Manual Mill Setup 221

adjusting screws

A screw that gradually moves a machine component with each turn. Adjusting screws on a manual mill allow you to align the mill head.

align

To accurately position machine components. Aligning the mill head to the worktable is an important step of manual mill setup.

alignment

The accurate positioning of machine components. Alignment ensures accuracy for machining operations.

alignment pin

A cylindrical metal rod that secures a workpiece or workholding device into position. Alignment pins fit into a worktable's T-slots to securely hold a workpiece.

angle milling

A cutting operation that removes material at a specific angle, opposed to a standard 90° angle. Angle milling requires that the mill head be tilted at a specific angle.

axes

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

axial rake angle

The tool angle formed by the tilt of the leading peripheral edge and a line parallel to the center axis. The axial rake angle describes how far the tooth face leans forward or backward.

backlash

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

blueprint

A design representing the dimensions of a specific finished part. Blueprints include part drawings, dimensions, and notes.

brittleness

A material's tendency to break when drawn, stretched, or formed. An increase in brittleness accompanies an increased hardness and tendency to fracture.

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. Cartesian coordinates are used to direct machine tool movements.

centerline

An imaginary line that defines the theoretical center of an object. The centerline of an edge finder pin is aligned to the part edge when the pin jumps off.

chip evacuation

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

clamp bolts

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

climb milling

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

coarse pitch

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

collets

A slitted device that expands or contracts to securely hold a cutting tool or workpiece. Collets, on the mill, hold tools in the spindle.

combination set

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

computer numerical control

CNC. A programmable system of software and hardware that directs the operation of a machine. Computer numerical control systems use mathematical data to direct machine movements.

concentric

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

conventional milling

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

cosine effect

The measurement error that occurs in a lever-type indicator from not aligning the direction of the feature being measured with the indicator tip. The cosine effect causes the indicator to read less than the actual displacement.

cross handwheel

The handwheel located on the front of the mill that moves the table in the Y axis. The cross handwheel moves the table forward and backwards.

cutting fluid

A liquid used to cool or lubricate a metal cutting process. Cutting fluids are typically oil-based, water-based, synthetic, or a blend of liquids.

cutting forces

A force generated by the motion of the cutting tool and the resistance of the workpiece. Cutting forces are affected by rake and relief angles as well as cutting speed.

cutting speed

In milling, the rate at which a single cutting edge of a cutting tool rotates past the workpiece. Cutting speed is measured in surface feet per minute (sfm) or meters per minute (m/min).

cutting tools

A device with one or more sharp edges that removes material in the form of chips to shape a part. Cutting tools are either single-point or multi-point tools.

deburr

A finishing process that removes sharp projections left by a tool on a workpiece surface or machine table. Deburring can be done by hand or in mass finishing processes.

depth of cut

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

dial indicator

An instrument capable of measuring variance in distances and angles. Dial indicators have multiple uses for manual mills, including fine positioning and alignment.

digital readout

DRO. A type of readout that uses an encoder attached to a machine that transfers information to a digital display. Digital readout provides the position of the mill's axes.

dowel pins

A short, cylindrical rod. Dowel pins are fitted tightly into T-slots on a mill to keep the workpiece parallel while clamped.

drawbar

A long metal bar that is threaded through the spindle and pulls the toolholder into a seated position. Drawbars secure the toolholder in the manual mill.

drawbar head

A hex head on top of the drawbar used to loosen or tighten it. The drawbar head has a hexagonal, or six-sided, shape.

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.

drip method

A manual way of applying cutting fluid 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.

dual dial indicator

A measuring tool with two dial indicators that attach into the spindle for tramming. A dual dial indicator is more expensive than a standard dial indicator but speeds up tramming.

eccentric rotation

Rotating in an erratic, non-circular motion. Eccentric rotation is the opposite of concentric rotation.

edge finder

A rotating rod-shaped tool that contains a pin used to locate the exact position of a part edge. An edge finder, also known as a wiggler or wobble finder, is commonly used in milling to locate part zero.

end mill

A narrow cutting tool that can be used to machine grooves, slots, pockets, and contours into workpieces. An end mill has one or more flutes.

