Handbook of Watch and Clock Repairs (1972)

BALANCES

Hold the hairspring in tweezers, lower it over the collet, insert

the inner end of the spring into the collet keeping the spring level

and central with the collet.

Insert the taper pin into the collet until the spring is just

gripped. Push the collet from the holder and lay the spring on the

white paper. In this way the coils of the spring can be checked

Fig. 56. Centralizing the hairspring to the collet.

t o m a k e sure t h a t they ar e central a b o u t t h e collet. If they ar e n o t

central the spring must be carefully bent to make them so (Fig.

56). All bending should take place within the first quarter coil

from the collet.

In figure 56, a, an oiler is inserted at A a n d given a twist. This

will push the coil away from the collet at that position but at the

same time bring it closer to the collet at B. In figure

56, b, the

diameter of the coil is reduced by applying tweezer pressure

across A and Β causing the coil to move away from the collet at C.

Before making any alterations study the contours of the spring

carefully and decide exactly where the spring needs bending to

produce the desired result. Two pairs of fine pointed tweezers are

best for this operation.

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WATCH AND CLOCK REPAIRS

To check for flatness of the spring the balance is mounted on

an arbor and is spun between callipers or turns. If the spring is

out of true it can be corrected by gripping it with tweezers close

to the collet and turning in the required direction. Providing the

pin was not put in too tightly the pin will move round with the

spring. Slowly spin the balance after making each adjustment to

check the result. When the balance can be rotated once with no

variation of the spring, the arbor can be removed.

Press the pin firmly into the collet using a strong pair of

tweezers. It is essential that there should be no movement of the

spring in the collet when the pinning is finished.

The next step is to pin the outer end of the spring to the stud.

Make a taper pin in exactly the same way as we did for the collet,

but this time the taper must be longer.

Move the index to the midway position. Lay the balance cock

on the bench with the index pins uppermost. Place the spring on

the balance cock with the collet centrally over the pivot hole and

note the position where the stud will be. Break off the surplus

length of spring allowing for a little to protrude beyond the stud.

Remove the spring and fit the stud to the balance cock. Replace

the spring on the balance cock and pass the end through the pin

hole in the stud. Push the pin into position. Examine the assembly

closely to make sure that the spring is supported parallel to the

balance cock. If it is not, turn the pin which is still in the pin-vice

and the spring will move with it. When the spring is parallel,

make the pin a short distance from the stud with a knife and

break the pin off. Push home tightly with strong tweezers.

The position and shape of the spring may now need altering.

The outer coil must lie naturally between the index pins without

side pressure or side play. If necessary the pins must be bent

closer together. The second coil must not foul the inner index

pin or stud, and the collet must rest centrally over the pivot hole

in the balance cock.

It is sometimes found that the position of the stud is a little too

far from the centre and this causes the spring to be out of centre.

To rectify this fault bend the spring close to the stud at A in

BALANCES

101

figure

57. If the spring touches one of the index pins, bend the

spring at Β in figure

57 until the coil lies naturally between the

pins.

The balance can now be fitted to the movement, the movement

set in motion and a final check carried out to ensure that the

spring is functioning correctly and that no fouling is taking place.

Repairing a hairspring. Once a spring is damaged the most

satisfactory repair is to fit a new one, but there are circumstances

when an attempt to straighten a bent hairspring is justified.

Fig. 57. Centralizing the hairspring and collet to the jewel hole.

Sometimes a spring becomes entangled. If it is caught on the

stud careful manipulation will often restore the spring to its

correct position. If this is not possible, the pin must be removed

from the stud, the spring withdrawn and, commencing from the

centre with a needle, the spring must be followed throughout its

length disentangling as you go.

I f the spring h a s j u m p e d over t h e r i m of t h e balance wheel, t h e

spring must be released from the stud, the collet must be removed

from the staff and the spring rotated in order to unwind itself

from the balance.

A spring can be o u t of true either in t h e r o u n d or in the flat.

That is to say the coils no longer conform to their original shape

or the spring is no longer flat.

Remove the spring complete with collet and lay it on a sheet of

stiff white paper. Follow the coils round with a needle starting

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WATCH AND CLOCK REPAIRS

from the centre. At the first irregularity of curvature bend the

spring correctly with the point of a needle holding the spring in

tweezers. Continue this process until the outer end of the spring

has been reached.

Now the spring must be checked for flatness. Hold the spring

up and look on its edge. Any upward or downward bends will be

immediately apparent. Once again starting from the centre note

each irregularity and bend the spring back into shape using two

pairs of tweezers.

Having restored the flatness of the spring we must now be sure

that it lies parallel to the collet. To check this, fit the collet to a

turning arbor and rotate the arbor in the turns. Correction can

be made by a slight twist to the spring as close to the collet as

possible.

