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33. MakiRg tletks . . i . ', .Stan Bray introduces the fascinating world of horology to the complete bKinner. This book explains th1 ' '& *of the clockmaker and provides general details of clock construction including layout of wheels and esc Cn ,a number of the Iatter being described. knMaking of wheels, pinions, escapements, plates pendulum - ' g , s, hands and faces A.s descriœsvilRvso v s . jalised items and choice- tî inecessary tools aod equipment are described with details y, ec jyj'slitnabsleramy ltaeris awiSriufoerntabeoirucmoonsrtœofoxtioonk' s on model enginejl itWlii %î'' tor of yodel Engineers' wo l ' ' ''èI .assistant editor of Model Engineer. ' qo F i ' .

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Introduction

Clock making appears to hold :1fascination al1 of its own, particularlyamongst m odt)l engineers, manydeciding to makc a elok:k after havingmade modcls iAt- variolls types. Tllereis something absolutcly fascinatillgabout clock luaking that seel-ns todraw one towards it. This book isintcnded as a brief introduction to thctools, materials and nRethods generallyused and to offer all explanation ofgeneral forms of construction. It is nota book of pl ans btlt those who haN'esuff-icient contidence could usc ll'1t?inforl-nation it contains to l'nakc asinlple clock.

thc work . Although a specialworkshop is not rtlquiredl one thingthat Bri 1 1 not do i s to work in auxlrkshop that i s ful I of svvarf andot 11cl- rubbi sh . a'Xtlcept ing that 'wecannot alsvays llaN'e a clinically elcanplaklc in Nvhich to operate, partictllarlyif it scrvkls stpsrtlral purposes, it is stillpossible to lllake a clean area forspcc i a l tl su- alld tl1 i s should be apriority. A tlorner of thtl Nvorkshop canbtl trlcalled ll1ld Llny oil 01- grease lying()1-1 tht? bench su abbcd off Keep th i sarea c l ean Nvll i I () cl ock nlak i ngoperations alv in progrcss. lt is a goodi d kl a to 1'11 aktl a fal se top for thesvorkbench and cover it with baize or asinai Iar naaterial which is sof't and wi 11not catlse damage to polished lmkltal .

As with a1l neu' projects, do not tryand run before yotl can walk. Don'tstart by trying to btlild a colmplicatcdlmechanism such as a ful I 'WkstminsterChilne but rather nlake somcthingsil-nplc, A mechanisll'l with a singlehand is a good idea. sttch :1 piecc w'llenwell polished tran look attractive aswell as being fascinating to watchwht,n it is working. Visit lmtlsetmns'wlnere (2l ock nRovcments can be

Although clocks come in a11 sorts ofshapes and sizes the basic principlebehind a lllechani cal clock llas notchanged for about fivkl hundred years.Of course modern materials and toolshave superseded some of the oldcrones but this apart the horologist willstill tend to work in the traditionalfashion . C lock nlak ing has long beenpart of the model engineering hobbyrather than being entircly thc preserN'c0f the horologi st and thc type ofworkshop owned by thc avtlragcmodel engincer i s quite suitablc for

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I 1-1 onc ptlrtrhases :1 very' oltl c l t'tlk' thtlkzllallces of it tlv'el- bkling lvgtllated tk)kcep acculute t ill'ltl al'k2 getlkpral ly veryslmal 1 . lNk art? tlsu'd i 1) th is day and ageto being able to tnt.lq' N'tlry cheap (2 Iocksallmost anysvhklrkl tllat ttre relmarkablyacctlrate. Thkly are control led by urhatanaounts to a eolllptltcr tr1'l ip and thi s i shou' that accuracy i s obtaincd . Theseti Inep i tlckls are vvhat onk? l11 i ghtdcscri bk? as sotl 1 -1 tlss- tllc).' tlo not havk2tllc l-astr i 11 a t i o1l ()f tllc I'llt?c 11 :.11-1 i kra 1dev i (2e- althotlgh it nntl sl bt? atll'n itteddo thkl i 1' 1 (3t3 pdrl-tlct Iy, Tllk? fact that ï.N.'tzc :.1 11 1) ot gtr t t 1) i s 1) i g 11 tl cg 1'tl k.'l () fltctr tl racy does 11 t'bt 111 tli.t 11 t 1'1 lt1 o tl 1* c l ockyN.' i 1 1 bc otltl-agklt.' tl s Iy i n:tc tl rêtte andafttll' al 1 t-t'll- n) ally y'klars i t Ns'a s q t.l i tec tl stollaary to sct :1 (.2 1 klck to t 1) k? corretrtt i I11 0 O l1C e t2V0 l-j' 'WC 0 k () 1, SO .

.A.1 I vve art't Iook ing t'-(.'r Nvhen ll'lt'tk' i l'lg aclock i s a l'neans of nlak i l1g a sp i ndl k.lu/îth a hand attaohed to it rotate at 11given specd. The spindle lltpeds to tnedri ven by sonn t2 fo rl'n o F p oNs'e r.u s u a I ly a very pri 1-n i t i N't': fo 1- 11'1 . AI'neans to regulatc that poNs'trr i s :l1 s()requ i red- i 11 order tllat it vv i l 1 rtll'l ;.tt :1Inartickllctr speed. I 1- ytltl llrt'r Ilollillg t()ti 11 i sh your ti rst e fforts i n 1 11 1 s s i tlk2 t)1'-tlle Ilobby- NN' i tl) êt lllastel'p itttrt't tlltttne itller I oost?s ()1' gCti l1s l'lltpl'e tllêtll :.1secontl or tvvo :1 yu'i.t 1' tllell ),,tltl Ctrk.lprtlbêtbly gkli l)g to bt't tl i sttllo i l'lted. 1 tu' i I 1 13 k2 13 (.) s s i b l t? t o ac 1) i tls'c tlrcasollablkl dklgree t'lt- ace Llracy al-ldl'nork? i I-llportallt Iy t() tl i sctlN'tll- Il(.)vs' to

Forttlnate Iy t-o r tllose u'ho a rebegi l'llli ng. thk? l-llateri al tllltt u.' 1 l l beused is llklilller tlxtktl-lsiv'e t)l' tlxpklllsik ktwllen klolllpared to thtl easti l'lgh;. tltc-used for model cngineering ptlrposes-so do not be frightened to l'nake a partl'nore than once if sonaething has gonevvrong. lt is far better than trying t()recovklr solmething that has not beencorrectly nladtl in tl'1c first place .Unli ke btlilding Imodel locoluotivcs ()1-

@tl-act 1 ol'l tpl-lgilles. NN'llt't1-k? 1I)t?l't'.- artlcxllensivc cflsti I'lgs tt' bil btltlgllt . solllcbl'êtss slletlt, a l2u' bi ls 111'1(1 1) 1 tlct'ts ofs 1 I &'e r slek'.t I and Nve are i n bus 1 ness .

NVe a I I t k.l n d to t 11 i 11 k' o f c I o tr k s be i 11 gnladk2 f-rol'n brass and steel btlt othernnaterial s can be used. Tl'lu'll-d are anu lnber of pl an s avail ab1 e tbr theconstrtletion of wooden c Iocks andNvh i 1e this l'nay not sound a suitabl k?lnaterials it is surprisingly robtlst. thc(.'J tlrnlans have used it for ycars tolllak' k? clocks col-nnlercial 1y. N ou'adayspl :! h:t i t? can be :1 uscfu 1 l'nattll-i al . I t i stzasy to u'klrk u ilh- it is hard u'earillgand a c lock I'nêtkltl o f a trallsparentp lastic can be a fasc i llat i l)g tI1 ing t()see. A I so Clq'ft i 1 ltblc arc plalls for k2 Iock sl'nad: frtl l)) pllper and card . Thcyappcar to u ork N'cry svel l and Iast for aI o n g t i 11 ) e .

Toolss'l()sl o1- the toklls I ikely to btl l'lcetltlt.lu'i I l be lbtlnd i 11 the 'tvorkshop of tllcaverage nlodel ellgilldtlr. Ntltldle f'i Ies-hacksavv, Iathe, stll-nc snla I I dri I ls andtaps are thc basic itellls that artlwanted. In addition a slmal I tiNze-sidttdbroaeh is possibly the only essential

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'altrll I-llak' i llg- i 1-1 'l-atrtPthcy arc o 1- doubtftll N'altlt? Nvhkln itconncs lo l'nak i ng k.r Iock h; . (.J- cntrral Iyspeaking tllt.r typc of lalhc ft'tlllkl il'l thklav'klragt't ll-lodel kpngi lleklr's yvorkshop isqu i ttr s tl i ttl b l kl . Th k? 1'n ost poptl I a r ()'f- al lthe s k.p a l't't p ro ba b I y th e N1 y fo 1-(1 7Scrikls. Nvh i ch havc a centre hcight o f3 r.''? i 1-1 s . T 1) o tlsa nd s o t- gootl c 1 ot? k s .l'lavt) bu-el'l I'nadc tlsi ng thcll't and otherl êt t 1) c h( o f a s i 1-1-1 i 1 a 1- si ze andspklc 1 f-i c at i k'l 11 . T1) k.'l l)1 1 !1 i attl re typclkttllk?s NN' i th ccntre h: i gllts ()t'' about11:.1 l f tllat haN'c thc atls'antage k)t- bei ngchcap and as they art? snaal l . ()bN' iouslylcss spact'l i s reqtl i red . 5,1 ost arc

tnc ;.1N'a i I abl t'r vN' i th :1. bo It tln 1'1) i l 1 dri l lllttaurhnlkll'll lhat l'nak t?!.i thtlll'l i tltra I l-k.n1-cëltting the teeth on l.N'11eklls. lt is l'lot

i tell't tlltll 111 iglll l'It'kt 1' l l'elttly be IA;tI'( (41'tl'lkl ï$'k)I'k' sllop eqtl i plllel'lt . Tllel'k2additit'llkll ttlols ol' trtltlrsk.- tltlt tiltly ttl'cl'1()t absoltltely t'tsstpllt i ê11 . Wrlaeel alltlpi l'liol'l ctlttcrs cotl 1 (1 be very' tlse l-tl l btltit is qtlilkl possiblc t() g() NN' itllklut tlltpll'l .Thertl arkr nAany people lllllk' i I1g N'eryli ne clock s ïvllt? l-laN'e llever btltlglltstlcll a c tlttcr i 11 tlle i 1- 1 i fd. A l-lellt 11 i l'lgt o o l ( S e e (7 13 :1 p t e 1- 6 fo r ftl 1-t 11 e ri nforlllatiol'l ) is useful for layillg tltltthe Nvhklt?l s btlt oncc l-nore fal' 1-1-(.)111essellt i a 1 . tlltzre are seq'tlra I Nvays ()ftloi l'lg tllc job Nsritllotlt stlcll :$11 itelllalltl 1 i k t! ctltlel's- Ctl-e el

