M e t a l S p i n n i n g

r f o . D . M P F S E . RED CRAW HAW , . ,

A ssista t D a n e n ,

Coll o f E i ri U i v rsi t o f li oi e ge ng nee ng , n e y Il n s

PO PU LA R M E C' AN I CS ' AN D B O O 'S

C 'IC AG O

P O P U LA R M EC 'A N ICS CO . C o ri hted I 0 py g . 9 9 ' ' W IN D R B . y . SO ' IS bo o k i s o ne o f th e seri es o f h andb o o k s o n i n dustri al subj ects b ei ng publi s hed by th e Po pul ar M e an s C o L k e th e m a az ne t ese ch ic . i g i , h “ bo o k s are wri tten so y o u c an und er ” stan i t and are nten e to f rn s d , i d d u i h inform ati o n o n m ech anical subj ects at a ri e W it in th e rea o f all p c h ch .

T h e tex ts a nd illustr ati o ns have b een prep ar ed ex p ressly fo r this H andb o o k S er es b ex erts a re u —to - a e a nd i , y p ; p d t , hav e b een revis ed by th e edi to r o f P o p ar M e an s ul ch ic . — i L ath fo r M ta l S p i i g F g . l e e nn n Ch a p te rs

The La the and

The Preparation o f Metal fo r

'ow to S pin aHollow Dish

'ow to Spin a [seep Dish

'ow to Spin a V a se

'ow to Spin S ome Unclassified

METAL S PINNING

z. 7. 8 6 5 iNTRODUCTlON

S e m i s now ss s m o va h et etal , which pre edand ta ped int a great 0 ri et of o ms for omm l uses was to w ars a o y f r c ercia , , up afe ye g , either hammered or spun into the desired shapes by a comparatively few artisans who had learned the art of cold-metal working in

Euro Lk so ma o of old- m r s o ne o f pe . i e ny ther the ti e c aft , the metal spinning has partially come into disuse beca use o f commer cial competition and the failure ofthe young er generation o fmen to familiari ze themselves with the handworlc oftheir fathers . In

S s is o l r s o ne oc the United tate , it nly in the a ger citie that ca sionally finds an artisan who does metal spinning ; when such a

so n is ou is us l O o o ms o ut per f nd , he ua ly ccupied in pr ducing f r ofthin metal that require great care in making or are difficult to ss m im s o o t s m o r . S o pr duce wi h a ta p pre et e , h wever, where only a co mparatively few articles of any particular shape are

s r s s of s m o ut to s os de i ed , they are pun in tead ta ped , ave the c t of s die .

I is som u r s mo m t believed in e q a ter , particularly a ng etal s n s ss s m m t k pin er , that pre ing and ta ping e al can never fully ta e

of s n is im o ss o ss or s m som the place pi ning it. it p ible t pre ta p e forms except as they are produced in parts and these parts so l

b un esir or o . s is m n s d dered , razed riveted t g ether Thi a ife tly a for m ki s of o ble any nd w rk. M ETA L S PINNING

The fact that modern commercial tendencies are in the dirce tion o f abolishing metal spinning wherever po ssible doe s not mean that large sheet-meta l working establishments do not em

o m l s s o s m a ow s men are pl y eta pinner ; it d e e n , h ever, that the e called upo n to do the hardest kind of spinning without much possibility oflearning how to do the simpler forms ofthis work .

it is for ou u os or o f mak n o ssi the d ble p rp e , theref e, i g it p ble for amateurs to be helped in meta' spinning and to renew this craft where metal spinning is really more serviceable than its su s s s ook is r t n b titute , that thi b w i te .

From s n o of c sm m l s nn n is a the ta dp int the raft an, eta pi i g craft which is highly desirable of attainment and which may

a c a n-m a ork so m ca s s o r m ca s s be repl e be te et l w in e e , , in any e s o nn cti on w fi of m u ed in c e ith it. The principal eld the etal s n r o r is o u o of o ms for a pi ne , h weve , the pr d cti n f r plated w re .

Prac i c all s a has m has ss t ally ilver pl te white etal , which been pre ed

s un n o s a as s . are so m n o ms s p i t h pe , a ba e There al a y f r u ed

con c on ma u a u s o a c fix ne ti with n f ct red article , n t bly ele tric

r s h c can be and ma m s are s un r r tu e , w i h , ny ti e , p with g eate certainty o f goo d results than could be possible if other methods are used .

For os who ke u s o k for the firs m is su th e ta p thi w r t ti e , it g gested that forms be undertaken after the order of tho se de scribed in the following chapters and that copper well annealed be us ed as the practice metal .

FRED D . CRAWS 'AW C'APTER I

T'E LATH E AN D I TS PARTS Metal spinning does not take a particularly prom i nent place among the trades in the United States . Inasmuch as it is perfectly possible to spin metal on o r an engine lathe a speed lathe , if either is properly o f equipped for this work , few manufacturers ma chine tools make a lathe specially for Spinning . The work requires a lathe which will not move side wise to any great extent a s a result o f heavy work running at a high speed . The ordinary engine lathe does not ful fi l the requirements of speed ; o n the i s fo r other hand the speed lathe , unless it designed heavy work , is liable to be unstable . 1 The frontispiece , Fig . , illustrates a strong speed lathe equipped for metal spinning . It will be noticed that the legs of the lathe are particularly well braced and that the entire machine presents o f the appearance strength . Inasmuch as the writer h a s worked upon a lathe similar to the one illus tra ted and has Spun different kinds o f metal o f vary ing disk diameters on it without inconvenience from lathe vibration , he feels that he can safely recommend a stro ng speed lathe fo r ordinary metal

Spinning work . The principal lathe requirement for good spin ning is a speed ranging from r . p . m . to which can be maintained with but slight variation whether light or heavy spinning is being f done . The length o the Spinning tools and the method o f holding them produce a fi rm contact b e

METAL S PI N NI N G

th ‘ to o l tween e and the m etal , and this requires a lathe which h a s in store a considerable amount o f Fo r reserve power . ordinary work , a spinner a h a lf- should us e at least horsepower lathe , but for o r e work in schools light work in shops , good r sults can be obtained with a quarter- horsepower lathe which has a large head cone and i s strongly belted . fo r The parts of the lathe , when equipped metal f spinning , which di fer from corresponding parts when the lathe is u sed for metal turning , are the