All that remains now is to check that the spring is parallel and

central with the balance cock. Fit the spring to the stud, ensure

that the outer coil rests naturally between the index pins and that

the collet is central over the balance staff pivot bearing.

Renewing index pins. If a hairspring is subjected to shock it

sometimes jumps from between the index pins or the second coil

jumps in. To prevent this, the index pins should be as long as

possible. If the tops can be turned inward slightly so that they

both meet then isolation of the outer coil will be maintained.

Old pins are cut off and filed down flush. The stumps are driven

out by a blunted needle with the index on a stake. The new pins

are made with a very slight taper, polished with the fine emery

stick and finished with a burnisher. The pins are then pushed

tightly into the index and cut off to length.

CHAPTER TWELVE

Shock proofing

THE parts of a watch most likely to suffer from shock are the

pivots of the balance staff. The diameter of these pivots is

approximately the same as that of a human hair. To knock or

drop a watch imparts shock to the movement and invariably

some damage is caused to the balance staff pivots.

If the shock is severe, at least one pivot will break off and the

watch will stop. A less severe shock is likely to cause one or both

pivots to bend. This damage may not be sufficient to prevent the

movement from functioning but it most certainly can cause bad

Fig.

58. Diagrammatic sketch of Kif Flector device, (a) Axial shock,

(b) Radial shock. Under the effect of a shock the balance wheel is

displaced, its pivot carrying away the jewel in-setting and end-stone.

The shock is absorbed by the part of the staff or the arbor which hits

the block. After the shock the spring instantly replaces the whole in its

initial position.

103

SHOCK PROOFING

105

time-keeping and also excessive and irregular wear to the pivot

bearings.

Spinning a balance staff between callipers and inspecting

through an eye-glass will reveal any such damage.

It seems obvious, therefore, that some means of absorbing the

shock is required. This in fact has been done and the principle

employed is to use mobile pivot bearings that automatically take

up a position of alignment under spring pressure

(Fig.

58).

Two housings are employed. One is fitted into the balance cock

and the other into the bottom plate. In these housings are

assembled the jewels, the end-stones and the springs.

Fig. 61. Kif Flector special tool. The mark on the handle indicates the

flat side of the point.

Shock will cause the balance to move from its normal position.

The pivots will move the pivot bearings until the balance staff

hits against the housings, and the housings and the balance staff

will absorb the shock. The springs then return the assemblies to

their positions of alignment.

Three of the more popular methods used have been selected

and are described in the following paragraphs.

Kif Flector (Fig.

59). A pointed tool is inserted into the spring

notch and the spring is turned in the direction of the arrow

(a).

The spring can now be hinged upward allowing removal of the

end-stone and the setting jewel

(b). The setting jewel and end-

stone can now be cleaned, and the balance staff pivot is suffici

ently exposed to be cleaned

(c). Setting jewel and end-stone are

replaced. The spring is hinged downward and the pointed tool

is used to lock the spring by turning it in the reverse direction (d).

SHOCK PROOFING

107

The method for dismantling the Kif Flector is illustrated in

figure

60.

The special tool

(Fig.

61) is inserted behind the hinge pin

(a).

The tool is then rotated a quarter of a turn to push the hinge pin

Fig.

66. Exploded view of Monorex. (a) Cap jewel in setting with cap

jewel spring, (b) In-setting with jewel for balance, (c) Upper end-piece

without fittings, (d) Lower end-piece without fittings, (e) In-setting with

jewel for balance, (f) Cap jewel in setting with cap jewel spring.

inward

(b). The spring is held by tweezers, unhooked from the

hinge pin and removed

(c). To remove the hinge pin from the

block, one arm of the pin is first removed from its groove and

the pin can then be lifted out

(d).

Figure

62 shows the parts in their order of assembly.

Incabloc

(Fig.

63). To dismantle, the spring must be swung

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WATCH AND CLOCK REPAIRS

clear. Press the ends towards the centre and raise the spring on

its hinge. The jewel cap, the jewel and the jewel bushing can now

be lifted from the housing.

In the case of the upper assembly the housing is secured to the

balance cock by a U-bolt underneath

(Fig.

64). The lower

assembly housing is secured to the bottom plate by a screw

(Fig. 65).

Fig.

67. Monorex shock absorber. Removing the jewel and bushing.

Monorex

(Fig.

66). The end cap is removed as shown in

figure

67. The jewel and bushing can then be lifted from the

housing. Both upper and lower housings are press fits into the

balance cock and bottom plate respectively.

