Chucks, Collets, and Vises 141

adapter

A metal sleeve that allows collets to fit properly in a spindle nose. The adapter attaches to the draw bar to open and close the collet jaws.

adapter plates

A circular metal device with a set of holes that are compatible with a chuck and another set of holes that are compatible with a spindle nose. Adapter plates, or backing plates, are used to provide additional setup stability or to connect otherwise incompatible parts.

air pressures

The force created by air at a specific location and in a specific amount of space. Air pressure can change through compression of air or a temperature change.

aluminum

A nonferrous, silvery-white metal that is lightweight, highly conductive, and non-magnetic. Aluminum is often used to make soft chuck jaws.

angle plates

A workholding device that consists of two surfaces connected at a 90° angle. Angle plates can securely hold rectangular workpieces or raise a workpiece from the worktable surface.

assembly

The larger, completed part created from fitting components together. Assemblies for collets include the collet closer, which has a draw bar and lever, and the Jacob's spindle-nose collet assembly, which as a handwheel and nose.

axis

An imaginary straight line that passes through an object. The axis of a workpiece on the lathe, often called the centerline, runs through the center of the part, either lengthwise or width-wise.

backing plates

A circular metal device with a set of holes that are compatible with a chuck and another set of holes that are compatible with a spindle nose. Backing plates, or adapter plates, are used to provide additional setup stability or to connect otherwise incompatible parts.

bar feeding

The process of running a long piece of bar stock through a machine to create multiple parts in the same operation. Bar feeding is more accurate with collets than chucks because collets automatically locate workpieces more precisely.

bed

The main supporting structure upon which the operating parts of the machine are mounted and guided. The bed of the lathe holds the headstock and tailstock and can hold rests as well.

bolts

A cylindrical threaded device used for fastening parts. Bolts are often used to connect chucks to the spindle nose.

boring

The process of enlarging an existing hole with a single-point tool. Boring is commonly performed on a lathe.

camlocks

A type of fastener with a rotating tab that fits into a compatible slot. Camlocks are often used to secure chucks to lathe spindle noses.

cast

Made though a manufacturing process in which liquid material is poured into a hollow mold and left to solidify into a solid part. Cast parts tend to have rough surface finish, making them better suited for machining with four-jawed chucks that can more accurately position them.

centerline

An imaginary straight line that passes through the rotating cylindrical workpiece. The centerline, sometimes called an axis on lathe workpieces, divides a shape into two equal halves.

centers

Positions a workpiece on a lathe so that it has the same axis as the machine tool. Operators must center workpieces for lathe operations to ensure that they are machined correctly.

charged

Possessing an electrical charge, either positive or negative. Charged materials can be attracted or repelled by a magnet.

chuck key

A device used to loosen or tighten the jaws on a chuck. A chuck key must be removed from the chuck before starting a machine.

chucks

A circular workholding device that secures a workpiece as it rotates on a lathe or other machine. Chucks commonly have three to four adjustable jaws that can be moved to clamp and secure a variety of workpiece shapes and sizes.

circular jaws

A chuck jaw with a curved edge that covers a larger portion of the workpiece diameter or width. Circular jaws, or pie jaws, provide excellent support and positioning but are more time-consuming to set up.

clamp

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

clamping ranges

The difference between a vise's most open position and its closed position. Clamping range determines the workpiece size the vise can hold.

clamps

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

clearance

The space between two objects. Clearance provided by collets is greater than chuck clearance because collets do not have protruding jaws.

CNC

Computer numerical control. A programmable control system for a machine tool, directed by mathematical data, that uses microcomputers to machine parts. A CNC machine is much quicker and more accurate than its manual counterpart and has unique setup considerations.

collars

A circular component that surrounds and supports another component. Collars include the openings on collet faces, which surround and grip a workpiece during manufacturing operations.

collet chuck

A type of metal collet that is set in an adapter or adapter plate that is in turn attached to the lathe. Collet chucks are the most commonly used form of collet.

collet closer

A device consisting of a draw bar and lever or handwheel that is used to make a lathe collet grip. The collet closer is attached to the headstock of a lathe.

collet rig

The various components required to set up a lathe to use a collet. Collet rigs can be simple, such as for collets with rubber collars, or complex, such as for collets that require a draw bar.

collets

A cylindrical workholding device that is a hollow metal tube used to hold small, fragile, or thin-walled workpieces. Collets come in a variety of sizes and generally have center holes that fit a workpiece of a certain dimension.

column

The rigid, vertical support section of the machine. Columns suspend tools over the workpiece on a mill.

