Handbook of Watch and Clock Repairs (1972)

WATCH AND CLOCK REPAIRS

Pressing the check-spring downward causes the castle wheel

to move down the winding stem, become disengaged from the

crown wheel, and mesh with the intermediate wheel which is in

mesh with the motion work.

In this position turning the winding stem will operate the

motion work and alter the hand setting.

A downward pressure on the winding button will overcome the

resistance offered by the check-spring and the pull-out piece and

the keyless work will be restored to its original position.

If the winding mechanism is stiff to operate, inspect the ratchet

wheel for freedom of movement. If the wheel is binding on the

plate either the shoulder of the barrel arbor is not projecting

clear of the plate or the arbor holes in the plate are worn.

In the first case, when screwing the ratchet wheel to the arbor

the wheel will be pulled down on to the plate. Inspect the plate

and the mainspring barrel for burrs around the arbor hole and

if necessary skim the surfaces in the turns. The alternative is to

fit a new arbor. If the arbor holes have become enlarged the arbor

will lean over causing the ratchet wheel to rub against the plate.

The remedy is to bush the arbor holes in the plate.

Slipping is caused by badly fitting wheels and badly meshed

wheel teeth. Turn the winding stem in the direction of winding

and observe the effect on the wheels. If the crown wheel slips on

the castle wheel, the cause will be worn teeth or worn winding

stem holes in the wheels or a worn winding stem. The wheels

should not be loose on the stem. Renewal of parts will effect a

cure.

If the up-and-down shake of the transmission wheel is excessive

the action of rotating the crown wheel will cause the transmission

wheel to be pushed away, until the shake is taken up, resulting in

insufficient depth of mesh and subsequent slip. The transmission

wheel shake must be reduced. First ensure that the transmission

wheel boss is screwed down tightly. If this is in order, then the

height of the wheel bearing must be reduced. Some transmission

wheels are made complete with a wheel bearing in the form of a

boss. The length of this boss can be reduced by stoning. If the

KEYLESS WORK

bearing forms part of the plate, then the height of the bearing

must be machined down in the turns.

Sometimes when pulling out the winding stem to alter the

setting of the hands, the stem comes away from the movement.

This is caused by the pin of the pull-out piece failing to retain the

stem in position. If the pin of the pull-out piece, or the groove in

Fig. 30. Pull-out piece.

the winding stem are worn, replacement parts will be required.

If the winding stem becomes loose in the plate caused by the

plate being worn, the excessive side-shake of the stem will result

in partial disengagement of the pin of the pull-out piece in the

winding stem groove. In such cases the plate must be bushed or

an oversized winding stem fitted.

Another cause of the winding stem coming away is the pull-out

piece becoming loose on the pull-out piece screw. When correctly

fitted the screw should be tight in the pull-out piece but free to

move in the plate so that when the winding stem is pulled out or

pushed in, the pull-out piece and its screw rotate as one.

CHAPTER NINE

Barrels, mainsprings and fusee

chains

BECAUSE the mainspring and barrel assembly operates very

slowly, it must be free-moving and smooth-acting. There must

be no possibility of rubbing or tendency to stick.

If rubbing has taken place, an inspection of the barrel and the

watch frame quite often reveals the tell-tale marks.

Let us first make sure that the barrel rotates freely and squarely

about the arbor.

Barrels. Place the arbor in the barrel and snap the cover on.

The arbor should have slight end-shake.

Now hold the end of the arbor in the jaws of a pin-vice with

the cover uppermost

(Fig.

31). The arbor should be held at an

angle so that the gear teeth on one side are just clear of the jaws

Fig. 31. Checking barrel for running true.

WATCH AND CLOCK REPAIRS

of the pin-vice. By rotating the barrel it will be seen whether the

barrel is running true.

If the barrel wobbles, then the arbor hole in the barrel or the

cover needs bushing. Enlarging the hole to take the bush is best

done on a lathe, and fitting the bush is carried out with the aid of

a watchmaker's punch and stake. If you do not possess this

equipment then the work will have to be sent away.

With the barrel free and square about the arbor, fit the barrel

between the plates. There should be no end movement of the

arbor between the plates. All that is required is freedom of the

arbor to turn when the spring is being wound.