- headstock , faceplate , tool rest and tail center . The d o g which is so commonly u sed in the metal work ing Shop to hold work from slipping in the lathe as it revolves is never used in metal spinning . The ordinary center screw fa ceplate o r outside screw faceplate used in wood - turning is screwed onto the headstock spindle . Upon the faceplate is screwed o f i s a block hard wood , usually hard maple ; this turned with wood - turning tools to the shape de sired for the fi rst form in the process o f spinning . The circular disk o f metal which is to be spun is centrally placed against this turned form and held in place by the tail center which i s brought in con b e tact with i t . Prior to the time when spinning i o f g ns , the circular disk metal is held in place by friction between the wooden form fastened to the a i s facepl te , over which the metal to be spun , and the o f tail center . The process Spinning will b e de i scr b ed later . Th 2 e lathe rest commonly u sed is shown in Fig . . A a nd B are both pieces o f wrought iron which h ave been fastened together by turning a shoulder o n the upper end o f B and fitting the part thu s made into a hole bored in the middle o f A and counter

M ETA L S PI NNIN G

to a re fa s sunk at the p . The two pieces securely tened together by riveting the end o f B into the ’ “ ” o f A T - countersunk part . This simpl e rest is o f I fastened into the slide rest the lathe . t replaces

e . the tool rest in the wood lathe equipm nt Now , a a c a e as will be expl ined in succeeding h pt r, the o f e o f plying the tool ov r the disk metal , to press th e it securely over turned form , requires the to a ct a s spinning tool a lever . The direction o f motion o f the lever varies from a vertica l plane at the beginning o f Operations to a horizontal plane at the completion o f the Spinning process . In order that this may be done without the tool slipping on r t a a o 1 . the rest , vertic l holes e bored about in . in apart in the horizontal portion o f the rest in which a o f is inserted movable pin . The position the tool i s 3 As on the rest shown in the illustration , Fig . . the metal is gradually pressed over the form the pin i s moved toward the headstock o f the lathe by changing it from one hole to another . For small “ ” work the horizontal portion o f the T - rest can be

3 - - - o ut o f i h o r i n . i h . made A . . square s tock A

- rod will answer the purpose for the rest pin . The pin should be shouldered squarely at the bottom to fi t 1 - i n . . into [i t holes bored in the rest “ ” The size o f the vertical portion of the T - rest will depend upon the hole in the Slide - rest which receives it . I am assuming , in this description , that an ordinary speed lathe is remodeled to serve for ffi m a Spinning purposes . Some di culty y be found in th e rest slipping wh en considerable pressure is used in the spinning process . This might be “ ” avoided by u sing a T o r square pin joint to fasten

M ETAL S PI NNI NG

a o f . the two p rts the rest together However , if the operator will shift the lathe carriage from time to time to keep the fulcrum point as nearly as possible o f ffi over the central portion the rest , little di culty will be experienced in this direction . In describing the spinner’s center I Shall illus trate and refer to three . All of these are shown in 4 to Fig . . The one at the p is to be found in the market . The one in the center of the illustration is described because a practical spinner , after years o f experience and after using many forms o f fi o fi t e centers , nally c ncluded that this one lled all qui rem ents better than any other he had ever seen o r used . Two things are absolutely necessary in any cen fi ' ter which is used in metal spinning . The rst light contact must be kept between the end o f the center and the surface o f the metal being spun . In other words , there must be absolutely no slipping ' o f at this point . The second this portion the center which sticks , as it were , to the spinning metal should move freely and without much , if any , wear o n the remainder o f the center which is i n s erted in the tailstock . I n order to have these two ’ essential factors p resent in spinners centers many ff devices have been constructed . Di erent spinners ff use di erent centers , often devices of their own ; but experience h a s shown that the two centers here — described have worked well I do not say perfectl y . 4 The center illustrated at the bottom of Fig . is one which the writer tried as a result o f som e trouble 4 which he had with the top center shown in Fig . , an d before he used the one shown in the center o f METAL S PINNING

o f this illustration . It has the advantage having o ne but moving metal part , which serves a good pur i n to pose some respects , viz , it reduces a mini to mum the trouble due many parts . On the whole , 4 o the middle center shown in Fig . proves the m st satisfactory . —A The stock center is made in three parts , B and

- C . A and C are cast iron parts and B is a washer made o f some hard substance such as hard rubber ' o r fi - vulcanized ber , ag ainst which cast iron will run to fi t o f freely. B is supposed tightly upon the pin C s o that A al o ne revo lves when the center is firmly o f t to pressed against the disk me al be spun . A may be made in different shapes to accommodate different forms and sizes in spinning and sho uld be lubricated by o ccasionally dro pping o il upon the pin o no t o f C . This pin sh uld enter A farther than is to o o fi t necessary form a go d bearing, and sh uld ab o ut as tightly in A as a shaft in a high - grade ma fi ts o ne ffi chine in its bearing . The di culty which the writer has had with this center , as well as with o i s o f the sec nd center described , the impossibility making the diameter o f A small eno ugh for some o no t o w rk . This may be considered an bj ection in o the trade work, but in sch ols , where small pieces will naturally be spun more than large ones , it sometimes forms a serio us drawback to acco mplish o o o ing g d results . The center shown at the bott m o f 4 o to o fi b e Fig . was f und overc me this dif culty cause the revo lving part o f the center can be turned o ne o as small as desires . Here , h wever , it should o co n be menti ned that , if the end bearing surface in to o tact with the work is made small , a perfect

M ETAL S PINNING

to easy matter duplicate A , and it may be said here that it is well to have a number o f this part o f the

o . o o o n e center in st ck A br om handle , sawed int inch lengths with the pro per h o le drilled at the o f - o ff o center each sawed part , will pr vide pieces fo r o o f a c nsiderable length time .

There is an idea among so me Spinners that the part c o ming in c o ntact with the metal to be Spun “ ” sh o uld be made o f w o od s o that a better stick may be secured than is possible with a metal end . o r no t o Whether this is a fact , h wever , must be de o o o cided by each w rkman . It is s metimes f und advantageo us to put a little resin o n the end o f the center in o rder to increase the friction between it t o . and the metal be spun Again , when the part A o f o to o is made wood , it is p ssible drive int the end next to the w o rk a few small brads . These may be left extending fro m the center - end just en o u g h to catch o n the disk as it revo lves in the Spinning process .

o ne o f Any the three centers described work well , no t but , as has been intimated , at all times per fectl o o fo r o y . I believe there is an pp rtunity s me o ne to devise a m o re perfect spinning center . I have wo ndered if so me ball bearing center might no t o ffi S s lve the present di culties . uch a center is illus

tra ted 4 . in Fig . It has been used with success in school work acco rding to the statement o f the i n h dividual w o devised it . CHAPTER I I

