chapter 9 milling, grinding, drilling, and slotting attachments

8/14/2019 Chapter 9 Milling, Grinding, Drilling, And Slotting Attachments

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Chapter 9

MILLING -GRIND ING -DRILLING AND SLOTTING ATTACHM ENT

(VERSA-M IL)

GENERAL

DESCRIPTION

The milling-grinding-drilling and slotting attachment iscommonly referred to as a Versa-Mil. It is a compact,portable unit capable of doing m any m achining op erationsthat n ormally require expensive single-pu rpose m achines.With the different attachments that are available with theunit, drilling, shaping, milling, and grind ing can beperformed quickly and inexpensively. This self-powered,

vertical-feed, variable-speed precision tool may be mounted inany position on the carriage, table, ram, turret, or tool arm ofother machine tools. With a two-directional feed table, theVersa-Mil unit becomes a complete machining tool for benchor inplace machining of parts too large to be moved or h eld inconventional machine tools.

USES

An im por tant factor in the efficiency of the Versa-Mil isthat machine tools already in the shop area p rovide the powerfor feeds, a means of holding and moving the work, and the

rigidity needed for machining. Faced with unusual machiningproblems, the Versa-Mil offers many solutions either as aseparate tool or combined with other machine tools andmachinery already in the shop to create special machines. TheVersa-Mil increases the capabilities of standard machines bydoing secondary operations without changing setups. TheVersa-Mil provides pow er to interchangeable attachmentsallowing th e un it to be used on site to perform d ifferentmachining operations on equipm ent being repaired or r ebuilt.Where space is limited, as in a shop area, floor space isneeded only for the lathe. Different sizes of the Versa-Milun it are available for light, med ium, and heavy m achining.This chapter will be limited to the Series 31 (light machining

unit).

SAFETY PRECAUTIONS

Safety in the shop area or arou nd power equipm ent cannotbe overemphasized. Each piece of equipment has safetyprocedures u nique to that particular p iece of equipm ent.Listed below are safety procedures that pertain to the Versa-Mil.

Avoid d angerous environm ents. Do not use the VerMil in d amp or w et locations. Do not expose the VerMil to rain.

Keep visitors away from running equipment. Kevisitors a safe d istance from th e Versa-Mil wh ile it ioperation.

Store tools when n ot in u se. Store or lock tools aequipment in the Versa-Mil cabinet.

Do not force the equipment. The Versa-Mil will do job better and safer at the rate for which it was designe

Wear proper apparel. Keep shirt sleeves above the elboRemove ID tags, watches, rings, and any other jewewhen working around the Versa-Mil.

Use safety glasses. Wear safety glasses when operatany type of machine shop equipment.

Do not abu se the electrical cord . Never carry the VerMil by the electrical cord or p ull on th e corddisconnect it from the receptacle. Keep the cord awfrom excessive heat, oil, and sharp edges. Replace econnectors or cords w hen excessive wear or d amageapparent.

Maintain tools with care. Keep tools and cutters shaand clean for the best performance. Follow instructioin the Versa-Mil Operation an d Service Manu al lubricating the basic unit and changing accessories.

Disconnect equipment not in use. Ensure the Versa-Mis disconnected when not in use, before servicing, awhen changing attachments, speeds, cutters, or arbors.

Remove chuck keys and w renches. Form a habitchecking to see that chuck keys and wrenches aremoved from the unit prior to operating the equipmeRemove all tools from the area that may vibrate off tequipment and into moving parts.


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ATTACHMENTS

External Grinding Attachment

The external grinding head (Figure 9-2) bolts to the face of

the Versa-Mil making the unit a precision external grinder.The head adjusts to 30 degrees range of angle to either side.A flat belt from the m otor provides pow er to the head forsmooth operation. Different pulley diameters allow matchingspindle speeds to the grinding wh eel size and rating. A wheelguard on the head offers protection to th e operator fromdebris coming off the wh eel during grind ing.

Internal Grinding Attachment

A wide variety of internal grinding jobs can be handled on alathe with the Versa-Mil basic unit and the internal grinding

unit (Figure 9-3). The internal grinding attachment bolts tothe face of the basic unit and is driven by a flat belt from themotor. The internal grinder handles grinding wheels from 5/ 8inch to 2 1/ 2 inches in diameter and grind s to a depth of 4inches. Five different speeds are available to match thespindle speed to the grinding wheel diameter and rating.

Heavy-Du ty Deep-Hole Grind er

The heavy-duty deep-hole grinder (Figure 9-4) may beattached to the face of the Versa-Mil for deep internal

grinding. The deep-hole grinder accommodates grindiwheels 3 to 5 inches in diameter and grinds to a d epth ofinches. A flat belt from the motor drives the deep-hogrinder for smooth operation. Six spindle speeds are availabto match the spind le speed to the grinding wh eel diame

and rating.

Tooth Stop Rest

Cutters held in the lathe chuck, collet, or between latcenters can be ground quickly and accurately with the VersMil unit equiped with an external or internal grinding heaThe tooth stop rest (Figu re 9-5) assu res un iform gr indingcutter teeth because th e finger on the gage ratchets over tteeth stopp ing each tooth in the exact same position. Thtooth stop rest is completely ad justable for height anposition.