combination chucks

A round lathe workholding device with jaws that can be adjusted independently or in unison. Combination chucks are more complex mechanisms and therefore more expensive and prone to error.

composition

The material makeup of an object. Composition affects the mechanical and physical properties of an object, such as its level of hardness and electrical conductivity.

compress

To push or press a material together. All collets are compressed, by various mechanisms, in order to grip the workpiece.

computer numerical control

CNC. A programmable control system for a machine tool, directed by mathematical data, that uses microcomputers to machine parts. A computer numerical control machine is much quicker and more accurate than its manual counterpart and has unique setup considerations.

connecting rod

An optional component in a collet rig that provides support for the collet closer. Connecting rods are attached directly to the lathe headstock and the collet closer.

contouring

The movement of a cutting tool along two or more axes simultaneously. Contouring is a lathe or mill operation used to create curved, non-linear features.

contours

A curved, non-linear dimension created by a cutting process. Contours can be created by precise tool movements in milling.

copper

A reddish, nonferrous metal that is ductile, thermally and electrically conductive, and corrosion resistant. Copper is a soft metal and sometimes used to make soft jaw covers for vises.

crank

A metal rod or rotating wheel used to open or close a vise. Cranks, or handles, shift the movable vise jaw along a screw.

crankshafts

A shaft that converts piston motion to rotary motion within an internal combustion engine. Crankshafts have complex, asymmetrical shapes that are created through eccentric turning.

customized

Created specially for a specific machine or customer. Adapters sometimes need to be customized to allow an operator to use a collet on a particular lathe.

cutting forces

The various stresses involved in a machining process. Cutting forces are determined by a combination of speed and feed rate, tool angle, workpiece material, and other factors.

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.

defective

Rendered unusable due to poor tolerance or damage. Defective parts must be discarded or reworked, which increases the costs of a manufacturing operation.

dial indicator

A measuring instrument with a contact point attached to a spindle and gears that move a pointer on the dial. Dial indicators are used to check center alignment or runout on a workpiece in a lathe.

diameter

The distance from one edge of a circle to the opposite edge, as measured through the center. Diameter describes the size of a cylindrical or round workpiece.

dimensions

The measurements of a part. Dimensions are typically indicated in length, width, and height.

draw bar

A hollow metal cylinder that runs through the headstock and attaches to the collet adapter in order to make the collet grip. Draw bars can be manual or powered.

eccentric turning

A machining process in which the workpiece is intentionally rotated off-center from the machine's axis. Eccentric turning is used to create parts with asymmetrical features, such as crankshafts.

electromagnetic chucks

A chuck that uses magnets that are activated when an electric current runs through them to hold a workpiece. Electromagnetic chucks have particularly strong gripping capabilities.

faceplates

A special fixture that is designed to hold a workpiece as it rotates on the lathe. Faceplates have a series of slots to which operators can bolt the workpiece.

features

A defining characteristic on a part, including corners, edges, holes, and grooves. Features must be precisely placed on a part, which can be ensured through the use of proper workholding.

feed

The rate at which a cutting tool moves along a workpiece in turning, milling, and grinding or into a workpiece in drilling. Feed is often measured in inches per minute (ipm), or millimeters per minute (mm/min), or in inches per revolution (ipr), or millimeters per revolution (mm/rev).

ferrous metals

A metal containing iron, generally as a primary ingredient. Ferrous metals are usually magnetic.

fixtures

A workholding device that can be customized to hold uniquely shaped workpieces. Fixtures include angle plates for the mill and faceplates for the lathe.

follow rests

A rest that moves along the workpiece in a machining operation. Follow rests are usually set up to move with the cutting tool, providing a large amount of support for a workpiece at the point of cutting.

foot pedal

A machine switch operated by exerting pressure with a foot. Foot pedals are sometimes used to activate hydraulic or pneumatic pumps for lathe chucks.

gage head

The component on a dial indicator at the end of the thin spindle that makes contact with the workpiece. Gage heads are spring-loaded so that they can move with variations in workpiece position.

grinding

A machining process in which an abrasive is used to precisely cut and shape the surface of a workpiece. Grinding operations commonly use chucks, collets, and vises as workholding.

gripping face

The surface of the chuck jaw that comes into direct contact with the workpiece. Gripping face size, number, and type varies depending on the jaw.

grooves

A narrow channel in the surface of a part. Grooves are cut into the face of independent chucks to help operators position the jaws.

grooving

The process of using a lathe to cut a channel or passageway into the inner or outer surface of a cylindrical workpiece. In grooving, the tool is fed into the rotating workpiece radially to a specified dimension.

handle

A metal rod or rotating wheel used to open or close a vise. Handles, or cranks, shift the movable vise jaw along a screw.