One of the features of these three systems is the ability to

expose both balance pivots without disturbing the balance

movement. This enables the pivots to be cleaned as well as the

shock absorber parts.

Oiling the pivots is accomplished by placing a drop of oil on

the inner face of the end-stone and placing the end-stone and jewel

together. They are then lowered into their housings and secured.

CHAPTER THIRTEEN

Cases

CASES are made of gold, silver, stainless steel or plated brass.

Typical designs are illustrated in figures

68 and 69.

Pocket watch cases. Bezels are snapped on to the case middle.

Domes are either hinged to the base of the middle or are fixtures

and do not open, some cases have no domes. Backs are either

hinged to the base of the middle or they are snapped on.

Wristwatch cases. Many are designed similar to pocket

watches but the modern trend is to fit movements into two-piece

cases as shown in figure 69. The bezel either fits over the back as

illustrated or snaps on. Because the two-piece case has only one

detachable part, the possibility of dirt and dust entering the case

is reduced. This type of case is becoming increasingly popular

among manufacturers.

The majority of American watch cases are fitted with screw-on

bezels and backs. This is undoubtedly the best method of main

taining internal cleanliness.

Fig. 68. Pocket watch case.

109

110

WATCH AND CLOCK REPAIRS

American manufacturers were the first to produce the gold-

filled watch case.

A sheet of brass is sandwiched between thin gold sheet and

all are brazed together. The metal is then rolled to the required

thickness, pressed out and polished. The result is a brass case

with a gold face inside and outside. These cases are very hard

wearing.

Fig. 69. Wristwatch case.

Opening a case. Before attempting to open a case it should be

examined to make sure that the method of assembly is under

stood. A screwed-on back will be indicated by slots or by a series

of flats cut in the edge to take a key or the edge may be knurled

to enable the back to be gripped in the hand and unscrewed by

hand pressure.

A screwed-on bezel will have a knurled edge.

Snaps can be identified by a shallow groove on the edge to

provide entry for a knife blade, or the edge may have a lip to act

as a lever.

If the snap has neither groove nor lip, a sharp knife blade is used

inserted in the join.

When opening a good fitting case, great care must be exercised.

The knife can slip and disfigure the finish. Damage can be caused

to the edge of the snap. The join can be bruised by the incorrect

use of the knife blade.

Most screw-on fittings can be removed without the use of

tools. Place the watch face down in the palm of the left hand.

Press down firmly with the other palm and at the same time turn

in a counter-clockwise direction.

CASES

111

To remove a snap by means of a knife blade, first ensure that

the blade is sharp. Next push the blade firmly and cleanly into

the join. Now lean the blade over so that the cutting edge presses

against the case middle allowing the blade face to push off the

snap. Never twist the blade when it is in the join ; the cutting edge

will damage both the snap and the case middle.

Removal of the movement from the case is dealt with in

Chapter

Repairs. A bruise in the case middle can be pushed out from

the inside by using a suitably rounded implement such as a piece

of boxwood.

Bruises in domes and backs can be lightly tapped out with a

wooden mallet whilst the dome or back is supported on a box

wood stake

(Fig.

70). The stake should be covered with tissue

paper to prevent marking the work.

Small bruises in the glass groove of a bezel can be pushed out

Fig. 70. Boxwood stake.

by using a small screwdriver from the inside. Considerable care

must be exercised otherwise the glass will not fit correctly.

Side movement of hinges should be eliminated. In many cases

the renewal of a hinge pin will be all that is required.

The old pin is carefully driven out a distance sufficient to

enable the pliers to obtain a grip. The pin can then be pulled

completely out.

Select a piece of steel rod of the correct diameter and cut it

about 1/8 in. longer than is required, insert the pin so that an equal

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WATCH AND CLOCK REPAIRS

length is protruding at each end. These ends are carefully filed to

blend with the shape of the case. File marks are removed by using

the smoothest grade of emery cloth and then polishing.

Worn snaps can be tightened by inward burnishing of the edge

with a wetted oval burnisher, or the snap on the case middle can

be burnished outward.

A snap that is too tight can be loosened by removing a little of

the metal all round the inner edge, finishing off with a burnisher.

Glasses. Some of the more popular designs are shown in

figure

71. A loose glass can frequently be fixed in its bezel by

applying some glue to the glass groove with the point of a

pegwood stick. Place the glass in position, rotate it in the bezel

to spread the glue and put aside to dry.

The edge of the glass groove should never be burnished

inward to make a glass fit as this will damage the bezel.

Glasses are fitted by hand and to snap a good fitting glass into

its bezel requires practice. Glasses should never be fitted with the

bezel in position on the watch case.

Fig.

71. Glasses,

(a) Flat crystal,

(b) Crystal,

(d) Lunette.

