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.

aluminum

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

axes

An imaginary straight line that is used to measure the location of an object in three-dimensional space. The Cartesian axes on an engine lathe are the X axis, Z axis, and C axis.

axial

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

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.

bar stock

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

bed

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

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.

brittle

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

burrs

A rough edge remaining on material, such as metal, after it has been machined. Burrs may cause injury and interfere with the fitting of parts.

C axis

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

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.

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.

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.

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.

carriage handwheel

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

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. Cartesian coordinates are used to direct machine tool movements.

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.

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.

centerline

An imaginary line that divides a shape into two equal halves or that runs through the center of a cylindrical object. A cylindrical workpiece rotates along a centerline.

centers

The device in a lathe that supports the end of a cylindrical workpiece opposite the spindle. The center is located in the tailstock.

chips

An unwanted piece of material that is removed from a workpiece. Chips are formed when a tool cuts or grinds a workpiece.

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.

chuck key

A device used to 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.

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.

collet

A slotted device that holds a workpiece or cutting tool in place as it rotates. A collet has a hole through which the workpiece or tool passes and is designed to hold specific dimensions.

compound rest

The part of the lathe that holds the toolpost. The compound rest makes smaller movements than the cross slide for making finer cuts.

concentric

Having a common center or sharing the same axis with another object. When the workpiece and lathe spindle share a common centerline, they are concentric.

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.

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.

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.

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 feedwheel brings the cutting tool into and out of contact with the workpiece.

cutting fluid

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

cutting inserts

A replaceable cutting bit or edge. Cutting inserts are often made from carbide.

cutting speed

The rate at which a workpiece and cutting tool move past one another at their point of contact. Cutting speed on a lathe measures the rate at which a workpiece rotates past a tool.

cutting tool

A device made of hard, tough material that is used to remove metal by creating chips. Cutting tools used for lathe operations are usually single-point tools such as carbide inserts.

cutting variables

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

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.

depth of cut

The amount of material removed from a workpiece in a single pass. The depth of cut is based on how far the cutting tool penetrates the surface of the workpiece during a cut.

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.

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.

dimensions

A measurement of space, especially length, width, and height. Dimensions of a part are detailed in a blueprint.

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.

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.

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.

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.

DRO

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

ductile

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

eccentric

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

engine lathe

The original and most basic type of manual lathe. An engine lathe holds a cylindrical workpiece on one or both ends.

facing

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

feed

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

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.

feeler gage

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

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.

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.

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.

form tool

A cutting tool ground to a specific shape that is used to machine a special pattern. A form tool makes the contour of its own shape in a workpiece surface.

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.

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.

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.

headstock

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

heat treatment

Controlled heating and cooling processes used to change a material’s structure and alter its physical and mechanical properties. Heat treatment often adjusts a material’s hardness.

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.

hexagonal

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

high-speed steel

HSS. A common cutting tool material that is relatively inexpensive and offers excellent toughness. Single-point tools are often made from high-speed steel.

ID

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

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 rotating 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.

independent chuck

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

indexable

Able to be rotated or changed. Indexable cutting inserts have multiple cutting edges that can be rotated as they wear down.

internal diameter

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

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.

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.

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.

lubricates

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

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.

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.

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.

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 when in automatic mode.

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 rotating 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.

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.

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.

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.

OD

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

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.

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.

operator

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

origin

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

outside diameter

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

parallel

Two lines or axes that are equidistant at all points along their length. Parallel lines, axes, or components never touch or intersect.

perpendicular

Meeting at a 90° angle. The cross slide movement is perpendicular to the spindle axis.

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.

print

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

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.

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.

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.

radial

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

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.

radius

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

reamer

A mutli-point cutting tool with straight cutting edges used to enlarge or smooth holes that have been previously drilled. A reamer can be installed in the lathe’s tailstock.

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.

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.

rpm

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

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.

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.

saddle

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

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.

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.

setup

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

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.

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.

soft

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

specifications

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

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.

spindle speed

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

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.

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.

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.

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.

tailstock

A toolholder and mount opposite from the headstock. The tailstock can hold a center to support long workpieces or cutting tools, such as a drill bit.

threaded spindle noses

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

threads

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

three-dimensional

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

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.

tool post

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

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.

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.

turning

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

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.

workpiece

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

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 that represents up and down movement, perpendicular to the X axis. The Y axis is not utilized on a manual 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.

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 and then resets the analog measuring devices or DRO display to zero.

diameter

The distance from one edge of a circle to the opposite edge that passes through the center. The diameter divides the face of a cylindrical workpiece into two equal halves.

diameter

The distance from one edge of the circle to the opposite end through the center. The diameter is always twice the size of the radius.

workholding device

A device for locating and supporting a workpiece for cutting operations. Common workholding devices in turning are chucks, collets, and centers.

workholding device

A device used to secure a workpiece for a machining operation. Workholding devices include chucks, vises, and bolts.