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possible to givc advickl on thtt bcstlathe for :1 ntlurcol-ner to ptlrchasc. ila1l depends (-71,1 a part ictl Iar prklfcrcnt)eand onc!.i budgel . I 1-1 addition lllany t)fthe fore igi 1 l atllt?s t l7;lt arta stlld '.1 rlx.only avai Iabld tbr :1 I inlitcd period ot'til-ne btlfore the spt?c i fi cati 01'1 i schanged . Anyonc u,anting to ptlrchasea lathe Nvotll d d0 vs,el l to vi sit ont.l (4fthe Inany luode l -engi ncu'ri 1) gexh i biti 011 h; 1) k.p l d th ro ugh out thccountry, vN'l'1dre it u.' i I l be poss i blu- tt)brosvse throtlgh :1 Iarge nun-1 bt'?l' ()t''l'nachines of tl it-ferent l'nakcs and typklsto 'hnd 'wrhich I'night btl thc nlost suitablc.

stltlllds friglltell i l'lg btlt real Iy it ll-lakcst2(.)11'1p1 kzttl sel) se . .A 1 thotlgl) tlleIl-ltlvtll-nent or ll-lecllan i sl-l-l i s rotat i ngcollti l'lual 1y. it i s l'lar(.l 1/.' go il'lg t() brcak'a113, ss.r()l'ld spklttcl l'klkrol'kls i 11 s() t.1() i llg. I tIlas 110 rklal yN't3l'k' to do il1 as l-ntltlll as i ti s (-717 Iy dris'i llg 1 tstl l f and s() thkl slllêt l lbcarillg stll-lèlct:t l'lfls tllt.l adN'êtl-ltage tllati t ctlts ti-i ct ltdl'l (.1tlu'n to a l'n i 11 i Il-ltlll'land its ël l'u-stl lt reduccs the p(.7vN't?l'I'lkltldtll.i tt' I'tlll 1 1) illgs.

Solue of the lllethods tlskrd by cl ocklm akc rs a 1-t't l i k e ly to nl a k () a 1)ex p cri t'l n c ed e ng i 11 eer u, i n (2 tt . Fo 1'example. u'h i 1 e tlle cngintltll' u' i l Ialways try and get as nluch beari l)gsurfacc for a spindle as possibl e. tllcelock luaker seenas to try to do theexact opposi le . Holes that arc to btrused for btzarings are dri 1 ltld slllall k)rthan thc di almeter of thtp sp i ndltt tllatNvil I fit il1 tllklll-l allkl then tlltlq' arereal-ned Nvith a tapcr broach unti I a titis l-nadc . z'Ns a restllt th: spi ndlt't i srtlnni ng on the th i nnest possiblc ri ngof brass. To the engi neer tlltl i dea

Term inologyThi s is alltlt her thing Nvh ich enginct-lrsl'nay fi nd a 1 i ttl kl d i ffic tllt loun d kr rsta n d . A sl) 11 ft or sp i n d l t'l i skllt-nvn as an arbor alld the bearillgsurfacc at tllk'l t'llld i s not 21 shaft t)l' ax 1k?but a pivot. (iears bceol-ne svheel s i 11spite of the s'ery obvious tecth al Iround thelm tht) I'naki ng of Nvhich is tlltll'nain part o f c l ot-k l'naki ng. A Ithotlghthe tccth on thc Nvhklklls are cal ltrdteeth, svhen they artl ()11 a pinion theyltrtp frequently desc ri btld as Itlavds .These gears ( u'heels) artl l-nade ol- thinsection brass, Nvhich is ideal for tllcI'nckrhanisl'n that is bcing constrtlctedin order to gi ve :1 good tit on tllc

@spindlcs (arbors) tlley are 'litled onbosses fron) now on known as col Iets.To an engineer, a e01 Iet is somcthingwhich opens and closes to hold toolsor material. To a clocklnaker tlle termincludes the length of brass tlsed tosupport a wheel- and fillally there isthe mechanism itself which is called amovement. It is a1I very confusing atfirst but we must relntlmber that everytrade has it own terminology. jtlst lookfor example at that ttsed by tht)computer engineer.

@H elp and AssistanceThere are :1 considerable numbcr ot'plans available for lnaking clocks ofvar i ou s type s . Som e su c h a s thedesigns of John W i lding are sold inbook form , compl ete with fu l linstructions', they are to be very highlyrecommended. Others silnilar booksare available as basic plans and insome cases compl ete kits can btlpurchased. Thc photograph on thefrollt covt!r of th is book is one of amoN'emttnt made from just such a k it,

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by Repton Cloeks and this too is anidea! way to learn the basics of clockconstruction. The British Horologicallnstitute, Upton Hall, Upton, NewarkNotts. N623 5TE stock a large rangeof books and other items dealing withclock making and in addition organisecourses, both residential and homebaseda on the subject. There are alsonumber of suppliers of clock parts andbooks based throughout the country,

@If we accept all thc oddities that areimposed upon us clocks are fascinating.There are no heavy castings to huluparoun4 the work is nice and clean andthe end result is worthwhile. Even ifafter reading this book the reader shoulddecide that clock making is not for himor her, it is still worth while taking aninterest in them, their history and thebeauty of the fmish on many, in itselfcan provide an everlasting interest.

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Chapter 1 - H istory

Before starting on constructionaldetails of clock making, a word or twoon the history of the subject may assistreaders in an tlnderstanding of time-keeping in general. lt is not only thehuman race that uses time-keepingmethods, anilnals know' when it timklto go to sleep or, if nocturnal, when tostart searching for their food. Someplants antl trees w i ) l c l ose tlownflowers at night and open them whendaylight appears. Of course this hasnothing to do with clocks as we havecome to know' them, they are reactingto light and dark and possibly also tochanging seasons. N o doubt thehuman ractl al so started in thi sfashion, sleeping during darkness andactive during the daylight. The clocksin use then wcre the sun and moon.not necessarily the most rel iablesources as for various reasons thcy arenot always visible. Sueh primitivemethods- while not exactly telling thetime of the day did give reasonablyaccurate measurement Of the scasonsphad their uses.

heavens has becn observed forthousallds of years and this movementhas been applied to time-keepingmtlthods. The new moon appearsevery thirty days and the seasonsrepeat themselves every twelfth timc itappears whicll fbrms the basis of theycar as we now record it. Thecqtlinoxes w'ere wrell known and tlsedfor religiotls ptlrposes and stars andsun were almost certainly used forcarly navigation, whether across sea orland .

During and prior to the Stone Age it isvery doubtful if anything moreaccurate than this would be required.If the sun was at its highest point thenit was half way through the day.Humans are ncvcr satisfied withbasics and we can only speculatewhen it became desirable to be able tosplit time i nto smallcr parts andexactly how it w'as donc. It seemsh ighly probably that a primitivesundial would be the flrst basic formof clock. Put a stick vertically in theground and when thc shadow cast bythat stick is at its shortest it is midday.W ho knows- perhaps it was a tree thatflrst gave someone the idea that the

lt uus not al I left cntirely to chance.Archaeology and ancient manuscriptstell tIs that the movement of thtt

shadow of the sun could be ttsed togive :,.11 approxilmation 0f time.

Sundials did not remain as sticks inthe ground and we k now stonecolumns werc used in early times.m etal pillars of varying shapesfollowing them . This is not however abook about stlndials but about clocks.The sundial subjeet is so vast that itcould take a separate book to discussit. W hat we do know is that sundialswere in use around 200 BC and :1hundrcd years or so later a gearedmechanical device was produced fornavigational purposcs at sca, whiehmay or may not llave been a prim itiv eform of clock. l n 600 BC the Popedecreed that all religiotls institutionsshould have a sundial as a means ofregulating tlle times for prayer so thehulnan race was really becoming nloretimc consciotls.

Not al I tlle Nvorld 's poptl I ation w'as(--llristian and Nvt.'t 1:11.1st Iook at thosecountrics that had not adopted thereligitln to set'.-. 'kvhcrtl possiblc, ht-nvtlley sorted tlli ngs out. It is knoNvn thatthtr (l-hincstt had the idea of tls ingu.'illcr a nd a l though t herc 'svas al1Ll1'llbi.?l- ol- v'al-iatitlns on ll1e tlltll'llt')- tllebasic princ i (3 lt.) Nvêls to ti I 1 a contai nerNsri t 1) svltter. A sllaal l l'lole in the bottol'l)yvotlld al l ()N.N' it to rtlll asvay and byI'lptlklsl-lrillg tlltr ttll'ltltll'ït tllat Ilad gol'!t'l itN5.':t s pos s i b l kl to sekl 11 oïv l'nuch t i lzle11:1(.1 passcd i'tll(1. if the containcr ysrasIlnark ed yN i l 1) gl-atltlllt iolls- tht? ti I'l')euklkllnst'tl.l cf-htlltl be sklel'l 1tt lt glance. Thistylèc k)'#- clklck eN'trnttlal Iy becalue used:1 l l (')N'e 1' tll c NN.'t)1-l d k)n d vari otls

il-nprovcluents Iuade to the systel-n.including 'htti ng a dial . ensured thatthe water clock remained in tlstl forhundreds of years.

û-andles were also used as a mklasureof time. Once it could be establishedhow nxuch a candle burnt down in apartictllar period of tilme. it was as i n4p I e ma tter to nl :1 rk the s i d e s ,showing how lnuch time had elapsedsince the candlc was lit. King Alfred iscreditcd with being the lirst pcrson touse candles for timekeeping, althotlghif he acttlally did burn the cakes thecandles could not have been veryrcliable. lt is still possiblc to btlycandles lmarked in this w'ay'' nowadaysthcy only have novelty value. Analmost identical idea to thc candle wasto btI rn o i I , i n a conta i ner wi thl'narkings to retrllrd the til'ne that hadpassed as the quantity of oi I 'wasrcduccd . For short time pcri ods thklrewas also the sand-glass with 'whichmany of us wiI I be fal-nilitlr as an cggtil-ncr. The glah;s and quantity of sandhad to be c'arefu I ly lzaatelled to thctin'le required and so the systelm Nvasge ne ra I ly u sed on l y for spkle i fi t2ptlrposcs, as indicating i nlen-nediateti 1'1'1t'l bkltsveen fi l I ing and enaptyillg thcglass u/as not ptlssiblc.

