor Diameter

The distance from root to root of an external thread or from crest to crest of an internal thread. Minor diameter of a tap measures the farthest distance from root to root on opposite sides of the tool.

Radius

The distance from the center to the edge of a circle. The radius is half the diameter.

Spindle Depth

The distance inside the workpiece that the spindle reaches during a cutting operation. Spindle depth on the manual mill is controlled by setting the micrometer adjustment nut or using the knee crank.

Pilot

The end of the counterboring tool that helps guide the cutter straight into the hole. Pilots are smaller than the rest of the tool and concentric to the drilled hole.

Reference Point

The established location of a tool, workpiece, or machine component. A reference point provides a location to accurately measure and create part features in a milling operation.

Crests

The external ridge, or high point, of a thread. Crests of screw threads fit in the internal grooves, or low points, of a tapped hole.

Origin

The fixed central point in the Cartesian coordinate system. The origin has a numerical value of zero at each axis.

Face

The flat, circular end of a cylindrical part. The face is perpendicular to the workpiece axis.

Base

The foundation of a machine that supports all other machine components. Bases stabilize mills and provide them with rigidity.

Cross-Slide Feed Dial

The graduated scale on the cross slide that indicates the measurement of the feed. The cross-slide feed dial measures how far the cutting tool moves along the X axis.

Tailstock Feed Dial

The graduated scale on the tailstock feedwheel that indicates the measurement of the feed. The tailstock feed dial measures how far the cutting tool moves along the Z axis.

Cross Slide Feed Dial

The graduated scale that indicates depth of cut. The cross slide feed dial setting determines how far the cross slide moves the cutting tool each pass.

Roughing

The initial machining operation that removes stock rapidly without regard to surface finish. Roughing achieves the basic workpiece shape and dimensions in milling.

Roots

The internal ridge, or low point, of a thread. Roots of screw threads fit against the external crests, or high points, of a tapped hole.

Quill Feed Selector

The knob on the left side of the mill head that allows the operator to set the automatic feed rate for the quill. The quill feed selector has three feed settings, which are small fractions of an inch or millimeter.

Tool Life

The length of time a cutting tool is expected to be operational before it must be replaced. Tool life can be extended through optimized implementation, including the proper tool geometry or using cutting fluids.

Worktable

The machine component that supports the workpiece and any workholding devices during machining. Worktables on manual mills move side to side, back and forth, and up and down.

Forward-Reverse Switch

The main directional control for the spindle that determines whether the spindle rotates forward or reverse. The forward-reverse switch is also known as the high-low range switch.

Quill Feed Handle

The main lever used to manually move the quill. The quill feed handle is located on the lower right side of the mill head and controls the quill feed.

Layout

The marking of lines, centers, or circles on metal workpieces. Layout shows the size, shape, and locations of features.

Toughness

The material's ability to withstand forces that attempt to break it. Toughness determines the ability of a cutting tool to withstand a sudden stress.

Swing

The maximum workpiece diameter that a lathe can accommodate. The swing can be calculated by measuring the distance between the spindle center and the ways and multiplying it by two.

Distance Between Centers

The maximum workpiece length a lathe can accommodate. The distance between centers is the distance between the headstock and the tailstock set at its farthest point on the lathe.

Pitch Diameter

The measured distance between points in the grooves between threads. Pitch diameter is the theoretical point where the threads of a fastener and the threads of a hole meet.

V-Ram

The moveable component attached to the mill head. The V-ram facilitates the machining of oversized parts or long parts that hang over the edge of the mill table.

Engine Lathe

The original and most basic type of manual lathe. An engine lathe uses a single-point cutting tool to remove material from a rotating cylindrical workpiece.

Periphery

The outer edge or rim of an object or tool. Both the periphery and face of the cutting tool are used in milling.

Cross Slide

The part of the carriage assembly on a lathe that holds the compound rest. The cross slide moves the cutting tool perpendicular to the workpiece.

Overarm

The part of the horizontal milling machine that reaches over the workpiece and worktable. The overarm supports the spindle and arbor.

Compound Rest

The part of the lathe that holds the tool post. The compound rest swivels to position the cutting tool and also makes smaller back-and-forth movements than the cross slide for making finer cuts.

Head

The part of the vertical milling machine that holds the spindle. The head also contains various speed and feed controls for the mill.

Threading

The process of cutting a long, helical groove into the exterior of a cylindrical workpiece with a single-point tool. Threading can also be an inner diameter operation, though outer diameter threading is more common.