handwheel

A circular device that is turned by hand in order to control a machine component. Handwheels are sometimes used to tighten or loosen the collet closer around a collet.

hard jaws

A chuck jaw made of a material that resists penetration, indentation, or scratching. Hard jaws, usually made of hardened steel, provide rigid support for workpieces but cannot be machined.

hardened steel

A carbon steel that has undergone heat treatment, tempering, and quenching in order to change the physical and mechanical properties of the steel. Hardened steel usually has improved hardness and strength compared to other forms of steel.

headstock

The end of a lathe that holds the spindle and spindle drive that rotate the workpiece. The headstock is the end of the machine where operators mount the chuck.

heavy-duty machining

A machining process that takes place at high speeds and heavy feeds. Heavy-duty machining requires a firm grip on the workpiece, provided by devices such as a Jacob's spindle-nose collet.

hexagonal

Six-sided. Hexagonal workpieces can be held by self-centering or independent chucks with three or more jaws.

hydraulic

Power created by the motion and pressure of fluids. Hydraulic force can be used to help chucks grip a workpiece more securely.

independent chuck

A round lathe workholding device with jaws that open and close individually. Independent chucks require more operator intervention but center workpieces more accurately than self-centering chucks.

inner diameter

ID. The interior surface of a hole or cylindrical feature. Inner diameter cutting operations include drilling, boring, and tapping.

inward force

A force that compresses an object. Inward force is exerted by a chuck clamped to the exterior of a workpiece.

Jacob's spindle-nose collet

A type of rubber and metal collet that is set in the spindle with an assembly that includes a handwheel. Jacob's spindle-nose collets allow for easy changing of the collet and a strong grip on the workpiece.

jaws

The component on a chuck that makes contact with and holds the workpiece. Jaws on a chuck can be straight or stepped or the can be hard or soft.

lathe

A machine used to create parts, often cylindrical, by removing material from a workpiece. A lathe holds a rotating workpiece while the cutting tool is either fed into the workpiece or along its side.

lathe centers

A hardened, pointed, cylindrical component used to hold one or both workpiece ends during a machining operation. A lathe center's tip is inserted into a hole on the end of a workpiece.

locating

Establishing a workpiece in a set position. Locating a workpiece correctly ensures it will be machined or otherwise manufactured to the correct specifications and tolerance.

locking screw

A screw used to fix the collet closer in a particular position. Locking screws are set into their locked position to hold the shell guard in place when the collet is properly gripped in the spindle.

low-carbon steel

A carbon steel that contains less than 0.30% carbon. Low-carbon steels are generally tough, ductile, and easily machined.

machining

The process of creating a part through the removal of material. Machining processes include turning, milling, drilling, and grinding.

magnetic chucks

A workholding device that uses the force of attraction between two metals to hold a workpiece. Magnetic chucks can be made using permanent magnets or electromagnets.

magnetism

The power of attraction and repulsion that exists in materials. Magnetism most often occurs between metals.

magnets

A material that has a field that attracts or repels iron or other magnetic substances. Magnets are used to secure magnetic workpieces with magnetic chucks.

mandrel

A workholding device that is threaded through a workpiece and held between two centers on a lathe. Mandrels are most useful for lathe operations with symmetrical, cylindrical workpieces.

mechanical

Using physical force. Mechanical tightening is used in all chuck setup operations.

mill

A machine that uses a rotating multi-point tool to remove metal from the surface of a workpiece. Mills most commonly use vises as their standard workholding device.

mounting holes

An opening on the vise that provides room for the bolt used to secure the vise to the worktable. Mounting holes are usually located on the side of the vise, often with one on each side.

multi-point tool

A metal cutting tool that has two or more cutting edges. Mill cutting tools, drills, and reamers are all examples of multi-point tools.

nose

A metal or rubber ring that sits over the collet to hold it in place, and sometimes tighten its grip, in some collet assemblies. The nose holds the collet in place for Jacob's collets and collets with rubber collars.

notched

Having a series of small groves. Notched jaws provide a firmer grip than smooth jaws but are less likely to damage the workpiece surface than serrated jaws.

nuts

A hexagonal fastening device with internal threads that mate with a bolt or screw. Nuts are used to secure workholding to the mill worktable.

operators

A person responsible for running a machine properly, safely, and efficiently. Operators are often responsible for correctly securing the workpiece in a workholding device.

outer diameter

OD. The exterior surface of a workpiece. Outer diameter cutting operations include turning, facing, and parting off.

outward force

A force that expands an object. Outward force is exerted by a chuck set and opened in the interior of a workpiece.