W llzdt of thkl re l igi otls orders that svtpntt() prayer lligllt and day? SolnethillgNvas needtld to teI 1 thel'n vvhen it Nvast i Im tl to go to the c 11 :1)3t)1 . F. vcn tho ugllt htl Ptlpe had dtttlrtlttd that :1 l l rcl i gi otlsilpstittltes shtltlld have a sundial. tl1 isNvas of no use a f-ter dark or in l'nuch ofthe Nvklather vve havc i n Bri ta i 1'1 .

various ingeniotls measuring dtwicesthat sounded alarms were deviseds'these included wcights on a pïece ofstring that was set 'lirtl to. After aperiod oftime the tlame burnt throughthe string and the weight would dropon to a gong telling the monks that itwas prayer tim e. The idca wasextended to include a number ofweights strung to a frame. The stringswere of diflkrent length and so burntthrough at different times. In this waythe gong could btt sounded atltomaticallyat set intervals.

Nobody knows whon the firstmechanical clock cam e into being. bywhom or how it was invented. Theoldest clock known of in Europe wasat Salisbury Cathedral antl is dated1386. lt is stil l in working order,although no longer in the tower it canbe seen in the nave of the Cathedral. ltis quite an advanced clock. whichincltldes a mdchanism for striking thehours as well as one for telling thetime. Even this is not the lirst knownmechanical device: in 1090 Stl Sungmade a device in China that rang bellsat given intervals in addition todriving automata although it did nothave a dial for timekeeping. Drivingautomata was popular withclockmakers and one early example atWells Cathedral . and built in 1 389.can still be seen working. It is a veryelaborate affair with knights jotlstingand a1l sorts of other movements at settimcs. We do know therefore thatelocks have been in use for manyhundreds of years and although theconstruction of early ones appcars to

be quite crude, many were in factsophisticated pieces of maehinery.Early clocks wtprc used for ptlblicpurposes and were very large.Generally they would be housed in thetower of a ehurch or cathedral.

There are records of clocks fordomestic purposes as early as l 343 inFrance and England. The earliestsurviving examples date from aroundthc fifteenth century and are of ironconstruction, the mechanism beingscaldd down from the larger oncs inpublic places. Al1 these early clockswere weight driven and exaetly whatdate the pendulum replaced the foliocontrol we cannot say. However aclaim is made that a clock was madewith pendu lum control in 1 656.Spring drivc is hrst heard of in 1450and thdrefore pre-dates the use of thependultlm . Regular improvementswere made to timekeepingmechanism, including in particularthe invention of new more reliableescapements and in l 7 l 5 GeorgcGraham invented the deadbeatescapdment making clocks morcreliable still.

lt is quite amazing to think thatmodern mechanical clocks work onexactly the same principle as they didwhen George Graham invcnted hisescapement. Materials have improvettwith brass and steel taking over fromiron, otherwise there is littlediffercnce in the basic construction ofany typc of mechanical clock. Massproduction was really the only bigadvancement from then on, but minor

Ct 11 (1i n) prove n-1 ent s to bol 1) c I o c k sNvatches collti llued.

In the twentieth century, clocks alltlwatches have sklen advancements thatwould not have beelt thought possiblc.cven at the start of the century. Aboutsjxty years or so ago people hrststarted to experimcnl with the ustl ofelectric clocks. t-'ertainly thcy u'crutvcry primitive in comparison withwhat was to come later, but they hadthe advantagc that it was possiblc tosynchronisc several clocks togcthcrwhich was ideal in a factory or similar(., sla b I i shm t) nt wh erc m any peop l ewerc elnp loyed and a ! I wou I d bestarting and stoppillg work at the salukltime. Prior to that a bcll or hooter wasused', a system that in may placcsIltstcd tlnti I quitc rccent times,

Betbre 'linishing Nvith the history ofclocks it is interesting to think howtinle itself has changed. Until quitelate in the ninetecnth century ey'erytown or district kttpt its own time.Communication between areas wasvery poor, with Iimited transport andit mattered not wllat timc it was in atown forty or lifïy miles away. W iththe coming of the rai Iways al1 thi schanged. A person travel Iing froln sayLondon to B i rmingham and thenwanting to get a connection tosomcwhdre else netlded to know whattime that connection would leave inrelation to the train on which he or shewould arrive. The rai lways thcreforeorganised their own time, known asRailway Time, which was consistentright throughout the country.Gradually this was adopted throughoutthc country until evcryone used thesaluc. Now time is relatcd directly tothkl f irccnwich M eridian, and knownas Grcenwich M ean Tim e. Othdrcountrics also take their time frol'n themeridian with allowances m ade fortime zones. As result it is possiblc foranyone, anywhere to know what timeit is in any othcr part of the world.

M any people buy nltlchani sl-ns forthese quartz clocks and l'nake cascs ofvarious types to housc thel-n: it is ahobby on its own in which largenumbers ofpeople arc happy to indulge.

I n-lprovclments in thc Iuanufacturc ofelttctric clocks were rapid unti 1 Nvereach the stagc at u/hich svt? are attoday where it is possiblc to buy aclock with :1 digita. I rcadotlt so thatIlobody trvtln needs to know how toteI 1 thkl time anymore. The moderneleclronic mastcrpicccs can keepperfbct tim: and are far more accuratethan any except the most expensivemechanical clock . Probably becauseot- thcir efficicncy they do not have thefasei nation of mechanical ones, whichartl sti I I m ade today 170theommercially and by alnateurs.

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Chapter 2 - The Fram e

The frame of a clock will generally bemade of two flat plates. joinedtogether, at or near the corners withpillars. Al1 parts are tlsually made ofbrass except in exceptional caseswhere we might gut a steel franle fittedwith bushes. The plates are sawn andfiled to size and after ensuring lhey areflat and square they should bc hcldf irmly togetller with clalups.preferably thc toolmakers' type urlliletwo or three smal 1 holes are dri I ledthrough somdwhdre lltlar tlltl corners.These holtls arut to actzdpt pins or rivetsthat are tlsttd to cnsurd tlle plates tlt)not separate duri ng operat io 11 s m' onct!the pins and rivots are i 11 plactr thkl(2l almps can be relmoved .

The next task is to mark thd position()f the pi l lars wh ich join the platestogether and drill the holes for thcl-n;wtl will col-ne to how they can btl fittedshortly. Occasional Iy clock designs donot have this type of plates insteadthey arc madc Nvith strips of brass.lmort) otztcn lhan not ctlt into fancyshapes and i nstead of four pi 1 lars tlleriaare only tu o- one al catrh tlnd. Theprinciple of join ing thelzn together andd ri l I i ng thtl p i I I :11' ho l t'ts renla i nsc x act 1 y t 11 kl sa 1'n e . .A. s 1.3 tl i ! d i n grogrklsscs 011 di ffcrences yvi I I elutpl-gt'!-Pfor klx :1 lu p 1 (., th cre Nvi I I 1'1 o t bkr apendtll ul')l alltl so they Nvi l l not befitted svith a back cock.

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that is conllllon to alI lnethods is thatwhen assel-nbled the fralmes must berigid and square.

The PillarsGencral Iy speak i ng the pi I lars orspacers as the layman woultl call themwill consigt of brass bars and they mayor may not be shaped. Shaping is amatter ftl1- the individual builder andin a limited way is the opportunity forhim or her to express hiln/hcrself.Fitting thc pillars to the framc is donein several ways: son'ld are hoI Iow anda stud is pushed right through and theparts held secure with a nute orperhaps the cnds of the pillarsnlachined dou'n and threadcd toakleept a nut . l n othe 1- k'laskl s they aredrilled and tapped and screws passedthrough the frames. into them. A thirdalternative, is to l'nachine a step in thepi 1 Iar cnds and pass th i s tllrough thtlholes in the fral-nes, vs'hich arc thellseeurcd 'with a taper pin, htted in 11hole drilled across the step. One thing

Setting O ut The TrainThe most Common way Of setting outthe train is to scribe a straight linelengthways down the plates and to setthe escapement, centre or hour wheeland the great wheel and barrel alongthis. The third whccl has to be set at oneside in order to allow the pinions andwheels to mesh. Just occasionally wecome across another dcsign where theescapement and hour wheel are in Iineand both the third wheel and barrel offset. This is very rarc and any detailsrequired for such an arrangement wouldbe available tiom the drawing and allyinstructions lhat might go along with it.

@M arking O utSometimos clock plans wil l givemeasurements showing where pivotholes wi 11 be placed', if not it will beI'ICCCSSCtI'Y to Wrrk Otlt Spacings foroneself. Start by lightly dot punchinga suitablc place for the great wheel onthe centrc line. Use a depthing tool tomark out position on the line of thcminutc wheel', thîs means meshing thegreat wheel pinion with the minutewheel so they run very smoothly andwithout any binding. W hen satisfsedwith the mcshings use the tool to make:1 seeond mark on the linc that hasbecn marked on the plate.

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Depthing ToolA depthing tool is sonacth ing thatsolne people Nvi l l nt't has'e eoll'eacross before: it is a tool for settingout gears to ensure that they runsmoothly. They can be bought but fornormal purposes a homc-made duwicewill do jtlst as well, those that areurchased be i ng far morePsophi sti cated than necessary foroceasional elocklnak ing ptlrposcs.The tool is silmply a nneans of meshingwhecl s and pi nionss or two wheels orthe escape w'heel and pal lets. sta that acheck can be nlade to ensure tllcy rtlnproperly. A professional ly-madc toolw i I l be spri l1g I oaded and fu I l yadjtlstable. but good rcsults can btpo b tai ne d fro 1,-t :1 s i m p l e dcv i c t!

18

@colèsisting of two lellgtbs of bar thatswivel togcther and with lnJ() holes toacccpt puncheh;. The ptlntrlles artl thesalue diameter as the whet!l arbors andso the wheel and pinion are simplysl ipped on and adj usted. I f differcntsized arbors are likely to btl useda f-itbrass bushes that can be intcr-changeablc. Onc of the punches is setin the n-lark already made and theother is lined up on the line on theplate. A sl ighl tap Nvith a snnal Ihammer and thtl correct place for thearbor of the hotlr Nvhcel is lmarked,John W-i lding, who i s one of the tinest(2 1 ock lmakers i 1,1 t he countryrtlcolllllltlllds a piece of slottkld bar forthe salutt purpose : an idea that worksvery wel 1 .