OD Threading

The process of cutting a long, helical groove into the exterior of a cylindrical workpiece with a single-point tool. Threading can be an inner or outer diameter operation.

ID Threading

The process of cutting a long, helical groove into the interior hole of a cylindrical workpiece with a single-point tool. Threading can be an internal or outer diameter operation.

Tapping

The process of cutting internal threads in a round hole with a multi-point tool. Tapping is performed only after first drilling a hole.

Boring

The process of enlarging an existing hole with a single-point tool. Boring removes small amounts of material to achieve tight tolerances and finishes.

Square

The process of machining a workpiece to make the sides parallel and even. Squaring is most often performed by face milling on the manual mill.

Squaring

The process of making the sides of a part even and parallel using a face milling operation.

Readout

The process of reading information from a machine and displaying it in an understandable form. Readout measures locations and movements on a lathe and can be analog or digital.

Reaming

The process of using a fluted, multi-point tool to produce to remove small amounts of material from the interior surface of a hole. Reaming achieves tight tolerances and refined surface finishes.

Drilling

The process of using a multi-point, or multi-edge, tool to penetrate the surface of a workpiece and make a round hole. Common drilling operations include center drilling and twist drilling.

Chip Evacuation

The proper clearance of chips during a metal-cutting process. Chip evacuation can become an issue if the operation generates a lot of vibration, as with grooving, or when machining without enough cutting fluid, which can result in a damaged cutting tool or scrapped part.

Roundness

The quality of a cylindrical workpiece characterized by the entire length of the workpiece having the same diameter relative to a common axis. All points on the exterior surface of a perfectly round cylindrical workpiece are equidistant from the axis of the workpiece.

Rough Cuts

The quick removal of metal from a workpiece without regard to tolerances or finish. Rough cuts are made with high feed rates and large depths of cut.

Cutting Speed

The rate at which a single cutting edge of a cutting tool rotates in one minute. Cutting speed is measured in surface feet per minute (sfm) or meters per minute (m/min).

Tool Wear

The rate at which the cutting edge of a tool degrades during machining. Tool wear may result from improper speed and feed rates.

Feed

The rate at which the cutting tool advances along the workpiece per revolution or unit of time. Feed on the lathe is typically measured in inches or millimeters per revolution.

Spindle Speed

The rate at which the machine spindle rotates. Spindle speed is typically measured in revolutions per minute.

Spindle Feed

The rate at which the spindle moves in and out of the mill head. The spindle feed is controlled by the quill feed handle or the manual feed handwheel.

Machinability

The relative ease with which a machining process, such as milling or turning, can remove workpiece material. Machinability depends on the properties of the workpiece material.

Backlash

The relative movement of interlocked mechanical components due to slack, or extra space, between them. Backlash often occurs when motion is reversed.

Pitches

The relative quantity of teeth on the periphery of the milling cutter. Pitch ranges from coarse, with few teeth, to fine, with many teeth.

Display Panel

The screen that displays information about a machine for the operator. Display panels indicate the position of the workpiece on a manual milling machine.

Numerical Display Panel

The screen that displays information about a machine for the operator. Numerical display panels indicate the position of the cutting tool on an engine lathe.

Tap Drill Size

The size of the drill required to create a specific threaded hole. Tap drill size determines the size of the hole before tapping.

Finishing Material

The small amount of material that is intentionally left for a finishing pass. Finishing material is used to ensure good workpiece finish and tolerance.

Chip Clearance

The space necessary for the proper formation and evacuation of small pieces of metal cut from a workpiece. Chip clearance prevents chip jamming and cutting tool failure.

Part Zero

The starting point of X, Y, and Z coordinates for a specific workpiece. Part zero acts as a reference point for all part dimensions.

Brittle

The tendency to break when drawn, stretched, or formed. Brittle materials usually have higher levels of hardness.

Ballscrew

The threaded device that controls the precise movement of the various components of the mill. On the mill, ballscrews are connected to the feed handles and knee crank, which an operator rotates to move the worktable.

Drill Point

The tip of a drill that contains the cutting edges. The drill point performs all cutting as the drill moves into the workpiece.

Deflection

The unintended repositioning or bending movement of a drill due to mechanical force. Deflection of a drill can cause poor hole location and inaccurate hole dimensions.

Milling

The use of a rotating multi-point cutting tool to machine flat surfaces, slots, or internal recesses into a workpiece. Milling includes a wide range of versatile metal cutting operations.