CHAPTER FOURTEEN

Magnetism

IT is not uncommon for watches to suffer from magnetism. The

effect is erratic time-keeping, gaining at irregular intervals

similar to that which is brought about by oil on the hairspring.

Much of the repairer's time can be spent chasing a watch fault

whilst the real cause of magnetism remains undetected. Therefore,

before we leave the overhaul of watches a few words about

magnetism may save a few frustrating hours in the future.

For magnetism to have any noticeable effect on a watch it must

be present in the hairspring. Other steel parts such as the keyless

work, screws and mainspring are not likely to effect time

keeping if they themselves become magnetized.

In many modern watches the escapement is made from non

magnetic metals for this very reason. However, there are still

large numbers of watches made with steel hairsprings that can

be magnetized and it is with these movements that we are going

to be concerned.

Remove the back of the case and with a pointed pegwood stick

close the coils of the hairspring and see if they stick together

when the pegwood is removed.

Now place a pocket compass on the balance cock. The compass

needs to be the smallest obtainable for lightness and sensitivity of

the needle. A very suitable type is the toy that is sometimes found

in party novelties.

Position the compass centrally over the balance pivot. Set the

balance in motion and note the effect on the compass. The needle

may vibrate in harmony with the balance or it may make

complete revolutions, but in either case the presence of magnetism

has been established.

If the needle remains stationary, tap the compass in case the

needle has stuck.

Lift the compass from the watch and take the watch away. If

113

114

WATCH AND CLOCK REPAIRS

the needle then moves it indicates that some other part of the

watch is magnetized and was attracting and holding the compass

needle in one position.

To check this, replace the watch under the compass in the same

position as before and the compass needle should swing back.

Another check is to lift the compass just clear of the balance

cock, slowly rotate the watch and see if the compass needle

follows the movement of the watch.

To demagnetize a piece of steel the part concerned is placed in

the magnetic field set up around a coil of wire through which is

passed an electric current. The part is first fully magnetized and

then slowly withdrawn from the magnetic field.

The hairspring must be removed from the watch and wrapped

in tissue paper in order to preserve its shape during the demag

netizing process.

If this were not done and the complete watch was put in the

coil, or if the hairspring alone was put in the coil without protec

tion, then when the electric current was switched on and the

spring subjected to the full magnetic force the pull would far

exceed the spring tension and the coils would become entangled.

The demagnetizer (Fig.

72), consists of a tightly wound coil

on a hollow bobbin, the hole being large enough to accept

watch parts with plenty of free space.

The coil is connected to an A.C. current through a

transformer which provides the coil with a pressure of about

six volts.

MAGNETISM

115

The hairspring is placed in the centre of the coil and the current

is switched on. After a few seconds the hairspring is slowly

withdrawn to arm's length and then the current is switched off.

It frequently happens that the first treatment of demagnetizing

does not provide a complete cure. Therefore, when the hairspring

is refitted to the watch and a further test is made, do not discard

the possibility of magnetism still being present if the compass

needle gives an indication.

Part Three

CLOCKS

CHAPTER FIFTEEN

The movement

As a time-piece the basic principle of a clock movement is the

same as that of a watch. It has its motive power, train of wheels,

escapement, and motion work with dial and hands.

Motive power is supplied either by a wound spring or by

hanging weights.

From figure

24 we can see that the order of the wheels in a

watch is: the barrel, the centre wheel, the third wheel, the fourth

wheel and the escape wheel.

In a clock the barrel does not mesh with the centre wheel

pinion. The order is: the barrel, the intermediate wheel, the

centre wheel, the third wheel and the escape wheel.

The three most common types of clock escapements are the

pin-pallet, the cylinder and the recoil. The pin-pallet is used

mostly in the lower priced alarm clocks and watches and has

been dealt with fully in Chapter

10.

The cylinder escapement is fitted to carriage clocks and is

described in Chapter 20.

Whereas these two escapements are fitted with balance wheels,

the recoil escapement, which is described in Chapter

16, is

controlled by a pendulum.

When mechanisms such as strike and chime are added they

tend to make the complete movement complicated. It is therefore

better to make a study of these mechanisms separately. Part

has been written with this in mind.

116

THE MOVEMENT

117

The procedure for cleaning varies with some movements and

in those cases it has been included in the chapter concerned,

otherwise cleaning is the same as described in Chapter

16.

The technique of oiling has been fully described in Chapter

and applies equally well for clocks.

The dials of some movements are screwed to the front of the

case. In others, the case itself is the dial.

Winding a pendulum movement is almost always done by

inserting the key at the front. This is to avoid disturbing the

clock and upsetting the balance. With other types of movement,

where this precaution is unnecessary, winding is done at the back.