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@urlleel and exactly the sanae prtlcupdtlreis tlsed. The l'nark should be lmade ol)the Iine used by tht? great wlleel alldlminut: whce! and that is the clocktrain lmarked out. Holcs for thc pivotscan be drilleda but don't forget theyshould be drilled tlndersize. svllell thepl atcs are separated they can beopened out with a taper reanler so thtlyare a nice running tit uzitla tlle pivtAts.

There is sti I I ond more opdrationreqtlired in order to make a11 the pivotholes, for the pa1 lets of theescapement also need to be set. Thepal lets and the escape wheel aremounted in tht, dcpthing tool andadjusted until they work slnoothly inthe same way as before.

Tl'e tool i s ntnv u sed t o sct t11 edistance of the third whecl - wh i chtlannot be sited 01'1 the line betrause itwould then be ilnpossible ttA nlesh al )the whecls properly. There i s nospecific angle at whicl) to sct the lhirdwheel and this, pltls whether it shouldbe set to the right or Ieft of thkl 1 i ne, isa matter of individtlal taste. Gencrallyspeaking an angle of about forty-fivedcgrees i s used '. whatever happensnaake a note of the angle j ust in case itneeds to be rcferred to later. Havingdecided where thc wheel will be goingrepeat thc operation with the depthingtool so that a nlark is nlade for thcthird 'vvheel pivot ll0lt). From there thkltool is used to 1ay out thc distanccfron'l the third whttt)l to the escape

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@SonAe people like to fret oul tl4tt platu.sto l'nake an attractive pattcrn and tl) i sis a nzatter of individual taste. Thcfretting wi 11 obviously need to bu- doncNvith the plates seeured together. Oneway of doi ng th i s i s to draw a suitabl epattern on paper, taking care to avoidall pivot holes, cut out the pattern,stick it on the plates and cut round it.Do not try and chain drill but dri I l acouple of holcs in strattlgic places anduse a p ierc ing saw or a powe r-operated scroll saw if one is avai lable,to complet: the job. Finally clean theedges of the cuts using small fsles.

The plates are now compltzle cxceptthat if the clock is to use a pendultllll aback cock lnust be fitltld. This is abracket that stlpports the suspttnsionjbr the pendul tlm , w1l i ch can bcfabricated or milled from a go1 id blockof brass. It takes thd tbl-jn of a bridgeto clear the pallet arbor. the pivot ofwhich locates in 11 hole in the cock, thesuspension being ïitted on ti'le arborbetween the plate and the bearillg, It isessential for the gootl runnillg of theclock that the cock is secured hrmly tothe plate and will not work loose. It isalso essl-ntial that the escape whcclarbor when fitted to the coek is atninety degrees to the plates.

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Chapter 3 -

Providing T he Pow erM ost people when starting clockmaking, begin with a weight as theower source and so we will Iook atPhow this is done lirst of all. A suitablebarrel is required roulld which a linecan be wound. This in turn is tied to aweight, but not directly because theweight is connectcd to :1 pulley and thedrive line passes through the pulleyand is anchored on or ncar the clock.The usual place is one of the pillars.Any tubing wi I I do for the barrel.although it must be thick walled.

23

Generally speaking brass is preferred,mainly because of its non-rustingproperties, btlt there is no reason whyit should not be of stecl: many yearsago most clocks were made of iron,although the use of that material is notto be encouraged tlnless trying tobuild a rcplica. A spindle, or arbor ashorologists prcfer to call it, is passedthrough thc lniddle and on one end ofthe arbor is lt square. Thi s is to accepta key u'ith which to rewind thc linewhen it reaches a 1ow point.

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The BarrelOne end of tllc barrel i s plain- otherthan for a hole through which the gutis secured. The other end forms aratchet referred to as the click wheel:this can either be made integral withthe barrel or fitted permanently inplace to an end cap. How the end capsare fitted is a matter of personalchoice, but there is much to be said forusing slnall screws to hold them inposition as it enables it to bedismantled should any work beneeded on the arbon Also conneetedto the arbor is a whcel or gear. if yotlprefer, callcd the great wheel. Thisconnects via a pinion to the train antlthe ratchet prdvents the barrel fromunwinding, except when controlled bythe rest of the clock. To Iocate in theratehet is a specially shaped metalplate known as a click and a spring tohold it in position. Although the barrclcan be left plain it is a good idca tomake a continuous groove in it toallow the gtlt to wind on and offevenly'. rather than pi le up. A small

The RatchetThe ratchet can again be of stecl orbrass although brass is generallyrecommended and the teeth are cut inthe same way as on aI1 the wheels. Thentlmber of teeth varies considerably-depending on the design of the clock.l 11 some in stances designers havcdeliberately kept tbe number of teethon the ratchet to the m inilnum . Thisallows it to be filed to shape, avoidingthe necessity to make or btly aspecially-shaped ctltter. In theseinstances the teeth are curved in agentle radius, both to facilitate filing

@round-ended tool. similar to a parting-off tool is ideal and ordinary screw-cutting methods call be adopted. Thedepth of the groove shotlld about halfthc diameter of the gtlt being used andabout seventeen or eighteen turns arerequired. Therefore ifthe barrel is zinslong the lathe needs to btl sd to cutnine threads per inch, or the ncarestavailable figure above that.

nd to make the ratchet smoother inause. The more normal type of ratchetwill have about tllirty-six or so teethand cutting by lmachine is almostessential. This is not to say that thework cannot be done by handm but ahigh degree of skill is required to getaIl the teeth to the samc proGle, not tomcntion that the task will take someconsiderable time.

@The G reat W heelThc grcat wheel is mounted on thebarrel arbor and drives the train via apinion and apart from cutting the teethit is quite straightfonvard. As the weightunwinds, it drives the great whecl andwhen the clock is being wound up theratchet allows it to slip past.

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The C lickThis is thd name given to the pawl thatlocates on the ratchet and prevents itunwinding. It is usually liled to shapeand the shape is not difhcult to makeqthe only critical part being thcdistance bctween the hole centre andthe tip of the blade. It should be madefrom gauge plate and hardenett thentemperdd to a dark blue colour. As analternative it could be made from luildsteel and case llardened and while notgiving quite as good a result as tlleprcvious mcthod a Iong lasting andreliable click would still be the result.

@Click SpringThtt spring holds the click down on theratchet wheel alld must therefore bestrong enotlgh ttA do so. while at thesame time not bcing so powerful as todrag and causc morc power to beneedcd than would otherwise havebeen so. The springs vary considerablyin length and shape and so materialslllay vary with di ffercnt spri ngs. M i ldstecl can be used tbr most springs andalthough it may sountl a most unlikclymaterial . hammering thin scctionscauscs a work-harden ing e ffect,resulting in springiness. Anothpr

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usefuk material that has a similareffeet is drawn phosphor bronze, amaterial with a natural spring to it andwhich is also very easy to work. Likea1l parts for clocks suitable springscan b: purchasetl eompleletl andready for use if one wishes-

Screw passes throughGreat Wheel.-into click ! Great Wheel

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The PulleyThe weight that will drive the cloek issuspended from the drum via a pulley,which effcctively halves the weight

27

appl ied. There is not :1 grcat deal canbe saitl about pulley construction-' wutare aI1 familiar with thut shape of thewheel which should generally be ofbrass and run on a steel axle. Theframe of the pulley can be made froma piece of brass plate and that is :111there really is to it. Appearanee can btli mproved by drilling holes in thepulley wheel.

@The eightVarious materials 111-: used as weightswhich arc also made in a variety ofshapes. A nicely polished length ofbrass tube filled with lead is ideal; doremeluber that a hook is required withwhich to hang the weight on thc cordand that this must be set centrally tothe diameter so that the weight hangsstraight and docs not lean at an angle.Althotlgh the weight is nzentioned inthis chapter. beeause it is part of thedriving mechanism, it will be one ofthe last items required. lt is obviousthat we cannot hang any old weight onthe clock and cxpect it to keep time. It1131.1st be sufhcient to kecp thc clockgoing without causing it to work at toofast a rate and so thc amount of weightrequired will be forexperiment.

A good idea is to gct a used food canand fit to it somo means of attaching itto the line from the drum, fill tlle tinwith pieces of lcad or other heavymaterial and run the clock. Keepemoving small amounts until therclock stops. This has to be done over aperiod of several days. W hen it hasstoppe; weigh the contents of the tin,add about half again and make thennished weight to this measurement.

@(; eneral ly the barre l wi l I di fferconsiderably from that described fbrthc wcight-drivcn clock. For a start itbecomes obvious that one end must beremovable in order that the spring canbe inserted but other major difTerencesalso occur. Although not unknown fora clock to be driven directly by aspring, particularly if one buys acheap one, it is most certainly notgood praetice. W hile the weight dropsat a given speed throughout its lcngththe spring behaves vcry differently.W hen tightly coiled it createsconsiderably more power that when itis only partly wound. W atch aclockwork-driven toy and see how itslows down when the spring starts torun down and of course that issomething that is not wanted in aclock.

Spring DriveSo far wt? have dcalt only with clocksthat are weight driven, which meansthey are either fittcd in a long case orhang on a wall. W hat if we want ourclock to sit on a shelf? It is hardlypractical to drill a hole in the shelfandrun a cord through that to a wcight.The answer is to drive the clock with aspring: something with which we areal1 familiar and springs are freelyavailable. They arrive coiled andsealed tightly with a fastening almostready for use and lit inside the barrelusing two hooks, one of whichattaches to a point inside the barrel,the other to the arbor. Great care mustbe taken when dealing with springs asthey can cause nasty injuries and it isadvisable to wear heavy gardening-type gloves and most definitely towear protection for the eyes. Specialdevices are available for settingSprings in barrels and. while it ispossible to do so by hantt if in doubtfind your nearest clockmaker and takethe lot along there, where a special deviceWill be available which will enable thejob to be done in a matter of minutes.

