Engine Lathe Basics 211

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. 4-position toolholders allow for quick tool changes and efficient machining operations.

apron

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

axis

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

bar stock

Raw material in the form of long bars or cylinders. Bar stock is commonly used in metal manufacturing processes.

bed

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

bench lathe

A smaller type of lathe. Bench lathes are used to produce smaller parts, such as for jewelry.

boring

A lathe cutting operation in which an existing hole is enlarged with a single-point tool. Boring is an internal diameter operation that removes a small amount of material to improve the surface finish and roundness of a hole.

boring bar holders

A toolholder that secures a boring bar for enlarging and finishing holes in a workpiece. Boring bar holders are a specialized toolholder for boring.

burrs

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

C axis

A rotational axis that describe motion around, or about, the Z axis. On an engine lathe, the C axis describes the spindle's rotation.

carbide

A common cutting tool material created by combining carbon with a hard metal, such as titanium or tungsten. Carbide cutting tools are the most commonly used in the metal cutting industry.

carriage

A component of the lathe that slides along the ways parallel to the spindle axis. The carriage houses the cross slide.

carriage assembly

The combination of the components that make up the carriage on an engine lathe. The carriage assembly contains the compound rest, cross slide, 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 carriage handwheel positions the cutting tool for cutting operations.

cartesian coordinate system

A numerical system that describes the location of an object by expressing its distance from a fixed position along three linear axes. The Cartesian coordinate system is used to properly align machining positions on a lathe.

center

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

center drill

A type of drill with a wide shank and a 60° angle tip. Center drills are used to start a hole and can be used to align the cutting tool to a center punch mark to ensure that the hole is machined in the right location.

center drilling

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

centerline

An imaginary line that runs through the axis of the lathe. The centerline helps to position the workpiece for accurate cutting.

chips

An unwanted piece of material that is removed from a workpiece. Chips form when a lathe cuts a workpiece.

chuck

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

clamp

A device that holds an object by applying downward or inward pressure. Clamps are often used as workholding devices in manufacturing.

collets

A workholding device composed of segments that tighten around a center hole with a fixed size. Collets can hold small and delicate workpieces.

compound rest

The mount for the tool post on an engine lathe. The compound rest allows for angular adjustment of the cutting tool.

computer numerical control

CNC. A programmable system of software and hardware that directs the operation of a machine. CNC machines are much more precise than their manual counterparts.

cross slide

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

cross slide handwheel

A hand-cranked wheel that moves the cross slide perpendicular to the workpiece. The cross slide handwheel moves the cutting tool toward or away from the workpiece.

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.

cutting speed

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

cutting tool

A device made of hard, tough material that removes material from a workpiece. Cutting tools are made out of different materials and can be single or multi-point tools.

cutting variables

A factor that affects how a cutting tool performs its job. Cutting variables include speed, feed, and depth of cut.

dead center

A center that remains stationary during a turning operation. The dead center is located in the tailstock spindle.

depth of cut

doc. The distance that a cutting tool penetrates the surface of a workpiece. Depth of cut determines the amount of material removed with each cutting pass.

drill chucks

A toolholder that tightens to grip holemaking tools. Drill chucks allow for the quick installation and removal of various tools, including drill bits, reamers, and taps.

emergency stop

E-stop. A button, pedal, or lever on the headstock of a lathe that automatically shuts off the power to the machine. Emergency stops can help prevent serious injuries.

engine lathe

The original and most basic type of manual lathe. Engine lathes hold a cylindrical workpiece on one or both ends.

E-stop

Emergency stop. A button, pedal, or lever on the headstock of a lathe that automatically shuts off the power to the machine. E-stops can help prevent serious injuries.

face

The flat, circular end of a cylindrical part. A part's face is machined during facing and turning operations.

faceplate

A circular workholding device with holes, slots, or both to allow the placement of fixture components. A faceplate is the most basic means of mounting a workpiece on the spindle of a lathe.

facing

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

feed

The rate at which a cutting tool travels along the length of a workpiece. Lathe feed measures a tool's linear travel across a workpiece surface.

feed rod

A long shaft that powers the carriage movement along the lathe for all turning operations except for threading. Feed rods may not be on all lathes because the leadscrew can be used for threading and other turning operations.

finishing

A cutting pass that emphasizes tight tolerances and smooth surface finish. Finishing is usually the final step in the machining process.