end mill holders

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

face mill

A milling cutter that cuts metal with its face, or bottom edge. Face mills often use cutting inserts and are good for creating wide, flat surfaces.

face mill assemblies

A manual mill component that includes a face mill cutting tool and a conical toolholder in one setup. The toolholder of a face mill assembly may also be called a face mill arbor.

features

A component's design specifications intended for specific functionality or enhanced capability. Features include holes, threads, and walls.

feed

The rate at which the cutting tool and the workpiece move in relation to one another. Feed in milling operations often describes a linear movement of the cutting tool or worktable.

feed per revolution

fpr. The linear distance that a tool advances during one rotation of the workpiece or cutting tool. On the mill, feed per revolution may be used to convert feed per tooth (fpt) to either inches per minute (ipm) or millimeters per minute (mm/min).

feed per tooth

fpt. The linear distance traveled by the cutter during the engagement of a single cutting tooth. Feed per tooth is the feed measurement for multiple cutting edge tools.

fine pitch

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

finishing

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.

fixed jaw

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

flood cooling

A coolant-delivery method that completely covers the cutting zone with cutting fluid. Flood cooling is the least commonly used fluid delivery system for manual milling.

flutes

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

grade

A type or category of cutting tool material specified for a particular use. The grade of a material indicates different types of carbide inserts.

hardness

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

heel

The back portion of a clamp that may go on a step block. The heel of a clamp should be slightly higher to apply downward force to the workpiece.

helical rake angle

The angle created by the center axis of the tool and the slope of the peripheral cutting edge. The helical rake angle, also known as the helix angle, can affect the strength of the cutting edge on a mill, among other properties.

helix angle

The angle created by the center axis of the tool and the slope of the peripheral cutting edge. The helix angle, also known as the helical rake angle, can affect the strength of the cutting edge on a mill, among other properties.

hex key

A hexagonal wrench that is used to fasten a compatible hex socket. Hex keys can be used to tighten an indexable insert into place.

high-speed steel

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

holemaking

A machining operation in which a single- or multi-point cutting tool creates, sizes, or finishes a hole. Holemaking includes drilling, boring, reaming, and tapping.

horizontal column and knee mill

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

impact resistance

A material's ability to withstand sudden shock or impact without deforming or breaking. Impact resistance indicates the amount of impact a material can withstand without deforming or breaking.

inch

in. A small unit of linear measurement in the English system. One inch equals approximately 2.54 centimeters in the metric system.

inches per minute

ipm. An imperial unit of measurement that indicates how many inches a tool travels in one minute. Inches per minute is used to measure feed.

indexable inserts

A cutting tool with multiple cutting edges that you can rotate into place as each becomes worn. Indexable inserts function as replaceable cutting edges on face mills and other tools.

indicator pin

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

keyways

A slot or groove in a machine part that fits into the corresponding path of another machine component. Keyways are located in the drawbar and toolholders for mills.

kick

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

knee crank

A handle that raises and lowers the knee and worktable of a manual milling machine. Knee cranks allow operators to adjust the feed rate in the Z axis incrementally.

lead angle

The angle formed by the tilt of the side flank of the insert and a line parallel to the center axis of the cutter. The lead angle helps determine depth of cut and the strength of the cutting forces generated during machining.

leadscrew

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

length-to-diameter ratio

L/D ratio. A numerical expression of the relationship between the length and diameter of an object. Higher length-to-diameter ratios offer less rigidity.

lever

A simple machine consisting of a rigid bar that pivots around a fixed point. Lever-style indicators are sensitive to angles.

linear

In a straight line along a single axis. Linear workpieces may be rectangular or bar-shaped.

lubricates

To use a substance 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.

machining

A manufacturing process that involves removing material to form an object. Machining includes methods such as milling, turning, and drilling that remove metal using cutting tools.

meters per minute

m/min. A metric system measurement of cutting speed describing the distance in meters that the cutting edge travels in one minute. Meters per minute is dependent on both spindle rpm and cutting tool diameter.

mill

A machine that uses a rotating, multi-point cutting tool to remove material from a workpiece. Mills, or milling machines, may be operated either manually or by computer numerical control (CNC).