The FuseeTo avoid this problcm it is usual toconnect the spring, via a deviceknown as a fusee, which is a taperedand grooved Iength of brass on anarbor, on which is set the great wheel.Much the same way as the situationwith the barrel on a weight-drivenclock. A cord is wrapped round thegrooves in the barrel and runs to thefusec. W hen the spring is fully woundthe chord round the smallestpassespart of the fusce, effectively acting asa brake. As the spring loses its powerso the chord winds to a largerdiametcr keeping the rotation of thefusee at an even speed. The arbor onwhich the fusee runs is similar to that

29

of the barrel on the weight-drivenclock and the barrel now worksindependently of the clock movement,providing the power and nothing else.The clock is wound via a square on thefusee arbor, which in turn rotates thebarrel. As the spring is hooked insidethat, it tightens up, to be released at aregular spee4 with the fusee aeting asa continuous gear and compensatingfor the unequal torque of the spring.To enable the fusee to be wound theconical-shaped part is not directlyattached to the great wheel but drfvesit through a ratchet as alreadydescribed for the barrel. From there thepower is tmnsmitted to the rest of the tain.

@of most people. Take a length of brassbar of a slightly larger diameter thanthe maximum diameter of the fusee,put it in the three-jaw chucks face theend and drill a hole through its lengthfor the arbor. M achine the outsidediameter to size and we can nowguarantee that the hole for the arbor istrue to the outside diameter. Set thetop slide over and machine therequired angle, then use either aradiusing tool or a hand graver togenerate the required curve, whichmust be smooth.

So far it has al1 been easy going butnow we come to the only tricky part,which is to machine the continuousgroove. A set-up for coarse screwcutting will take care of the spacingwhich is the same as that for barrel, soal1 we need is to organisc a tool thatcan be adjusted in depth as thecarriage moves along. This too is not

Fusee ConstructionM any people fight shy of making thefusee and prefer to purchase it, but itis a task that is well within the ability

@djmcult: make up a piece of steel withjbur pins stted in it as shown in thedrawing and clamp it in the tool postarallel to the lathe axis and f5t aPuitably radiused tool in the end of asuare bar that slides nicely throughsq

the gap. Either fit a handle to theopposite end or wrap a quantity ofinsulating tape or similar materialround it to avoid injury. (Do not useloose material: it must be held srnalyon the tool with no danger of itcoming offè) It is now possible toapply gentle hand pressure to the toolprotruding through the tool post as thecarriage mtwes along alld in this w'ayto make the required grooves. If thefirst cut is not deep enough theoperation is easily repeated by pickingup the groove with the tool, betbre theIathe starts to rotate. The Iathe must be

set at its lowest possible spced for theoperation, in back gear if possible.Better sti 11 tlstn :1 handle in lhc mandreland rotate the lathe by hand. Althoughit is suggested above that the tool bemade from square bar, this is purely toprevent it from rotating. Readers withsut-ficient conf idence in their ownability can use a round one. The toolmust remain at or near the same anglethroughout operations to besuccessful. The operation is notdiflicult and there is a 1ot of cnjoymentto be gained from the tkeling ofhaving created a nicely-shaped ftlsee .lt is probable that the grooves willhave a rough finish on them so cut apiece of dowel to a shape that wil I fitthem and using Brasso or similarpolishing materiat and with the latherunning under power and in back gear

Distance between pillarsan exâct fit for widtb oftool being used

Clamp this end intool post

W31

@run tllt- dovvutl i:ll())llg the groove ullti l asluoolh finish is obtaincd. Finally parttl'le vvork 0ff t)r i f it is thought to betoo large to be parted off, saw it off. l fsawn, lllotlnt il on a l'nandrcl bdweencentres, tlsillg a half centr: at tl3c endthat is sawns which can then be facedto size. A suitable hand-ttlrning restfor using a hand graver to get thecurvc and a self-releasing handlc to titthe nnandrel are described in the bookK U seful 'Work shop Tool s ' 'which i snulmber 3 l in the 'Workshop PracticeSeries.

Untbrtunately lhkl above methods onlyapply' w'hen a lathe has suitable screw-cutting facilities and this is not alwaysso. Generally il 'would be advisable forthose w ith otlt these fac i l it i cs topurcllase a fusec ready madc. Son'l:pcopl tt do not l i k c to buy such iten'ls asthey like the feeling of having nladdevery part for thenlselves. For thosdpeople, lt is possible with a littlei ngen tti ty to put on a continuousthreakl in these circulmstances ifsttffic iently detcrl-ninedo or perhapsjust to beat the odds and do thesethings tbr thennselves.

Thc fusee will have to be hnished asfar as shap i ng and dri I l ing i seoncerned. M ake a suitable well-fitting mand re1 but fit the end that wi I 1go in the tailstock centre with a lengthof studding wilh a coarse thread. Thisthread w i 1 I tl lti mately bc the onetransferred to the fusee so it will needto have a Iarge diameter, in order toget a suff iciently coarse pitch. if

32

studdillg is not avai lable it nlay bepossi blt) to oblain a Iarge dianleterbolt '. 21 l'netal scrap yard i s a goodplac: to searcl) for solnething suitable.Thtl other cnd of this nlust be centredand stlpported by tlle tai 1 stock . Take allut that fits the thread and silverso Ider. or i 11 sol'ne other fashion fit ashort length of mild steel bar to it. If itis Iarge enotlgll perhaps a couple ofsmal I scrdws urould do the J'ob. Use apiece of bar at right angleg to this toconnect to thd screw-cutting tool, via aslot in the first picce. W hen the lathe isrotated the tool will now movc alongthe thread and with the tool in contactwith the fusee the continuous grotwewi1 ) be made. M ost people with thesnaall lalhes lhat are tlle ones likely tolack seresv-ctltt i ng faci l iti es, aretlnlikely to be luak' ing a clock whichwould reqtlire 8, Iarge dialnete'r fuseeand the above method w'il l therefordvvork qu i te Nve I I .

Contintli ng from the power supplytowards the dscapement are a pair ofwheels and pinions designated as thcthird and hour wheels. They form thcmain part of the train of wheels knownas the gofng train which eonnects thepower unit. whether it is a drum andweight or :1 spring and fusce, to theeseapement. svhen first looking into aclock it appcars to be a iungle ofwheel s and pi ni ons and it is thisapparcnt disorder that freqtlently putsCt op I e o ff m a k i 11 g or rep ai ri n g aPclock. W hile these gears and pinionsmay be in a number of eombinations,the actual tbrmation is the sal'ne for

virtually eNrery cltnck, The great w'heeldfivcs a pinion, which in turn drivcsthe centrc wheel '. tllc pinion connectedto that gocs to tlltl third wheel and theinion for that is in turn connected toPthe escape wheel .

Basically therefore we have fourwheels and three pinions, which is anice easy manageable number,artictllarly for anyone versed inPengineering matters. Variouscolnbinations of wheels are tlsed butthere must be a logical sequence. Letus start with a hypothetical clock,althougb the train used will be onethat is quite comlllon.

The great wheel connected to thedrum arbor has ninety-six teeth andwill connect with an eight-leaf pinion

on tl'le salllt't :1 rbol- as tllkl centrc svllee I .Thc centre wheel has sixty-four teelhand as if carrics 11)e Ininute hand 111:1strotate once an hour. This in turnconnects 'with an ei gbt-leaf pi nion onthird wheel arbor, w'llich has sixtyteeth. It connects to another eight-leafpinion on the cscape wheel. 'W hendesigning 11 train it is essential that theescape wheel shall makc sixtyrevolutions (seconds) for each onerevtalution of the centre wheel(minutes). To check this multiplytogether the number of a11 the teeth inthe driving wheels and divide theanswer by the numbers of leaves in thepinions, lmultiplied together. W ith theexample lhat bas becn used thetkmmula in tht! appentlix gives all thedetails required to see how it works out.

V.1 I'..kudkk i

@ @

Chapter 4 - Pendulum s

A pendulum is described as a heavyparticle, suspended from a fixed pointby a fine inextensible massless rigidthrea4 so that it is free to oscillate ona vertical plane. Galileo the famousastronomer is credited withdiscovering it and legend has it that hewas watching the movement of aswinging lamp in church which he

timed by using his pulse. Theimportant thing about it was that theoscillations were isochronous whichmeans simply that the time for onecomplete oscillation was always thesame. His son is credited with the frstuse of the pendulum and whatever thetruth of the story it has stoodhorologists in good stead ever since.

Back Ccck. < . ... : . @ P - - . . .- ''Sprlng Support ' ' '

Block ------ z s nsicn/ tlspeRivet or Back Plate - '-- SpringScrew

1 ' 4 . .a

PendulumRod

PendulumBob: : : J ...--'

.4 ; : - u .2) .. ., ,.: :

'

,' : ! . . ': ; . .. .. :. : . *. .: . : : :1 : .. : : )

'

.: ., :

'

, ..

'

.

'

1. .. ..: : : -- ul um Rod, . : *

'

v * .

' square where ItMake up t?f pendulum . ..- passes through. y ,. Ratjng Nut b k)assemblv, x ou lng v o .'

. Nw xNuubpension spring and .Ratlng Screwmethod ofadjustment.

35

. I .iIA

!I

Although a pendulum appears to movebackwards antl forwards it actual lytakes a sinusoidal l'notion

, amovement that is not quite a circularone, but which for all praeticalpurposes we can consider as anordinary backwards and forwardsmovement. This is controlled bygravity and as a result the distancefrom the train to the bob variesaccording to where the pendulum is inuse. There is a also a variation ingravitational pull, depending on theheight above sea level

. Tl4e latter issuch that adjustments can easily bemade to takc eare of the variation

.

Q

A

A

(1 O l

Relatiollship r?/'/pt,?;t/l//l/?A? to c.q'tqw/.?t.? nlovenjf?nt

36

The t7r/.//c./7 is the Jplrf that f.q tnoved /)j.' theb'v'ing t?/' the ./'pt/?7pl,k/zfzn. It ./i'lx on the ttçtwrt?arbol) th t, prongs f'aa eilh t??- side ft'?(?tr//?kg'n $'/ the pEa/llf/?,fp? suspension spring

.t/gtzl .

@Together with the escapemtlnt and viathe suspcnsion and crutch th

ependulum is rcsponsible folmaintaining time, using Galileo'sdiscovery that each oscillation take

sthe samc pcriod of time

. A simplependulum consists of three parts; th

erod, the bob and a rating nut

, a1lrequiring careful attention if tbe clockis to function properly and is to b

eaccurate. The number of times thependulum vibrates or swings dependson its length and is selected accordingto the type of cloek being made

. Longcase and wall clocks more often thannot will have a pendulum that vibratesonce per second,' smaller clocks willhave correspondingly short

crpendulums and will vibrate faster

.

