Before mounting work, clean the threads in both the chuck and the lathe spindle with a piece of bent wire. Clean the face of the shoulder on the spindle nose and the back face of the chuck.
Put a few drops of oil on spindle nose. Mount the chuck carefully and not too tight, first removing the center and sleeve from the spindle. The soft thud indicates a good firm seating against the shoulder. Be careful when tightening work in the chuck jaws.
Too much pressure on the jaws will affect t he accuracy of the chuck and may spring the work if a light piece is being turned. Try to have the jaws tighten around the more solid parts of the work. Always use the wrench which comes with the chuck. When chucking work in the universal or headstock chuck, turn the work as the jaws are tightened-an accurate "form fit" will result.
Small diameter work should not project from the chuck jaws more than four or five times its diameter-cuts should be short and light. Heavy cutting pressures will often cause small work to spring out and "ride the tool. The an gle plate shown in F igure 93 is bolt ed to any point on the face plate for machinin g irregular shapes and for off-center drilling and boring. Figu res 94 and 95 show two typical jobs.
Whenever ex treme accuracy is required on small diameters, t h e draw-in collet chuck attachm ent is the logical method of chucking. Some typical collet work: precision tools.
The collet attachm ent , as shown in Figure 96, include s a hollow draw-in spindle w h ich exten ds t hrough th e lath e headstock spindle, a tapered holdi ng sleeve and t h e split h oldi ng collets.
Cast iron, with hardened tool steel plugs for the ends, is often used in making a mandrel for large work. The mandrel should be tapered about. When finished, the mandrel diameter should be a force fit for the h ole in the work and the tailstock end should be. To make removal easier, put a drop or two of oil on the portion of the mandrel which will gr ip the work.
Never drive a mandrel with a steel hammer without protecting the end. The best tool for forcing a mandrel in or out of the work is an arbor press, or mandrel press Fig. Be sure the work is started perfectly straight and on the entering end of t he mandrel. Drill with proper lip clearance. The c utting lip an d h eel, S, H eel line. B, is lower than cutting are in th e same plane. Checks bo th length and angle of drill li ps. Reaming a cast iron h an dwhee l. Figure shows a typical reaming job on the lathe.
For best results, follow the same rules in reaming as in drilling and general turning. Use slow speeds, feed in evenly and be sure there are no burrs on the reamer teeth. The type of reamer shown in Figure is generally used in the lathe.
A reaming allowance between. Bot h are mounted in the tailstock r am as shown in Figur es and The drill pad serves as a table for flat or square work and is especially valuable for drilling large holes when a drill press is not available.
The crotch center automatically centers round work for cross drilling. The work is held in the left hand and advanced against the drill by turning the tailstock handwheel.
The met al s tan d has a h o le for each drill with the drill size and its decimal equivalent clearly m arked. The drills can also be purchased separately. Note high-spe ed boring tool mounted directly in tool post fo r maxi m um rigid ity. Boring operation s require only slightly differe nt tools and methods than those for external turning. T he b ig problem is t hat of tool rigidity, beca use m ost internal tools project considerably from their support. Fi gure shows a typical b oring operation.
There are several types of boring tools and m ounting methods. The tools shown in Figure 11 9 are mounted directly in the tool post. The exact amount of front clearance depends up on the size of the hole being b ored. F igur e sh ows how a f ront clearance angle can b e too small for one hole b u t satisfactory for a larger h ole. HE EL. Side Cl earance: Same as for external tools. Back and Side Rake: About half of external angle s-in some cases, less than half. Then b y putting the cuttin g edge on exact center, the correct amount of back rake is p rovided.
The general rules for the use of external tools apply to boring tools. For maxim um r i gidity. This g r adual process avoids spring in the tool- the final finish cut should be continuous. In Figure the lines representing the diameter "PD," are located so as to make spaces "aa" and "bb" equal. On a 60 0 Vee-type thread and on National Form threads, the pitch diameter is simply the major diameter less t he depth of the thread.
Thus, knowing the major diameter required, subtracting from it the double depth of thread for the required pitch, gives the minor diameter. Information on double depths of National Form threads for different pitches will be found on page PITCH-The distance from a point on a screw thread to a corresponding point on the next thread, measured parellel to the axis see Fig.