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Diamond Dresser

The diamond dresser (Figure 9-6) is used with all Versa-Milrinding attachments and clamps to the workpiece, tailstock,r lathe face plate to true the grinding wheel. A 0.35-karat

ndu strial diamond moun ts in either of two positions to dresshe face or side of the grinding wheel. The cast-iron framewith V-notch clamp s securely to round shap es up to 3 1/ 2nches in diameter.

Universal Milling Head

The universal milling head (Figure 9-7) mounts to the facef the Versa-Mil and is driven by the spindle of the basic unit.his feature eliminates the need for special belts and permits

he head to op erate at any angle. The milling head and theasic unit have the same spindle taper and use the samerbors. With th e un iversal head, machining can be performed

long the side of the work, allowing the machining of mucharger parts. Angular operations such as thr ead m illing canasily be performed on large diameter material using theniversal head.

Internal Keyseater and Slotter

This unit bolts to the face of the Versa-Mil and is driven byhe basic unit spindle. The An internal keyseater and slotterFigure 9-8) commonly called a Versa-Shaper, bolts to theace of the Versa-Mil Versa-Shap er opera tes in any an gularosition and in either direction of stroke for cutting internaleyways, slotting, or shaping. Thestroke length adjusts from

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0 to 4 inches with a speed of 44 to 450 strokes per minute.Tool holders for l/ 8, 3/ 16, 1/ 4, 5/ 16, and 1/ 2 cutters areavailable for use in the Versa-Shaper.

HIGH-SPEED END MILLING

For speeds higher than the basic unit can provide, a high-speed end milling and drilling head (Figure 9-9) bolts to theface of the Versa-M il. The head rotates 30 in either d irectionfrom center. Graduation marks on the face of the basic unitindicate the angle setting. Thirteen spind le speeds areavailable to the head directly from the m otor through the use

of a V-belt and p ulleys. Arbors may be m ounted in either endof the high-speed head. The spindle taper is the sam e as thebasic un it. The high-speed head is used m ostly for smalldiameter work such as end milling, drilling, or other relatedoperations.


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Indexing Head

The indexing head (Figure 9-10) mounts in the lathe headstock spindle to index work held in the lathe chuck, collet, orbetween lathe centers. The indexing head mandrel locks into a1 1/ 8-inch or larger spindle bore; however, adapters for otherbores are available. Forty turn s of the dividing h ead crankrotates the lathe spindle one revolution. The indexing plate has18 circles of holes allowing for d ivisions to be mad e indegrees, number of sides, or the number of teeth on gears orsplines.

T-Slot Moun ting Adapter

Versa-Mil units are furnished with an adapter (Figure 9-11)that fits the T-slot of the compou nd rest on m ost conventionallathes to lock the Versa-Mil unit to the compou nd rest withtwo hex-head bo lts. Four holes in the base of the Versa-Mil

unit allow m ounting the basic unit in any of four positions 90apart. Mounting the basic unit by this method p ermits the useof the compou nd rest for angular m ovement wh ere lowmoun ting of the Versa-Mil is not required. Any operationnormally done above the centerline of the workpiece isusually accomplished by using the T-slot adapter and the com-pound rest. Such operations include milling keyways, slots,and splines, angle milling, and gear cutting. Other operationssuch as d rilling or boring may also be accomplished if theyare performed above the center line of the work.

Adapter Base Moun ting

When a lower moun ting of the Versa-Mil unit is requiredthe compound rest can be rem oved and replaced w ith a speciaadapter base (Figure 9- 12) that mounts directly on the crossslide. The base plates are semifinished and may requir

drilling tw o mou nting bolt holes and a pivot pin hole. Thlocation of these holes depends upon the lathe model and sizeThe base plate adapter shou ld be used for operations on obelow the centerline of the w orkpiece. Such op erationinclude milling keyways along the side of a shaft, surfacmilling w ith a shell end mill, and drilling or boring on thcenterline of the w orkpiece. The comp oun d rest m ust bremoved prior to m ounting the base plate adapter.

FEED TABLES

Although not part of the basic unit accessories, the feedtable may be found in some shop sets. Rigid accurate feed

tables (Figur e 9-13) make th e Versa-Mil un it a portablemachine tool by providing two additional directions of. travelPrecision finished ways, adjustable gibs. and accurate leadscrews calibrated to 0.001 inch assure accurate positioningand feed for the most p recise machining. Feed tables foVersa-Mil units are available in four different models and alfeed tables can be quickly converted to reduce table heighwhen only one direction of travel is required.

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Machining done on the lathe with a Versa-Mil allows theutter to move along three different axes: vertical, lateral, andongitudinal (x, y, z). However, not all machining can be donesing the lathe. Because the lathe allows longitudinal andateral movement, mounting the Versa-Mil directly to a benchr piece of equipment would severely restrict its machiningapabilities. Feed tables eliminate that restriction by providinghose two add itional directions of travel. Feed tables mountedirectly to a bench or piece of equipment allow the Versa-Mil

o perform machining in all three directions.

SELECTION OF ARBORS

When the basic unit is to be used independ ently or with anttachment other than the grinding attachments, an arbor andutter must be selected and mou nted. The cutter should be

mounted onto the arbor first. The arbor should be secured in aise to properly mount the cutter.

This ensures a properly torqued cutter and prevents the arborrom bending or causing d amage to the Versa-Mil basic unit.

When tightening the arbor nut, the pressure applied to thewrench shou ld always be in th e direction of the operator in

ase of slipp age. Listed in the following p aragrap hs arearious arbor styles and some of their uses. Note that th ey areimilar to, but smaller than those used on a milling machine.efer to chapter 8 for illustrations not listed.