millimeter

mm. A small unit of linear measurement in the metric system. One millimeter equals approximately 1/1000 meter, or 0.039 of an inch in the English system.

millimeters per minute

mm/min. A metric unit of measurement for feed that indicates how many linear millimeters a tool travels in one minute. Millimeters per minute is used to measure feed.

mist cooling

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

multi-point tool

A cutting tool that has two or more cutting edges. Multi-point tools include mills and drills.

negative axial rake angle

A measurement that indicates a tooth face that leans toward a line parallel to the center axis of a milling cutter. A negative axial rake angle allows for greater depth of cut but also requires more machine power.

negative radial rake angle

A measurement that indicates a tooth face that tilts away from the center of the mill. A negative radial rake angle demands greater machine power but has improved cutting edge strength.

origin

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

outer dial face

The ring surrounding the face of the dial indicator that positions the indicator's needle to a specific point. The outer dial face may need the bezel lock loosened before adjusting.

parallels

A pair of identical support blocks. Parallels help reinforce and raise workpieces in a variety of milling, drilling, and grinding operations.

part zero

The starting point of Cartesian coordinates for a specific workpiece. Part zero acts as a reference point for all part dimensions.

personal protective equipment

PPE. An article of clothing or a device worn or used to minimize exposure to hazards and prevent injury. Personal protective equipment for operating a manual mill may include safety glasses and steel-toed boots.

plunger

A component of a measuring instrument that is pressed against a part to record a reading. When pressed, the plunger is pushed inside the base of the measuring instrument.

positive axial rake angle

A measurement that indicates a tooth face that leans away from a line parallel to the center axis of a milling cutter. A positive axial rake angle has decreased edge strength but improves metal removal rates.

positive radial rake angle

A measurement that indicates a tooth face that tilts toward the center of the mill. A positive radial rake angle has lower cutting edge strength but can be operated with less machine power.

precision machinist square

An L-shaped tool that a machine operator can use to align square or linear workpieces. A precision machinist square is less exact than a dial indicator.

precision-ground flat stone

A tool made of steel or another hard material that is used to remove burrs or flatten machine parts. A precision-ground flat stone ensures that the mill table is flat.

preload

The minimal turning of a dial indicator to ensure the indicator pin is engaged. Preloading ensures accurate readings.

quill

A component on manual mills that moves the spindle in and out of the mill head. The quill can be controlled automatically or manually, such as with a lever or handwheel, to adjust spindle depth.

radial rake angle

The angle formed by the radius or diameter of the milling cuter and the face cutting edge. A radial rake angle describes how far the face cutting edge is twisted toward or away from the mill.

radius

The distance between a point on a circle's circumference and its center. The radius is equal to half of the width or thickness of a round or cylindrical object.

reference point

An established location of a tool, workpiece, or machine component from which you measure or determine other locations. Reference points act as the origin for coordinates used to create part features in machining operations.

revolution

One complete rotation or turn. A revolution is a full 360 degree movement around an object or point.

revolutions per minute

rpm. A measurement of speed that indicates how many times the spindle has rotated in one minute. Revolutions per minute is measured from the center of tool or spindle rotation.

roughing

An initial pass of the cutting tool that emphasizes heavy material removal rates, high feed rates, and a heavy depth of cut. Roughing cuts remove most of the material quickly without regard to surface finish.

rpm

Revolutions per minute. A measurement of speed that indicates how many times the spindle has rotated in one minute. Revolutions per minute is measured from the center of tool or spindle rotation.

rubber mallet

A hammer made of softer material to decrease impact. Rubber mallets should be used to loosen the drawbar on the manual mill.

runout

The accumulated position error and deviation from an axis as a mill rotates. Excessive runout can cause issues like reduced tool life and poor surface finish.

saddle

A mill component that enables the worktable to move side to side and back and forth. Saddles are located between the knee and worktable on a mill.

safety glasses

A form of protective eyewear, usually made of thick plastic, which shields the eyes from flying debris and other potentially hazardous materials. Safety glasses should be worn during milling.

safety placards

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

setscrews

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

setup

All of the tasks and steps necessary to prepare for a machining operation. Setup includes preparing machines, tools, and materials.

shank

A cylindrical part of a tool or device opposite the cutting edges. Shanks that are shorter and thicker provide more rigid support for cutting tools.