In Figure , the distance between points X and Y represents one inch. T hread Gauge. The form of this tool also provides ample clearance for even the coarsest threads. The tool is resharpened by simply grinding the top edge, adjusting the tool as it wears. I FIG. The beginner often finds it h elpful to turn the grooves C and D Fig. In F IG. With the point of the tool about an inch to the right of the start of the thread.
Start the lathe and engage the half-nut lever on t h e carriage. Appply plenty of lub ri cant to t h e work. W hen t he p oint of the tool reaches the groove at t h e end of the thread groove D in Figure , raise t h e half-nut lever on the ca r r iage, b ack out the cross feed a tu r n or two, and return t h e carriag e by h and t o the starting point.
Advance the cross feed to its original posit ion at 0, advance t h e compound rest for the desired d epth of cut, and engage the half-nut lever for the second cut. All feeding is done with the compound rest. A final pass through the thread with no advance whatever will often clean up any remaining high spots. Take the last cuts with extreme care. H eavier cuts can b e taken on soft metals such as brass or aluminum, but if a fine finish is desired, the last cuts should be very l ight.
W ith other metals use the type of lubri cant recommended for g eneral turning operation s. If the thread is to be cut with a sharp pointed 60 0 tool, the major diameter is equal to the minor d iameter plus the Vee-form Double Depth of Thread Table I, page When the tool point has cut to the depth of groove C, the thread has been finished.
Groove D should be about twice as wide as the thread pitch and a few thousandths larger than the major diameter. This groove provides a brief interval at the end of each cut during which the work can revolve freely while the half-nut lever is disengaged.
The grooves C and D can be omitted after the operator has learned internal thread cutting operations. Acme Screw Throad and Formulas. T h e A cm e screw thread Fig is often found in power transmi ssions, wh ere heavy loads necessitate close-fitting threads. Anot her common application is in the lead screws and feed screws of precision m achine tools.
T h e very light cuts w hen turning or boring a square t hread. Dra w line "a b" equa l to the circumference of the thread 3. Then draw line "ac " at right angles to flab" :J a nd eq ml in len gth to th e th r ead pitch o r lead, if a multi ple threa d. Draw lin e F IG. If the stock FIG. F i gure shows a typ e of pipe center recommended for s up port ing the stock w hil e cut ti n g p ip e type L.
This procedure is n ecessary b ecause metric th reads have no definite relation to the t hreading dial. Tool Ve! The position of t h e lever is indicated at the left end of the row of numbers in wh ich you find the thread or feed desired.
Righ t H and Quick-Change L ever - shifts to nine positions. They are numbered on bottom row of chart beneat h carriage feeds. T h e indexing position of the lever is always directly below the thread or feed des ired.
See Controls, Step "D", for location of gear positions. The position of the sliding gear is indicated on the chart in the same row as the thread or feed desired.
These positions are marked on chart directly above left hand group of indexing holes in gear box. The lever position for a thread or feed is shown in same row as thread or feed desired. The indexing position of the lever is always directly below the thread or feed desired. When writing specify thread or feed required - for coil winding f eeds, give name, type and size of wire.
The positions of the gears on the stud assemblies are denoted as "N"and " F" i n the gear set-up tables. Cross section of chan! Gear clearance does not reduce the accuracy of a thread cutting operation, because all play in t he gears is taken up in one direction. A small amount of grease, preferably graphite grease, applied to gear teeth will often aid in obtain i ng smoother. All the lubrication cups on the gear housing are shown in illustration at right.
Put a few drops of oil in each oil cup once a week if lathe is used constantly. Qu ic k-Change lever bear in gs a nd shaft oil once a week.
Occasionally apply a small amount of heavy outer gear lubricant to the feed gears and tumbler gears-it will aid in obtaining smooth er, more quiet operation. Extra gears, stub assemblies, and spacers necessary to make up the gear train are available from factory at nominal cost. Left Ri. These designations will be found on the lathe threading chart as well as in all of the following gear data. Gear bracket positions. The outer end of the longest bracket slot is called "Position A," the inner portion of the same slot is "Position B.
The gear bushing has a double key which fits into the keyways in the gears. The gear bushing and two gears fit over a stud bushing, and the assembly is bolted to the gear bracket. The washer is a bearing for the outer end of the gear bushing. Cross section of c hang e gear stud as sembly. N oti c e t h at in o rder to make this assembly complete, two gears m us t be m ount ed on the gear bushing at one time. When both of th e g ears on a g ea r bushing mesh with other gears in the train, they fo r m a " com p ound " g ear assembly.
