T H E R E is a wide range of a l a r m clocks on the m a r k e t especially in the lower-priced models, a n d different m e t h o d s of casing a r e employed.
Before dismantling an a l a r m clock it will be necessary to study the case to u n d e r s t a n d the design a n d m e t h o d of assembly.
It is usual for the back of the case to be m a r k e d with a r r o w s to indicate the direction of t u r n i n g the winding keys. T h e reverse direction will unscrew t h e m .
If the winding-click is b r o k e n any a t t e m p t to unscrew the key will only result in the key a n d a r b o r t u r n i n g together. To over- c o m e this, some clocks have a slot m a c h i n e d in the o u t e r end of the spring a r b o r . A screwdriver is held in the slot a n d the a r b o r held stationary while the key is unscrewed.
T h e hand-set b u t t o n is usually a p u s h - o n fit a n d only needs a straight pull to r e m o v e it. T h e alarm-set b u t t o n is removed by unscrewing it against the direction of setting the a l a r m .
Sometimes the threads of the feet pass t h r o u g h the case a n d i n t o the m o v e m e n t plate preventing the m o v e m e n t from being w i t h d r a w n . Unscrew the feet by w r a p p i n g t h e m in t w o or three thicknesses of cloth a n d gripping t h e m in pliers.
T h e r o u n d case is the m o s t c o m m o n type in the lower-priced models. T h e bezel either p u s h e s i n t o the front of the case, or it forms p a r t of t h e case a n d the back p u s h e s in from the rear. Sometimes the back is held in position by three or four screws. H a v i n g r e m o v e d the external p a r t s a n d opened the case, t h e m o v e m e n t is n o w ready to be lifted o u t complete with dial a n d h a n d s .
T h e m i n u t e h a n d a n d the a l a r m h a n d can b e removed b y using the lever shown in figure 10. N o w b e n d back t w o of the t a b s holding the dial t o the m o v e m e n t a n d r e m o v e the dial c o m p l e t e with the h o u r h a n d a n d h o u r wheel.
T a k e care n o t to b e n d the dial tabs any m o r e t h a n is absolutely necessary because they h a v e to be bent a g a i n d u r i n g assembly, a n d t o o m u c h bending will cause t h e m to break off.
C u t off a short length of p e g w o o d whose diameter will j u s t fit inside the h o u r h a n d . S u p p o r t the dial in the left h a n d a n d place t h e tip of t h e t h u m b a n d fingers between t h e wheel a n d the dial. P u s h the p e g w o o d p u n c h i n t o the h o u r h a n d a n d gently t a p the p u n c h until the h o u r wheel a n d the h o u r h a n d separate.
It is unlikely t h a t any w o r k will have to be d o n e on the dial or h a n d s a n d so, when they a r e free, p u t t h e m in a safe place a w a y from the possibility of d a m a g e . If the h a n d s a n d dial n u m e r a l s h a v e been coated with l u m i n o u s paint, extra care m u s t be taken d u r i n g h a n d l i n g to p r e v e n t the p a i n t from c r a c k i n g .
Pull o u t the a l a r m wheel p i n a n d remove the a l a r m wheel. Before dismantling the m o v e m e n t , the escapement m u s t be examined. T h e majority of the lower-priced a l a r m clocks a r e fitted with the pin-pallet type of e s c a p e m e n t a n d it is therefore necessary to read C h a p t e r 10 in conjunction w i t h this c h a p t e r . If when checking the shake of the lever against the balance staff it is found t h a t the shake is u n e q u a l , the lever can be bent side- ways w i t h o u t removing it from the m o v e m e n t . A suitable tool for this p u r p o s e can be easily m a d e a n d is illustrated in Figure 89.
H a v i n g c o m p l e t e d the inspection of the escapement, the balance m a y n o w be r e m o v e d . Pull o u t the balance spring p i n from its stud a n d guide the spring o u t of the stud a n d index pins. Slacken off the u p p e r balance bearing screw a n d remove t h e balance from the m o v e m e n t .
W i t h a p a i r of tweezers check the e n d - s h a k e a n d side-shake of the wheel train pivots a n d the pallet pivots. A n y pivot holes t h a t h a v e b e c o m e enlarged s h o u l d be n o t e d . They c a n be dealt with after t h e m o v e m e n t h a s been dismantled.