TOO LS

Th e tools used by metal spinners are difficult to name . Very few spinning operations require the a us e o f any one particul r tool . This fact contributes to the present condition regarding metal spinning — tools in general , viz They are usually not to be found in stock and , when found , the forms used for the different processes vary considerably in differ f a r ent sections o the country . There e a few stand ard forms , however , and while it is true that old o w n spinners usually make their tools , they con form to regular pra ctice in making these few stand ard forms . The tools commonly spok en o f by the machinist as the h a nd - tool diamond point and the cut -o ff tool are the only edge tools used in metal spinning ; is consequently , there little danger of the operator a id being cut while spinning metal . To further in

' d a n er i n o f eliminating the factor of g the use tools ,

- nearly all spinning tools , except the above men ti o ned two , may be used with the end of the tool placed under the work . In most lathe processes the tools are pu shed into a revolving piece o r placed on top o f it as is the c a s e in some kinds of wood turn o ne ing . This feature of comparative safety is which recommends itself to many who contemplate starting metal spinning in schools . Because all spinning tools are u sed by pressing their ends against the work , considerable friction M ETAL S PINNING

s to result , and minimize this as much as possible , ’ o o the to ls in a spinner s kit , except those menti ned fo r cutting and trimming 'the diamond point and - o ff o o o cutting t ols', sh uld be gr und perfectly o o o sm th and then well p lished with emery . ’ I have said it is diffi cult to fi nd spinners tools o o kept in st ck . Perhaps this is the reas n why their no o ld names are t well kn wn . In talking with an o o o f o s et spinner c ncerning the names the to ls in his , “ s i r fo r he said , Why , I have been a spinner thirty years in Sweden and in the U nited States and it seems as th o ugh I had always known h o w to use o o n t o o u every t ol his shelf, but I cann t give y the o f o n o f b o name e them . As a y I was carefully h o w to o n e taught , why and where use each but I ‘ ’ ‘ ’ always heard them called this to o l o r that to ol . ’ o I d n t believe they have any names . I suggested that no o n e o ught to be better prepared to name ’ ’ spinners to ols than he after h i s life s experience and s o o o , with s me persuasi n , he suggested the names which I shall use in c o nnection with the to o ls de scribed and illustrated in the next few pages . Some o f fo r were named because their shape , and others names were suggested by the kind o f work which they performed .

’ In the average s et o f tools in an expert spinner s s et will be found from o n e to two dozen forms . Perhaps no t m o re than s ix o r eig ht too ls are in o r d i na r us e i s y . As it with most specialists , the ' individual metal spinner will c o llect a number o f fo rms which he will use o nly o nce in a great while . I Shall make reference to o nly s ix o f the more i m portant tools here , and I venture to say from some METAL S PIN NI NG experience that any spinning except that which “ ” may b e designated as special can be done with a , l o f part or a l these .

- 5 - i n The round nose , Fig . , is made of . round , hexagonal or octagonal steel . Round stock , for the o work which this tool d es , is probably the best . It is forged into the desired shape and at least 3 in . of the end carefully ground ; probably o ne- half or more o f this distance ought to be polished . The kind of work to be done , and the peculiar tastes of the workman can alone determine the exact shape most o Fo r suitable for this or other t ols . this reason two

- or three round nose tools , varying in form from the to a d v a n long the short pointed, may be used to tage . The extreme end must not be a sharp point in any case for fear of its catching the revolving metal and tearing it . It is advisable , however , in order to press the tool into small grooves , to have the end a s pointed as possible and yet have it slightly rounded . The round—nose i s u sed to a greater or less degree according to the regularity o f form in the obj ect

' being spun , but , in general , it is used to the exclu o f sion all others in starting to Spin a piece , and by many workmen it is used more than any other o n e o t ol . It is especially u seful in compressing metal into cavities and in pressing o ut any irregularities

' o r b efo r r m n wrinkles e e o v i g work from the lathe .

The tool which is probably a s di ffi cult o f con 6 o f struction as any is shown in Fig . and , for lack

- u . a better name , will be called the raising p tool As this to ol is used in o perations which require considerabl e force applied by the workman , and ,

M ETAL S PI N NI N G

a e a k i s e also , bec us in forging the tool nec form d a e a i s us e sm ll r th n the regular stock , it well to steel

- a trifle l a rger than that used for the round nose . —i n W here . stock is used for the tool j ust de

- 3 - i n i n . fi scribed , . or even A material can pro tably

‘ be used in the construction of the o ne now under o r discu ssion . Hexagonal octagonal steel is gener ally considered more desirable for the raising - up - o f tool than round stock . The forging this tool o fi must b e d ne with a great deal of care . The rst f process is to upset the end o the tool . The second process is to draw down the neck , leaving a knob of metal on the end which is suffi cient in size to fi o n t form the nished end . There is e danger agains which the forger must constantly guard in upset ting and hammering the tool into shape . I refer to l ea fi n o r the g lapping of metal which , unless a weld fi ing heat is reached , will leave seams in the nished tool that will make it almost useless . Again , in tempering , great care must be taken not to produce a crack in the neck j ust back of the head . The u se - u to which the raising p tool , is principally put th a t o f forming concave bottoms o n dish forms o r Operations which require surfaces to be spun co n cave instead o f convex toward the headstock makes it necessary that the head o f this tool should 6 have a lobe left at the point lettered A , Fig . , in order that the tool can hook under the metal and draw it up into an undercut groove .

I have endeavo red to make the drawings o f these tools a s nearly correct as possible according to the suggestions which I have received from spinners o wn o f and from my experience , and in the case this

METAL S PI NNING

a th e 'at ca n care i s t ken , surface be ground without o f burning the steel . This flat surface is the part the tool which is used principally ; the one operation o f grinding together with polishing puts it in condi i s o f tion . It well to have the cylindrical part the

o . t ol , opposite the flat surface , ground and polished

This surface can sometimes be used . It i s believed that the tools o f which mention has already been made might conclude the list of th o se ’ making up the necessary tools in a spinner s kit , if it were not for so me extraordinary o r unusual Fo r o f shapes in spun work . the purpose spinning these peculiar forms Special tools may be made at any time .

two There are other tools , the groover and the - — 8 9 t e knob raisi—ng tool illustrated in Figs . and s p ecti v ely which may be used in places as s ub s ti f tu es for those already described , with perhaps som e additional ease .

The groover , as the name implies , is used in mak fi ing grooves . The operator nds the use for this tool almost entirely in spindle form s and , then , only fo r small grooves . It will be noticed from the cross sectional view shown that small grooves o f varying sizes may be made by simply using the tool in con tact with the metal a t different points o n the curve o f o n o f - the tool . It is placed top the lathe rest with the end hanging d o wn and o n the lathe side o f the o n rest . The operator presses down the handl e , thus making a lever of the tool with the rest as the fulcrum .