When only one of two gea rs on a gea r bushing m eshes with the other gears in the train, It is called an "idle r. A method often used to ob- P ro p e r ge a r clearance. A small am ount of g rease, p r eferably graphite grease, applied to gear teeth wi ll oft en aid in obtaining smoother, more quiet operation.
Whenever a n ew gear train has been set up, shift the reverse fee d leve r t o t est th e dir ection of the carriage travel. Because som e set-ups a re s im p le-g ea red an d some are compounded, the carriage tra vel w ill n ot ne cessarily b e to the right when the r everse lever is shi fted t o t h e right. Swing entire gear bracket upward an d ti ghten so t hat 64 tooth gear in Position A meshes with the 32 tooth compounrl tumbler gear.
Gear set-up for 8 throu g h 16 threa d s per in c h. Place on back position of screw stub the gear list ed in "Gear on Screw" column of threading chart. Place 64 tooth gear and 20 tooth gear on b ush ing in Posit ion B with 64 tooth gear in back position.
Tight en s o th at 64 t oo th gear meshes with gear in screw posit ion. The 64 tooth gear is an idler; the 20 tooth gear is a spacer. Swing entire gear bra cket upward and tig h t en s o that 64 tooth gear in Position B meshes w ith 32 tooth compound tumbler gear. Place on front position of screw stub the gear listed in "Gear on Screw" column of threading chart.
Place 20 tooth gear and 64 tooth gear on bushing and mount in Position C with 20 tooth gear in back position.
Tighten so that 64 tooth gear meshes with gear in screw position. Exception; When cutting 32 threads per inch, substitute a 56 t ooth gear for the 64 t ooth g ear..
Place 64 tooth gear and 32 t ooth gear on b ushing an d m ount in Position A with 64 tooth gear in back p osition. Tighten so that 32 tooth gear meshes with 64 tooth gear in P osition C.
P lace 32 t ooth gear and 64 too th gear on bushing and mount in Position B with 32 tooth gear in b ack position. Tighten so that 32 tooth gear meshes with 64 tooth gear in Position C.
Exceptions: 1 When cutting 36 threads per inch substitute 24 tooth gear for 32 too th gear and 48 tooth gear for 64 tooth gear. S wing entire gear bracket upward so that the 64 tooth gear in P osition B meshes with the 16 tooth compound tumbler gear. G ear set-up for '12 thre a ds per inch. Place 64 tooth gear in back position of screw stub. Place 54 tooth gear an d 24 tooth gear on bushing and mount in Positio n B with 24 tooth gear in back position.
Tighten so that 24 tooth gear meshes with the 64 tooth gear in screw position. Place 56 tooth gear and 20 tooth gear on bushing and mount in Positi on A with 20 tooth gear in back position. Tighten so that 56 tooth gear meshes wi t h 54 tooth gear in Position B. T h e 56 tooth gear is a n idler; the 20 tooth gear is a spacer. Swing entire gear bracket upwa r d and tighten so that the 56 tooth gear in Position A meshes with the 16 tooth compound tumbler gear.
Place 48 t ooth gear on front position of screw stub. P lace 40 tooth gear and 24 tooth gear on bushing in Position D with 40 tooth gear in back position. Tighten so that 24 tooth gear meshes with 48 tooth gear on screw stub.
Exception: Wh en cutting 96 th reads per inch substitute 20 to oth gear fo r 24 tooth gear. Without the threading dial it would be necessary to reverse the motor at the end of each cut and "wind" the tool out FIG. A n y one of the fOUI dial markings may be used for following cuts. When cutting odd-numbered threads such as 7. Either the "I" or "2" dial marking may be used for following cuts.
Other lines m a y be marked in by t he same mark on the threading operator as needed. The setting of the compound rest feed is changed only after each of the four grooves has been cut to the depth of setting. The cutting operation is the same as in the preceding paragraph. The sett ing of the compound rest feed is changed only after each of the four grooves has been cut to the depth of setting. To cut multiple threads by slipping teeth on the compound gear: cut the complete first groove to a minor diameter dependent upon pitch of the desi r ed th r ead.