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.

gearbox

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

grooving

A lathe cutting operation that cuts a narrow channel into a rotating cylindrical workpiece. Grooving can be an inner or outer diameter operation.

hardness

A material's ability to resist indentation or scratching. An increase in hardness generally leads to an decrease in toughness.

headstock

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

high-speed steel

HSS. A common cutting tool material that is relatively inexpensive and offers excellent toughness. High-speed steel tools are used for general cutting operations.

holemaking

A lathe cutting operation that uses a single-point or multi-point cutting tool to create, size, or finish a hole. Holemaking includes drilling, boring, reaming, and tapping.

hollow spindle lathe

A type of lathe with a larger, hollow spindle. Hollow spindle lathes are used to machine larger, hollow workpieces.

horizontal

Parallel to the horizon or ground. A horizontal axis runs side-to-side rather than up-and-down.

ID operations

Inner diameter operations. Cutting operations that take place on the interior surface of a workpiece. ID operations on a lathe include drilling, reaming, boring, and tapping.

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.

indexable inserts

A removable, replaceable cutting tool with multiple edges that can be rotated into place. Indexable cutting inserts must be replaced or repositioned when a cutting edge wears out.

inner diameter operations

ID operations. Cutting operations that take place on the interior surface of a workpiece. Inner diameter operations, also known as internal diameter operations, on a lathe include drilling, reaming, boring, and tapping.

internal diameter operations

ID operations. Cutting operations that take place on the interior surface of a workpiece. Internal diameter operations, also known as inner diameter operations, on a lathe include drilling, reaming, boring, and tapping.

inverter lathe

A manual lathe with a spindle that rotates at high speeds to finish or polish a piece. Inverter lathes, also known as speed lathes, have fewer components compared to other lathes.

knurling

A lathe cutting operation that adds a texture on the exterior surface to produce better handling. Knurling is an outer diameter operation that slightly increases the workpiece's diameter by displacing material.

knurling toolholders

A toolholder that holds knurling tools, which create a texture on a workpiece for grip. Knurling toolholders are a specialized toolholder for knurling.

lathe

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

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.

leadscrew

A long threaded bar that transfers power between lathe components. The leadscrew is located beneath the lathe bed and extends from the headstock to the end of the lathe.

lever

A simple machine consisting of a rigid bar that pivots upon a fulcrum. Levers on the headstock of a manual lathe control speed and feed rates and direction.

live center

A center set on bearings that allows it to turn along with the workpiece. Live centers create less resistance during turning.

locate

To establish a designated location. Locating a workpiece ensures it will be machined to the correct specifications and tolerances.

machine guards

A rigid shield or cover that encloses hazardous areas on a machine. Machine guards prevent accidental machine contact with body parts and prevent debris, such as chips, from exiting the machine.

machine tool

A power-drive piece of metalworking equipment for cutting or forming metal, such as lathes, mills, and presses. Machine tools can hold a variety of cutting and manufacturing tools.

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 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.

motor

A machine that converts one form of energy into another. Motors may transform electrical energy into mechanical energy.

multi-point cutting tools

A cutting tool that has two or more cutting edges. Multi-point cutting tools used in holemaking include drills, reamers, and taps.

OD operations

Outer diameter operations. Cutting that takes place on the outer surface of a cylindrical or round workpiece. Turning, facing, and parting off are all examples of OD operations on a lathe.

outer diameter operations

OD operations. Cutting that takes place on the outer surface of a cylindrical or round workpiece. Turning, facing, and parting off are all examples of outer diameter operations on a lathe.

parallel

A set of lines, components, or axes that are equidistant from each other at all points along their length and thus never intersect. On an engine lathe, the Z axis is parallel to the ground.

parting off

A lathe cutting operation that uses a cutting tool to separate a finished part from the rest of the stock. Parting off is an outer diameter operation.

parting toolholders

A toolholder that secures parting tools or cut-off tools to separate a finished piece. Parting tooldholders are a specialized toolholder for parting off.

perpendicular

A set of lines, components, or axes that meet at a right angle. On a vertical lathe, the Z axis is perpendicular to the ground.

personal protective equipment

PPE. An article of clothing or device worn to minimize exposure to hazards and prevent injury. Personal protective equipment is essential for manual lathes because the moving parts are dangerous.

profile turning

A turning operation that uses a single-point tool to machine the outline of a part feature. Profile turning is used to produce intricate shapes.

prototyping

The process of creating a preliminary model of a part to evaluate its performance. Prototyping may be done on a manual lathe.

quick-change tool posts

A toolholder that uses a master toolholder that holds rapidly releasing interchangeable tool blocks. Quick-change tool posts increase production speed.

reaming

A lathe cutting operation that enlarges an existing hole with a multi-point tool by removing small amounts of material from the interior surface of a hole. Reaming is an internal diameter operation that achieves tight tolerances and refined surface finishes.