A loose barrel cover can be tightened by placing it on a flat

steel stake and gently tapping all round the edge with the flat of a

hammer. The hammer face must meet squarely with the cover if

marks and bruises are to be avoided. Use a stroking action by

bringing the hammer downward and outward. After each tap,

rotate the cover a little until the place of starting has been

reached. This will spread the metal until a good fit is obtained.

To fit a new mainspring hook to a barrel, first drill a hole in

the side of the barrel at a slight angle pointing away from the

direction of pull of the mainspring. The hole is then threaded

slightly undersize.

Taper a piece of steel wire by filing and cut a thread with a

screw plate, holding the wire in a pin-vice. Remove the pin-vice,

cut the wire close to the screw plate and shape the protruding

piece of wire into a hook by filing.

Unscrew the threaded wire from the screw plate and insert the

small diameter end of the wire into the hole in the barrel entering

from the inside.

The protruding wire on the outside is now held by the pin-vice

and the wire is screwed into position by unscrewing from the

outside.

The hook should project into the barrel a distance no greater

than the thickness of a piece of the mainspring.

When in place remove the pin-vice, cut off the wire on the out

side, file down close to the barrel and finish with an oilstone slip.

BARRELS, MAINSPRINGS AND FUSEE CHAINS

7 3

Similarly, new hooks can be fitted to barrel arbors. A hole is

drilled in the arbor and a steel pin is driven in tight. The new

pin is shaped by filing and finished with an oilstone slip.

Occasionally a barrel tooth becomes bent as the result of a

mainspring breaking. The bent tooth can often be straightened

by inserting the blade of a knife at the side of the bent tooth and

gently levering back into position.

Mainsprings. If a mainspring breaks close to the outer end, it

can be repaired. A break anywhere else necessitates the fitting of

a new spring.

When a replacement mainspring is needed, it is better to

purchase a spring from the manufacturer of the watch. The

length of the spring will be correct and it will be hooked and

ready for fitting into the barrel.

The alternative is to purchase a suitable spring, cut it to

length and shape the outer end. Assuming the spring to be

replaced is the correct gauge, width and length, then the purchase

of a replacement should present no problems.

However, it is as well to know a little about the design of a

mainspring and a barrel assembly in case the spring to be replaced

does not conform to the specification laid down by the watch

manufacturer.

Two identical springs, but of different lengths will, if bent to

the same curve, apply different forces. If one spring is half the

length of the other it will apply twice the force.

A long spring will take up more space in the barrel and it

therefore cannot be wound as many turns as a shorter spring.

This will result in the watch unwinding itself too quickly.

A spring that is too short will when wound exert too great a

force and cause a high rate of wear in the wheel train and

escapement.

A simple way to establish how long the spring should be is

illustrated in figure

32. Place the barrel on a sheet of metal and

with a sharp pointed tool scribe a circle using the barrel hole as

a guide. Mark the centre of the circle. Take a pair of dividers,

place the point of one leg on the centre of the circle and adjust

WATCH AND CLOCK REPAIRS

the dividers until the other leg just touches the base of the barrel

wall (Fig.

32, left). Measure this distance and readjust the dividers

to two-thirds of the original distance. With the barrel still in

position on the sheet of metal lightly scribe a circle on the barrel

inner face

(Fig.

32, centre).

Fig.

32. Marking barrel to show correct mainspring length. A. Space

for unwound spring. B. Space for wound spring. C. 1/2 diameter or arbor.

Fig. 33. Methods of hooking outer ends of mainsprings.

When the new spring is in the barrel, it should take up the space

between the barrel wall and the scribed line.

The force of a spring also varies with the thickness and the

height. If it is twice the thickness the force is increased eight times.

A spring which is twice the height will have twice the force.

If the spring is too thick it will not be possible to obtain the

required number of turns. If the height is too great the spring

will foul the barrel and the cover, and if the height is insufficient

then the spring will buckle and once again foul the barrel and

the cover.

BARRELS, MAINSPRINGS AND FUSEE CHAINS

7 5

If the inner face of the barrel cover is recessed, the height of the

mainspring should be level with the shoulder in the barrel wall

upon which the cover rests. If the cover is not recessed then the

height of the spring should be just below the shoulder.

There are various methods of hooking the outer ends of main

springs to barrels and figure

33 illustrates those in common use.