@This means that the length of theendulum is also in direct relation toPthe clock train: a pendulum thatvibrates every second will needdifferent train to a half-second one.

SuspensionThe suspension consists ofa tlat springthat is strengthened at the ends withmetal blocks allowing one end to besupported by the back cock and theother to connect to the pendulum. Thespring must not be too long or toostrong and at the same time it must notbe too weak either. M ost designs willgive intbrmation on the correct sizc ofspring to be used: if not it will have tobe a matter of trial and error.Fortunately there is a rcasonableamount of latitude available in springselection btlt if in doubt it is worth

The RodThe rod must be straight and have 21stlitable means of connecting it to thcsuspension tlnit at one end. The endthat fits through thkl bob is threaded toaccept the rating nut. Depending onthtl type of bob it may be necessary tomake the end square so that the bobcannot twist out of line. Selection ofmaterial for the rod is important. lt hasalready been stressed that for correctoperation the weight of the pendulum

considering the purchase of a ready-made unit frol'n a supplier, having inmind that unless the spring selectionand make-up is right the clock will notftlnction prtlperly. The back cock alsoneeds to bk'l made and assembledcarcfully as, if it is out ofalignment, thependultlm cannot function properly. ltmust also be made with suflieient strenjprthto give good stlpport to the set-up.

. . . . Li 1

@that is used. A more modern materialis Invar which although expensivemay not be prohibitively so and hasthe advantages of being light, easy towork with and not subject to changesof temperature.

The end of the rod has to be threadedto accept the rating nut, which allowsadjustment of the height of theregulator. lf a round or tubular bob isbeing used then the rod can be Ieftround where it passes through', if oneof the flat type is used then the rodwill have to have a square on it toprevent the bob from twisting in use.Ensure that the square is positioned insuch a way that the bob will remainparallel with thc train w'hen swinging.lf allowed to twist at an angle thebalance of the pendulum will bc upset.

must be concentrated in the bob and ifa heavy rod is employed this wil! takethe weight away from that area. Thereis also a slight problem of expansionand contraction of the rod withtemperature changes. M any ideashave been introduccd to compensatefor this: some simple, others verycomplicated. W hether or not the homeconstructor will want to go to theeffort of making a compensatingversion is a matter for individualchoice. Doing so involvesconsiderably more work than makinga simple one but no doubt could initself be an interesting project.

Assuming that at this stage anyway,readers are going to be content with asingle rod then the material chosen forit is worth consideration. W hile brasslooks nice it is also the metal thatsuffers most from temperaturechalzges and so if it used f'br reasons ofappearance the rod shotlld be as thinas possible or alternatively usc thin-walled tubing. Aluminium tubing isalso a useful material and has theadvantage of being light and allowingthe weight to be concentrated in thebob. Wooden rods have the advantagethat the m aterial is less likely toexpand or contract with climaticconditions and on a long case clock apiece of dowel can make a veryeffective rott as it is also lightweight.It should be well sealed with varnishor similar medium to prevent theabsorption of moisture from theatmosphere. M ake certain that thedowel is perfectly straight in the firstplace. as indced must be any matcrial

38

The BobAlthough we tend to think of bobs asbeing made either in a lens shape orrountt in fact. many clocks used quitefancy shapes, in particular Frenchclocks were adorned in this way. butof course many French clocks werenoted for their ornate appearanceanyway. ln general the home worker isgoing to use one of the two standardtypes and so it is these we willconccntrate on.

For small clocks and probably wall-mounted ones as well the standardlens-shaped bob is usual and notdiflicult to make. Start by machining ahollow in a piece of hard wood; makesure the machined surface is perfectly

@

smooth. Cut out two disks k)f brass ktlittle larger that thc outside dianletcrof the proposed bob and allneal tllcnh,if necessary re-nlarking the circltlsafter annealing. A good alternative tobrass is giltling lmaal which is l'nuchmore ducti Ie and needs less annealillgthan norlual brass shcet. Using êtwooden bossing lmallcts shapc the twt)disks by gcntly hammcrillg them intothe hollows in the block. As soon asthe brass starts to work-hardcn. annealthem again antl kccp do i ng sowhenever necessary-' do not under anyeircumstances try and w'ork the l'netalif it hardens. Dtlri ng tlle shapillgoperations take care that tlle work iskept centl-al to the ciretlluferenee of

thc 1,k) l I()wrs. lt is al I too easy to havethe Nvork slide to one side during thehoI 1 ou' i ng-otlt process and i n 'whichcase the bob ï.v i I I be o f no use at al l .Periodi cal ly put the tu'o ))i ecestogether to check the 'ht- until thek'ldges naeet al I thc u'ay roulèd. Eachpiece ntlcds a snnall section 'Iiled outfor the rod und and at thi s stage l ittlclmore than a 11 i c k yv i 1 l do . W' lpk?nsati s fied wi th the ho1 1 ou' i llg-otltproccsss dril l a holc about 5.. 1 ('linsdianzeter in the celltrtl of ontl of tllepieces and deburr the ilolcs .

Clean the pieces tlp by soak' ing thel'ni 11 a s o l u t i () n o f c i t r i c ac i d : t wotablespoons to a bucket of water i s

39

. I . 1. d u.

@ @bout right. Tllt?y need to stxlk in it forauple of hours or so to cnsure theya co

k) clean entAugll to be silver solderedarether. M ake up a soltlti on of fluxtog

by m ixing il with methylated spiritsinto a smooth paste and sprcad itround the inside edges of each piece.put the two pieces together, with theiece with 11 hole in it on top, makingPsure the edges meet and that nicks thathave been filed otlt are level witll eachother. Lay the assembly on a brick andput a weight on top so the picces willretain their position. W hell completelysatislied that thc parts artl located

correctly heat then) u p and applysi I ver sol der abotlt tllree or four p lakresround 1 htl edges. f 'ool it tlff and put ilback in thc acid to elean it.

W'ith a needle filea open the placesu'here the nick s have been made andfile a square tbr the pendulum rod togo tlzrough. The top hole can bcopened with a taper reamer to obtain around hole. M achinc a Iength of brasstubing so that it is a push lit in the5/ l 6ills diameter hole. Nlake up ashort length of rod the salne diamderas that used for the pendulum and with

.. ...1*

a square on it that is also the same.Paint this. using either cmulsion paintor by using the white Puid w'hichtypists use for corrcetion purposes.W hen dryo push it into the bob- fit thetubing into the hole and then heatsome lead to mclting point and pour itthrough the tube until the bob is full. ltwill spi 11 out of the edges btlt this is ofnO COIISCQIJOFICC aS ally Stlrplus Can becleaned off later, Solder a disk in the

%....'k'(.'' dianleter hole in place o f the tubc .Finally use a fine file. ttmttry paper orcloth and any other abrasive materialthat might be a personal favourite, totidy the surfaees of the bob and makeit look presentable.

Round BobsRound bobs at first glance seem to befar casier to make than the lens type

nd in some ways they are:, this doesaot mean that care need not be takennjn thefr manufacture. The finish that isrequired has considerable bearing onhow they are made. For example someeople are content to drill a piece ofPcast iron bar and use that, which whencleaned and painted can look quitegood while at the same time it is theminimum of trouble to make. The onlything that needs particular care andattention is to ensure that the holedrilled should be a nice fit for thethread for the rating nut. The sameprinciple could be applied using alength of brass rod and this would givea better appearance but less weight.

A more common way is to use a pieceof brass tube and after ensuring bothends are perfectly square, start bysilver soldering a piece of plate to oneend. This is then trimmed to the edgesof the tube to give a nice neat finishwith a hole drilled centrally in it. Thescrew for the rating nut will betravelling through a piece of brasst'ube Etted inside the bob and the holeshould be a close fit for that to slideinto. M ake up a length of mild steelbar with a step to 'lèt the inside of theother end of the tube and a hole drilledcentrally in it to accept the centraltube, referred to above. M ake sure thatthis tube is exactly central when fittedoOthenvise the bob will be off centreand this will intertkre with theOperation of the pendulum. Fill theOuter tube with lead. lf necessary heatthe base to ensure that the material

American and French clocks often usea fancy shaped bob and these areusually east'. they ean be bought. Tomake thcm oneself requires either ahigh degree of skill in beating sheetmetal to shape or the ability to makesuitable patterns to have the shellscast. Any casting would be best doneusing the lost wax process. This wouldmean the bob coming straight fromthe foundry with a finish suitableimmediately for use. Trying to cleanup an ordinary sand casting would befar from easy and even then it isdoubtful if a suitable llnish could beobtained.

@fills al1 the space. A good alternativeto lead is one of the low-melting pointalloys sold for casting in rubbermoulds. These also have theadvantage that they are not toxic in thesame way that lead can be. Dependingon the amount of weight requiredo thetube does not have to be filled to thevery top, but make sure that the sllingmaterial fills the area completely andthere are no air pockets that couldthrow the bob off balance. The fnalaet is to remove the steel spaeer andput a brass plate over the top: this canbe soft soldered in position.Alternatively a brass end can be madewith a lip so that it is a push-fit in thetube. This allows more weight to beadded if required.

42

The Rating NutThe rating nut is made to fit the threadon the rod and can take almost any

43

. .â .0

fon'n or shape that the constructorlikess although it is as wt?ll to ensurethat it can be adjusted by hand easi ly.Fit thc rod through the bob and put onthe nut to check whether or not the rodwi 11 naove as the nut is adiusted, 1 f itshotlld stick at any point easc the

i nsi de by (Jrivi ng a pi ece o f squaremild steel through the hole. tlsing ahammer alld tappillg lightly. The stetllwill be sufficient to clear any lead thatmigbt just be in the way. This shouldnot apply to tubular pendulunls with acentre tube.

