The Clock Repairer's Handbook

Introduction

This book has been written with the intention that it should prove useful to both the absolute beginner and the more experienced clock repairer, without baffling the former or annoying the latter. I hope that the intention is realised.

Please read Chapter 1 first. If, like me, you are in the habit of skipping through a book looking for particularly interesting parts, restrain yourself. This first chapter gives an overall coverage of repairs and it tries to persuade you to tackle them systematically. Thereafter the book deals with the subject area by area and you are invited to jump directly to whatever covers the problem of the moment, but a disciplined approach to diagnosing faults is well worth cultivating. Whether you pursue the craft for gain or for pleasure, I believe that you will profit from avoiding the ‘dive straight in’ method, tempting though it is.

For those of you who are new to clockmaking, let me assure you that it is not necessary to invest in a workshop and an expensive collection of tools, good work can be done at the kitchen table with simple, good household tools — just take care and apply a lot of consideration to what is probably the oldest and most loved domestic machine in our homes.

Enjoy yourself!

Laurie Penman

Totnes, Devon

1

Finding Clock Faults

This first chapter is intended as a quick reference aid for solving clock repairing problems. Most of the solutions are not set out in great detail — the other chapters do that. Here I simply try to help you to locate the problem and to give a little help in making what may be perfectly obvious corrections. On occasion you will find that there are two solutions proposed, one in this chapter and another in the specialised chapter. There is frequently more than one good solution to a problem and this is a convenient method of showing them.

FAULTS COMMON TO MOST CLOCKS

Diagnosis

The first necessity is diagnosis. Often the locality of the fault is clear: a hand is catching on the dial, or a gear is badly damaged, for instance. But this is not always so and it is worthwhile adopting a simple pattern of testing that will assist in finding faults. Of course the clock may be so dirty that it does not have a hope of going until the dirt and old oil has been removed. In this event it is useful to take the movement out of its case and carry out a crude (but safe) ‘dunking’ in paraffin (kerosene) that contains about 5 per cent of good lubricating oil. After draining it should be possible to proceed with the following tests. Do remember that this is not a proper cleaning; it is simply a means of loosening-up the clock for testing.

Consider the clock as a series of systems connected together and test each system in succession. The first thing to test is the power. Is the clock wound up? Is the mains or battery supply making a proper connection? Then test as follows:

Open any part of the case that can, conceivably, come into contact with any part of the movement (including weights and pendulum).

Check to see if the clock will run now. This check follows each test.

Remove the hands or disconnect the display.

Remove the dial.

Remove the pendulum. Many clocks will need the crutch adjusted to put it ‘in beat’. Recoil escapements will run without anything further being done, but dead-beat escapements need a little weight added to the crutch so that it will unlock the escape wheel. Blu-tack or a similar stick-on product performs this service very well.

Remove the hour and minute pipes.

If the clock runs after carrying out any one of these tests, the fault lies in the part that has just been removed. In a movement that has been working for years, you will most probably have to carry on and strip and clean the complete movement in a proper fashion (see Chapter 2). The tests should ensure that you do not waste time in correcting parts that look suspicious but in fact are working satisfactorily, or in taking a movement apart when the fault is caused by some exterior factor. After repairing the movement there is sometimes a disappointing lack of response from the mechanism. Repeat this series of tests — do not assume that there is an undiscovered fault in the movement until you have proved it, for life is too short to strip clock movements unnecessarily. Besides it is not fair on the clock. It is always best not to strip a clock if there is no sign of dirt, stiff oil or obvious wear or corrosion. The wheels and pinions will have worn together over the years and if the wheel count of teeth is precisely divisible by the pinion count, each leaf will have its own set of wheel teeth that it complements. Changing the set of wheel teeth that each leaf meshes with, will leave a meshing of wheel and pinion that is not as good as existed before dismantling. (This is the main reason for filing or stoning out any ‘pocketing’ of the pinion leaves.) A movement does not need dismantling if it operates and:

It is clean, with no stiff oil or ‘varnish’.

It has slight pocketing but no evidence of black or metallic particles.

It has sloppy holes that are round, with no evident wear of the pivots.

In those few movements that hold the escapement pallet arbor between the clock plates, if:

the escape pallet arbor does not lift as the wheel rotates.

In longcase or grandfather clocks, if they:

stop at the same day each week (eight-day clocks).

stop at the same hour each day (thirty-hour clocks).

These last two faults typify those that disappear when the case door is left open, and are a result of sympathetic vibration.

OPENING THE CASE

This first test should eliminate stoppages due to the hands fouling the glass and, in weight-driven pendulum clocks, any impedence to the steady fall of the weights. It will also allow you to see if the pendulum and weights touch at some part of the clock’s going, or if there is any sympathetic vibration. All these will be fairly obvious, but sympathetic vibration is unusual and, when it occurs, quite difficult to spot. At a time when the weight cords have unwound to approximately the same length as the pendulum, there is a tendency for the weight or weights to oscillate in harmony with the pendulum bob. This may be sufficient to rock the seat board or case if they are imperfectly supported, or cause interference between pendulum, weights or case. In any event the clock will show the habit of stopping, for instance, every fourth day, or always at three o’clock in the morning. The cure for sympathetic vibration is to improve the support of seat board and case — in extreme cases associated with very heavy clock weights fasten the case to the wall — and to ensure that there is plenty of space between the weights and the bob at the time when they are almost level. Clocks often have two suspension positions (Fig 1), and moving the pendulum from one to the other of these will change the position of the bob in relation to the weights and the case. The position of the cord anchorage on the seat board will also affect the position of the weights in relation to the door or pendulum bob as the cord unwinds and the weight moves over in the direction of this anchorage.