The change gear train should be arranged for the desired lead. It is important to use the same o point of reference to cut each thread - be sure to remember this point during the cuttin g operations. Refer to the table on page , then slip the r equired number of teeth by marking adjacent teeth on the compound gear and the gear meshing with the compound gear. Drop the entire gear bracket low enough to disengage the gears and turn the compound gear forward the proper number of teeth by rotating spindle by hand.
Raise the gear bracket so that the previously marked gear tooth meshes with the newly selected compound gear tooth. Place 64 tooth gear in front position on screw stub.
Place 56 tooth gear and 20 tooth gear on bushing in Position D, with 56 tooth gear in b ack position. Tighten so that 20 tooth gear meshes with 64 tooth gear on screw stub. Place 24 tooth gear and 48 tooth gear on b ushing in Position A, with 24 tooth gear in back position.
Tighten so that 24 tooth gear meshes with 56 tooth gear in Position B. Swing entire gear bracket upward and tighten so that 48 tooth gear in Position A meshes with 16 tooth compound tumbler gear.
Place 64 tooth gear in front positIon on screw stub. P lace 20 tooth gear and 40 tooth gear on b ushing in Position D, w ith 40 tooth gear in back position. Tight en so t hat 20 tooth gear meshes with 64 tooth gear on screw stub. Place 48 tooth gear and steel spacer on bushing in Posit ion B, with 48 tooth gear in back position. T ighten so that 48 tooth gear meshes with 40 tooth gear in Position D. Place 44 tooth gear and 20 tooth gear on bushing and mount in Position A with 20 tooth gear in back position.
Tighten so that 20 tooth gear meshes with 48 tooth gear in Position B. Swing entire gear bracket upward and tighten so that 44 I tooth gear in positio n A meshes with 16 tooth compound tumbler gear. Gear set-up for. Place 64 tooth gear and 20 tooth gear on bushing in Position B, with 64 tooth gear in back position. Place 20 tooth gear and 56 tooth gear on bushing in Position A, with 20 tooth gear in back p osition. Tighten so that 20 tooth gear meshes with 64 tooth gear in Position B.
Swing entire gear bracket upward and tighten so that 56 tooth gear in Position A meshes with 16 tooth compound tumbler gear. Place 20 tooth gear and 56 tooth gear on bushing in Position D, with 20 tooth gear in back posit ion. Tighten so that 20 tooth gear meshes with 64 tooth gear on screw st ub. Place 52 tooth gear and 20 tooth gear on bushing in Position C, with 52 t ooth gear in back position.
Tighten so t h at 20 tooth gear meshes with 56 tooth gear in Position D. Place 36 tooth gear and 64 tooth gear on bush ing in Position A, with 36 tooth gear in back position. Tighten so that 36 tooth gear meshes with 52 tooth gear in Position C. Swing entire gear bracket upward and tighten so that 64 tooth gear in Position A meshes with 16 tooth spindle stud gear. These threads and all others must be cut in the same manner as metric threads See Page Extra gears available from the factory at nominal cost.
When the material or job requires a certain feed, refer to the table below. Extra gears are available from the factory at nominal cost. Each stud assembly has an outer gear bushing long enough to accommodate two gears.
Cross section of change gear stud assem bly. Notice that in order to make t his assembly complet e, two gears must be mounted on the gear b ushing at one t ime. W hen bot h of the gears on a gear bushing mesh w it h other g ears in the train, they form a "compound" gear a ssem bly.
W hen on ly one of two gears on a gear bushing m eshes with t he other gea rs in t he t rain, it is called an "idler.
A met ho d ofte n used to ob - FIG. A small amount of greas e, preferab le graphit e grease, ap plied to gear teeth will often aid in obtaining smoother , m ore q uiet operation. Whenever a new gear train has been set up, shift the tumbler gear lever to test the direction of the carriage travel.
Because some set-ups are simple-geared and some are compounded, the carriage travel may be right for on e set-up an d left for another set-up, even though t h e l ever has b een shifted t o the same position in each case. A lways test th e directi on of carriage travel before starting to cut a thread.
Gear set-up lor 11 through 16 threads per inch. Place in front position of screw stub the gear listed in "Gear on Screw" column of threading chart. Place 20 tooth gear and 40 tooth gear on sleeve in Position C with 20 tooth gear in back position.
