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. These tools can then be selected by the lathe operator as required.

apron

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

bed

The base of the lathe. The base supports all of the other lathe components.

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.

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.

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.

boring

The process of enlarging an existing hole with a single-point tool. Boring is an internal diameter operation.

brazed

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

brazed-tipped cutting tools

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

carbide

A common cutting tool material that is used to make both indexable inserts and solid cutting tools. Carbide tooling can cut many materials at speeds up to four times faster than high speed steel.

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.

carriage assembly

The combination of the components that make up the carriage. The carriage assembly moves the cutting tool in relation to the workpiece.

carriage handwheel

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

cast iron

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

center

A toolholder with a 60° point, mounted in the headstock and tailstock that supports a workpiece at one or both ends. A center is inserted into holes drilled into the ends of the workpiece.

center drilling

Cutting a 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 to act as a pilot hole for drilling operations.

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.

centers

A workholding device with a 60° point. Centers can be mounted in the headstock and tailstock of a lathe.

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. A chuck commonly has two, three, or four jaws that can be adjusted to fit various workpieces.

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 mount for the toolpost. The compound rest moves perpendicular to the workpiece and can swivel to change the cutting angle.

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.

computer numerical control

CNC. A self-contained system of computers and precision motors that executes program instructions to guide machine tool components and manufacture parts. A computer numerical control machine is controlled using a combination of software and hardware.

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 feedwheel

A hand-cranked wheel that moves the cross slide back and forth, perpendicular to the workpiece. The cross slide feedwheel controls the cross slide.

cross slide feedwheel

A hand-cranked wheel that moves the cross slide on a lathe back and forth, perpendicular to the workpiece. The cross slide feedwheel controls the cross slide.

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.

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 inserts

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

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.

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 are either single or multi-point tools.

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.

cylindrical

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

dead center

A center that remains stationary during a turning operation. A dead center does not turn with the workpiece.

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 plunges into a workpiece.

diamond

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

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.

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.

engine lathe

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

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.

facing

A turning 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.

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.

feed

The rate at which a cutting tool travels along the length of a workpiece. Lathe feeds measure a tool’s linear travel across a workpiece surface.

feedwheel

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

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.

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.

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.

gearbox

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

gears

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

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.

headstock

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

high-speed steel

HSS. A category of tool steels used for cutting tool applications. Single-point tools are usually made from high-speed steel.

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.

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.

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

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

inner diameter

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

internal diameter

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

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.

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.

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.

live center

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

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.

Morse taper

A standardized tapered hole in the tailstock sleeve of a lathe that narrows to a point and holds tools or a center. A Morse taper allows the tool to lock in place and be easily removed with a fastener.

multi-point tool

A cutting tool with more than one cutting edge used to remove material. Multi-point tools include drill bits, tapping tools, and reamers.

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.

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.

operator

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

outer diameter

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

outer diameter

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

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.

personal protective equipment

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

quick-change gearbox

The location of the gears that control the power being transferred from the lathe 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 that holds rapidly releasing interchangeable toolholders. Quick-change tooling increases the production speed.

quill

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

reaming

The process of enlarging or smoothing an existing hole with a multi-point tool. Reaming is an internal diameter operation.

revolutions per minute

A unit of measurement that indicates the number of revolutions a machine component makes in one minute. Revolutions per minute is abbreviated rpm.

rotating

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

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.

saddle

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

single-point tool

A cutting tool that has a single cutting edge. Generally, single-point tools remain in constant contact with the part surface during operation.

spindle

The part of the headstock that rotates the workpiece. The spindle can be mounted with a faceplate or other workholding device to support the workpiece.

spindle

The part of the machine tool that spins. On the lathe, the spindle holds the workpiece.

spindle speed

The speed of a machine spindle. Spindle speed is measured in revolutions per minute.

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.

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.

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.

tailstock

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

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.

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.

tapping

The process of cutting internal threads in a workpiece with a multi-point tool. Tapping is an internal diameter operation.

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.

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.

tolerance

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

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.

toolholder

A mechanism used to rigidly hold a cutting tool in place during machining. Toolholders used in turning are the compound rest and the tailstock.

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.

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.

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.

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.

workholding

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

workholding

A method or device for securing a workpiece for a machining operation. Workholding can include chucks, vises, and bolts.

workpiece

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