specifications

A description of the essential physical and technical properties of a finished part. Specifications outline important information, including finished part dimensions and acceptable tolerance ranges.

speed

In milling, the rate at which the tool rotates. Spindle speed is typically measured in revolutions per minute (rpm), surface feet per minute (sfm), or meters per minute (m/min).

spindle

A component of a machine that rotates or spins. The spindle holds and rotates the cutting tool on a manual mill.

spindle brake

A lever that engages a mechanism to slow down and stop the spindle for emergencies. Brakes on a mill can prevent injury.

spindle speed

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

spray bottle method

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

square

A 90° orientation to another object. A cutting tool that is square to a workpiece is perpendicular to the workpiece axis or surface.

step block

A tool used to raise clamps to the level of a workpiece. Step blocks are inserted into T-slots and have teeth that mesh with the teeth on clamps.

step clamp

A type of workholding device that uses a fixture and step blocks to secure the workpiece. A step clamp is the most common type of clamp used on manual mills.

surface feet per minute

sfm. An Imperial system measurement of cutting speed describing the distance in feet that the cutting edge travels in one minute. Surface feet per minute is dependent upon both spindle rpm and the cutting tool diameter.

surface finish

The degree of roughness and variation on the surface of a part after it has been manufactured. Surface finish can be improved with finishing cuts.

T-bolts

A type of fastener designed to fit into T-slots. T-bolts have a flat, rectangular head with threads beneath the head.

three-dimensional

3D. Having length, width, and depth. Three-dimensional space can be represented by the Cartesian coordinate system.

toe

The front portion of a clamp that holds the workpiece. The toe of the clamp should be as far onto the workpiece as possible.

tool geometry

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

tool wear

The gradual erosion of material from the surface of a cutting tool due to contact and friction. Tool wear can affect part dimensions and part tolerance.

toolholders

A device used to hold a cutting component in place. Toolholders for manual mills include collets, drill chucks, and face mill assemblies.

tooling

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

toolpath

The course followed by the tool as it creates the workpiece. Toolpaths are described by a series of coordinate positions.

toughness

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

tramming

The process of aligning the mill head to ensure the cutting tool is perpendicular to the table. Tramming is accomplished by using a dial indicator.

T-slot nut

A type of fastener that secures clamps to machine table T-slots. T-slot nuts are adjustable and allow you to accurately position a clamp.

T-slots

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

variance

The degree of deviation between one measurement result and the next when the same object is measured. High variance between consecutive measurements indicates low measurement precision.

vertical column and knee mill

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

vise

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

water-based cutting fluids

A cutting fluid with a high percentage of water content. Water-based cutting fluids are not flammable and have additives to increase their boiling point.

workholding device

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

workpiece

A material being machined or undergoing another type of processing. Workpieces for milling operations are commonly metal.

worktable

The part of the machine that supports the workpiece and any workholding devices. Worktables move to change the position of the workpiece relative to the cutting tool.

wrench

A hand tool that tightens and turns bolts and nuts. A wrench produces torque when the operator applies force to the handle.

X axis

An axis in the Cartesian system that measures movement towards or away from the Z axis. The X axis describes a mill worktable's side-to-side movement.

X axis adjusting bolt

A cylindrical, threaded device on the side of the mill that adjusts the mill's head in the X axis. The X axis adjusting bolt moves the mill head left or right in the X axis.

X axis handwheels

The handwheels located on either end of the mill that moves the table in the X axis. Either of the X axis handwheels can be used to shift the table from side-to-side.

Y axis

An axis in the Cartesian system that is perpendicular to the Z and X axes. The Y axis describes a mill worktable's forward-and-backward movement.

Y axis adjusting bolt

A cylindrical, threaded device on the back of the mill used to adjust the mill's head location in the Y axis. The Y axis adjusting bolt moves the mill head up or down.

Z axis

An axis in the Cartesian coordinate system that represents motions and positions perpendicular to the X and Y axes. Z axis movement on the mill describes vertical, up-and-down movement.

zero out

Changing a digital reading to measure zero. Zeroing out a dial indicator can be done by pressing a button or turning the outer dial face to zero.