Fig. 34. Fitting a riveted hook.

To fit a riveted hook, soften the extreme end of the spring in a

spirit flame by heating to a black heat. Hammer the end of the

spring flat and drill a small hole to take a rivet. Select a short

piece of spring the same width and thickness as the mainspring

and drill a hole in one end using the same drill as before. File the

other end square with the sides. Hold the two pieces of spring

together and broach out both holes as one. Remove the burrs

and polish both pieces with fine grade emery paper working the

grain down the length of the spring.

Cut off a short length of steel wire, hold it in the pin-vice and

file it to fit the hole. Push the wire into the hole and grip the wire

in a vice

(Fig.

34, a).

Cut the wire close to the face of the spring and rivet over with

a round-face hammer.

Remove the pin from the vice and cut off the other end as

before. Place the riveted head in a riveting stake or dolly and

complete the operation by riveting the other end. File the end as

shown in figure

34, b, and remove the burrs. Polish with a fine

grade emery paper.

WATCH AND CLOCK REPAIRS

A very narrow spring such as would be found in a flat watch

would be weakened by drilling a hole. An alternative method of

hooking such a spring is shown in figure 35.

Break off the end of the spring to within two or three inches

of the required length. Heat the spring, at about the point where

the end is to be, in a spirit flame and bend upward and over using

Fig. 35. Making a loose-piece.

flat-nose pliers. The pliers should be pre-heated to prevent the

heat of the spring being absorbed by the cool pliers. Keep the

spring in the flame whilst bending is taking place and do not force

the spring. Once the correct temperature has been reached,

bending will be found easy. Take the piece of broken spring and

place a short length in the loop of the mainspring. Reheat and

slowly close the mainspring loop over the short length of spring

and gently but firmly squeeze in to shape. Withdraw the short

length of spring.

Cut a groove across the face of the short arm of the loop with

a file, bend back and snap off. File the end square and remove

the burrs.

BARRELS, MAINSPRINGS AND FUSEE CHAINS

7 7

From the short length of spring cut a piece long enough to form

the hook, file the ends square and remove the burrs.

Polish both springs with fine grade emery paper and push the

short length of spring into the hooked end of the mainspring.

To make an eye, soften the extreme end of the spring by heating

in the spirit flame. Drill a hole in the end and then enlarge it with

a broach to fit loosely over the barrel hook. The last few cuts of

the broach should be made at an angle to correspond with the

angle of the barrel hook. The burrs produced by the broach must

now be removed.

The end of the spring has to be curved to the same radius as

that of the barrel. This will ensure that the spring is correctly

hooked.

Place the spring, outer face downward, on a block of lead, and

tap the inner face with a watchmaker's hammer. This will

decrease the radius of the curve.

Finish off by polishing the end of the spring with fine grade

emery paper.

The brace method of hooking a mainspring is used in almost all

American watches. The brace consists of a short length of spring,

the same width as the mainspring but slightly thicker. It carries

two pivots that project into a hole in the barrel base and another

hole in the barrel cover.

The brace is secured to the end of the mainspring by a rivet. It is

better to purchase a new brace rather than make one. Replace

ment braces are supplied drilled and complete with a rivet. When

the spring is fully wound, the brace swinging on its pivots, moves

across the barrel.

Make sure that the pivots do not project beyond the barrel or

the barrel cover. The width of the brace should not be greater

than the width of the mainspring because fouling may occur

between the edges of the brace and the faces of the barrel and the

barrel cover during unwinding of the spring.

Fusee chains. Hold the broken end of the chain and insert a

thin blade beneath the link plate. Gently lever the plate away

from the rivet until the outline of the rivet can be seen.

WATCH AND CLOCK REPAIRS

Place the chain on a graduated stake and with a blunted sewing

needle held in a pin-vice push the rivet out. It may be necessary

to tap the pin-vice with a hammer.

Treat the other broken end in the same way.

Select a sewing needle from which to make the new rivet and

heat it to a blue. File the needle almost to size with a very fine

file and finish off with an oilstone slip.

Fit the ends of the chain into each other, making sure that

the two end hooks are on the same side, and insert the needle

into the rivet holes. Replace the chain over the stake and gently

tap the needle home.

Cut both ends of the needle off close to the side plates and file

flush. Lay the chain on its side on a metal stake and gently rivet

each end of the needle with a round-face hammer.