Taper Arbors

Taper arbors (Figure 9-14) are designed primarily for use

ith Brown and Sharpe, or Morse standard taper shank tools.

Fly-Cutting Arbor

The fly-cutting arbor may be used for boring, facing, gearepair, keyway milling, and form milling. This type of arborllows the tool bit to be positioned at either 45 or 90 to the

rbor a xis.

Side-Milling Arbor

The side-milling arbor (Figure 9-15) is used with arbor-typeutters and slitting saws. This arbor is supplied with 1/ 8 and/ 8 spacing collars.

Shell End Mill Arbor

The shell end m illing arbor is used primarily for facing;how ever, milling a w ide slot with a shell end m ill can beaccomplished.

Geared Chuck Arbor

This type of arbor is used for moun ting chucks with a #3Jacobs taper. The chuck itself is used primarily for drilling.

Straight Shank Arbor

The straight shank arbor with setscrews is used w ith straightshank drills of the correct size, end mills, and Woodruff keyseat cutters.

Stradd le Mill Arbor

The straddle m ill arbor is u sed for m illing splines on a shaft,milling hexagon or square shap es, and large keyw ays. Sixspacers come with the Versa-Mil accessories, allowing millingof areas from 1/ 8 to 3 inches wide in 1/ 16 inch increments.

Threaded Angle Mill Arbor

The threaded an gle mill arbor is used for m illing angulargrooves and dovetails.

SELECTION OF CUTTERS

After selecting the arbor, select the desired cutter for themachining process, mou nt the cutter on or in the arbor, andmount the arbor in the Versa-Mil unit or attachment. Ensurethe arbor and spindle are free of dirt and burrs.

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Woodruff Key Slot Cutters

This cutter has a l/ 2-inch straight shank and is used forcutting Woodruff keyslots in a shaft. This cutter may also beused for cutting straight keyw ays in a shaft or similaroperations.

Side Cutters

Side cutters are available in two basic styles. The staggertooth side m illing cutter should be selected for millingkeyways an d d eeply milled slots, while the straight sidemilling cutters are usually used in matched sets for straddlemilling or individually for side milling.

Shell End Mill Cutter

This cutter is used for slabbing or surfacingface milling.

Form Cu tters

cuts and end or

Form cutters are manufactured in a variety of shapes.Selection of the cutter depends upon the desired shape or formto be machined.

Fly Cutters

Fly cutters are usually square tool bits ground with th eproper clearances for boring, facing, or counterboring. Flycutters can also be ground to particular shapes for special jobssuch as gear repair or spline milling.

END MILLS

End mills are manufactured in a variety of shapes and stylesand should be selected in accordance with the job to beperformed. The two fluted end mills are recomm ended forcutting keyways and for deep milling w hile the multiple fluteend mills are designed for end milling and routing work.

SLITTING SAWS

Slitting saws ar e man ufactured in a variety of styles andsizes and should be selected in accordance with the job to beperformed. Use slitting saws to cut d eep slots in the work an dfor cutting slots.

SELECTION OF GRINDING WHEELS

When the external grinding head, internal grinding head, deep-hole grinding head is selected and moun ted on th

Versa-Mil, a wide range of grinding operations is madavailable. The data books published by the leading abrasimanu factures should be referred to for prop er selection grinding w heels as the variety of grinding d one by Versa-Mis to great for complete coverage of wheels in this manual.

WARNINGUse only abrasive wheels designed for the external or

internal grinding heads that have been tested and found to besafe when operating at the speeds attained by these heads.Using incorrect untested wheels may result in breaking theabrasive wheel causing wh eel fragments to be projected intothe work area endangering personnel and equipment.

Straight Abrasive Wheels

Straight abrasive wheels are furnished in 46 and 60 grsizes. The 46 grit wheel is a general-purpose wheel and shoulbe selected for rough-grinding cylindrical parts, face platgrind ing, and so forth. Select the 60 grit wheel for finishinand for tool and cutter grinding where finerrequired.

Straight Cup Wheels

Select a straight cup wheel should be selectedcutter grinding, face plate grinding, and internallarge holes.

Flare Cup Wheels

finishes a

for tool angrinding

Select a flare cup wheel for general tool and cutter grinding

Dish Wheels

Select a d ish wh eel for tool and cutter grinding su ch a

grinding flutes and individual teeth of milling cutters.

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VERSA-MIL OPERATION S

The Versa-Mil add s

SETUP

important machining functions to alathe. With built-in power and vertical feed, it adds a thirdmachining dimension, allowing the op erator to m ill, drill,bore, slot, shape, grind, and perform other special operations.The success of any Versa-Mil operation depends largely uponhe jud gment of the operator in setting u p the Versa-Mil,

selecting the proper cutter, and holding the cutter by the bestmeans possible under the circumstances.

Preoperational Checks

Gibs should be as snug as possible and still allow themovem ent needed . Tighten all gibs not requ ired for the

operation being done to prevent movement and chatter. Thedjusting bar on the back of the lathe carriage that holds thearriage onto the lathe bed shou ld be snug enough to still

allow a slight drag when feeding the lathe carriage. If thework is held between centers, they should be tight against thework and long pieces should be supp orted at the point wheremachining is being done. Unless both the Versa-Mil and thework are rigidly supported, it is difficult to obtain accurateesults.