There are many methods of securing movements to cases, but

whatever the method it will be obvious after inspection.

The remaining chapters in this section are devoted to different

types of clock movements, it seems fitting therefore that in this

chapter some mention should be made of clock cases.

Quite often a great deal of work is put into the overhaul of a

movement which is then replaced in a case that contains enough

dirt to stop the clock on sight.

Apart from the important task of cleaning the case interior, a

few moments spent on the exterior often makes a big difference

to its appearance.

Materials used for the manufacture of clock cases include wood,

metal, stone, plastic and glass.

If the case is dirty give it a good cleaning. If it needs repairing,

assuming the damage is not extensive, then a few minutes spent

on a minor repair are worth while.

Clean the interior of the case. It is surprising how much dirt

and dust can collect.

If the case is made of wood, examine ornamental pieces on the

outside for security. Do the same with any strengthening blocks

inside. Loose pieces can be glued into position.

Dust in carvings or scrolls can be removed by using a soft

brush. Furniture cream will improve the appearance of polished

wood.

Inspect bezel hinges and door hinges for security and condition.

118

WATCH AND CLOCK REPAIRS

Renew the screws if necessary. If the screws continue to turn when

being tightened remove them and plug the holes with pieces of

match-stick and replace the screws.

Other cases can be wiped with a clean soft cloth moistened in

warm soapy water. Finish off with a soft dry rag.

Make sure the dials are clean. Lightly brush them with a

watchmaker's soft cleaning brush. Enamel dials can be wiped

with benzine.

Clean and polish the glass. Do nothing with lacquered brass-

work other than rub it lightly with a soft cloth. Tarnished brass

is best left alone.

CHAPTER SIXTEEN

Pendulum clocks

IN this chapter we are going to overhaul a simple pendulum clock

of the lower priced domestic variety. It seems reasonable to say

that these clocks are one of the most popular clocks in the home

today.

Their low price is brought about by the high rate of mass

production. Large quantities are manufactured in Germany,

the United States and Great Britain.

The movements themselves are readily recognized. The plates

and wheels are coated with lacquer and many of the parts are

pressed out by machine. Providing they are kept clean, oiled and

adjusted these clocks give excellent service over long periods.

In Chapter 15 we spoke about taking movements from their cases

and removing dials and hands. Let us assume that this has been

done and that we are now ready to proceed with the overhaul.

First of all we need a small but strong cardboard box on which

to place the movement and so prevent the many protrusions from

damage. Better still of course would be a home-made box of ply

wood cut to fit the movement.

Now let the mainspring down. If the movement is very old the

chances are that the mainspring will not be contained in a barrel

in which case a mainspring clamp will have to be fitted.

Place the key on the winding square and turn it in the direction

of winding. This will throw the ratchet click out which must then

be held in this position. Allow the tension of the spring to turn

the key backwards until your hand can go no farther. Release

the ratchet click back into the ratchet and then you may let go

of the key. Repeat this process until the spring is completely

unwound.

These springs are very powerful and could cause personal

injury to hand or fingers if allowed to run down out of control.

Apart from this, to do such a thing would most probably result

119

120

WATCH AND CLOCK REPAIRS

in a broken spring. So take care and make sure that the movement

is held firmly, that the key will not slip in your hand and that the

click can be released immediately and at any time.

Remove the minute wheel collet, lift off the hour wheel and

then remove the minute wheel.

Worn pivots and pivot holes have an effect on the depth of

mesh between the wheels and their pinions and the locking of the

escapement. Hold each arbor between the finger and thumb, or

stout tweezers if the arbor is not accessible, as near the pivot as

possible and check the amount of side-shake. Make a note of

any holes that are considered to be in need of bushing. The best

way of assessing whether or not the side-shake is excessive is to

compare it with a movement of similar size that has had little or

no wear.

Once having experienced the amount of side-shake in a new

clock, subsequent inspections will prove less difficult.

Examine each arbor to make sure it has end-shake. There must

be sufficient clearance to prevent the shoulders of the pivots

binding against the plates.

Providing there is no excessive side-shake in the pallet arbor

pivot holes and the escape wheel arbor pivot holes we can go on

to check the recoil escapement, otherwise checking the escape

ment must wait until the worn pivot holes have been bushed.

Wind up the mainspring a few clicks, hold the movement in

the left hand and operate the crutch with the right hand. Examine

the faces of the pallets for wear. Observe through an eye-glass

the action of the escape wheel teeth dropping on to the pallets and

at the same time form an idea of the angle of swing the pendulum

must make to release the escape wheel teeth.