In carrying out this repair, frequent checks are necessary to

ensure that the centre plate on one end of the chain is free to

swing between the side plates of the other end of the chain.

CHAPTER TEN

Escapements

THE two most popular forms of escapement today are the lever

and the pin-pallet.

Whereas the lever has great precision and can be relied upon

to function accurately over long periods, the pin-pallet is a cheap

and robust product that lends itself well to mass production.

Even so, the good service obtained from a pin-pallet escarpment

cannot be ignored.

The lever (Fig.

36). To enable faults in a lever escapement to be

identified a working knowledge of its function is necessary.

Fig. 36. Lever escapement.

WATCH AND CLOCK REPAIRS

We have seen how power from the mainspring, passing through

the train of wheels reaches the escape wheel. We have learned

that it is the pallets of the lever, interrupting the teeth of the

escape wheel, that prevent the wheel train from rotating at a high

speed during the unwinding of the mainspring.

The escapement consists of the escape wheel, the lever, two

banking pins and the balance. Figure

37 illustrates the lever in

detail and figure 38 shows the roller which is fitted to the balance

staff.

In figure 39 we can see the stages through which the escapement

passes in order to release the escape wheel one tooth at a time.

Fig. 37. The lever.

Fig. 38. The roller.

Fig.

39. The lever escapement—sequence of movements.

ESCAPEMENTS

The escape wheel tooth hits the locking face of the entry pallet

stone and the escape wheel is brought to rest

(Fig.

39, a). The

power in the escape wheel causes the tooth to press against the

locking face of the entry pallet stone pulling the stone down. This

downward movement is called the draw (Fig. 40). The draw pulls

the lever hard against the banking pin and holds it there. This last

movement of the lever is known as the run to banking. If the

watch received a shock sufficient to overcome the draw, the lever

Fig. 40. The draw.

would no longer be held against the banking pin and would be

free to pass across to the other banking pin. This would cause the

watch to stop. To prevent this happening, a guard pin is fitted at

the end of the lever which, under conditions described above,

would come in contact with the roller and further movement of

the lever would be checked.

To allow the lever to pass under normal conditions, a groove is

cut in the edge of the roller level with the ruby pin.

The balance completes its swing, stops and reverses under the

tension of the balance spring. The ruby pin enters the notch of

the lever and moves the lever away from the banking pin. This

causes the entry pallet stone to be pulled away from the escape

wheel thereby releasing the tooth

(Fig.

39, b).

The ruby pin continues to move round pushing the lever

farther over and the exit pallet stone moves in towards the escape

WATCH AND CLOCK REPAIRS

wheel. The adjacent tooth strikes the exit pallet stone on its

locking face and the lever is held firmly against the other banking

pin (Fig.

39, c).

The balance completes its swing and reverses direction. As the

ruby pin re-enters the notch in the lever, the lever is moved away

from the banking pin, pulling the exit pallet stone away from the

escape wheel tooth. The escape wheel tooth, being freed from the

locking face, now presses against the impulse face of the exit

pallet stone. It is this impulse, transmitted through the lever, that

gives a further swing to the balance

(Fig.

39, d). While the exit

pallet stone is being pushed away, the entry pallet stone is moving

in to stop the next tooth and the cycle of operations repeats itself.

For such small surfaces to perform these operations efficiently

over long periods calls for a high standard of workmanship.

Slight damage or wear can destroy the timing of the escapement

or cause the movement to stop altogether. Let us then examine the

escapement to detect any faults that may be present. Check the

balance staff end-shake by holding the balance arm in a pair of

tweezers and moving the balance wheel up and down. To know

when the end-shake is excessive calls for experience, but if you

remember that providing the end-shake is just sufficient to retain

a film of oil, then any excess is undesirable.

Another test for end-shake is to wind the mainspring a few

turns and set the movement in motion. Apply light pressure to

the balance staff end-stone with a piece of pegwood and if this

stops the balance, the end-shake is insufficient. Hold the watch

movement between the thumb and forefinger of one hand and

place the tip of the forefinger of the other hand lightly on the

rim of the balance wheel. Very little movement of the finger is

required to rock the balance.

Examine with the aid of an eye-glass the side-shake of the top

and bottom pivots.