Mounting on a Lathe

The Versa-Mil may be mounted on the front or the rear ofhe lathe carriage. On the front, it may be set on the compoundest or d irectly on the cross slide. A m ore perm anent andenerally more useful mounting is at the rear of the lathearriage, where it may be left until it is needed.

Squaring the Versa-Mil to the Lathe

For accura te milling cuts, it is necessary to squ are the Versa-Mil to the lathe (Figure 9-17). The front compou nd face of theVersa-Mil is a reference surface machined in relation to t hepind le. A squar e can be set across this face and squa red tohe chuck or face plate of the lathe. For work between centers,

he Versa-Mil can be squ ared to the w orkp iece. After themachine has been squared on the compou nd rest of the lathe,he compound rest can be loosened for adjusting the spindle toarious angles using the graduated scale on the compoundest. For extremely precise adjustments and settings, use theial indicator or vernier protractor.

MILLING SQUARE END KEYWAYS

Conventional milling is recolmm ended when using theVersa-Mil on a lathe as the lathes feeds and bearings are notdesigned for upw ard p ressure on the carriage. Cutting squareend keyw ays (Figure 9-18) can be accom plished w ith theVersa-Mil using a variety of different cutters and speeds. TheVersa-Mil is usually set on top of the compound rest with thespindle of the Versa-Mil parallel with the travel of thecompound rest. Select and m ount the cutter to the approp riatearbor. A stagger tooth side milling cutter the w idth of thekeywa y is the most satisfactory cutter to u se for squa re end

keyway milling operations; however, plain m illing cuttersmay be u sed. Mount the arbor into the Versa-Mil spindle andtighten.

CAUTION D o not over tighten as the pin in the back ofthe Versa Mil may shear

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Speed Selection

If a good flow of coolant is ava ilable to the cutter, choose orselect speeds near the top of the recommend ed cutting speedsfor the operation being performed, type of cutter used, andmaterial being milled. If milling is to be done dry, then use aspeed at the lower end of the recommend ed cutting speeds.

Centering th e Cutter

To center the cutter over the work, tirst ensure the backlashis removed from the cross slide. Next, start the Versa-Mil andreference the cutter to the side of the work using a paper shim.Zero the cross feed dial; then, raise the Versa--Mil above thetop of the w ork. To determine the distance the cutter m ustmove, add one-half of the diameter of the cutter plus one-halfthe diameter of the workp iece plus the thickness of the paper

shim. Keep in mind some latches only move half the distanceshown on the crossfeed dial. After the cutter has been movedover the center of the work lock the cross slide to preventmovem ent d uring milling. See Figure 9-19.

Depth of Cut

Start the Versa-Mil and reference the cutter to the top ofthe workp iece using a p aper shim. The depth of cut equals

one-half the key thickness plus the chordal height plus thethickness of the paper shim. Tables for chordal height maybe found in the new American Machinists Han dbook orMachinerys Handbook. A simple approximate formula forchordal height is key thickness squared, divided by fourtimes the shaft diameter. After the depth of cut isdetermined and set, tighten the p ost bind ing setscrew toprevent the basic unit from moving during machining.

Feed Rate

The rate of feed will vary from 0.001-inch chip t hickneper tooth to as mu ch as 0.008 inch per toot h. Determine thfeed rate by mu ltiplying the num ber of teeth on the cutttimes the desired chip thickness times the RPM of the cutteA chip thickness of 0.001 to 0.004 is considered a finishincut while a chip thickness heavier than 0.004 is consideredroughing cut. Most milling operations involving the Versa-Mare fed by hand . The operator should attempt to feed the cuttat a consistent rate with each tooth taking the same chithickness. Power feeding is recomm ended when long cualong a shaft or w orkp iece are necessary. To do th is, mouthe steady rest on the lathe close to the headstock and clamthe steady rest tightly against the workpiece. Lubricate thheadstock center or use a ball bearing type center to allow thheadstock spindle to rotate freely while the workpiece remaistationary. If a ball bearing center is not used , maintain lo

spindle speeds to p revent overheating the work. Feed ratedu ring power feeding are ad justed u sing of the quick changgearbox on the lead screw.

INTERNAL KEYWAY AND SPLINE

CUTTING

After the internal d iameter of gears or sleeves have beemachined to size, keyways or splines may be cut into the worwith the Versa-Shaper w ithout removing the w ork from thlathe chu ck (Figure 9-20). This has a ma jor ad van tage osaving time by not having to change setups.

Sizes of Keyways

Each of the standard widths of keyways from 1/ 8 to 1/ 2 incmay be cut w ith one of the standard keyway cutters availablwith the Versa-Mil. Wider keyways may be cut with one othe standard cutters by cutting the slot to the proper depth anenlarging it by feeding the cutter first to one side and then thother through the use of the cross slide lead screw.

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Depth of Cut

Determine the depth of cut by the amount of feed applied tothe basic unit lead screw. However, it is necessary to allow theVersa-Shaper to take additional cuts (free cuts) until no furthermaterial is removed before taking a measurement. This willassure accurate keyways or splines being machined in the gearor sleeve.

Direction of Feed

Whenever practical, mill keyways and splines by feedingupward with the Versa-Shaper. This will cause the lathecarriage to be held more firmly in contact with the lathe waysand the lathe bed, permitting heavier cuts to be taken.

Clearance

After the Versa-Shaper is set up, run through the entire

stroke cycle turning the worm sheave by h and . This willensure that the cutter clears the work at both ends and does notstrike the lathe chuck or encounter any other obstructions.