- As will be discerned later , the knob raiser may b e used in raising up o r hoo king under the metal in M ETAL S PINNING spinning a dish concave toward the headstock ; o r it may be used by pressing it endwise to ward the o f o n to o o o n line centers the lathe , f rm a c ncavity o o o a spindle f rm . It sh uld be a c mparatively easy to o o - a s matter f rge the kn b raiser , inasmuch the end is simply upset in the fi re and afterwards . o o o gr und int the desired shape and p lished .

Figure 1 0 gives the shape and the dimensions o f fo r o the accepted handle spinning t o ls . In this fi o gure , also , is represented the meth d used in fas tening the tool into the handle . Probably the best woo d o—ut o f which handles may be turned is straight grained , hard maple .

It is necessary that all tools , except those used fo r o o cutting and trimming purposes , sh uld be l ng enough to permit the end o f the handle to rest under the arm and thus aid the workman in getting a strong leverage by thro wing the weight o f his b o dy o o 1 2 d wnward . The handles are usually made fr m 1 5 o o to in . in length and the t l long enough to admit o f i ts being driven into the handle fro m 4 to 5 in .

Pieces o f gas o r water pipe make very go o d ferrules . The to o l and handle when fastened to gether Sh o uld

2 to 30 . be from ft . in in length . Inasmuch as the o to to ls are highly tempered , the wearing due the spinning p ro c es s d o es no t change their shape rap o no t idly . C nsequently, reforging is necessary except after the tool has been in service for a co n s id erabl e e length of tim . CHAPTER I I I

T'E PREPARATI ON O F ME TAL FOR SPIN N I N G

The metals commonly used in spinning a re cop

a . per, white metal , br ss , zinc and aluminum M etals a n must be used which , by some process such as nealing, can be made perfectly pliable . It must be evident that only when metal is perfectly pliable can it be spun over irregular shapes . The constant friction between the tool and the metal tends to harden the metal , and hence it mu st be softened and made pliable , many times it may b e , during a

spinning process . The thickness o f metal most suit able for ordin a ry 22 work varies from B rown and Sharpe gage No . 26 i 22 i to No . , inclusive . M etal gag ng s u sed for the largest work only and then principally when G 24 b e the metal is copper . age m brass and zinc comes pliable with proper treatment and can be successfully used for forms varying in diameter and 3 5 o r 6 o f height from in . up to in . Metal B . and 6 . 2 i s S gage No . more easily spun than thicker

material , due to the fact that it assumes easily and

quickly the desired form . B ecause of this fact ,

however , articles spun from it are sooner ruined G 26 than those spun from thicker meta l . age will no t stand the continual pressure of the spinning 26 tool very long . Metal of No . gage is naturally

adapted to the smallest work , but to be successfully spun should be used by workmen o f some ex p eri

ence . M ETA L S PINNING

Thus far we have sp o ken Of metals in a g eneral no o n e way, and Of metal in particular . We will dis cuss b ri efiy the preparatio n and best uses Of the fo ur metals mentio ned ab o ve .

Copper

Copper , varying in thickness between the gages ’ f tO a b o v e mo fo r re erred , is perhaps st suitable all fo r o fo r general spinning , especially school w rk and amateurs . It is tough and when heated is very no t o pliable . It is s o easily shattered by verheat o r o o o ing , numerous heatings l ng c ntinu us working o o o as are the ther metals menti ned . It sh uld be o o o understo d that all perati ns , in preparing the metal fo r spinning and th o se used after spinning i s begun , should be as brief as possible and never As duplicated unless necessary . a matter Of fact the annealing process will be repeated many times

Of necessity, especially by beginners . In learning to o ne o o ne o n Spin , will keep the to l in place the metal until it beco mes hard and tempered in a o o fi nd d iffi sense . As a y ung spinner will pr bably culty in successfully pro ducing a desired fo rm in o ne Operation it will be necessary fo r him to anneal o r soften the copper befo re he completes Spinning . fi One must rst calculate , with some degree Of pre ci s io n to o , the size Of circular disc necessary f rm the spun article . If spinning is properly done , the o metal will be thinned very little , if any , in w rking it consequently the computati o n Of the disc size W 111 o involve in most cases s me mensuration , but , o principally , a g od supply Of common sense and o judgment is needed . The w rkman will be greatly aided in his computati o n if he will make a cro ss M ETAL S PI NNI NG sectioned drawing 'through the axis O f revolution' i s O f Of the Obj ect he spinning , and , with a pair divid r s et O ff O f e s , to a small span , step the length the 1 1 outline desired . Thus if in B , Fig . , 'Cup and Chucks'one should start at O and step carefully by 1 and 2 to 3 he would have the radius O f the disc out Of which the cup could b e spun . It will be de sirable to make the radius Of the disc slightly greater than the distance thus determined , if the o n metal is to be compressed any . If , the other hand , the metal is thinned due to unnecessarily ' working the too over the metal , the radius need not be quite as large as the outline distance spoken of. — The disc a fter being cut from a large sheet in — which form the metal is best purchased i s heated in an annealing furnace o r over a B unsen burner until it changes to an iridescent color and a film O f copper oxide burns Off. If an annealing furnace is c used , the temperature may be ontrolled ; but in

- — case a Bunsen burner o r blow lamp i s used o ne Of which meth—ods would be followed probably for small work the coloring Of the metal , when the a a proper temperature is re ched , must be the me ns o f determining when the copper has been hea ted fi suf ciently . If it i s heated beyond the proper point the strength O f the metal is weakened a nd it may be even exhausted entirely . N evertheless , in rough ” a h o i m work , copper is he ted until it is red t and mediately plunged in water . This constitutes the annealing process . Some spinners , especially where considerable c a re i s taken to preserve the o f strength the metal , cover copper with Oil when a a anne ling it . This is by no means an undesir ble M ETAL S PINNING

M ETA L S PINNING

need to be annealed . In the trades it is used as the base fo r most silver- plated ware ; and consequently fo r o ut forms which cannot be pressed , the spinning o n process is a necessary e. If the lig htness Of the plated piece has no t a large consideratio n in its o o us e pr ducti n , it is advisable to quite heavy white o metal . There will be an explanati n made in a — future chapter concerning the drawing o ut Of metal in spinning . As the Spinning process continues , the metal is liable to be worked thin by being drawn o ut . This is especially true in the case Of white metal and thus the suggestion with reference to the use Of heavy metal is Opportune .