It will be seen that deep locking will necessitate the pendulum

passing through a large angle of swing which in turn demands

more power. Remember also that if the pallet fails to release an

escape wheel tooth just once, the clock will stop.

If on the other hand the depth of locking is too shallow mis-

locking is likely to occur.

There are two types of pallets used, the strip pallet (Fig. 73, left),

PENDULUM CLOCKS

121

and the solid pallet fitted to the Garrard escapement (Fig. 73, right),

both of which are provided with means of adjusting the depth.

In the case of the movement fitted with a strip pallet, the screw

holes in the pallet cock are elongated and all that has to be done

is slacken off the two screws, reposition the pallet cock and tighten

the screws. It is a matter of trial and error but the correct position

is quickly found.

Adjusting the depth of a solid pallet is done by altering the

position of a screw on top of the back plate. Slacken off the two

Fig.

73. Recoil escapements. Strip pallet {left) and solid pallet (right).

pallet cock screws, rotate the adjusting screw and tighten the

pallet cock screws. By turning the adjusting screw in a clockwise

direction the pallet cock is raised which reduces the pallet depth,

and of course, to increase the depth the screw must be turned

counter-clockwise.

Having checked and adjusted the pallet depth we have ensured

that the escape wheel teeth will be properly locked. Now we can

examine the amount of drop.

The drop of an escape wheel is the distance it travels from the

release of a tooth from one pallet to the next arrest of a tooth

by the other pallet.

To check the drop apply the same technique as was used when

checking the pallet depth. In determining whether the amount of

drop is correct, again the best advice is to compare it with a

similar clock that has had little wear. Make a note of the adjust-

122

WATCH AND CLOCK REPAIRS

merits that are needed then remove the pallet cock and lift the

pallet arbor from the movement.

If the pallet is the strip type all that is needed is to bend the

offending pallet or pallets. Bending the entry pallet outward will

decrease the drop on that pallet, and bending the exit pallet

outward will increase the drop on that pallet.

These strip pallets are quite soft and can be bent cold but as a

precaution against cracking it is advisable to heat them first.

Now that the pallet is out of the movement this is a good

opportunity to deal with worn pallet faces. Use a dead-smooth

file to restore the faces to their original surface, smooth off with

the finest emery stick and finish with a burnisher.

With the solid type of pallet the drop can be increased by

reducing the entry faces. These pallets are too hard to file and a

stone must therefore be used. An oilstone such as is used by a

cabinet maker is best for this job. Make sure the stone is kept flat

and that it follows the contour of the pallet.

The marks from the oilstone are then removed by an oilstone

slip keeping the grain flowing with the pallet. Finish off with a

very fine emery stick and then burnish.

Little can be done to decrease the drop in the solid type of

pallet but this is not important. What is important is to avoid

having too little drop. Such a condition can, after pivot holes are

worn, lead to the pallets fouling the tops of the escape wheel

teeth and stopping the clock.

One last word about checking the drop of the escape wheel.

All escape wheel teeth must be checked with both entry and

exit pallets. Any variation in drop on one side of the wheel to a

position diametrically opposite will indicate the wheel being out

of round.

With the pallet arbor out of the movement we are now ready

to check the depth of mesh between the wheels and their

pinions.

Gearing is a subject about which complete books have been

written. It matters little whether we are interested in horology

or civil engineering, the theory of gearing is the same. Correct

PENDULUM CLOCKS

123

depth of mesh, one of the many aspects of gearing, plays a very

important part.

Figure 74, a, shows a wheel and pinion in correct mesh, b the

mesh is too deep, and c it is not deep enough.

Our main concern is to ensure that the wheels and pinions in

the clock movement do not suffer from too much depth of mesh

causing harshness in operation. This can be checked by the sense

Fig.

74. Gear wheel and pinion in mesh, (a) Correct, (b) Too deep,

of touch and is not as difficult as it may seem. After a little prac

tice you will soon be able to detect those gears whose mesh is

causing trouble.

We will commence with the third wheel and the escape wheel

pinion. Hold the escape wheel by the tip of the first finger of the

left hand and with the other hand rock the third wheel backward

and forward. Although the movement is small any stiffness

present can be felt.

Now press down lightly on the escape wheel arbor and slowly

rotate the third wheel. Apart from your finger pressure causing

slight resistance the action should be smooth and free from any

roughness.

If tightness is experienced in one position but not in another

the possible causes are :

(a) damaged teeth

(b) bent arbor

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WATCH AND CLOCK REPAIRS

If the teeth are broken or damaged beyond repair, new teeth

can be fitted as explained in Chapter 6. If a tooth is bent towards

an adjoining tooth it can be straightened by inserting the blade of

a pocket knife between the two teeth and levering the bent tooth

back into position. If the tooth is bruised it can be shaped with a

thin smooth file and finished with a very smooth emery stick.