@

Chapter 5 - E scapem ents

The escapement is part of thcmechanism of a clock which isdevoted to the speed at which thcclock works. lt consists of a coarqc.specially shapk!tt toothed wheel andan oscillating brackd with two pegs,called pallets that locate in the teeth.The title cscapement is used becausethis is the point wherc tlle power of the

clock. which is derived from a weightor a spring, is prevented fromescaping and is converted from rotaryto reciprocating motion. The arbor onwllich the escape wheel, 01- as it isoftcn called, tscape whecl' is locatedis connected via a pinion to thc mainwheel trai n. Thu. action is such that atootll of the scape wheel is trappcd

45

@There are many types of escapement,so many in fact that whole books havebccn written on that subject alone. Thebeginner to clock making is generallyonly likely to use one of about fourtypes, but anyway any clock plan onemight work from is certain to give fulldetails of construction. Even so it isuseful to know what we are aiming forand how to set about making this partof the clock.

and then released at regulatedintervals and this movement in turn issent back through the train to thehands. W ithout the escapement thetrain would just unwind at no givenspeed and the clock would be of nouse. M any escapements work at a rateof one movement per sccond and so ifa hand is stted to the end of the pivoton which it runs the seconds can becounted offl

The Verge and Foliotearlicst forlu of escapenlentThe

known to be in general use was theerge and foliot.v

It is a very simple device to make btltfortunately is not known for goodun

ime-keeping. Even so it i s antinteresting experiment to make one asit gives some idea of what we will belooking for when making a moreadvanced version. The * scape is in thetbrm of a crown wheel. with the teethat ninety dcgrces to the luovement.There is a sligilt radius ol) each toothand the number of teeth wil I depend

@on the ntllmbers tlsed in the train. Theluovement o f thtt - scape whtlkl I i srcgulatcd by the pal Icts, whicll alvpieccs of basically tlat nletal, shapedto a k ni fe edge, attaclled to the vergethat runs vertical and is positioned sothat the pallets enter the teeth of the*scape wheel. Tllese pallcts are set atan angle of j ust ovcr ninety degrees toeach other and as onc tooth of thetscape wheel passes one of tht, pal letsit is Iocked by thc one opposittl. Theshape of this causes thc lockcd palletto be pushed out of the vvay and causcsthe folio. vvhich is a cross bar, tosw ing and in doing so it lock s thetootll on the opposite side. In this waythtl process is repeated continuallyw itl) the f-o l iot movi ng backwurds andforu ards as illltzll toot h i s lock' et1 andul't l oc Ik kltt .

Thkl spced at urhich thc mtlchan i slmopklratk!s is êt(.lj tlsted by uroights at cachend of thtl fo l i t'lt- i 11 Ns'llicll 1't. series ofroovcs ll1-(J ctlt as a nlcans 0t- holdin ggtlle u'cights i n ptlsititln . (3f coursc thttfo l iot l'nust be Nvel 1 balanekld alld thcgrooves spaced evenly on klithklr sidtlso that a good balance is l'naintaincd.It is a sil-nple idea alld as such servtldclocknlakers weI l for nlany years untilmore sophisticated ideas came along,Tlle nearer the weights are to thecentre the faster the l'novel-nent wi l I goand vice vcrsa. if the weights arc takentowards tlle end it wi I l slow down.

To n-laktl the escapelmcnt thkl whct)lcan be madc on a flat plankl and thenrollcd into kl i rcular fornl and the cndssilver soldcred togdher then a cross

Crown Wheel

. palle'ts:

. - .

O

wer suppweight connected todrum with cord.

.. Folio with..-..' weights for

A

balanceadjustment

Ili$

p .

)f/.

11!';

i13'' 'f'' X'K. ; .

. >x.. ., .> ', : s

@luinutes. Elsesvhere details wi I l btpfound of hoNv to convcrt this to hotlrsand so using l i tt le materia l or til-ne aclock can be l'nadc in this way. It willnot be a11 that accurate but it ccrtainlylnakes an interesting starter foranyonc who fecls that clock making isa d i flicult art.

A later development of the verge andfol io escapennent was the verge andbalance, thd tblio being replaeed by :1whecl and speed was altered by eitherchanging the driving weight or byclaangi ng the depth to Nvhich thepallds entert!d the wheel . Ulllcss :1replica of 11 particular clock that usedtl-ltl dcvice is being l-nadtl it is notsolnething that is likcly to appcal ingeneral to tl'le afnateur.

bar in which a holtl for thtl pivot hasbeen drillcd is si lNrtlr soldered on.Needlcss to say it is essential that thepivot hole is placed central to thecircunaference ()f the wheelo antl abrass bush will also need to btp htted tohold the pivot. The teeth can beluachined to shape but this is anexalnple of an eseapelnent where it ispossiblc to carefully file the teeth toshape, with stlfficient accuracy for thedtwice to work well enough. As alueans of getting an idea of what clockmaking is about thc escapement hasmuch tt) rtltlolnnlend i t: collnect to acouple of whtpels to give sixty-to-onercduction, fit a winding drul'n andweight to lhat and we have a crtldeelock which wi 11 show secollds and

e and PendulumVergt is possible to tlse the crown whek?lld verge antt wh i le retaining itsanimplicity, ilnprove accuracysonsiderably. The escapement workscin exactly the samtl way, tlxccpt thatthe folio is replaced with a pendulum.This is made with a crutch in exactlythe same way as pendulums used withother escapements and full dctails ofhow to go about those will be found inthe relevant chapter. Ond maj ordifference in the use of the idea is thatthe û scape whetll w i 1 1 now l i ehorizontal and so the. dircction ofmovement in the train will net)d to bechanged. In normal enginecringpractice we would use a pair of bevelgears for such a purposc, but in clockmaking the method is to use anothcrcrown wheel. sct in tht) N'crticalposition and locating wïth thtt pinionat-tached to the tseape whtltrl.

@Recoil Escapem entRQ 11()Wr 0 0111 0 t() th e 113 Ore C Om 113 Ontype of eskrapelnents which will btpfound in many of the publisheddesi gns and the fi rst noticeabl edifference is that the leeth arc tztlt inthe edge of the wIleel rather than atnindy dcgrtres as betbre. The palletsarC 111tlCh ITIOFC COmP3Ct 2nd Workfrolm a pivot situated above that of the:scape wlleel, which generally hasthirty teeth, but this will depend on the

ztt-t48

@and if so the position can be obtainetlby the use of somc sil-nple geol-nctry.Start by drawi ng the ci rculuferellce o t'the wheel and ti-om the centrc pointdraw two lines at forty-five tltlgrees.svhcl'e these intersect thecircul-nference draw 1 ines at rightangles toward thc centre line. Tht)position at w1) ich these two lines crossis thc one where we 'want the palletarbor to be.

train. The action is silnilar to beforo'.one nib of thc pal 1et locks into a toothand then as it is unlocked prtwides aslight il-npulse as the result of theshape of both teeth and pallcts. 'whilethe other in the l'neantime is locking at00th further along. The movennent issuch that there is a very slightbackward lnovel-nent as ul) Iock ingtakes place: an action known as recoi 1.

with a pencil is more dim cult. Anjjowance ofone degree is also left foratjw drop and this means the pallets aren degrees of the circle.te

once the pallets have been drawn it iscustomary to cut out the drawings andstick it to a piece of gauge plate and tocut and 5le round it to get the requiredshape. To an engineer it may sound arather primitive way of going aboutthings but the system llas worked forclockmakers for hundreds of years andthere is no reason for anything moresophisticated.

$# 'Dead flf-2t.7/. Escapelïïent. Nf)Jt? //7(?/ the /'t?f?//? ut'eunJt??r1// bv .s'j.v degrees in ol'der that onlv the/ï.p will be in contao't u/I'//l the pallets.

Brocot Pin PalletEscapem entThose readers who wish to go it aloneand to design their own movementsm ight well be interested in the brocotpin pallet escapement, the eseapewheel for which is virtually identicalto that for the dead beat. The pallets,however. are completely different.They are in pairs instead of the morenormal nibs that are found in theprevious two escapements. Half round

('ienerally full detai Is Nvi 11 be given onany plans of how to lay out theescapel-nents which 1n:1st be plannedas a whold in order to find the eorrectproportions. The pallet eentrcs arereconlnaended to be at a distance t)f1 .4 t i nlcs thc wvhcel radi us frol'n itscclltre and althotlgh therc arcoccasions vvhttn thi s nlay vary w'e u,i1ltlsc it is our tigure. A 1 1 tllat is neetledtl4t)l1 is to dravv a centre l ine. Iuark theposition o f tllc 'vvl'lce l ccntre, lmeasure1 .4 tilues the raditls, l'laktr allotherl'nark and wtz have the correct position .Sonlctilnes that tigure of 1 .4 can btl anextrenlely aw'k ward (Al)e to nleasure

Assuming the - scape' wheel wi 11 havethirty teeth- their position can bklnaarked on the drayving. It is llotnccessary to lmark the position of a11the tetrth. about tcn Nvill do. There 'willbe tvvel'te dcgrees beturen each but anal lowance has to be n-ladc for the factthat tlltlre is a flat 011 each onc and it isusual to al ltlu' one degree lbr that. Usca protractor to put the positions ol'l thcdrauzi ng. Readcrs who have acolnpuler w'i th Con'l pultlr A i dedDesign ( CAD ) softsvar: uri 11 find thatdrasving thtt eseapel-ncnt is very t-asyindeed, tlsing 11 protractor and ruler

x,.. t / gX

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Dead Beat Escapem entUnlike the previous escapement, inthis case when the pallets lock on tothe tscape wheel teeth with this typethere is no recoil action, hence thename dead beat. lt is a eomparativelyeasy device to make and is capable ofproducing accurate timekeeping,although it should be pointcd out tbatit is really more suitable for largeclocks than small ones. GeorgeGraham invented it around 1730 andso has stood the test of time. lt isparticularly effective with weight-dliven clocks where there is a constantSource of power. Generally the (scapeWheel will consist of thirty teeth andthe pallets span anything from eight tofourteen teeth. The pallets arerelatively easy to make and the teethCan be cut with a fly-cutter. As with allescapements the pallets should behardened and polished

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sections arc used and thesc ean belnade from round silver steel. steppedto fit in holes in the arm s and tilcd ormilled exactly in half. Only these partsneed to bc hardened and the an'ns canbe made froln mild steel and the nibssecured with a suitable retainingcompound.

Pin heel Escapem entAlthotlgh at first glance this type ofescapement 'would seen't to be thesilzlplest of a1I to make, as there is r)oescapc wheel as such to eut teeth ons itis not quite as straightforward as itmay seelm. Consisting of :1 whcel witha se ri e s o f h o I e s i n to wl1 i c h areinscrted pieces of half-rotlnd steel. ina sinailar fash ion to thkl nibs in thebrocot cscapennents the spacing of theholes is a sîmple cnotlgh propositionbut it is essential to ensure that whenthe pins. which arc usually nnade fronaa good quality brass are halved this isdone with absolute aeeuracy, It is

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@thereforc necessary to do the work ina mill ing m ach ine or by using 21vertical slide on the lathe to obtain therequired accuracy. lt wi 11 involvemaking a j ig that will hold the pinssecurely in such a way that the cuttercan rcach thc ccntre line of the pin.Mounting the pins aecurately on tht?wheel also requires a simple jig to bemade up. This can bc from a stiff cardif one wishes antl assuming it is onlyto be used oncc, otherwise mild steelshould be tlsed. The arms are made intwo parts and are fairlystraightfol-ward and will present Iittleproblem to any one even slightlyversed in mctalwork techniqucs.