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 spindle speed.

rotational axes

An axis that describes rotation around a linear axis. The rotational axis for an engine lathe is C, which rotates the spindle.

roundness

The degree of circularity in a cylindrical hole. The roundness of a hole can be improved by boring and reaming.

saddle

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

safety glasses

A form of protective eyewear, usually made of thick plastic, that shields the eyes from flying debris and other potentially hazardous materials. Safety glasses protect machine operators from chips.

safety placards

A type of warning sign that communicates important information about hazards. Safety placards are important to read before operating a lathe.

single-point cutting tools

A cutting tool with a single cutting edge. Single-point cutting tools are primarily used for operations on a lathe.

speed dial

A mechanism on the headstock of a lathe that shifts the gears to control the spindle speed. Speed dials, also known as spindle speed selectors, usually have multiple speed ranges that should be chosen for the particular cutting operation.

speed lathe

A manual lathe with a spindle that rotates at high speeds to finish or polish a piece. Speed lathes, also known as inverter lathes, have fewer components compared to other lathes.

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 speed

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

spindle speed

The rate at which the spindle rotates. Spindle speed is measured in revolutions per minute (rpm).

spindle speed selector

A mechanism on the headstock of a lathe that shifts the gears to control the spindle speed. Spindle speed selectors, also known as speed dials, usually have multiple speed ranges that should be chosen for the particular cutting operation.

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. Station toolholders allow for quick tool changes and efficient machining operations.

support

The process of locating from underneath the workpiece. Some workpieces require additional support that turning between centers can provide for turning on a lathe.

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.

tailstock

A component of an engine lathe opposite the headstock that supports the end of longer workpieces. The tailstock can be fitted with a cutting tool.

tailstock handwheel

A hand-cranked wheel that moves the tailstock quill in and out. The tailstock handwheel brings the cutting tool in and out of contact with the workpiece.

tailstock quill

A component within the tailstock that slides in and out of the tailstock. The tailstock quill helps adjust the distance between the workpiece and the center.

taper turning

A lathe cutting operation that gradually increases or decreases the diameter along a length of the workpiece to create a conical shape. Taper turning is an outer diameter operation.

tapering

A lathe cutting operation that gradually decreases the diameter of a workpiece, creating a conical shape. Tapering is an outer diameter operation.

tapping

A lathe cutting operation that creates internal threads in a workpiece with a multi-point tool. Tapping is an internal diameter operation.

thread cutting

A method of producing threads by using cutting tools to remove material from a workpiece. Thread cutting generally involves the use of a lathe.

threading

A lathe cutting operation that cuts a long, spiraling groove into a cylindrical workpiece. Threading can be an inner or outer diameter operation.

three-jaw chuck

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

tolerance

A specification indicating an unwanted but acceptable deviation from a given dimension. Parts outside of a required tolerance must be discarded or reworked.

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 tool post.

tool geometry

The angles formed by the shape and positioning of a cutting tool. Tool geometry is a key factor in machining.

tool post

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

tool room lathe

A type of lathe that is highly precise. Tool room lathes are used to produce intricate parts.

toolholders

A component used to hold a cutting tool in place during machining. Toolholders for lathes depend on the cutting operation.

toughness

A material's ability to absorb energy without breaking or fracturing. Toughness is a key property that determines a material's ability to withstand a sudden stress.

turning

A cutting operation that rotates a cylindrical workpiece while gradually passing the cutting tool along the surface of the rotating part. Turning is performed on a lathe and is commonly used to create cylindrical parts.

turning

A lathe cutting operation that rotates a cylindrical workpiece while gradually passing the cutting tool along the surface of the rotating part. Turning is the most common cutting operation performed on a lathe.

turret

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

turret lathe

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

twist drill

A common drill characterized by helical flutes along its length and two cutting edges at the drill point. Twist drills are the most commonly used type of drill.

twist drilling

The use of a multi-point tool to machine a new round hole into the surface of a workpiece. Drilling is an internal diameter operation.

vertical lathes

A lathe with a spindle axis that is perpendicular to the ground. Vertical lathes are ideal for turning large and heavy workpieces.

ways

A set of parallel tracks that allow machine tool components to move accurately. The ways on an engine lathe allow the carriage and tailstock to move along the bed.

workholding

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

workpiece

A material being machined or undergoing another type of processing. Workpieces can be cut on a lathe.

X axis

An axis in the Cartesian system that measures movement towards or away from the Z axis. On an engine lathe, the X axis is where the cross slide moves on an engine lathe.

Z axis

An axis in the Cartesian coordinate system that represents motions and positions perpendicular to the X axis. On an engine lathe, the Z axis measures movement parallel to the workpiece and spindle.