parallel

Extending in the same direction and equidistant at all points. Parallel lines or objects never intersect.

permanent magnet chucks

A chuck that uses two sets of permanent magnets to hold a workpiece. Permanent magnet chucks are activated when an operator rotates a lever that lines up the sets of magnets in the chuck.

perpendicular

An intersection of two lines or objects at a right, or 90°, angle. Vises are often set perpendicular to the mill's column.

pie jaws

A chuck jaw with a curved edge that covers a larger portion of the workpiece diameter or width. Pie jaws, or circular jaws, provide excellent support and positioning but are more time-consuming to set up.

pivot

A set point that allows an object to move around a fixed position. Operators tighten one nut on a bolt threaded through a vise's mounting hole so that the bolt acts as a pivot when the vise is tapped with a positioning hammer.

pneumatic

Power created by the motion and control of gas, often air, under pressure. Pneumatic force can be used to help a chuck grip a part more securely.

pockets

An interior recess in the surface of a workpiece. Pockets may be round, rectangular, or irregular and generally are created using an end mill.

positioning hammer

A hammer made of a soft material, such as rubber, that will not damage an object upon impact. Positioning hammers are used to tap vises into their correct location on the mill worktable.

pressure

A force or stress exerted on a workpiece. Pressure caused by tool contact with a workpiece can result in the workpiece bending or otherwise deforming if not properly secured in workholding.

prototypes

A preliminary model used to evaluate the look and performance of a design. Prototypes often require unique or flexible workholding, such as universal vises.

range

The difference between the smallest and the largest values within a numerical set. Range for a chuck indicates the smallest and largest workpiece diameter or width it can safely hold.

reaming

The process of enlarging an existing hole with a multi-point tool. Reaming is performed to improve the surface finish and concentricity of a hole.

repeatability

The ability of a machine or process to continually deliver accurate and precise results. Repeatability is higher when operators limit setup changes between operations, such as using the same chuck settings for a series of similar parts.

rests

A device used to support long workpieces on a lathe. Rests are circular in shape with adjustable fasteners or wheels that are tightened to grip the workpiece.

reversed

Turned completely, or 180°, around. Reversed stepped jaws have one gripping face similar to a standard jaw.

rigid

Stiff and inflexible. Rigid machine setups, such as using hard jaws on a chuck, lead to parts with better tolerance.

rubber

An elastic material made from organic or artificial latex. Rubber changes shape and compresses more easily, providing a better grip than metal when tightened around a workpiece.

runout

A difference in the axis of rotation for two objects. Runout on a lathe indicates the separation between the workpiece axis and the lathe machine axis.

scroll chuck

A round lathe workholding device with jaws that open and close in unison. Scroll chucks, or self-centering chucks, automatically center workpieces, but are less accurate than other workholding, such as independent chucks.

scroll plate

A threaded circular device in self-centering chucks that holds and moves the jaws. The scroll plate turns when the operator turns the chuck key.

securing

Holding an object firmly in place. Securing of a workpiece is often accomplished through the clamping pressure of a workholding device.

self-centering chuck

A round lathe workholding device with jaws that open and close in unison. Self-centering chucks, or scroll chucks, automatically center workpieces, but are less accurate than other workholding, such as independent chucks.

serrated

Having a series of connected, usually similarly sized, jagged edges. Serrated edges on chuck jaws give them a firmer grip.

setup

The position of tooling and fixturing for a machining operation. Operators need to evaluate and adjust the setup of workholding to ensure proper shaping of the workpiece.

shell guard

A rotating, cylindrical component located at the back of the collet closer. The shell guard is turned to connect the threads of the draw bar and the collet, which also allows operators to tighten the collet grip.

sleeves

A tubular metal part designed to fit over another component. Sleeves include collets, which are hollow metal tubes that fit over a workpiece.

small-batch runs

A production of a limited number of parts, usually under 500. Small-batch runs are often made using flexible workholding devices to facilitate quick production without creating dedicated workholding devices.

smooth

Flat and even. Smooth surfaces do not grip well, which reduces workholding stability but also decreases workpiece marring.

soft jaw covers

A device that fits over the jaw of a vise to protect the workpiece. Soft jaw covers are made of softer materials, such as aluminum or copper, that do not damage the workpiece as harder material might.

soft jaws

A chuck jaw made of a material that can more easily be bent, penetrated, or scratched. Soft jaws can be machined to the exact dimensions of a workpiece.

speed

The rate at which a workpiece rotates past the cutting tool in turning or the rate at which the tool rotates in milling, drilling, and grinding. Speed is often measured in revolutions per minute (rpm) in turning, milling, and grinding and in surface feet per minute (sfm), or meters per minute (m/min), in drilling.