A bent arbor can be straightened cold. Find out first of all

where the bend is by spinning the arbor and then place it on a

flat steel stake and tap it straight with the peening end of a

watchmaker's hammer.

If a wheel is out of round it can only be put right by renewing

the wheel or by recutting the teeth with a topping tool.

The equipment for topping wheels is unlikely to be in the

possession of a beginner, therefore this job will have to be sent

away to be done. The same comments apply to bushing worn

pivot holes. In both cases the repairer will require the front and

back plates, pillar nuts and the wheels and pinions that are

causing trouble.

To continue with the dismantling. Remove the pillar nuts and

carefully lift off the back plate. Take out the escape wheel,

third wheel, intermediate wheel and barrel. Hold the front plate

in the palm of the left hand with the cannon pinion uppermost.

Strike the centre arbor a sharp blow with a brass-faced hammer,

this will free the cannon pinion allowing the centre wheel to be

lifted out.

Now the barrel needs inspecting. Hold the square end of the

barrel arbor between the jaws of the brass-faced pliers and try

the end-shake. If there is none, place the barrel over a piece of

tubing and gently tap the arbor and try the end-shake again.

Repeat this until the end-shake is just perceptible.

It matters little which end of the arbor is tapped by the hammer

but remember that the end-shake has an influence over the

position of the barrel in the movement. Consideration should

be given therefore to other parts in the immediate vicinity of the

barrel in deciding which end of the arbor to hit.

Next, remove the barrel cover. This is done by levering it off

PENDULUM CLOCKS

125

with a screwdriver. Make sure it is marked before you take it off

so that there is no difficulty in putting it back into its correct

position.

Examine the condition of the spring. If it is clean and oiled

with no signs of corrosion don't disturb it. If the spring is broken,

or if it has to be removed for any other reason, then first remove

the arbor. To do this it will be necessary to turn it back a little

to unhook it from the eye of the spring.

Pull out the centre of the spring very carefully using the brass-

faced pliers. As soon as enough spring to hold has been pulled

out, the rest of the spring is allowed to uncoil itself from the

barrel. This operation must be done slowly and carefully.

If the spring were allowed to fly out, it is doubtful whether it

could be used again due to distortion.

This completes the dismantling of the movement.

It is a recognized fact that when two dissimilar metals move

against each other, such as a steel pivot revolving in a brass plate,

the harder of the two metals will show signs of wear first. This

is because fine particles of dust embed themselves in the soft

metal which then becomes an abrasive and cuts the hard metal.

It follows then that if pivot holes need bushing the pivots

themselves will most certainly need polishing, and further to

this, bushing cannot be carried out until the pivots have been

polished because the bushes have to be drilled to suit the pivots.

When the work of bushing the plates is sent away the repairer

will polish the pivots at the same time.

Having carried out all necessary repairs we are now ready to

proceed with the cleaning. We will need a tin measuring about

6 in. x 4 in. and about 1 1/2 in. deep to hold the cleaning fluid.

A 1/2-in. paint brush makes a good brush for washing the parts.

We will also require a tapered strip of chamois leather, a piece

of soft linen, some pith sticks, some pegwood and a folded

newspaper.

Hold the parts over the cleaning fluid and well brush them with

the wet brush, continually dipping the brush into the fluid. Make

sure all the wheel teeth and pinion leaves are well brushed. Treat

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WATCH AND CLOCK REPAIRS

all the parts alike, both brass and steel, and lay them on the

folded newspaper to drain. Use the linen cloth to dry them and

to polish the arbors. Lightly brush the parts with a medium watch

brush charged with chalk.

Shave a point on the end of a pegwood stick and peg out the

bearing holes. Larger holes can be cleaned out by the strip of

chamois leather. Clamp the wide end to the bench, thread the

narrow end through the hole and run the plate up and down the

strip.

Push the pith stick well on to each pivot and twist it round a

few times.

If the mainspring has been washed, dry it with the piece of

linen.

Finish off by brushing all the parts with a clean soft watch

brush.

Now wind the mainspring into the barrel. Start off by hooking

the outer end to the barrel wall and then slowly feed the spring in

and at the same time rotate the barrel. When the spring is in do

not attempt to push it down because of the possibility of

causing damage. Tap the barrel on the bench two or three times,

this will cause the spring to settle down to its correct position.

Now put the arbor in making sure that the eye of the spring is

properly hooked and wrapped around the arbor.

Oil the edges of the mainspring and snap the cover on. Oil the

arbor bearing hole in the cover and in the barrel. The movement

is now ready for assembly.