B ra s s

B rass is prepar ed fo r spinning in the manner de O o f scribing the annealing f copper . The chang e o o i s no t s o ffi c l r in brass perceptible , when su cient C heat has been applied , as in opper , and couse quently the metho d Of covering the metal with Oil before heating will pro bably be the safest in anneal Fo r ing brass . ordinary Spinning it is quite imma teri a l whether o r no t o ne applies the same am o unt fo r s o o Of heat each annealing , l ng as the metal is n t o o . overheated Brass hardens m re rapidly, through the use Of the spinning fo o l than Copper does . When we remember , then , that there is O f g reater danger _ spoiling the metal by annealing it many times than by slightly overheating it once , we will understand why brass is more diffi cult to n o e spi than copper. Wherever possible , n should use a s thin brass a s will be consistent with the strength required . M ETAL S PI NNI N G

' VVe have sa id th a t it w a s perh a ps a dvisable to im merse Copper and bra ss in Oil before annealing . \V h eth er This i s still more important with zinc . it is necessary o r not to Oil o r grease zinc while heat i s ing it may be a question , but it certainly advisable in the minds Of Old spinners . The theory seems to be that the O il tends to soften the metal when heat is ' applied . inc has a decidedly crystalline formation a nd the friction caused by the spinning tool rubbing a gainst it tends to make it more , rather than less , crystalline . This molecular condition weakens the metal by decreasing its tensile strength and it b e comes decidedly diffi cult to spin ; especially is this tru e in thick pieces which have to be turned over o abrupt c rners . The melting point for zinc is about ° 780 i s Fahrenheit , which considerably lower than o r the m elting point for copper good brass . This necessitates much more care in annealing zinc than is necessary with any other metal which is capable O f being spun . It is decidedly advisable not to ° ° a 3 50 400 reach temperature above or F . Of course this point in temperature cannot be deter n mined except i an annealing furnace . It should be understood that after zinc is heated as above ex ’ plained it i s plunged i nto co ld wa t er before a ny a i s ttempt m a de to spin it .

Al umi num

no t a a . Ordinarily, aluminum does need nne ling It may be better to he a t it slightly when the m etal

is thick , but this is a matter which the operator L must determine for himself by experiment . ike white metal , aluminu m is easily worked , but it is M ETA L S PINNING also easily shattered ; and consequently the ease with which it can be spun s o metimes results in a spoiled piece after co nsiderable w o rk has been do ne o n o o o o it . Aside fr m the p int Of its being a g d base fo r nO plated ware , there is advantage in using aluminum . It is , however , light , and therefore

desirable large spun pieces . CHAPTER IV

'OW TO SP I N A S HA LLOW D I S H The very simplest spinning Operations possible are involved in the spinning Of a shallow dish Of a small diameter , such as a pin tr y . Shallow forms fi to may be dif cult Spin , however , if they are irreg

- ular and complicated in cross sectional outline . The o ne thing which makes them good examples for amateurs is their shallowness . They should be fi simple in form , also , if they are rst pieces in spin a f ning . I shoul d s y the amount O depression should no t 1 exceed in . and the diameter should not be 6 ’ greater than in . in the spinner s initial dish . A shallow dish may b e in either Of two general —0 ne classes , depending upon form , viz in which the curve O f depression is gradual from the rim to the bottom ; o r o ne in which the bottom O f the dish is comparatively flat and the rim i s formed by abruptly turning the metal over a corner , the rim being perpendicular to the general plane O f the bot

' fi l a fi nd . c s s w e tom In the rst the saucer , and in the second such a form as the cover to a tin box a - baking can , for example . It will be evident that o ne o f two things will tend to make a dish diffi cult to spin ; either its great depth or some sharp corner which forms the divid ing line between two surfaces . Right angle corners , ffi s o therefore , are di cult to Spin ; especially when a s a the surface turned over, in the ri m Of dish , is very high .

META L S PI N NI NG

Either of the two faceplates sent with a wood turning l a the may be used for the wooden form blocks over which the metal is spun . It is best to use the center - screw faceplate for work Of small s ur diameter , such as a cup , for example ; and the - O f face screw faceplate for work large diameter . If us e this suggestion is followed , one will probably

- the surface screw faceplate to spin low dish forms . The wooden form - bl o ck is made according to a c ce ted - p methods Of wood turning . Two things must be true if the form is to serve satisfactorily the pur pose for which it was turned ' It must be perfectly smooth and it must be hard . Hard maple , well a scraped and sandpapered , makes very good form for most spun work .

a a s In some c ses , will be illustrated later , it is necessary to split a form in order to release it from the spun article . Dogwood is considered the best

- for this purpose , although straight grained hard maple will answer the purpose very well . When a o ne number Of particular form are to be spun , it is economy O f time and labor to construct a cast - iron - no t - form block . I t is best to loosen a form block from the faceplate after it is once put in place until fi all spinning is nished . This may require the con structi o n o f duplicate faceplates for each lathe in case a lathe is used for some purpose besides the o ne in question before a spinning j ob is completed . i s It better to do this , however , than to have the work running out Of true due to removing the form block from a faceplate to a llow other work to be o n put it .

W hen th e m etal disc h a s been cut a nd c entered

M ETA L S PINNING

tO O l o n rev lu left , and the spinning its right . The o tion Of the lathe draws the to o l down S O that it is nearer the axis and a little l o wer than the end Of o o o o the w den supp rt held in the left hand . The b dy to throws the handle the right , which causes the end o f the to ol to press to the left and c o nsequently m o ve the metal gradually toward and fi nally o — o ag ainst the f rm bl ck . When the metal has at o - o last been spun tightly ag ainst the f rm bl ck , the diam o nd p o int i s used to trim the edge and the Spun U u l o piece is c o mplete . s ally in spinning a w dish Of regular shape it is no t necessary to anneal the fi o metal after it is rst put in the lathe . It sh uld be o o o underst d , h wever , that annealing is necessary no a n whenever the metal beco mes hard . If it is t nealed as soon as it becomes hard it will shatter .

The spinning pro cess may be accomplished also o o o to by h lding the t l as described , except have the to ol end ab o ve the center Of the lathe instead Of b e l i t o w . If this position is taken , the movement Of two - o ' o to the body must be f ld , viz d wnward and o o o the right , which will result in the to l p int w rk ing upward instead Of downward .