PLAIN MILLING

Plain milling or slabbing (Figure 9-21) is a term applied tomany operations such as face milling, milling a hex or squareshape, or milling flat surfaces along the side of a workpiece.The process of plain milling normally involves removing largeamounts of material with either a shell end mill or side millingcutters to form a flat surface. Work may be held either in thelathe chuck or between centers for plain milling.

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Depth of Cuts

In the case of shell end mills, the depth of cut shou ld notexceed the d epth of the teeth or flutes. With side m illingcutters, the dep th of cut is controlled by the diam eter of thecutter. For deep cuts, a staggered tooth, side milling cutter isrecomm ended . Extremely light cuts should be avoided ifpossible as the cutter tends to slide over the work, heating anddulling the cutter which may result in putting undo pressureon the arbor and carriage causing excessive chatter.

Milling Feeds

The best milling performance is obtained when each toothof the cutter takes a full chip. When milling steel, forexamp le, the ideal feed is 0.005 inch. Depen ding on th ewidth of the cutter and machinability of the material, itmay be d esirable to reduce the depth of cut an d increase therate of feed to maintain chip th ickness. Chatter is likely toresult when chips are too thin, causing cutter life betweengrindings to be reduced.

DRILLING

Many d rilling and boring operations not ordinarily possibleon the lathe are easily performed with the Versa-Mil mountedon the lathe. The Versa-Mil is usually fed by hand u sing eitherthe either carriage, cross slide, or compou nd rest. Check theoperators man ual sup plied with the Versa-Mil for informationconcerning power feeding when drilling.

Off-Center Drilling

Off-center drilling and boring may be performed bypositioning the Versa-Mil spindle parallel with the lathe axisand maneuvering the d rill by means of the cross slide and theVersa-Mil lead screw. This allows the complete machining ofirregularly-shaped items without removing them from thelathe chuck. See Figure 9-22.


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Angular Drilling

With the Versa-Mil mounted on the compound rest, holesmay be drilled at any angle in relation to th e lathe axis bysetting the compound rest at the desired angle and feeding thedrill into the w ork with the compou nd rest lead screw. To usepow er feeding with the tap er attachm ent, set the taperattachment and Versa-Mil spindle parallel with the hole to bedrilled. The work mu st be held in position to prevent turn ingwhen the lathe carriage feed and head stock spindle areengaged . See Figure 9-23.

Index Drilling

Stock held in the lathe chuck or between centers can bedrilled a t regular intervals around the center or perimeter of aworkpiece by using the indexing head to p osition the w ork. Aconsiderable amou nt of setup time and effort is saved afterpositioning the drill for the first hole to be drilled.

Additional D rilling Applications

Drilling with the Versa-Mil attached to a feed table, turrlathe, or vertical boring mill is unique. Special drillinoperations with these pieces of equipment are covered in topera tors manu al on the Versa-Mil. See Figure 9-24.

WOO DRUFF KEYSLOT MILLING

Milling Woodruff keyslots (Figure 9-25) in shafts is vesimilar to m illing straight k eyways in th e basic setucentering the cutter, and feed rate. The only difference milling a Woodruff keyslot is that the carriage must be lockedown in addition to the cross slide, if cutting from the top the workpiece, to prevent the basic unit from moving durinmilling. Cutting a Woodruff keyslot is relatively simple sin

the proper size cutter has the same diameter and width of tkey to be inserted. The work may be held in the lathe chuck between centers and the cutter may be on an arbor or in a d rchuck. After the cutter has been centered on the w ork, thcutter is fed directly into the work until the proper depth of chas been achieved.

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INDEXING

An indexing head comes with the Versa-Mil and is installedn the h eadstock of the lathe to permit indexing a workp iece.ven though the workpiece is mounted in a conventional

mann er in the lathe, the headstock spindle should n ever belowed to rotate under power with the indexing head attacheds this would cause severe dam age to the equipment. It isways a good practice to unplug or turn off the main power

witch on the lathe in this situation.

Mounting the Workpiece

A workpiece may be supported in the lathe between centers,gainst the faceplate, or in th e lathe chuck. If the w ork isounted between centers, a lathe dog is mounted on the work

nd used to transfer movement from the faceplate to the work.

Indexing the Work

Indexing is the process of controlling the rotational positionf a workp iece du ring machining. The indexing h ead attacheso the left end of the lathe headstock and locks into theeadstock spindle using an expansion adapter. With the

ndexing head mounted to the lathe, the work will not rotatenless the crank arm of the indexing head is m oved. Fortyomplete turns of the crank arm move the lathe spindle oneevolution. The indexing plate contains a series of concentricngs with each ring containing a different number of holes.he workpiece is indexed by moving the crank arm from oneole to another through a calculated pattern of turns and holes.o determine the correct pattern of turns and holes and wh ichng to use, refer to Chapter 8, Indexing a Workpiece.

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FORM MILLING

Form milling is the process of machining special contours,composed of curves and straight lines or entirely of curves, ina single cut. Gear cutting may be considered form milling bydefinition; however, the definition iS usually restricted to theuse of convex, concave, or corner rounding cutters. Theseform cutters are manufactured in a variety of radii and sizesand m ay be grouped or ganged together on an arbor to millintricate shapes. Convex (curved or r ound ed ou tward ) cuttersmill concave (curved or rounded inward) shapes whileconcave cutters are used to mill convex shapes.