Lay the front plate over the cardboard box and place the

barrel and the wheels in position. Lower the back plate on to the

movement and with a pair of tweezers manipulate the pivots into

their respective holes

When all the pivots are in, the back plate should be resting on

the pillars. The pillar nuts can then be put on finger tight.

Make sure that all the arbors have end-shake and then tighten

down the back plate. Oil all the pivots in both plates.

Wind up the mainspring two or three clicks and check the

wheel train for freedom.

PENDULUM CLOCKS

127

Now fit the cannon pinion. Place the movement on a block of

hard wood front plate uppermost. Push the cannon pinion on to

the centre arbor and drive it home using a hollow punch and a

hammer. Check the centre arbor to make sure it has end-shake.

Again wind up the mainspring a few clicks to make certain

everything is free.

Refit the motion work, the pallets and the pallet cock. Apply

a spot of oil to each pallet and oil the pallet arbor pivots.

The movement is now ready to be fitted into its case. When this

has been done, hang the pendulum and the movement should

function.

Refit the hands making sure that when the hour hand points at

one of the numerals the minute hand is immediately over the

12.

CHAPTER SEVENTEEN

Striking clocks

THE striking mechanism of a clock can best be understood if it is

divided into two groups, the motive power and the release

mechanism.

A typical striking clock is shown in Plate VII. The striking

mechanism has been illustrated diagrammatically in figures

and 76.

It will be seen that when the strike mainspring is wound up,

energy is transmitted to the fly wheel. On the face of the fly wheel

is a pin. The upper end of the hour locking lever is bent so as to

arrest the pin and prevent movement of the wheel train.

The cannon pinion cam lifts the hour warning lever which in

turn raises the hour locking lever. As the hour locking lever

rises :

(a) the fly wheel pin is released, the fly wheel rotates half of a

turn and is again arrested by the hour warning lever.

This movement of the fly wheel is known as the 'warning'.

(b) The hour locking lever releases the gathering pallet which

rotates a short distance during the half turn of the fly wheel.

The hour warning lever continues to rise and releases the fly

wheel, the wheel train goes into operation and at the same time

the rack falls on to the snail. The edge of the snail is shaped into

twelve different steps, one for each hour. Whilst the wheels are

turning the star hits against the hammer lifting pin causing the

hammers to operate.

The gathering pallet revolves and the gathering pin engages the

rack teeth lifting the rack one tooth at a time.

During the period when the pin is moving round to engage

another tooth the rack is held by the hour locking lever engaging

with the teeth.

128

STRIKING CLOCKS

129

Finally the rack is gathered up which allows the hour locking

lever to fall and engage in the slot of the gathering pallet and

at the same time to arrest the fly wheel from further movement.

Now to proceed with the overhaul. Let both mainsprings down.

Remove the hammers, the back cock and the pallets.

Fig. 75. Strike wheel train.

Unpin and remove the rack, the hour and minute wheels, the

hour warning lever and the hour locking lever.

Inspect all pivot holes for wear and note those that require

bushing. Place the movement, back plate uppermost, over a

suitable box and unscrew and remove the back plate. Lift out the

STRIKING CLOCKS

131

barrels and mark one of them to ensure that they are refitted in

their original positions, then lift out the wheels.

Remove the cannon pinion as described in Chapter

16 and

treat the gathering pallet in the same way.

Carry out any necessary repairs and lay the parts out for

cleaning. If the parts are lacquered it is sufficient to wash them

and lightly chalk-brush them. Clean out the pivot holes.

We can now go ahead and assemble and oil the movement in

the usual way and therefore we must consider the strike mechan

ism once again.

When all the parts have been positioned on the front plate and

the back plate has been properly located, screw on two nuts

finger tight diagonally opposite each other.

Turn the wheel train in the normal direction of rotation until

the warning pin on the fly wheel is pressing against the hour

locking lever. In this position the hammer lifting pin should be

midway between two teeth of the star. If it is not, the back plate

must be lifted and the star wheel disengaged and moved round.

Replace the back plate and check again. When these two wheels

have been correctly positioned the back plate can be fully

tightened down with all four nuts.

With the hour locking lever in the downward position and

arresting the movement of the fly wheel, the gathering pallet is

fitted to its pivot so that the bent arm of the hour locking lever

is engaged in the notch of the gathering pallet.

Operate the strike mechanism and note the position on the

snail where the rack falls. If it does not drop on to the beginning

of a step then the hour wheel will have to be moved round.

Complete the assembly of the movement and fit the dial. Turn

the minute hand round until the strike operates. Fit the minute

hand so that it points to

12 and the hour hand to point to the

hour that had been struck.

Handbook of Watch and Clock Repairs (1972) - page 4