Tighten so that 40 tooth gear meshes with gear in screw position. Place 64 tooth gear and spacer on sleeve and mount in Position A with 64 tooth gear in back position. Tighten so that 64 tooth gear meshes with 20 tooth gear in Position C. The 64 tooth gear is an idler.
Swing entire gear bracket upward and tighten so that 64 tooth gear in Position A meshes with 32 tooth compound tumbler gear. Place on back position of screw stub the gear listed in "Gear on Screw" column of threading chart. Pla ce in front positi on of screw stu b the gear listed in "Gear on Screw" column of t hreading cl, -' r t. P lace 20 t ooth gear and 32 tooth g ear on sle eve and mount in Po si t ion C with 20 tooth gear in back posit ion.
Tig hten s o that 32 t ooth g ear m esh es w ith gear i n screw p osition. The 32 tooth gear is an idler; th e 20 toot h g ear is a spa cer. Tighten so t hat 64 tooth gear mesh es w it h 32 toot h g ear in P osit ion C. The 64 toot h g ear is an idler. Swing entir e gear bracket up wa rd s o that the 64 t ooth gear in P ositio n A m esh es w ith th e 16 tooth com pound tum b ler gear.
P la ce in b ack p osition of screw stub the gea r listed in " Gear on Screw" column of threading chart. T ighten so t hat 56 to oth gear m esh es with t he g ear in screw position. Place 64 tooth gear and 32 too t h gear on sleeve a n d mount in posi tion A w ith 32 toot h gear in back position.
T ighten so that 32 tooth gea r mesh es with 56 tooth gear in P osition C. Figure shows the interm ediat e points between the four mainmarkings. T h ese poin ts can be mar ked with penc il, or t he posit ions eas ily estimat ed. T o cu t the s econ d groove of a double t hrea d, the B FIG. The line and the "b" positions. Lin es for "A ," "B," and " C" p os itions ar e mark ed.
Set up the change gears for th e l ead in threads per inch 12, not Engage t he half nut lever for the fi rst cut wh en t h e stat ionary mark on the ou tside of the threading dial is in line with anyon e of t h e f our main marks on the rotating portion of t h e di al. T hen r eturn t o the start ing point and engage half nuts at any on e of the "b" positions, taking the first cut on the second groove of the th r ead. The com pound rest feed remains at one s ettinJ! A s ingl e t h read of t h is lead can b e cu t only by engaging the half nut leve r at the "0" or "B " markings, on t h e thread ing dial.
T o cut the second groove of th e double thr ead, the half nuts a re engaged at t he HA " or "e" markings, an d t he cutting operation is the same a s in the pr eceding para graph. Each thread groove is cut to its complete depth and finished before starting the next groove.
The feed in inches is equal to 1 For example, a feed of. Refer to the threading chart and the four following paragraphs when changing these gear set-ups. Table II on page includes gear set-ups for other carriage feeds. Tighten so that 32 tooth gear meshes wi th 64 tooth gear on screw stub. Tighten so that 24 tooth gear meshes with 64 tooth gear in Position C. Tables I and II give proper gear set-ups for a wide variety of special threads and feeds.
Most of these set-ups are exact- some are accurate to the limits mentioned. Table III gives set-ups for metric threads with pitch between 0. Thus, it is possible to cut metric threads very close to the standard metric pitches.
Refer to page when cutting metric threads. A small piece of cellop han e slip p ed bet ween the jaw and th e w or k is somet imes u sed to a id in obtaining the proper bearing - advance t h e j aw u n til it just t ouches, t hen remove cellophane. W hen the work is being held in a chuck, the jaws of the steady r est can be set more accurately if th e work is held between lathe centers w hile t h e jaws a re bei ng ad justed.
Take extreme care in locat ing t h e tailst ock ce nt er see page F or jobs requiring maximum a ccuracy, check t rueness of the work with a dial gauge as shown in Fig ure 75, p age During th e cutt ing operation app ly plenty of lubricant on the work at t he p oint of bearing with the jaw s.
B oth t he follower rest and steady rest are often used to brace a slender F I G. Threading a long screw with t h e aid rod Fig. The cut-off tool must be set int o the w ork at an exact r ight angle and '"""1 with the cutt ing edge on dea d center see Fig F igures and 21 2 show t he t ool r ecommended for ,. This tool is FI G. Cut-off Tool.