Pro bably in spinning a simple dish form no d iffi culty will be experienced in keeping the metal to a uniform thickness and the same thickness appro x i m a tel y as it was in the sheet . If , however , it is o o o f und that the metal is thinning , the t l , by revers o to ing the m vements Of the body , must be made travel toward the center Of revoluti o n . This will c o mpress instead Of draw o ut the metal . It must be ‘ very evident that an inward m o vement o f the tOOl point will tend to bulge the metal at the point

M ETAL S PINNING where it is held between the center and the form to fi block . It is avoid this , principally , that the rst movement Of the tool is taken away from the center o r axis . Moreover , the metal must be worked _ fi against the form , at rst , at the center until it is fi - rmly in contact with the form block . This is very o o imp rtant . If spinning is successfully d ne , it will be largely due to fi rst establishing a fi rm contact b e - o tween the metal and its form bl ck at the center . Gradually this contact surface is increased as the o tool continues to w rk outward . It has been assumed that the dish form will be o spun with c mparative ease . This will probably be d o true if the bulging, just referred to , and buckling no t o r h a s together separately hinder . As been ex i s - o plained , bulging the result Of over compressi n

o o ne . with the to l . Buckling is phase Of bulging tO O l i s o While the working t ward the center , bulg tOO l ut ing may take place . While the is working o ward and when it is pressing against metal that is no t in contact with the form - bl o ck but is simply b e ing supported by the stick in the left hand , buckling to is a common danger . The metal begins feel rough under the tool and the tool will seem to jump to U o o from point point . p n investigati n it will be found that the metal i s fo lding o r lapping in places . ffi If it is at once annealed , the di culty may be over o fi come , but therwise it will continue and nally the tw o metal will shatter, ruining the piece . There are fo r fi o ne ' no t reasons this . The rst the stick is kept ' o a d d iti o n to directly opposite the tool p int , and , in ' no t fi this , is probably pressed rmly enough against a it . It may be true , also , that pressure is being p

M ETAL S PINNING

h as fi speeds are required . When the dish nally been fo rmed and smoo thing and p o lishing are the o o fi nly perations left , the speed may pro tably be f r to 2000 . o r o increased r p . m . even more than this T O O small diameters . great a Speed will , throug h centrifugal force , throw metal away from - form block . CHAPTER V

'OW T O SPI N A D E E P D I S'

Under this head I shall treat forms which a p proach the cylinder and require the u se Of two

- form blocks 'for beginners at least'instead o f o ne . The illus—tration on page 42 shows forms O f this character cups , toothpick and match holders , etc . pinning metal into a cylindrical form involves a S — diffi cult Operation that O f turning the outer por tion Of the circular disc which is being spun , through an angle approaching 90° and consequently compressing very materially the metal at the outer i s portion O f the disc . I n addition to this there the diffi culty Of turning the sharp corner between the bottom O f the form and the cylindrical surface forming the sides . An experienced hand will do both o f these things with apparent ease by u sing the tool and stick as described in Chapter I I I .

However , as the metal is bent or turned through an angle approaching 90° the Operator must spin in the s u air , as it is called . In other words , nothing p ports the metal from the time it leaves the circular disc Shape until it reaches the fi nished form except the tool and the supporting stick ; the m etal is there o ne fi fore spinning in the air . If is pro cient in the art O f o ne - Spinning in the air , only form block will be needed for deep forms a s was the case with shallow

forms . Few m en , however , are capable Of spinning large pieces in the air when the metal at the outer portion Of the disc must be compressed consider

- I . ably . ntermediat e form blocks are therefore used M ETA L S PINNING

TO expl ain better deep dish spinning I sh all refer to a specifi c pro blem which I have shown by line 4 o n 3 . 1 1 . drawings page , Fig A and B are vertical cross - sections through two form - blocks which in this case may be fastened o n center screw face o - o n plates , each f rm block being turned and kept a i s o i s single faceplate until all spinning d ne . A the intermediate fo rm -bl o ck and B the fi nished fo rm o fo r 1 1 bl ck the cup illustrated at C , Fig . . The o s o dotted line in A is a duplicate Of the f rm B , that o n e can easily estimate the relative amount Of spin o ing which must be d ne o n each bl o ck . It i s s up posed that the metal being spun will be annealed after it i s taken fro m fo rm - bl o ck A and before it is o - put On f rm block B . — In showing only o n e intermediate fo rm block the writer is taking it fo r granted that the instructions given in Chapter IV will enable o ne to spin the metal o n each o f the two fo rm -blocks with o ut d i ffi no t a s culty . If this is true many intermediate form -blocks as desired may be prepared consistent with the number Of annealings which the metal will i to d o o stand . It s always necessary s me spinning o o in the air , therwise the supp rting stick which is o no t held in the left hand w uld be needed . This o o supp rting stick , h wever , is in reality , only a

- makeshift form block , and when the intermediate o - o o f rm bl cks are many , the process Of supp rting the metal by the use Of the supporting stick is no t called spinning in the air . It will be n o ticed that the dotted outline and the o o no t o o n s lid utline in A coincide at the right , nly the line which pictures the end Of the chuck , but

o r o r o n . also f in . in . the cylindrical surface

M ETAL S PINNING

not same time thickening it . It will bulge during this process because the base Of the cup i s fi rm no t against the chuck . It must be supposed that the inward movement must b e used to the ex o o o ne to elusi n Of the utward . I mean infer that o the former should predominate . By careful w rk and gradual pressure the metal will fi nally touch o - the f rm block at all points . Mention has not been made thus far Of the tools to be used , as it is believed enough was said in Chapter IV to enable the beginner to use his j udg tO O l s ment in the selection Of . My opinion is that - to o ' the round nose and lifting , if they are properly d o formed , can successfully all dish and cup Spin F r ning Of an ordinary character . o the purpose Of o o l sm othing, however, s me tool with a f at surface , o r such as the tongue planisher , will undoubtedly be used with more facility and possibly with better o r results . I would suggest the use Of copper fo r aluminum all work thus far described , if strength Of material is an Object and if the Operator is an amateur Of spinning work . However, white metal is m o re easily worked than Copper and i s the cus to m r a y metal fo r the base in plated ware . Brass i s to o to o rather tough and hard , and zinc is brittle fo r o n to e us e in the experimental stage Of spinning .