Fully wind the mainspring a n d the a l a r m spring a n d h o l d t h e m in this position by fitting spring clamps.
Place a piece of p e g w o o d t h r o u g h t h e escape wheel a n d o p e r a t e t h e lever c o n t i n u o u s l y until the p e g w o o d prevents a n y further r o t a t i o n of the escape wheel.
Slacken the plate n u t s j u s t e n o u g h to lift the lever from the m o v e m e n t . Tighten the n u t s , remove t h e p e g w o o d from t h e escape wheel a n d allow the wheel train to r o t a t e until the spring c l a m p s prevent any further m o v e m e n t of the springs. W h e n the wheel train c o m e s to rest, t h e plate m a y be r e m o v e d a n d the wheels lifted out.
Fig. 89. Tool for bending lever.
In m a n y a l a r m s the c a n n o n p i n i o n is a driving fit to the centre a r b o r , a n d , once r e m o v e d , m a y b e always loose o n the a r b o r . It is better therefore to leave this u n d i s t u r b e d a n d clean the pivot hole below the p i n i o n by s o a k i n g a n d careful brushing.
H a v i n g d i s m a n t l e d the m o v e m e n t a n d laid o u t the p a r t s separately we c a n n o w c o n t i n u e with the inspection.
E x a m i n e the balance staff e n d s for w e a r . Usually it will be found t h a t the conical faces h a v e w o r n a w a y a n d p r o d u c e d a ridge. T o rectify this t h e balance spring m u s t f i r s t b e r e m o v e d . M a r k the b a l a n c e wheel to s h o w t h e position of the collet. M a k e a t o o l similar in s h a p e to a w a t c h screwdriver b u t w i t h a longer t a p e r a n d p u s h t h e blade i n t o the slot of the spring collet.
A slight twist a n d pull m a d e in o n e m o v e m e n t will r e m o v e t h e collet a n d spring from the balance staff.
t h e conical face m a k i n g sure t h a t the original angle is n o t destroyed. B u r n i s h the n e w face a n d the p o i n t . T r e a t the o t h e r e n d of t h e staff in t h e s a m e way.
E x a m i n e t h e pallet pins for wear. If they n e e d r e n e w i n g t h e old o n e s c a n be t a p p e d o u t over a g r a d u a t e d s t a k e . N e w p i n s c a n be
W o r n pivot hole be- fore reaming.
Pivot hole after ream- ing, showing entry of tapered bush.
Bush pressed into position ready to be filed to length.
Fig. 90. Fitting Bush to worn pivot hole.
m a d e from sewing needles. C u t off a suitable length a n d t a p the n e w p i n in position from the u n d e r s i d e of t h e lever.
E n l a r g e d p i v o t holes c a n n o w be dealt w i t h by fitting n e w b u s h e s .
Bushes a r e supplied r e a d y m a d e . T h e pivot hole is drilled a n d t h e outside d i a m e t e r is m a c h i n e t a p e r e d . E a c h bush is m a d e oversize in length.
A convenient m e t h o d of p u r c h a s i n g is to o b t a i n f r o m a n y materials supplier a b o x c o n t a i n i n g bushes of a s s o r t e d sizes.
Select a suitable b u s h a n d r e a m o u t t h e w o r n pivot hole f r o m t h e b a c k o f t h e p l a t e until t h e d i a m e t e r o f t h e h o l e will j u s t allow t h e small e n d o f t h e b u s h t o enter. T h e b u s h can t h e n b e pressed o r t a p p e d into position.
W h e n t h e b u s h is in tight b o t h ends m u s t be carefully filed flush with the plate.
Finally t h e pivot hole is enlarged by r e a m i n g , to suit the size of the pivot.
E x a m i n e the wheel train for b r o k e n teeth. N e w teeth c a n be fitted as described in C h a p t e r 6, b u t in place of brass pin-wire, strip brass will p r o b a b l y be needed.
E x a m i n e the wheel pivots a n d if w e a r h a s t a k e n place t h e pivots m u s t b e polished a n d b u r n i s h e d i n the t u r n s .