It is almost certain that wear will be the cause of excessive shake

and the remedy is to fit a new staff and to renew the pivot

bearings.

Now remove the balance cock and lift out the balance. In this

ESCAPEMENTS

condition the pallet staff can be checked for shake, the same

remarks applying here as for the balance.

We now turn our attention to the locking of the escape wheel

teeth by the pallet stones. First, let the mainspring down. Now

fold a small piece of tissue paper and place it under the guard pin

of the lever ; this will hold the lever in any position we like to put it.

Take a pointed pegwood stick and position the escape wheel

and lever so as to bring a tooth in contact with the impulse face

of the entry pallet. Very slowly move the escape wheel forward

until the tooth is just clear of the pallet. In this position the exit

pallet should be locking a tooth against its locking face.

Now raise the exit pallet stone slightly and move the escape

wheel forward so that the tooth comes on to the impulse face.

Make sure that in this position the entry pallet stone moves in

to lock the next tooth. This test must be repeated for all fifteen

teeth. If the entry stone mislocks on any tooth the cause must be

investigated.

Examine the tips of the escape wheel teeth. If they are showing

obvious signs of wear, the escape wheel must be renewed.

Examine the escape wheel pivot bearings and the pallet pivot

bearings for wear. Any of these faults will cause the escape wheel

and the pallets to function at too great a distance from each other.

If no fault is found here, then adjustment must be made by

altering the positions of the pallet stones.

The stones are held in the pallets by shellac. If the shellac is

warmed, the stones can be moved and held in their new positions

until the shellac has set. If the entry stone is pulled out, the exit

stone must be moved in by the same amount, otherwise the exit

stone will be too deep when locking.

Remove the lever from the watch and examine the impulse

faces of the pallet stones. If they are pitted they must be replaced

by new stones.

Place the lever on a blueing pan together with a small chip of

shellac. Heat the pan in a spirit flame until the chip of shellac

is softened. This will be the correct temperature at which to

move the stones.

WATCH AND CLOCK REPAIRS

Leave the lever on the pan and, holding the lever in a pair of

tweezers, adjust the stone with a second pair of tweezers (Fig. 41).

In many watches the undersurface of the pallets carries a film

of shellac. If this film is disturbed when adjustments are made, be

sure to make it good before replacing the lever in the movement.

Fig. 41. Adjusting pallet stone.

If new pallet stones have to be fitted, the lever must be sent to

the supplier with the order.

Place the lever on the blueing pan and hold it over the spirit

flame. Insert the new stones the right way up. Put a small chip of

shellac on the back of each stone and let it run over the face.

Move the stone in and out of the pallet allowing the shellac to

run in the join. If most of the shellac runs into the join, add

another small piece to run over the face to restore the film. Fit

the lever into the movement and test the locking. When the

locking is correct, lift out the lever and remove any surplus

shellac but leave the film intact.

The next test is to see whether the lever has the correct run to

banking. It is this free movement of the lever that makes draw

possible.

A few turns are given to wind the mainspring. The lever is

wedged with tissue paper as before and very slowly moved to one

side until a tooth of the escape wheel just touches the locking face

ESCAPEMENTS

of one of the pallet stones. At this point the distance between the

lever and the banking pin should be about the thickness of a thin

razor blade. Both sides of the lever should have the same distance.

If the run to bank is too great, the distance between the banking

must be reduced. If banking pins are employed, the pins are bent

towards each other and then given a second bend to bring them

parallel

(Fig.

42). This is important, otherwise if the pins were

left tapering towards each other the run to banking would be

further reduced when the movement was turned over.

Some American watches use pins placed eccentrically in screws.

All that is needed here is that the screws are turned until the pins

are in the correct position in relation to the lever. The problem of

maintaining the pins in a vertical attitude does not arise.

Solid bankings are employed in some movements and with

these a little extra work is required to make adjustments.

To decrease the gap a slot must be cut in each banking with a

very thin file such as one used for deepening the screwdriver slots

in screw heads (Fig. 43, a). The two pillars thus formed are bent

inward and their inner faces filed vertically.

Increasing the gap of solid bankings necessitates the removal

of a thin shaving of metal from the inner face using the blade of

a sharp screwdriver (Fig. 43, b).

Fig. 42. Adjusting banking pins.