ANGLE MILLING

Angle milling is milling flat surfaces which are neitherparallel nor perpend icular to the w ork. Angular milling can bedivided into several different types of setups.

Single Angle M illing Cu tters

Single angle milling cutters are mounted on an arbor and thearbor is then mou nted to th e basic unit or u niversal head. Theunit is then squared to the workpiece and the work is milled ina conventional manner. This type of cutter is man ufactured ina variety of angles with the most common a ngles being 45,50, 55, or 60.

Dovetail Milling

When cutting dovetails with the Versa-Mil, the workpiece isusually held in the lathe chuck or m ounted on a face plate.The tongue or groove of the dovetail is first roughed out u singa side m illing cutter, after wh ich the angular sides and baseare finished with the dovetail cutter. See Figure 9-26.
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Compound Rest

Angular milling may also be accomplished on the Versa-Milby squaring the Versa-Mil on the compound rest and settingthe compound rest to the desired angle. With this method ofangular milling, the cutter is usually a shell end mill and thework is either held in the lathe chuck or moun ted on th efaceplate.

Universal H ead

Angles may also be milled on a workp iece using theuniversal head. This head may be tilted to 180 in eitherdirection of center. Complex angles may be machined with theuniversal head used in conjunction with the compoun d rest orthe tailstock offset m ethod . See Figure 9-28.

Tailstock Offset

This type of angular milling is accomplished by squaring thunit to the tailstock spindle or faceplate. Normally, a shell enmill is used in this type of milling. Work is mounted betwee

centers and the tailstock is offset to the desired ang le fmilling. The work may be rotated with the indexing head mill add itional surfaces on the w orkp iece. See Figure 9-29.

STRADDLE MILLING

Stradd le milling (Figu re 9-30) is the m achining of twparallel surfaces in a single cut by using two cutters separateby spacers, washers, or shims. Use straddle milling in spli

milling or the cutting of squares or hexagons on the end ofcylindrical workpiece. The workpiece is mounted betweecenters to mill splines on a shaft and moun ted in the lathchuck to mill squares or hexagons. In both cases, the indexinhead is used to rotate the work after each cut.

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GANG MILLING

Gang m illing differs from strad dle milling in that two ormore cutters of different diameters or shapes are mounted onhe sam e arbor to m ill horizontal surfaces. Cutterombinations in gang milling are virtually unlimited and areetermined by the desired shape of the finished product.

SPLINE MILLING (EXTERNAL)

Splines are often used instead of keys and keyw ays toansmit power from the shaft to a hub or gear. Splines are aeries of parallel keys and keyways evenly spaced around ahaft or interior of a hub. Splines allow the hub to slide on thehaft either und er load or freely. This feature is foun d inransmissions, automotive mechanisms, and machine toolrives. Manufactured splines are generally cut by bobbing androaching; how ever, this d iscussion will be limited to fieldxpedient methods. Standard splines on shafts and splinettings are cut with 4, 6, 10, or 16 splines.

The dimensions depend upon the class of fit and the shaftiameter. The class of fit may be permanent, sliding fit notnd er load, and sliding fit under load. Table 8-8 in Appendix

A lists the standard dimensions for the different classes of fits.hafts may be milled several different ways.

The most common w ay is to use two side milling cutterseparated by spacers, with the width of the spacers equal tohe width of the spline. The splines are cut by straddle milling

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each spline to the proper d epth and indexing around the shaftfor each spline. A narrow plain milling cutter is used to millthe spaces between the splines to the proper depth. It may benecessary to make several passes to mill the groove u niformlyaround the shaft. A formed cutting tool or cutter may also beused for this operation.

SPLINE MILLING (INTERNAL)

After a hub or gear has been drilled and bored to thefinished internal minor diameter, internal splines may be cutinto the hub or gear by using the Versa-Shaper (Figure 9-31).The indexing head provides the means to locate each spline tobe cut. For this opera tion, the milling is continued un til thedesired class of fit is obtained. For field expedience, it is bestto machine the mating parts to match if possible.

SLOTTING

Slotting w ith the Versa-Mil (Figure 9-32) covers a w idevariety of operations from milling long wide slots in materialto cutting curved or thin slots. Workpieces may be mounted inthe lathe chuck or between centers for slotting operation.
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Longitudinal Slots

Longitudinal slots along a shaft or other large piece may becut in the material in the same m anner as m illing keywayswith end mills. It is often desirable to use a cutter smaller than

the width of the slot. The reason for this is, when the cutter isas w ide as th e slot, one side of the cutter is climb millingwh ile the opp osite side of the m illing cutter is performingconventional milling. This causes a difference in the finishbetween the two sides of the slot. A roughing out of the slotshould be m ade first, followed by a finishing cut dow n oneside of the slot and returning on the other side.

Narrow Slots

For narrow slots, use slitting saws rather than end millingcutters. When u sing slitting saws, reduce speeds and feeds toextend the life of the cutter.

FLY CUTTING

Fly cutting (Figure 9-33), also called single-point m illing, isone of the most versatile milling operations available to themachinist. Fly cutting is done with a single-point cutting tool,like the lathe or shaper cutting tool, held in a fly cutting arbor.Formed cutters are not always available and there are timeswhen special form cutters are n eeded only for a very limitednum ber of parts or op erations; therefore, it is m oreeconomicalto grind the desired form on a lathe cutter bit rather than ordera special form cutter. The fly cutter is used to great extent in

the reshaping of repaired gears because the tool bit can beground to the shape of gear teeth available. Fly cutting canalso be used in cutting standard and special forms of splines.