T he blade must be at a right angle to the work. Do not use too slow a speed. W hen cuttin g off on a small lathe, the lubricant is usually applied with a b rush or oil can. S et t he cutting edge o f th e tool on the lathe center line-the tool blade should be at an exact right angle with the work Fig.
If the tool " hogs-in" an d s tops the spindle rotation, stop the m otor and reverse th e spindle by hand before backing out the tool with t he cross fe ed. Aft er resetting the tool, feed in slowly and remove the bad s pots. Never complete a cut-off of work which does not swing free at one end. Cut off as close t o the headstock as possible. W hen c utting off soft copper or aluminum, refer to page S6 or To resharpen the cut-off to ol shown in Figure , grind the fro nt edge only, aIlowin g fron t clearance see Fig.
Fig ure 5 8, page Each groove is slightly less dee p than the finish-diameter-this simplifies the turnin g o peratio n by providing an easy stopping place after each cut. Experiment to determine the proper spindle speed and rate of feed for the diameter and material being cut off-this is the best way to get the "feel" of the operation.
When the work is held in a chuck, cut the knurl as close to t he headstock as p ossible. Advance the tool into the work with the cross feed until t he dial reading has been advanced about. Stop the lathe and without b acking out the tool, check the pattern produced. When the pattern is not as desired, back out the tool and take a cut in another place on the work. After the correct desi gn is obtained the test cuts will be rolled into a perfect k nurl du r ing the final cutting process.
When a test cut shows the proper pattern, engage carriage feed. Apply plenty of lubricant. At t h e end of the cut shift the reverse lever to "Neutral," fo rce the tool. Continue t he knurling operations until the desired depth is reached. A fter the knurling process is started, never back out the tool until the knur l is com pleted. The bar is bein g fe d t hrou gh the beadstoc k s pin dl e.
T he carriage stop Fig. It is clamped on the front b ed way as shown in Figure The cross slide stop, combined with t he micrometer graduations of the cross feed contr ol handle on the lathe, a ssure an ac curate " z ero" r eading before the compound rest feed is advance d for the n ext cut.
Do n ot run the compound rest against the cross slide stop with too much force. The work is held in the mill in g vise ja ws. The e nd mills are s uitab le fo r milling slots, facing and ro u t in g small wo rk, s quar ing or splining shafts, cuttin g straight k eyways, and gene r al milling oper at ion s. T h e primary use of the Woodruff cutters is the cutting of Woo druff keyways-ot her uses include the cutt ing of slots, groov es, T s lots, etc. Th e complete co llet set includes one arbor f or holding straight a.
T his set consis ts o f : draw bar. A collet b ushing or arbor is also required for a ll st rai ght shank end mills except the Yz inch diameter. P ass the draw bar through the spindle and tighten t h e arbor into spin dle taper by turning handwheel. T ight en cutt er in arbo r by locki n g socket-head set screw. The draw bar, arbor, bushing, cutter shank and lathe spindle must be wiped clean and dry.
When mounting the mi ll ing cutter in the coll et arbor, be sure t o select the proper size of collet bushing if one is r equired. Take light cuts and feed in evenly and slowly until t h e correct feed can be judged.
Never force the work into the cutter t oo fast. A D iam. Optimum key w idth is e qual to one-quarter the shaft diameter.
Keys s hould h e c hosen to appro x imate this relation as closely as possi ble. This should nominally be eq ual to o n e-half FIG. If des ired. This dust is extremely harmful wh en allowed to fall and remain on the lathe bed ways and cross slide. A lways c ov er the bed ways and the cross slide during grinding op erations. Paper, oilcloth or canvas makes a good cov er. When using a cloth, be sure it is closely woven.
After t h e grinding opera t ion, clean the b ed ways and carr iage dovetails t h oroughly. Th en a pply plenty of clean oil. Figure shows h ow the dress ing tool is mounted in the holder which h as b een clamped to the lathe bed. T he diamon d point of the dresser should be at an angle and slightly below center as shown in Figu re Wheel Dresser w ith Diamo nd Po int.
At " AU it is necessary to r everse lathe spindle-at "B" the same effect is obtained by ru nni ng the lath e spindle i n a "Forwa rd " dire cti on. The work should be turned as close to t h e final fin ish size as possible before the g rinding operation is begun. With the w ork and the grinder mounted in position and the grinding wheel d ressed prop erly, ad vance the w h eel into one end of the work. T ake light cuts across the entire length of the wor k.