If considerable diffi culty is experienced in s ecur ff s u ing the desired results , I O er the following as g es ti v — g e helps . First Endeavor to spin a saucer Of small diameter and Of simple o utline o r a cup whose Sides make an ang le Of about 75 with the ffi base , before attempting something more di cult . M ETAL S PI N NI NG

' - I us e o r ev en fo ur Second zf n cup spinning three - form blocks , if perseverance will not accomplish the desired result with two . The speed o f the lathe for work coming in the class here considered be a trifle higher th a n th a t given a v erage p revious chapt er . M ETA L S PINNING CHAPTER V I

HOW TO S PI N A VAS E In this chapter we will consider all forms which o may be called vases . In s me cases the word vase form implies a neck or a top smaller in diameter o than the b ttom . It is this peculiarity which seems to make it necessary that the Spinning Of vases should be dealt with separately . The manipulation o f the tO Ol s in this group o r class O f forms will b e spoken O f briefly as very few tOO l new Operations in work are introduced . Usual ly a greater number Of tOO l s are required to co m pl ete a vase form than are used for simpler Obj ects ; these will be mentioned later . The principal variation from the general method o - Of work c mes in making the form blocks . Usually three form - blocks will be needed for a vase - form w o ne hich has a neck smaller than its base , unless As is an adept at spinning in the air . this book i s supposed to be used by amateur workmen , as wel l as others , I shall consider that preliminary and intermediate form - blocks will be used in beginning fi work at least . We will consider a Speci c problem again in order to illustrate and describe to the best 1 2 advantage detailed methods O f spinning . Figure shows vertical cross - sectional drawings Of a pre liminary and intermediate chuck , and the end view and elevation Of the fi nal form - block used in spin

- ning a vase form represented at C in this s a me cut . 1 3 a a - In Fig . lso wil l be seen a vertic l cross section

M ETAL S PI N NI N G

' view Of a form -b lock showing the co ns tructic n Of o r a block chuck for a vase with a small neck . a s a re Here 'Fig . in Chapter V , A and B simply used as easy steps in Obtaining the form It i s shown at C . only necessary , I believe , to call attention to the fact that the diameters shown at 1 2 3 a nd and , in A , B and C , and , in B C , are the same . The Obj ect Of this i s to produce contact surfaces fo r - each succeeding form block . One i s not advised to undertake th e spinning O f - a vase form befo re simpler forms h a ve been tried . This i s because the work as a whole is more diffi cult a i s th n it is in simpler pieces . There a particular fi to o dif culty , , which should be mentioned . The neck Of the vase being smaller th a n its base the metal must be compressed to an unusual degree

- as it is drawn over towa rd the several form blocks .

- After this compression comes a drawing out process , the result Of which is the neck Of the vase . Such severe treatment Of the metal is safe only in the hands Of spinners Of some experience . I n order to dra w the form - block out of th e vase O f - form after it is spun , some kind split chuck must be used , such as is shown at C , or else the solid chuck must be burned and bored o ut Of the fi nished ffi article . As this last Operation is much more di cult o ne fi than might at rst suppose , and , also , as by this method Of ridding the va se from its form the vase i s to a liable be d maged , it has become customary to devise some form O f split- chuck with a key piece t a a which , when w i hdr wn , will allow the rem inder to t e Of the chuck parts loosen , when they may be ca s e moved with . In p reparing the s e s plit -chucks one should fi rst M ETA L S PINNING carefully select a piece Of dogwood o r a very

- straight grained piece Of hard maple , and bore a o o to h le , with the grain , thr ug h the block from end o end . It is desirable that this h le should taper b e o fi b o r slightly . This may acc mplished by rst ing a straight hole and then carefully gouging it to a taper . A better method Of tapering the hole is to use a o taper reamer after the straight hole is b red . The reamer will leave a h O l e that will be true and co n sequently an arbor will touch the stock at all p o ints . o If neither Of these meth ds seems feasible , the straight, cylindrical hole may be made tapering by o o using a tapering, w den spindle covered with sand o o paper . When the h le has been pr perly prepared to two receive the spindle , the parts Of the chuck sh o uld be put to gether and the desired form turned . o r o - o This form f rm bl ck , as we have called it , is next driven O ff Of its arbor 'the spindle'and split 1 2 - as illustrated in C , Fig . . The form block is split S O that all parts taper to ward the center Of the block “ ” n 1 o e . except , marked in the illustration This piece , the key piece , will be larg e at the center and n o o f - small o the utside the form block . Besides being careful in turning and in Splitting the chuck , o ne must use j udgment in s o proportioning all parts that the key piece may be fi rst withdrawn throug h fo r o the hole which was bored the arb r , and then o thers may be withdrawn without diffi culty if they n t tO O fi are o left thick . When the chuck has nally fo r been prepared as described , it is ready use . The parts will be held together at the base by the metal , which has the same shape at the base Of the vase t e as h last formed chuck . The parts are held to

M ETAL S PI NNI NG gether at the to p Of the vase by some device similar t 3 12 ‘ o ne a . a to the shown , Fig , or similar device 3 1 . more clearly illustrated in Fig . Probably the m o s t diffi cult spinning to be done - 1 2 in the V ase form shown in Fig . will be changing the form from A to B . Here the means Of compres sing the metal by Spinning in the air will be em ployed . Bulging ought not to be the result , if the metal fits tightly at the base Of the vase . A con s id era b l e o O f am unt compressing must be done , how ever, to get the metal into the cylindrical form shown in B and one must use a great deal Of care to O f prevent trouble in this Operation . Instead keep ing the metal as thick as the original sheet o n e must compress it enough 'in the vase - forms which have a neck'to allow it to be drawn out on chuck C , in making the concavity for the neck . This requires simply that the process Of compression should be ’ continued longer than usual . The neck is formed by placing the tO O l point under the axis O f rev o l u tion and working from the larger diameters toward the smaller diameters after the cylindrical form spun on B is placed on block C . Attention is called to the fact that the diameters at 3 in B and C are

2 . the same , and also the same as the diameter at Another method for forming the neck is to use such a tool as the lifter ; it is pushed toward the axis and worked downwa rd from each side toward the small diameter . Should a form be desired with a substantial roll to 1 4 at the p , as in Fig . , an additional chuck may be required which will allow the whole vase , with O f to a s the exception the top , be admitted , shown 4 1 O f . in Fig . at the bottom the sheet In this kind M ETAL S PINNING

- o Of a vase f rm , in which the base is larger than the to o p , the chuck used in making the r lled neck must be split in halves o r quarters in order to all o w the to fi — chuck be withdrawn from the nished vase form . I have o nly indicated the meth o ds employed by o - - Old spinners in Obtaining d uble curve vase forms . There is great Opp o rtunity fo r o rig inal devices and methods in Spinning any article , but in this class o f wo rk perhaps there is more chance fo r the de v elo pm ent Of individuality o n the part Of the wo rk ' man than in work such as has been described in previous chapters . Little more need be said concerning the use o f

o . t ols , annealing , etc . than has already been said

Annealing must take place whenever necessary , but o fi w rkmen should be pro cient enough in spinning , ffi when undertaking a di cult form , to require the minimum number Of annealings fo r a particular tO O l s fo r o piece Of work . The used any f rm should be selected with reference to their size and shape . As a rule the ro und - n o se is considered the g eneral tool . The knob raiser is the tool used particularly fo r lifting o r raising in Shallow porti o ns Of the fo rm o r o r in grooves . The planisher the tongue is a o fo r o r satisfactory t ol smoothing straight , conical c y lindrical surfaces . CHAPTER V I I

'O W TO SPI N SOM E UN CLASSI FI ED FORM S Whatever a man ’s occupation may be he is at any time liable to be confronted with new problems .