Provided n o o t h e r repairs h a v e t o b e carried out w e a r e n o w ready to proceed with the cleaning. A tray will be required for the cleaning f l u i d a b o u t t w o inches deep a n d large e n o u g h t o t a k e the back plate. We will require s o m e tissue p a p e r , t w o cleaning brushes, soft a n d m e d i u m , a 1/2-in. flat p a i n t b r u s h , p e g w o o d , pith, chalk, a piece of clean soft linen such as an old handkerchief a n d s o m e cleaning fluid.
Place o n e of the plates in t h e tray a n d p o u r the cleaning fluid over it until it is covered. B r u s h it with t h e 1/2-in. brush a n d w h e n it is t h o r o u g h l y clean r e m o v e it from the cleaning fluid a n d dry it in t h e cloth. T r e a t the o t h e r plate in t h e same way.
T h e balance spring is held in t h e tweezers a n d gently washed in the cleaning fluid by m o v i n g it a b o u t . W h e n it is clean, lift it o u t a n d place it between t w o pieces of tissue p a p e r c h a n g i n g the p a p e r each time it becomes s a t u r a t e d .
D o n o t immerse the m a i n s p r i n g a n d the a l a r m spring i n t h e cleaning fluid because, in their w o u n d c o n d i t i o n , they will n o t dry.
W a s h , b r u s h a n d dry all the r e m a i n i n g c o m p o n e n t s i n the s a m e way as was d o n e for t h e b a c k plate.
T a k e the cleaning b r u s h with the m e d i u m bristles a n d charge it with chalk. R u b it briskly over t h e faces of b o t h plates. T h i s will p r o d u c e a semi-polish which is less likely to a t t r a c t dust.
T r e a t t h e wheels in t h e s a m e way m a k i n g sure t h a t the spaces between t h e teeth a r e clean.
L a y the balance spring on a piece of white p a p e r . T a k e t h e cleaning b r u s h w i t h t h e soft bristles a n d charge it with chalk.
W A T C H A N D C L O C K R E P A I R S
H o l d the balance spring d o w n with the tip of a finger a n d carefully d a b the bristles of the b r u s h i n t o the coils of the exposed p o r t i o n of the spring. C o n t i n u e r o u n d until the complete spring has been cleaned.
T h e pivots, pivot bearings a n d p i n i o n s n o w need a t t e n t i o n . Shave a p o i n t on the e n d of a piece of p e g w o o d , insert it in the pivot b e a r i n g s a n d lightly r o t a t e it. T h i s will ensure t h a t all bearings are clear.
T h e p o i n t o f t h e p e g w o o d i s n o w used t o clean t h e pinions. R u n the p e g w o o d u p a n d d o w n each leaf r e m o v i n g any dirt t h a t m a y be present.
T h e pivots are cleaned by p u s h i n g t h e m i n t o the end of a pith stick a n d r o t a t i n g the p i t h a few times.
H a v i n g cleaned a n d polished all the p a r t s we are n o w ready to assemble t h e m .
Oil the ratchet wheels a n d clicks a n d fit t h e m to the back plate. Place the balance a n d lever to o n e side a n d assemble the r e m a i n i n g p a r t s t o the b a c k plate.
Lower the front plate i n t o position gently guiding the pivots i n t o their respective bearings. M a k e quite sure the wheel train is free- r u n n i n g , tighten d o w n the front plate a n d again check the freedom of the wheel train.
T h e lever m a y n o w be fitted by slackening the front plate n u t s , lifting t h e front plate slightly a n d inserting t h e lever i n t o position. L o w e r the front plate again, check the lever for freedom a n d tighten the front plate n u t s .
T h e m a i n s p r i n g m a y n o w b e fully w o u n d u p a n d the c l a m p r e m o v e d . C h e c k the action of t h e wheel train a n d the e s c a p e m e n t lever by o p e r a t i n g the pallets a few times.
W e are n o w ready t o assemble the balance. S u p p o r t the balance wheel by placing the lower pivot in a stake. Place the collet on the u p p e r pivot a n d with a t u b u l a r p u n c h gently t a p the collet i n t o position. By inserting the tool previously m e n t i o n e d in t h e slot of the collet, the collet c a n be t u r n e d until it coincides with the m a r k m a d e o n the b a l a n c e wheel d u r i n g dismantling.
position of the stud. T h e balance spring m u s t lie quite flat when secured in the stud hole.