If usi ng the autom a t ic carriage feed, set up the change gears for the. Hand feeds should be very slow and even. The last finishing cut should b e less than. When hardened stock is being ground.
T h e quill which holds t he grinding wheel for internal work is threaded and tapered to fit inside the grinder spindle after the external wheel is removed s ee Fig. Mount internal wheel on grinder spind le an d align spindle with tailstock cent er pa ge W ith compound rest set at 0, dress g rinding wheel.
Feed up to the cent er with the carriage handwheel, lock carriage in p osition and feed a cross center slowly with compound rest feed.
Take light cu ts. See that the work is held rigidly- vib rati on ca uses poor w ork. No lubricant or cutting com poun d is n ecessary exce pt fo r production work.
Keep the tool post g rinder clean and w ell oil ed. T he bearings are grease packed at t h e tim e o f assem bly and need no furthe r attention. Th e too l shown in Figure has been found satisfactory by many auto repair mechanics. Grind the tool bit to the angles indicated-hone it thoroughly at regular intervals. Set u p the gear train for a fine feed-the three fines t fe eds sh own in t he carriage feed table, Section 7, Threading, are recommended.
Take light cuts with a surface speed of to feet per minute pages 45 and After t h e trueing cut, choose an u ndercutting saw which is t he same widt h as the commutator slot. Mount sa w on cutter arbor. Adjust undercutter so that saw is exactly on the lathe center line and in position to take a cut of about the same depth as the wi dth of t h e slot.
In the table below, tangent s are listed for every 15 minutes of angle. For example : The tangent of the taper in t h e example on page is. The exact reading is obtained as follows : [. The upper part of the tailstock is locked in position by tightening two headless set screws, one in the front and one in t h e back of the base casting see Fig.
Loosen the headless set screw on the side toward which the tailstock will be moved. Then t h e upper tailstock w ill move in that direction when the other headless set screw is tightened. The index line at the handwheel end of the tailstock indicates the approximate amount of setover see Figs. Taper C utt ing A tta chment in Operat io n.
The taper cu tting atta chment shown in Figure has many advantages over the tailsto ck setover method. L athe centers are n ever taken out of alignment ; bea r ing surfaces of the lathe centers a re n ot affected; dupli cate tap ers may b e cut quickly on pieces of different length; and taper b oring, impossible with tailstock s etover, is handled quickly and easily. The slide bar is installed parallel to the lathe bed way and set at the desir ed angle.
A slotted draw bar connects the slide bar and the car ri age cross slide, guiding the cutting op eration. Attach t he point er to t he end of the guide bar with the screw furni shed. Ma ke sure t h at both the top and side surfaces of the guide b ar a re p a ra llel with the machined ways of the lathe bed when the poin ter is set at zero. This adjustment should be m adt' with great care using an indicator to insure accuracy.
When the large and small diameters are specified for a certain length, apply the formula on page In making this check, make a light mark along the entire length of the taper with chalk or Prussian Blue and insert in a standard socket. Twist the taper and remove. If t he entire lengt h of the chalk line has been rubbed off, the taper is being cut at the proper angle and the finish cuts may be taken.
Make the necessary changes and repeat checking until the entire length of the chalk line is rubbed out. Sockets to fi t s t andard tapers should be cut to approximate size and r eamed with a standard taper reamer.
Each of the tapers, except the No. The No. Take cuts until the diameter at the small end is equal to the dimension given in t he table on page When cutting tapers, always have the point of the tool bit on the exact lathe center line. Be sure to check the taper in a standard socket before the final cuts are taken.
Screw Cente r. Cu p Cente r. These tnr ee c en t ers are com p anion pieces fo r wood tu rning on t he metal lath e. Each center h a s a No. The sc r ew cent e r Fig. The spur center Fig. The cu p center Fig. Revolve work b y hand to see if work turns f reely; if it is too t igh t, back off t he cup center slightly.
L arge pieces of square or rectangu lar stock will turn much more easily if th e corner edges are pla ned befor e the work is mounted. Catalogs, manuals and any other literature that is available on this site is made available for a historical record only. Please remember that safety standards have changed over the years and information in old manuals as well as the old machines themselves may not meet modern standards.
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