The school cannot teach all , even though it strives f r to lay the foundation o all . I have attempted in these chapters to give the foundation for all metal spinning as it is now practised . In this chapter I shall speak only Of a few Operations which may add to the information thus far given , and , should the reader spin o ther fo rms than th o se previously de scribed , this chapter may be helpful . Spinning in the air has been referred to as the control O f the metal when it is spinning between the tool in the right hand and a stick in the left . i s It true that this is one kind Of spinning in the air , but there is an o ther kind that I wish to describe . o r In general , air spinning Spinning in the air is any spinning Operation in which the desired form is Oh

- ta i ned with o ut the u se O f a form block or chuck .

Usually this kind Of spinning requires great skill , o but there are perations in this class which , with little practice , are perform ed with comparative ease . 5 i ec . 1 a e The illustration , Fig , shows t p Of spindle spinning which has an irregular shape in the center where the diameters are smaller than those at the ends Of the spindle . If all Of this should be Spun o l o to ver a so id f rm , it would be impossible with o draw the f rm when spinning was completed . It is al so practically impossible to make a workable M ETA L S PINNING METAL S PI N NI NG

o ne split form , due to the small diameters . Either

O f two . the following methods seems possible One , that Of spinning over a solid form which will , in the o r o r end , be burned bored out , , the other , that Of spinning the metal without the us e O f a defi nite i s form . The former of these two methods slow , i s and dangerous to the article spun . The latter quickly accomplished and , when the spinning Opera

i s . tions are completed , additional work unnecessary Figure 1 5 shows two chucks u sed in forming the i fi i s s . spindle . A solid and the form rst u sed B shows the second form used . It will be noticed that the sh ape o f the chuck A permits Of i ts removal from the spun article without diffi culty . The shape fi Of the nished piece , however, woul d interfere in

' a i s d ev i s ed such removal , consequently some chuck which will hold the metal spindle at each fend and may be withdra wn when the centra l part o f the spindle i s fi nished . The part Of the Spindle betw een points 1 a nd 2 i s i s spun in the air . The tool carefully pressed a s against the metal it revolves , working from the large diameter which wa s formed on chuck A to the sm a ll diameters a s indica ted i n the drawing . Here o ne can use such tools as the groover and tongue to good advantage . This illu s tration Of spin ning in the air will serve to explain the meaning Of this expression a nd to Show the possibilities in T h e s co e a this direction . p Of this p rticular kind o f spinning can only be realized a s o ne practises and to strives , be ingenious in the invention Of means fi m whereby dif cult forms ay be produced . fa r Thu s , with the exception Of a single mention Of a m eans o f producing a large roll at the to p o f

M ETA L S PINNING M ETAL S P I NNIN G

fi ly with each movement . When suf cient compres a sion has been Obtained , the metal may be dr wn over the chuck as described in previou s chapters . The chuck with the c o ncave bottom i s used when fn ta l h a s fi the e been spun to the rst form . The basket a s it comes from chuck 1 has a large contact fo r 2 surface prepared chuck , and if the contact is o ne a good , the center may here be dispensed with and the rest may be placed at right angles to the lathe - bed and directly in front O f the work after the i s - u neck Of the basket spun . The raising p tool , round - nose or knob raiser may be employed in co n caving the bottom by gradually working the tool o utward , principally , and inward but Slightly . The hole in the bottom can be drilled through while the o n work is still the chuck , by placing a drill in a a s - tailstock chuck in regular machine Shop work . Probably the hole may be as satisfactorily cut by using the point O f a diamond point hand - tool j ust before removing the basket from this chuck o r form b 14 e . block , which must split as in Fig , as by drilling . I believe we have considered all the necessary o perations for spinning single pieces O f metal . I shall attempt to give the reader an idea O f the method Of spinning two pieces O f metal together . N O better example , I believe , can be given than O f the hollow sphere . Illustrations this are shown in 1 7 Fig . . Two hemispheres are sepa rately spun a s illus tra ted a t A ' In fact each should be greater in depth than in diameter to allow for the inw a rd a nd o ut O f ward turns the edges Shown at B . After the two pieces have come from the convex chuck , each is

M ETAL S PI N NI N G put into a concave chuck which permits the hemi s et w a s spheres to inside with the amount , which i s left for the turn , proj ecting . The outward turn made by gently pressing the round - nose o r the back Of the tongue tool against the edge Of the meta l on the inside Of the hemisphere a nd a llowing the tool to follow the meta l as it rolls outwa rd . After the rOll h a s been made it may be pressed down to the regular Shape and thickness . The half which has the edge turned inw a rd i s placed in the same chuck which wa s used for the first half a nd the turn accomplished i n practically a the s me manner , except that the tool is pressed against the metal from the outside and follows it as it turns inward . When the turn has been com l eted p to the satisfaction Of the workman , he presses the end Of the grooving tool or round - nose against the inside O f the hemisphere j ust at the end Of the turn and makes the slight roll shown at B . This form s a slight shoulder against which the second h a lf Of the sphere presses when the two a re o r formed together . Either the inward outward rolled edge may be formed by the use O f the spin ’ 1 8 a re . ners pliers which shown in Fig . If these a tO O l s are employed inste d Of the ordinary spinning , they grasp the edge Of the metal a s it revolves and o r o ut the workman throws the handle in , depending upon the formation Of the inw a rd or outward turn . It is best to complete last th e h alf having the in rO ll ward . This half Should remain in the chuck t o r when the w halves a e formed together . L a fi i ts th e ving the rst half i n place in e chuck , the second half is pressed into it until the two rolls a u come together , wh en the t il center is drawn p\ M ETAL S PINNING

fi rm and presses the two halves firmly together . A but slight pressure with the end Of the gro over spins t o o the w halves t gether . If the sphere is desired o r o f perfectly air water tight , a bit solder may be run into the seam . The method Of making the Sphere just described is by nO means a simple o ne no r is it o ne that can o o be f llowed with success by all w rkmen . C in 1 7 o Fig . shows an ther means Of reaching the same results in an easier way , but here an extra strip is s o ldered o n the inside Of o ne Of the hemispheres wh ich d o es no t permit Of spinning operati o ns al o ne being used in the pro duction Of the fi nished article . S uch a pro blem as this is more practically done by pressing machines than by Spinning metho ds as herein described . a s In closing this chapter, and a last word , I wish to express the h o pe that many will undertake this o o alm st entrancing form Of cold metal w rk . It de a o serves place am n g the crafts , and , I believe , is wo rthy consideration from commercial stand -r point .

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