I have mentioned sympathetic vibration and the need for a proper support for seat board and case without pointing out that improper support is a frequent fault in longcase clocks. Do not stand these clocks directly on thick carpet, or floorboards that cross doorways. If the clock must stand over a thick carpet, make a support for it by standing a board underneath that rests on three screws eased through the weave of the carpet and into the floor. In similar fashion do not fit shelf clocks or wall clocks to walls with doors let into them if you can avoid it, or walls that have a piece of vibrating equipment such as refrigerator, freezer or central-heating boiler resting against them.

REMOVING THE HANDS

Obviously removing the hands will cure any interference between the hands, but there are a few points that are not immediately apparent.

Occasional fouling of one hand on the other can be the result of using the wrong washer beneath the hand-retaining pin. The washer should be dished so that when it is pressed down by the pin its outer edge bears on the hand rather than any other part of its surface resting on the minute pipe. If the washer bears on the pipe, the minute hand will most probably be unstable, even though it may feel firm (Fig 2). The hour hand and pipe should not rub against the back of the minute hand; this is often prevented by the design of the cock that supports the compound wheel (the minute wheel), or the post that performs the same task. The hour wheel is trapped either by the overhang of the cock or by a washer under the retaining pin on the post. If there is no room for a washer, the taper pin alone will do the job if it is sufficiently long and positioned to reach past the root of the teeth (Fig 3).

Fig 1

Fig 2

Fig 3a

Fig 3b

REMOVING THE DIAL

Old clocks with heavy dials place a great deal of strain on the support pillars; and if these allow the dial to droop, the hour pipe can be fouled quite enough to stop the clock. The single plate of a Victorian period dial is particularly liable to do this because the pillars were very often held in place by small screws and were not riveted into the plate. The fault can be corrected by filing out the hole that the pipes reach through, but this does nothing to remove the cause and, what is more, will give the impression that the dial has been ‘married’ to the movement and is not original. For a brass dial, either re-rivet using a polished planishing hammer and polishing and silvering afterwards if necessary, or use slightly larger screws and re-tap the pillars. Painted dials do not allow re-riveting, the best solution for them is to support the lower edge of the dial by attaching a piece of thin plywood to the uprights that carry the seat board, or any other form of support that is unobtrusive and does not mar the original work of the casemaker.

REMOVING THE PENDULUM

If the clock can be persuaded to go reliably when the pendulum is removed, the fault is either one already discussed or is caused by some idiosyncrasy of pendulum or suspension (which includes the cock). We must also consider the crutch. Faults and the necessary corrections to pendulums, suspensions and crutches are dealt with in detail in Chapter 9, but there are some simple points that can be looked at now.

The pendulum should not rattle anywhere — the connections between suspension and cock, suspension and rod, rod and crutch, rod and pendulum bob should be firm. In the case of the fit of the suspension in the suspension cock and the rod in the crutch there should be easy movement, but not looseness, between the two parts. Ensure that the path of the pendulum bob when viewed from above is at right angles to the crutch arbor and that it is not twisted on the rod so that it exposes more than its minimum cross-section to the direction of movement (Fig 4). A significant twist to the bob will give a sideways thrust to the pendulum and cause the pendulum to weave about instead of beating in a single plane.

Fig 4a Fig 4b

The suspension springs in longcase clocks are always much longer than is strictly necessary. If there is any sign of damage or corrosion and it is desirable to retain the original spring, it is quite acceptable to shorten it, making certain that the crutch will engage the rod, or extension to the rod, that is normally provided. No more — and probably a lot less — than 18mm (0.75in) of spring is needed for proper operation of the suspension.

REMOVING THE HOUR AND MINUTE PIPES

If the clock has been working for any length of time it is unlikely that parts of the pipes are rubbing to an extent that will cause failure; but dirt, old oil and airborne grit have a surprising affinity for the inside of pipes and often cause a clock to stop. Examine the mesh of the cannon, hour and minute wheels; damage as a result of people forcing the hand round often shows here and will stop the clock. Completely irregular faults, with no obvious cause, can often be traced to variable meshing as pipes move, or result from bent posts that present the minute pipe at an angle to the other wheels. I once discovered a broken tooth held in place by a thin flap of metal so that although it was capable of leaning over and jamming, it almost always flopped back again and presented an undamaged appearance when the dial was removed. It was only discovered when the faulty wheel was removed and handled. I have never known this fault to occur in the train wheels.