Fit the balance to the m o v e m e n t a n d adjust the u p p e r bearing screw until end-shake of the balance staff disappears. N o w unscrew the bearing screw slightly until there is j u s t sufficient end-shake for free m o v e m e n t .
R o t a t e the balance until the impulse p i n enters the lever a n d at the same time guide the e n d of the spring t h r o u g h the index pins a n d i n t o the stud hole. T h e actual position of the spring to be pinned in the stud will be indicated by the kink in the spring caused by the previous pinning. Insert the pin into the stud a n d carefully squeeze it in tightly using the thin pliers. T h e balance should n o w be free to vibrate.
H a v i n g assembled the balance it is necessary to check the beat of the escapement.
M o v e the balance wheel r o u n d with the tip of a finger a n d watch the action of the escape wheel. Immediately a t o o t h of the escape wheel falls away from a pallet, s t o p the m o v e m e n t of the balance wheel a n d n o t e its position. N o w reverse the direction of the balance wheel a n d c o n t i n u e m o v i n g it until a t o o t h of the escape wheel falls away from the o t h e r pallet. Stop m o v i n g the balance wheel a n d n o t e its n e w position. If the e s c a p e m e n t beat is correct, the balance wheel will have m o v e d the s a m e distance on each side.
R e s t t h e centre a r b o r on a stake a n d fit the c a n n o n p i n i o n by gently t a p p i n g it d o w n with a hollow p u n c h . T h e a l a r m wheel is n o w placed in position a n d the a l a r m wheel pin fitted.
Oil the wheel train pivot bearings, the balance bearing screw sinks a n d the pallets. P u t one d r o p of oil on each p i n i o n . Oil the r i m of the a l a r m wheel a n d the edges of the m a i n s p r i n g a n d the a l a r m spring.
N o w f i t the h o u r wheel a n d the m i n u t e wheel a n d secure the dial. F i t the h a n d - s e t b u t t o n a n d the alarm-set b u t t o n a n d screw o n the t w o winding keys.
W e n o w h a v e t o synchronize t h e a l a r m m e c h a n i s m with the time m e c h a n i s m . R e m o v e the tension from the a l a r m
spring c l a m p by further winding the spring a n d then r e m o v e the c l a m p .
Slowly t u r n the alarm-set b u t t o n until the a l a r m wheel pin d r o p s i n t o t h e base of the c a m . This is the position at which the a l a r m will o p e r a t e . T h e a l a r m h a n d is n o w fitted so t h a t it exactly p o i n t s to o n e p a r t i c u l a r h o u r , say 9 o'clock. T h e clock h a n d s m u s t therefore indicate the same time. F i t the h o u r h a n d to 9 a n d the m i n u t e h a n d to 3 m i n u t e s before the 12. To check the setting t u r n the alarm-set h a n d to ring at 10 o'clock a n d then o p e r a t e the h a n d - s e t until the h a n d s p o i n t to four m i n u t e s before 10 o'clock. Leave the clock to function a n d n o t e t h e time at which the a l a r m operates. Adjustments c a n be m a d e by r e m o v i n g the m i n u t e h a n d a n d repositioning it. T h e m o v e m e n t is n o w ready for fitting back i n t o its case.
There is an alternative m e t h o d of c l e a n i n g which is quicker b u t n o t so reliable. T h e m o v e m e n t is t a k e n from its case a n d the h a n d s , dial balance a n d the lever a r e r e m o v e d .
T h e m a i n s p r i n g a n d the a l a r m spring a r e w o u n d u p a n d the m o v e m e n t is totally immersed in the cleaning fluid d u r i n g the r u n n i n g d o w n of the t w o springs. T h e m o v e m e n t is then lifted o u t of the fluid a n d a b r u s h is used to clean the pivot holes in the plates. T h e springs are r e - w o u n d a n d the m o v e m e n t once again immersed in the cleaning fluid.
W h e n the springs are fully r u n d o w n , the m o v e m e n t is r e m o v e d surplus fluid is shaken off, the plates are wiped with a clean piece o f linen a n d the m o v e m e n t h u n g u p t o dry.
T h e balance a n d the lever are treated as previously described a n d a r e refitted to the m o v e m e n t when the m o v e m e n t is c o m - pletely dry. Oiling is carried o u t as before.