Now let us look at the draw to see that we have the right

amount. Remove the tissue paper wedge from the lever, and slowly

move the lever to one side until the locking face of one of the

pallets is just clear of the escape wheel tooth.

WATCH AND CLOCK REPAIRS

At this point release the lever which should jump across to the

banking. Both pallets must be tested in the same way.

If the lever is sluggish when moving indicating insufficient

draw, the attitudes of the stones in the pallets must be altered.

Fig. 43. Solid bankings.

Let the mainspring down and lift the lever from the movement.

Place the lever on the blueing pan with the shellac side uppermost

together with a chipping of shellac. Hold the pan in a spirit

flame and heat until the piece of shellac becomes soft. Place the

pan on the bench and hold the lever with tweezers. Push the

pallet stone to one side in the direction required and hold it there

until cooled.

ESCAPEMENTS

Replace the lever in the movement, wind the mainspring a few

turns and test again. If the draw is still insufficient another pallet

stone, slightly narrower must be fitted.

Sometimes a lever movement stops each time it is shaken or

receives a slight shock. If examination reveals the lever at rest

on the wrong side of the roller, the fault is a short guard pin.

Shaking the movement causes the lever to pass the roller in the

wrong direction and when the balance reverses its swing the ruby

pin comes to rest on the edge of the lever horn instead of entering

the notch.

The remedy is to lengthen the pin and this can be done either

by bending it forward or by fitting a new one.

Fig. 44. Pin pallet

The original pin is pushed out in the direction of the pallets. A

new brass pin with a long taper is made by the pin-filing method.

Smooth the pin with the finest grade emery stick and finish with

the flat burnisher.

Insert the new pin from the pallet end of the lever. Cut off the

surplus length at the back with the nippers, and file the operating

end of the pin to the required length. Finish off the end with an

Arkansas stone.

Pin pallet (Fig.

44). In this form of escapement the pallets are

fitted with pins instead of stones, and the impulse faces are cut

on the ends of the escape wheel teeth. The draw of the escape

wheel teeth on the pallet pins causes the pins to bank against the

bottom of the teeth, it is therefore quite usual for some manu

facturers not to fit banking pins with this type of escapement.

WATCH AND CLOCK REPAIRS

Mislocking is a common cause of failure in this type of escape

ment but it is quite easy to test and the remedy is simple.

Give a few turns to the mainspring. With a pointed pegwood

stick rotate the balance very slowly until an escape wheel tooth is

released. In this position make sure that the other pallet pin has

locked another tooth. For the locking to be correct the locking

face of the tooth must be above the centre of the pallet pin

(Fig.

45, a). Incorrect locking is illustrated in figure 45, b and c.

Fig. 45. Pin pallet locking, (a) Correct. The escape wheel tooth strikes

the pallet pin above the centre, (b) Incorrect. The escape wheel tooth

strikes the pallet pin below the centre,

struck by the impulse face of the escape wheel tooth,

(d) Draw. The

pallet pin is pulled down to the base of the tooth.

Fig. 46. Direction of bending the tongue to overcome mislocking.

ESCAPEMENTS

Now carefully rotate the balance a little farther in the same

direction and watch the draw. The tooth should pull the pallet

pin down to the base of the tooth (Fig. 45, d).

Repeat this test on both pallet pins and for all fifteen teeth of

the escape wheel.

If mislocking occurs anywhere the pallets must be brought

closer to the escape wheel. This is done by slightly bending the

Fig. 47. Lengthening the guard pin.

tongue that carries the pallet pivot bearing hole. The tongue is

held by the long nose pliers and bent sideways towards the

escape wheel (Fig. 46).

After bending repeat the above tests.

To test the draw of the escape wheel teeth rotate the balance

until the impulse pin is clear of the lever. Hold the balance in this

position and move the lever against the roller. If the escapement

has sufficient draw, the lever will jump back into its original

position when released. This test must be carried out on both

pallet pins and with all fifteen teeth of the escape wheel. If the

draw is weak the remedy is a replacement wheel.

The amount of shake on the roller needs to be checked. By

moving the balance round so that the impulse pin on the roller

WATCH AND CLOCK REPAIRS

is clear of the notch in the lever, the shake can be tried. Now

swing the balance in the opposite direction and try the shake

again. Both should be equal.