spindle

The part of the machine tool that spins or rotates. On the mill, the spindle holds a cutting tool, while on the lathe, the spindle holds the workpiece.

spindle nose

The component of the spindle onto which the workholding device is mounted. Spindle noses can be threaded or tapered.

stability

The ability to remain firmly in position. Stability is improved in lathe operations through the use of hard jaws, which limit workpiece movement.

standard jaws

A chuck jaw with a single flat or slightly curved gripping face. Standard jaws allow for good repeatability but have more limited range.

standard vises

A vise that can only open and close its movable jaw. Standard vises are the most commonly used type of vise.

steady rests

A rest that remains in place during a machining operation. Steady rests are easier to set up than follow rests but provide less support.

step chucks

A type of collet that must be machined to a specific workpiece shape and dimension. Step chucks, also known as step collets, allow for precise gripping of unique workpieces.

step collets

A type of collet that must be machined to a specific workpiece shape and dimension. Step collets, also known as step chucks, allow for precise gripping of unique workpieces.

stepped jaws

Designed to have a series of flat gripping faces connected at 90° angles similar to stairs. Stepped jaws allow operators to select between various ranges on the same chuck.

supporting

Reinforcing an object against external forces. Supporting a workpiece prevents it from deforming during a manufacturing operation.

supports

A device used to raise a workpiece out of a mill's jaw and prevent the workpiece from becoming deformed. Supports must be level and, when using more than one, parallel.

surface finish

The degree of smoothness on a part's surface after it has been machined or otherwise shaped. Surface finish can be improved through final machining processes such as grinding.

swivel vises

A vise that can rotate around a vertical axis, in addition to opening and closing its movable jaw. Swivel vises allow operators to more easily make cuts at angles on a workpiece surface.

symmetrical

A quality in which all the features on either side of a point, line, plane, or blueprint are identical. Both sides of a symmetrical part have the same dimensions.

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.

tapping

A metal cutting process that uses a rotating multi-point tool to produce internal threads in a workpiece. Tapping is performed only after first drilling a hole.

threaded

Having a long spiraling groove. Threaded objects can be securely connected to other compatible threaded objects.

threaded fasteners

A reinforcing device with uniform spiraling grooves that can be turned into and out of another component. Threaded fasteners, such as bolts and screws, are used to connect workholding devices and support workpieces.

tilt

Set at an angle. Universal vises allow operators to tilt a workpiece and create angled features and cuts.

T-nuts

A type of nut that is shaped to precisely fit in a T-slot. T-nuts allow operators to mount workholding anywhere in a T-slot on the mill worktable.

tolerance

The acceptable variation from a specified dimension. Tolerances represent the amount a part can deviate from its specifications and still perform its desired function.

T-slots

A T-shaped opening that runs the length of a machine table or through a lathe faceplate. T-slots enable machinists to clamp vises and other workholding components onto the table or faceplate.

turning

A machining operation in which a workpiece is rotated on a lathe while a single-point tool is guided along the workpiece. Turning is one of the most common machining operations and often uses chucks and collets as workholding.

universal vises

A vise that can open and close its movable jaw, move around a vertical axis, and tilt at a variety of angles. Universal vises allow for the most flexibility in shaping a part but are less stable compared to other vises.

vacuum

An area with negative or low air pressure. Vacuums draw air rapidly from areas with greater air pressure, creating suction.

vacuum chucks

A workholding device that uses the force of suction to hold a workpiece. Vacuum chucks create different air pressures between two areas in the device, which in turn generates suction.

vises

A workholding device with two jaws, usually one fixed and one movable, that grip and hold a workpiece in place. Vises are often used to hold workpieces for milling, drilling, or grinding operations.

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.

width

The thickness of a rectangular or irregular part. Width is usually a measurement of the size of the part from one side to another, rather than from end to end.

workholding

The process of securing, supporting, and locating a workpiece for a manufacturing operation. Workholding helps to ensure that parts are created accurately and with good repeatability.

workholding device

A component used to secure, support, and locate a workpiece during a manufacturing operation. Common workholding devices include chucks, collets, and vises.

workpiece

An unfinished part that is subjected to one or more manufacturing operations in order to create a finished part. Workpieces can be shaped and finished through the various machining operations.

worktable

A component on a mill that supports the workpiece and any workholding device during machining. Worktables on the mill have T-slots that allow operators to attach a range of workholding devices.

wrench

A type of manual assembly tool that turns and tightens bolts and nuts. Wrenches can have fixed or moving jaws or a round attachment that grips nuts or bolts of a specific size.