Cutting

The use of single- or multi-point tools to separate metal from a workpiece in the form of chips. Cutting processes vary based on the requirements of a finished part.

Column

The vertical support, or backbone, of a milling machine. The column is supported by the machine base.

Abrasion

The wearing away or gradual removal of material from an object's surface. Abrasion can create a smooth or refined surface.

Touch Off

To determine the exact location of a tool tip by touching it against an object with a known measurement. To touch off establishes a starting point for the cutting tool on the workpiece.

Locate

To establish a designated location. Locating part zero sets a starting point on the workpiece for a manual milling operation.

Set Zero

To establish a starting point on a workpiece or machine by setting the coordinate values to zero. To set zero, or zero the tool, an operator positions the tool in a location and then resets the analog measuring devices or DRO display to zero.

Zero The Tool

To establish a starting point on a workpiece or machine by setting the coordinate values to zero. To zero the tool, or set zero, an operator positions the tool in a location then resets the analog measuring devices or DRO display to zero.

Retrofit

To modify a machine or tool with a new part. Retrofitting manual mills with quick-change tooling reduces the time spent changing toolholders.

Lubricates

To use a fluid to reduce the friction between components. Lubricating a cutting tool typically reduces resistance, heat, and wear.

Tailstock Sleeve

Tubing that fits into the tailstock of a lathe and moves towards and away from the headstock. The tailstock sleeve, also called a quill, can function as a toolholder.

Rotating

Turning in a circular motion. Rotating objects can be described as spinning.

Parallel

Two lines or axes that are equidistant from each other at all points along their length, and thus never intersect. On a horizontal mill, the spindle is parallel to the worktable.

Flush

Two or more level, adjacent surfaces. Flush surfaces form a flat plane.

Dovetail Ways

Two parallel angle-shaped rails that guide movement of a machine component. Dovetail ways help to keep the mill table aligned to the knee as it moves.

Box Ways

Two parallel box-shaped rails that guide movement of a machine component. Box ways help keep the mill table aligned to the knee as it moves and are also referred to as square ways.

Square Ways

Two parallel square rails that guide movement of a machine component. Square ways help keep the mill table aligned to the knee as it moves and are also referred to as box ways.

Parallel Faces

Two surfaces of a workpiece with all opposing points equidistant from each other. Parallel surfaces are often a requirement on cylindrical workpieces machined on an engine lathe.

Deflecting

Unintentionally deviating from a straight line or plane when a force is applied. Deflecting in drilling can cause poor hole location and dimensions.

Walking

Unintentionally moving off-center or away from the intended tool location. Walking is another term describing deflection.

Center-Drilled

Using a center drill to make a tapered hole in the end of a part. Once a part is center-drilled, the center can support it using the tapered hole.

Runout

When two rotating objects do not share the same axis of rotation. Runout determines the accumulated position error and deviation of a workpiece exterior or interior from a center axis as the workpiece rotates.

Helical

Winding around in the shape of a spiral, spring, or coil. End mill and drill flutes are helical.

Chip Load Per Tooth

clpt. The thickness of a chip, or amount of material, that is removed by one cutting edge of the tool. Chip load per tooth is also known as feed per tooth.

Feed Per Tooth

fpt. The thickness of a chip, or amount of material, that is removed by one cutting edge of the tool. Feed per tooth is also known as chip load per tooth.

Inches Per Minute

ipm. The distance that the cutting tool advances in one minute. Inches per minute is a standard measurement for the feed of a cutting tool on the lathe.

Inches Per Revolution

ipr. A measurement of how many inches a cutting tool advances along a workpiece in one revolution of that workpiece. Inches per revolution measures feed.

Meters Per Minute

m/min. The measurement of how many meters of workpiece material pass a cutting tool in one minute. Meters per minute measures cutting speed.

Millimeters Per Minute

mm/min. The distance that the cutting tool advances in one minute. Millimeters per minute is a metric measurement for the feed of a cutting tool on the lathe.

Millimeters Per Revolution

mm/rev. A measurement of how many millimeters a cutting tool advances along a workpiece in one revolution of that workpiece. Millimeters per revolution measures feed.

Revolutions Per Minute

rpm. A unit of measurement that indicates the number of revolutions a machine component makes in one minute. Revolutions per minute measures rotation from the center of a tool or spindle.

Surface Feet Per Minute

sfm. The measurement of how many feet of workpiece material pass a cutting tool in one minute. Surface feet per minute measures cutting speed.