French Pin heelEscapem entThis too is an escapemcnt that mightprove of intdrest to the lllotlk?! engincerwishing to go it alonc and design hisor htlr own clocke as it isstraightforward . Un1 ike the brocoleseapement the pins are left round andtbe arms ofthe pallcts 'ht either side ofthe wheel. It is very attractive andelegant to see when working. Becausethe pins are rotlnd they are easier tomake and if a modtrrll material such asTellon is tlsed tbr the pallet nibs, theprobleln of lubrication, which at onetimc lmadtl the escapemcnt unpopularneed be no problen: at all. Both typesof pin pallet escapement rcquire thcpallets to be offset from the wheel,rather than in line, as is the case withthe previous types.

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M aking Escape W heelsThe wheels of any type of escapementare always mortp difhcult to make thanthe normal wheel tbund in the train,because of their shape. Special cutterscan be purchase; which are designedto deal with a particular type of wheelso are only usable for the oneescapem ent type and retkrencd to thevarious drawings will show readerswhy this is so. Suitable cutters can bemade for the recoil type ofescapement from silver steel and asOnly onc radius and a straight edge isrequireda they are easy to make. TheCutter can bc made as a 'Ily cutter but itis far better to use a multi-toothedCutter if possible as a fly cutter alwaysSeems to apply too much force forComfort as it makes its single cut oneaeb rotation and there is always a

First of alI a form cutter will berequired in orddr to get the requiredradius. use a piece of ground flat stockor gauge plate as it is more oftenreferred to these days and drill a holeusing a drill with a diameter twice theraditls needed. Filc or saw off themetal left at the side of the hole andjust file a slight rcliefon the front edgethat is left: do not touch the radius thatremains. A slight chamfer can also beput on the top if one wishes but this isnot necessary as the tool is only goingto be used for the one job. Cut the flatstock to the required length and soak it

tendency t() feed a tly cutter into thework too töast. To make a six-toothcutter is not 81 great deal more diflicultthan making a fly cutter and it w'ill bemueh easier to use.

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.j.'..'.,'...,,',.:.:',y,','i;è.;,'..yi )4 tin washing-up liquid. Without wipingthe liquid off, heat it until it is a brightred colour, similar to the colour of aboiled carrot and then quench it asquickly as possible. This can be donewith salt water but then there is aslight chance of the metal cracking asit cools. It is far better to use avegetable oi1 of some sort or another.There must be suëcient quantity ofthe oil to ensure a thorough cooling: itis no use trying to quench thc metal ina cupful. It is well worthwhileinvcsting in a bottle of cooking oil andkeeping it in a suitable container justfor this purpose. Even if so far youhave never had cause to harden metalthere will be two or three instanceswhere you will need to when clockmaking and it is as well to have someavailable. Take care; sometimes the oiIwill catch fire. lf so do not try and putit out with water but just exclude theair. Any such happening is unlikely tobe a herce blaze but work on a suitablesurface, just in case hot oil splashesXPiece will fallout Ieavinj correctraditls. Trlm withfile( h te #'h- . - .y''Grind anglesfor clearance%X..->**) îDrill HoleMakeSaw Cutskfaking a /t*?/.,z? tool lk.1 produce ??'lld//I' tooth t.orcfzptamgzl/ ('lltterQ

o j Qo QoUse form tool to Bemove metal ctlt awayshape cutter edge in front of cuts on radiusmake six cuts as as shown to leaveshown. ctltting edge

g'Vethod rl/'z?pr.?l'l'uj..; multi tooth (-lf tlel'. U.%e silver .$'/t?t?l The same /JrI'ncf#/t? applies /tpu,/7(2(,/ and pinion c?,?//t?r.s'.

54

t The best type of eontainer to useou .for the ptlrpose is something Iiktt abiscuit tin and the lid wil I not onlykeep the Oil in place when not in usesbut will also put out any llamtls thatmight result from quenching the metal.

clean off the scale tlzat has appearedon the metal and when it is nice andbright place it in a small tin. (a sardinetin will do nicely) which is half tbll ofsand. Heat tlle sand from underneathuntil the metal turns a dark strawcolour and then quench it in the oilonce more. Finally just rub the top ofthe cutting edges witll tt slnall oilstoneto put som ething of an edge on themand the tool is ready for ust).

@dcpth required for various wheel sizcs.M ach i nty a I ittl: o ff the otlts i dt7diatnetcro .jtIst sufficient to take care ofany occentricity that thd chuck has andthen tlrill the hole for the bore: wenow know that the bore is perfectlyconcentric with the outside diameter.Gcntly run the radius tool you havejust made until the edgd of the silversteel bar has the rcquired shape. Use acutting oi1 for the operation as theoriginal form tool is only just aboutetïicient cnough for the job and needsany help it can get in rounding off thesi lver steel bar.

To make the actual cutter. start with alength of silver stecl bar mounted inthe three-jaw chuck. The diameter ofthe bar, within reason, is not importantas long as when the mandrel to whichit will be fitted is allowcd for,suë cient depth is Ieft to obtain thefull depth of the teeth. The chartshows the radius and therefore the

The final task is to part the bar off andthis is something which some peopleGnd dim ctllt. M uch depcnds on tbeqtlality and sizc of the Iathe as to howeasy it is and if possible it is better touse a rear tool post for the work. Forthose who really cannot face up to theidea of trying to part off a piece ofsilver sttpel of this sort of diametertherd is another w'ay round things.W hen the material is first put in thechuck, leave an overhang of about aninch and a half, or forty millimetres,but still machine the outside edges forconcentricitys but don't drill a hole.Turn the radius as deseribed and thenmachine a stem at the back of the tool;providing the work has remained inthe chtlck the whole time the stem willbe perfectly concentrie with the tool.The bar can then be removed from thechuck and the part sawn off and wehave our shaped metal but with aspigot instead of a hole for mountingit on a mandrel.

55

Sizes for m aking Cuttersfor Recoil Escape W heels

Escape W heel Pitch Radius ofless thickness of Cutter

t00th tip

0.05': 0 l 25''0 06,' O 16''0 08', 0 2''0 10'' 0 25.'0. l 25'' 0.3 1 25''0 1 6'' 0 40',

@btlt they also tlo a great deal of work'w'ith the pallets ballging up and downon thcnl for tnvnty-four hours a day.NVI'I i le thereforc it n-lay be desirable totlstl soluething a I ittle thinncr to saveweight. doing so cotlld defeat its ownpurpose, as it is more likely to distortduring operations.

Some readcrs may not have sumcientequipment to make the above tools ornot feel entirely conhdent about sodoing. It is possible to file the teeth byhand after very careful marking out. Itgot)s without saying that a grcat dcalof earc is nccded and in particular it iscssential that the straight sections artlreally that and are not angled in anyway. I f :1 small template is made 'hrst itcan bc used to check that the radius ofcach tooth is correct . it is almost

impossible to do so when just workingto markings. The template can bemade from a pi ece of card, butsomething more permanent ispreferable and plastic is ideal. Asuitable piece can be obtained bycutting up an old cretlit card andfinishing the radiusa with an emeryboard ofthe type used for manicuring.On many very old clocks a11 the teethon the wheels are hand cut, and incomparison to a great wheel an escapewheel is very simple indeed.

To complete the escapement werequire the pallets and to lind the sizeand shape of these it is necessary 'Iirstto draw the necessary angles. Thepallets can then bc ctlt out, usinggauge platc to make them. There isreally no way to make them except

To make the teeth. mark 01-#- or index itat six equal divi sions alltl mi 1 l a tlat asshown i 1'1 thc draw i ng . Fi na1 IyI'nachine another fla! so that tllere isplenty of clearanckl : again thedrawings sllow Nvhat is required. Weshould now' have six sections evenlyspaced and the tool will work like this,but if the square edges have a smallrelief filed or machined on thcln it willwork evcn better. If howevcr you arenot entirely confident of being able toget these re1 ief angles withoutdamaging what will be the cuttingedges, leave things as they are. Finallyrepeat the hardening and temperingexercise as detailed already and yotlhave a eompleted û scape wheel cuttcr.lt wil 1 not be as e ff ic icnt as aprofessionally-made one, these havesixty tceth as a rtlle, but it will do thejob and after al1 it is unlikely to beused for cutting more than one or twowhcels.

When cutting whtrttls and in particularthis type it is essential that they arewell supported to as near tlle pointwhere the teeth are being cut aspossible, partictl larly where hom cmade cuttdrs of any sort are in use.The pressure reqtlired to cut the teeth,even though we are only removing alittle material at a time is considerableand the tool will tcnd to bend themetal as it cuts. That is the last thingwe need. Generally *scape wheels aremade from material of 1 .5mm or1/ 1 6ins thick and we are torn betweentwo possibilities here. To get themaximum efficiency the %scapewheels need to be as light as possible

jth a fi Ie and sau'. althtlugll perllapsWughing Out could btl done on 11ro

rnill ing l'nacll i ne . lt is cssenti al that llleallets are made accurately and tllatPthe nibs- which ard the pointdd piecesthat stick out have polished workingurfaces. As much pol ishi ng assossible should be done before theyPare hardened but in doing so the shapeand size must be maintained. Finalpolishing can be com pleted aftcrhardening and methods of so doingwill be discusscd elsewhere.

The j-inal task to krolllplctk? theescapelncnt will be to trroh;s otlt theu'hccl , 'svhen that is col-nplettxd. lllot,ntit oll a collet and sccure it to tllt't piq'ot.It can then be tdsted. tlsillg a depthingtool, to check that the pallets wiI 1 do

their j ob. A s tlzkly are Imovedbackwards and forwards the actionshould be suflicient to slowly rotatethe wheel.

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Chapter 6 - T he G oing Train

& M otion W orkThe going train as it is properly calledconnects the power unit, whether it isa drum and weight or a spring andfusee, to the escapement via series ofwheels and pinions. W hen firstlooking into a clock it appears to be a

jungle of wheels and pinions and it isthis apparent disorder that freqtlentlyputs people off maki