If it is found that there is more shake on one side, the lever must

Fig. 48. Closing the pallet arms.

be removed and bent sideways in the direction of reducing the

greater shake. The lever is placed on its side on a stake held in

the vice. A chisel with the cutting edge rounded off is placed on

the upper side of the lever and a light tap given with a hammer.

This will cause the lever to bend upward.

Sometimes it is found that both sides have no shake at all, in

this case the length of the guard pin must be reduced.

If the shake is excessive on both sides the guard pin must be

increased in length. This can usually be done by first straightening

the pin and then re-bending it as close to the lever as possible

(Fig.

47). In some watches the guard pin is cut from the solid in

which case the metal has to be stretched by light tapping with a

ESCAPEMENTS

hammer, with the guard pin resting on a metal strip held in the

vice.

After any adjustment replace the lever, re-check the shake, and

make sure the guard pin engages on the roller and that the impulse

pin engages freely in the lever notch.

The distance an escape wheel tooth moves before being stopped

by a pallet pin is known as the drop. This distance must be the

same on both pins.

Move the balance round slowly as before and note the amount

of drop on the pin. Reverse the direction of the balance and note

the amount of drop on the other pin.

If one side is greater than the other, then the pallet arm on the

greater side must be bent toward the other arm.

Fig. 49. Closing the pallet arms.

WATCH AND CLOCK REPAIRS

Remove the lever and bend the arm sideways using the brass

faced pliers or a made-up tool as shown in figure 48. If the pallets

have no arms, a slot must be cut in the pallet and then carefully

closed by tapping with a hammer (Fig.

49).

If the pallet pins are badly worn they must be renewed before

making adjustments to the escapement.

Place the lever over a graduated stake and with a length of

blunted sewing needle gently hammer the old pins out.

The replacement pins can be made from a sewing needle. Select

one that is slightly oversize, cut two pieces to the length required

and carefully hammer them into the pallets over the stake

(Fig.

50).

Fig. 50. Fitting replacement pin.

CHAPTER ELEVEN

Balances

A W A T C H balance consists of a hairspring and collet assembly,

a balance wheel and a roller, all of which are fitted to a common

staff.

If a balance is subjected to a rise in temperature, the wheel

diameter will be increased causing the bulk of the weight to

move away from the centre. This will have the effect of slowing

down the movement. A drop in temperature will have the reverse

effect and the movement will gain.

Fig. 51. Compensated balance.

WATCH AND CLOCK REPAIRS

To overcome this, the more expensive watches are fitted with

a means of compensating for variations in temperature.

Compensated balance (Fig.

51). The wheel is made of steel but

the outer edge of the rim is faced with brass. This is known as

bi-metallic.

Fig. 52. The hairspring.

The rate of expansion of brass is greater than that of steel

when both are subjected to identical conditions. If a straight

bi-metallic strip was heated, the brass would increase its length

more than would the steel and the bi-metallic strip would curve,

the brass being on the outside.

This is the principle upon which temperature compensated

balances are made. With a rise in temperature the wheel expands,

which would normally slow down the rate of swing. In expanding,

the two halves of the rim curve inward bringing the bulk of the

weight closer to the centre.

If the effect of inward curvature balances out the effect of

expansion, the watch will maintain a constant speed.

BALANCES

Provision is made for fine adjustment by fitting screws into

the wheel rim.

Usually it is not necessary to make any adjustment here after

the screws have been set by the manufacturer.

In addition to the compensating screws, there are four quarter

screws placed equidistant from each other. These screws have

longer threads than the compensating screws and are used to

change the speed of the balance.

Unscrewing an opposite pair will slow down the movement

and screwing them in will increase the speed. This is because the

distance from the centre to the bulk of the weight is being altered.

Hairspring

(Fig.

52). The hairspring is made from steel wire

rolled flat and thin and coiled into a spiral. The strength of the

spring will vary according to the width and thickness of the

material. The inner end is pinned to a collet and the outer end

is pinned to a stud.

Most collets are made of brass and shaped in the form of a

split collar or bush. The centre hole is made to fit tightly over the

balance staff. One side of the collet is split to provide springiness.

Some of the best English lever watches have steel collets, they

Fig. 53. Steel collet.

are shaped with two flats, one on each side, and are not split

(Fig.