Plain or Face Millin g of Soft Non ferrous Metals

Plain or face milling of soft nonferrous metals such aluminu m, w ith a fly cutter p rodu ces a high qu ality finisBoring holes with a fly cutter is generally not desirab

because of the difficulty in positioning the cutter ancontrolling the diameter. The short arbor allows boring of onvery shallow holes.

Gear Cutting

A variety of gears, pinions, and sprockets can be fabricaton the lathe using the Versa-M il. By referring to various texand references for detailed da ta and instructions on gears angear cutting, the operator can develop different method smounting the Versa-Mil to the lathe to perform gear cuttinThe basic unit and the indexing head are the tw o baselements needed to cut gears. When large diameter gears neto be cut, the universal head is u sed to m ill the side of tgear.

Spu r gears are the most common typ e of gear used in tfield and the correct cutter to u se for this type of gear determined by the pitch of the teeth and the number of teerequired. Standard cutter catalogs supply the data necessary select the correct cutter.

Gear Cutting with the Basic Unit and anInvolute Gear Cutter

In this setup, Figure 9-34, the gear blank is first turned to tcorrect diameter using a mandrel mounted between centerThe blank should r emain on the m andr el after turning. Thlathe dog shou ld be w edged against the faceplate to eliminabacklash and the indexing head mounted to the lathe spindto position the individual teeth. The basic unit is moun ted othe comp oun d rest w ith the faceplate parallel to the lathcenter and an arbor with an involute gear cutter, stamped withe correct pitch and number of teeth, is installed in the basunit. After the cutter is positioned, lock down the cross feeby tightening the gibs. When th e correct d epth is reachetighten the post locking screw on the basic unit. The cutter then fed into the blank by hand using the lathe carriage whee

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Gear Cutting with the Basic Unitand a Fly Cutter

When an involute gear cutter is not available or delay inobtaining one is too great, a fly cutter is used . The onlydifference is that a fly cutter with a 5/ 16-inch square tool bit,ground to the correct shape, is used instead of an involute gearcutter. See Figure 9-35.

Gear Cutting w ith a Un iversal Head

Used this setup with either a fly cutter or an involute gearcutter on gear blanks larger than 8 inches in diameter. SeeFigure 9-36.

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WHEEL DRESSING

Wheel dressing (Figure 9-37) with the diamond dresser is amust for accurate precision grinding. Dress wheels beforestarting any grinding job and again prior to the finishing cut.The diamond dresser is the most efficient type of wheeldresser for truing w heels used in precision grind ing. Thediamond point is the only usable part of the diamond and m ustbe inspected frequently for wear. Rotate the diamond slightlyin the holder between dressings to keep the point sharp. A dulldiamond will press the wheel cuttings into the bonded ores of

the wheel, increasing the wheels hardness. When truing thewheel, the diamond should be centered on the wheel andslanted between 5 and 15 in the direction of wheel rotationto prevent chatter and gouging.


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Tapered Spind le Grinder

For shallow a nd small diameter holes up to 6 inches indepth, use the tapered spindle internal grinder. Tapers mayalso be ground on the work by using either the taper

attachment or the compound rest. See Figure 9-40.

Deep Hole Grinder

The deep-hole grinder with the extended housing offers arigid precision grinder for holes as deep as 18 inches. Tapersmay also be ground with the deep-hole grinder. See Figure 9-41.

Versa Grinder Head

The Versa-Mil external grinder with the wheel guardremoved may be u sed for internal grind ing of large boredpieces if a considerable amount of stock mu st be removed andthe hole depth does not exceed the unit clearance. This setuppermits the operator to grind internally, externally, and facein one setup, assuring a tru e relation between the three

different surfaces. See Figure 9-42.

SPECIAL OPERATIONS

TOOL GRINDING

the use of the Versa-Mil soon develops methods for grinding

The Versa-Mil mou nted on the compou nd rest of a lathe

will duplicate the full range of tool and cutter grindingoffered by conventional tool grinders. For successful results,the lathe should be in excellent operating condition andpreferably small in size to permit the close setting of feedsand angles. Versa-Mil spindles use precision, spring-loadeddu plex bearings to eliminate play in the grinding w heelforsuccessful tool grinding. The Versa-Mil tool rest is solidlyconstructed to provide rigid support with a tip that is designedfor smooth, solid contact under the teeth or flutes of the toolbeing ground. The operator familiar with tool grinding and

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the various types and forms of cutters. Tool grinding cannotbe completely covered in this manual, and it is suggested thatreference material covering tool grinding be consulted forcomplete detailed instructions.

Selection of Grin din g Wheels

Grinding wh eels should be in the m edium grit range fortool and cutter grind ing. The shap e of the cutting tool willdetermine which wheel design to use. Abrasivemanufacturers catalogs should be referred to for proper wheelselection.


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Depth of Cut

Light traversed cuts should be used to avoid overheating andburn ing the cutting edge of the tool. Dry grinding isrecommended for sharpening high speed steel because coolantremoves heat from the cutting edge too quickly causing

cracking.