53). The clearance between the flats and the inner coil of the

spring enables truing of the hairspring to be made more easily.

There are different types of studs in use. One of the most

common types in use is a brass block with a pin machined on one

WATCH AND CLOCK REPAIRS

face, the pin being either a push fit in the balance cock or held in

position by a screw entering the balance cock at the side.

The balance staff moves in two jewel bearings, one in the bottom

plate and the other in the balance cock.

A regulator or index is fitted to the balance cock and is free

to move within a restricted arc. The hairspring passes between

two index pins in the index.

When the index is moved from one position to another the

effective length of the hairspring is altered causing the movement

to gain or lose according to the direction in which the index was

moved.

Fitting a flat hairspring. The original hairspring with its collet

must first be removed. Hold the balance between finger and

thumb at each end of the balance arm; holding it this way will

prevent distortion. Push the blade of a steel oiler into the slot of

the collet, this will spring the collet and reduce the grip on the

balance staff. Turn and lift the oiler in one movement and the

collet will be freed from the staff.

If the slot in the collet is too wide for the oiler, a thin knife

blade inserted beneath the collet will lift it from the staff.

It is not advisable to hold a stock of hairsprings because of the

very wide range in use in present-day watches.

Springs are made in varying strengths in different sizes and to

enable your supplier to select the correct spring it will be necessary

to send the count (number of vibrations in one hour), the balance

and the balance cock with your order. We have seen how the

count is calculated in Chapter 6.

On receipt of the spring we must ensure the strength is correct

and to do this the spring is temporarily fitted to the balance and

a count is made.

First, lay the spring on the underside of the balance cock

centrally over the pivot hole. The diameter of the spring must be

sufficient to allow the outer coil to pass through the index pins

of the balance cock and then be pinned in the stud. If the spring is

too large make a note of the approximate position that will be

pinned to the stud.

BALANCES

Lower the spring over the balance staff and hold it temporarily

in position by fitting the collet above it. Grip the hairspring in

tweezers at the position where the spring passes through the index

pins. Lift the balance wheel and spring so that the wheel hangs

under its own weight. Lower the balance until the staff just

Fig.

54. Method of counting vibrations.

touches the glass of a watch that is fitted with a seconds hand.

With the finger and thumb of the other hand rotate the balance

wheel about half a turn and then release it. Count the number of

double vibrations made in one minute

(Fig.

54). If the correct

spring has been supplied the count will be the same as was calcu

lated for the gear train. Remove the collet and then the spring

from the balance staff.

We are now ready to fit the spring to the collet, but first we will

need a tool to enable us to break off the surplus length of spring.

Drive the point of a sewing needle into a slender wooden

WATCH AND CLOCK REPAIRS

handle and stone away the top of the needle eye leaving a fork

end (Fig. 55).

Lay the collet on a sheet of stout white paper and place the

spring centrally over the collet. Hold the spring in a pair of

tweezers about a quarter of a turn from the centre. Place the

bending tool over the spring and close to the tweezers. Bend the

short length of spring backward and forward a few times and it

will break away. Repeat this process until sufficient length of

spring has been removed from the centre to allow it to pass

freely over the collet.

Bend the end of the spring inward using two pairs of tweezers

and then straighten it. The length of the spring to be bent inward

is a little more than the length of the pin hole in the collet.

The pin that is going to secure the spring to the collet must now

be made. Take a piece of brass wire, file a taper to fit the collet

and burnish it with the flat burnisher. File a flat down one side

of the pin a depth of approximately one-third of the diameter

of the pin. Polish the flat with the finest emery stick.

Straighten one of the pieces of broken spring and insert it in

the collet. Push the taper pin tightly into the collet with the flat

side against the piece of spring and mark the pin at each end of

the pin hole with a knife. Remove the pin and cut off the piece

between the two knife marks. Polish the ends to remove all burrs.

Fig.

55. Tool for breaking off end of hairspring.

Refit the pin and the piece of spring to ensure that the pin finishes

a little more than half-way through the hole.

A collet holder must now be made. A piece of steel rod is filed

at one end to produce a long taper. Polish the taper with a fine

emery stick and finish with a burnisher.

Lower the collet on to the taper until it just grips. Make sure

it is square with the holder and not at an angle.

Handbook of Watch and Clock Repairs (1972) - page 3