Direction of Wheel Rotation

It is generally safer to have the wheel rotate off and awayfrom the tool cutting edge. This allows the tooth rest toposition the tooth and prevent th e cutter from tu rning. Thismethod, however, has some drawbacks, in that the heat fromgrinding is directed toward the tool cutting edge and leaves aburr w hich m ust be removed w ith an oilstone.

TOOL SHARPENING

The efficiency of a cutter is determined by the sharpness ofits cutting edge. Therefore, it is important to sharpen a cutterat the first sign of dullness. A dull cutter not only produces apoorly finished surface, but if used continu ously, the cutterwill need excessive sharp ening to r estore it to its originalefficiency.

Grinding Cutters Cylindrically

Certain typ es of cutting tools, such as ream ers and plainmilling cutters, are ground cylindrically to remove warpagefrom heat treating, to remove nicks, to obtain a specificdiameter, or to produce a cutting edge with a slight clearance.When grind ing tools or cutters, the work rotates in theopp osite direction from that u sed in conventional grinding.This allows m ovement in th e same d irection at the p oint ofcontact. Mount the cutter so that the heel of the tooth makescontact with the grinding wheel first, allowing the heel of thetooth to be ground slightly lower than the cutting edge. Thisclearance will vary slightly depending on the rigidity of thetool being ground and the job setup. The tool to be ground canbe held in one of three ways: between centers, on a mandrel,or on a short arbor moun ted in the lathe headstock spindle.There are actually two methods of sharpening the cuttingedges of individual teeth or flutes found on cutters.

Down Method

In this method, the rotation of the wheel is from the body ofthe tooth off and away from the cutting edge. The direction ofwheel rotation holds the cutter on the tooth bu t will raise aburr on th e cutting edge, which must be removed by stoning.This method h as a tendency to draw temper from the metal.See Figure 9-43.

Up Method

In this method, the wheel rotation is from the cutting etowards the body of the tooth. With this method, there is danger of burning the tooth. However, the operator mensure that the cutter is held firmly against the tool rest. Ifcutter tu rns d uring grinding, the cutter will be ruined.

Cutting Tool Clearance

Correct clearance on th e cutting ed ge of any tool is essenfor heat distribution, resistance to wear, and cutting efficienNot enou gh clearance will cause the teeth on the cutterdrag, produ cing heat caused by friction, and slow cutting. Tmuch clearance produces chatter and dulls the teeth rapidPrimary clearance angles are determined by the typema terial the cutter w il1 be used on. Secondary clearanangles are usually 3 to 5 more than primary clearanangles. This produces a strong tooth that provides easy conover the wid th of the cutting land. The width of the ladep ends on the diameter of the cutter and varies between 1inch to 1/ 16 inch. When the w idth of the land becomes wide after several sharpening, the secondary clearance anmust be grou nd to restore the land to its original width.

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Clearance angles are produced by positioning the wheel,cutter, and t ooth rest in different locations. When usin g theVersa-Mil, it is easier to reposition the wheel by raising orlowering the basic unit. To determine the distance inthousand s of an inch, multiply the d esired clearance angle bythe diameter of the cutter times the constant 0.0088. Theconstant 0.0088 is the decimal equivalent of the distancemoved 10 on the circumference of a l-inch-diam eter circle.

EXAMPLE: Using the following formula clearance angle xcutter d iameter x 0.0088, a clearan ce angle of 7 on a 1 l/ 2-inch-diam eter cu tter w ould be 7 x 1.5 x 0.0088, or amovem ent of 0.0924 of an inch.

Grind ing Form Cutters

Formed or eccentricity relieved cutters (such as gear cutters)and concave and convex cutters cannot be sharp ened in th e

same manner as profile cutters. Form cutters have a definiteshape th at mu st be retained, even after several sharpening. Toretain this shape, only the face of the cutter is ground.Increasing or decreasing the rake on th ese cutt ers alters thefinal shape of the cutter, so care must be taken to ensure thathe rake remains at the original angle. The indexing h ead m ay

be used to assure even spacing of the teeth faces.

THREAD MILLING

The Versa-Mil with the universal head will enable a lathe tomill threads to full depth an d complete profile in a single passFigure 9-46). Milling threads saves time and reduces thehance for error over single pointing. USS threads may be cut

with standard 60 included angle cutters.

Acme and special form threads are cut with cutters designedfor the pitch d iameter required . The Versa-Mil will cutinternal, external, right-handed, or left-handed threads. Squarethreads can be cut with an end mill mounted in either the basicor the milling and drilling head.

Lathe Preparation

Thread milling speeds and feeds are approximately the sameas those used for keyway m illillg and slotting. The lathespindle speeds needed for thread milling are generally lowerthan those available on standard lathes. It is usually necessaryto use a reduction unit mounted to the lathe to obtain the

required lathe spindle speed. Large diameter workplaces mayrequire speeds as low as 1/ 2 or 1/ 3 RPM. Other than lathespindle reduction, no other modification of the lathe is neededfor thread milling. The quick change gearbox and lead screware set the same as for single point threading. The indexinghead m ay be mounted to the lathe and used to rotate the lathespindle when a reduction unit is not available.

Moun ting the Versa-Mil

Even though the cutter is at or below the centerline of thework w hen the basic unit is moun ted on the compou nd r est, itis advisable to mount the unit directly to the cross slide for

rigidity.Supporting the Work

Work of sufficient diameter and rigidity may be supp ortedeasily between centers. For long or small diameter work, asteady rest or follower should befrom bending away from the cutterof cut.

used to prevent the workthereby reducing the depth

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