Escapement faults

When the previous tests have been made and a fault remains, one must turn to the rest of the movement. In most cases it is still not necessary to take the plates apart, because the escapement is fitted with a cock or is on a separate platform.

PLATFORM ESCAPEMENTS

Before removing the platform examine it closely, you will find a magnifying glass very useful. Give a sharp twist to the clock movement to see if the balance wheel will swing and the escape wheel rotate. If neither will move, there is either a broken pivot or the escapement is gummed up. Usually a broken pivot is obvious because if it is touched lightly with a thin piece of pivot wire, it will tip from side to side. Sound pivots allow the wheel to be lifted vertically and then drop again, without tilting. There are two types of common platform escapements — cylinder and lever — and these are illustrated in Chapter 6; only one, the lever, is available as a replacement. Repairs to a platform escapement are the province of the watch repairer rather than the clock repairer, but there are only a handful of craftsmen in Britain that are willing to accept repair work on these items. It follows then that if a cylinder escapement is broken you will almost always have to replace it with the lever type.

Proper cleaning of platform escapements requires dismantling the device, including the jewelled bearings; quite obviously this cannot be done when the platform is still in position on the rest of the movement. Before undoing the screws that hold the platform, make sure that the train wheels cannot turn by slipping a thin piece of pivot wire through the crossings of the wheel that engages the escape pinion.

Most good watch repairers will undertake to clean a platform escapement, or you can take advantage of a broken example and practise on it. Carbon tetrachloride is a good cleaner and there are several proprietary compounds available; lubrication with a good watch oil should be carried out before assembly. Since disassembling platform escapements makes use of watchmaking techniques this book contains only simple adjustments, but Further Reading includes titles that will be useful if you wish to carry out this type of repair.

ESCAPE WHEELS AND PALLETS

Set up the clock movement so that the escape wheel is being driven by its spring or weight. If all is well, the escape wheel will turn as the crutch is moved from side to side and the amount that each tooth moves before striking the impulse face (the incline plane that lifts the pallet) will be the same for the teeth entering the escapement as for those leaving it. This free movement is called the ‘drop’; it should not be greater than about 10 per cent of the distance between two teeth. If you use a feeler gauge to measure this distance, bear in mind the fact that the gauge will be measuring from the tip of the tooth across the shortest distance to the escape pallet; for a recoil escapement this is not the drop, which should be measured as the length of a tangent from the tooth tip. If the angle of the impulse face is 45 degrees (see Chapter 5 for more information on the recoil escapement), the drop will be 1.4 times the gauged dimension. The drop for a dead-beat escapement can be measured directly with feelers.

If the pallets catch on one or more teeth, the space between the teeth is uneven (varying pitch), either because of inaccurate manufacture or because the tooth tips have become bent. Inaccurate manufacture can be ignored as a reason for the clock stopping if the escape wheel is original, or at least has clearly been working for some years. The clock is obviously accustomed to coping with the error. Bent teeth can be put right with a pair of flat-nosed pliers. Gently pinch the tip so that one jaw of the pliers rests half-way down the curved side and the other lies flat on the radial side (Fig 5). When the tip bends towards the radial side, which is the most common state, a slight squeeze of the pliers will bring the tip upright. If it leans towards the curved side, the pliers must be rocked over until the tip is vertical again.

Fig 5

An escape wheel that passes some teeth through the escapement more easily than others has a great deal wrong. This cannot be treated without dismantling the movement completely in most clocks. There is nothing very complex about this, but this would seem to be the place to make three relevant points. Weight-driven clocks have the pendulum removed before the weights. Spring-driven clocks must have the spring let down and the ratchet or the click removed before attempting to dismantle the movement. If you are not familiar with the clock, make a sketch of the position of all parts as you take them off.

To correct an escape wheel that works unevenly, take the wheel and arbor out of the movement and turn it — or have it turned — until all teeth are the same height. The method of holding the wheel for turning is similar to that shown in Chapter 4 when machining the seating for a wheel. If the job is done properly, the shortest tooth will just have scratches on it from the turning tool and will show some of the old tip surface. The tooth tips will now be too thick; use a half-round file to remove metal from the curved side of the tooth until the tooth thickness has been reduced to leave a flat on the tip 0.1 mm (0.004in) to 0.2mm (0.008in) wide. Do not touch the side that is radial or (in the case of the dead-beat escapement) nearly radial; this is probably still accurate so far as pitch is concerned (Fig 6).

Replace the wheel and arbor in the plates to test that it is rotating evenly beneath the pallets. It is not, however, sufficient to correct the wheel, because having altered this the pallets will no longer suit.

Fig 6

CORRECTING PALLETS

The pallets are driven by the escape wheel, and the impulse is transferred to the pendulum by the crutch. Since the latter is pivoted quite close to the point of flexure in most clock suspension springs, it will swing through approximately the same arc as the pendulum. For a longcase recoil escapement, this should be about 3 degrees on either side of the vertical. Keep contact between the escape wheel and the pallets and slowly rotate the wheel; mark the swing of the crutch with a soft lead pencil. The angle between the two extremes of the swing ought to be about 6 degrees — degree measurement is difficult to apply but 6 degrees is equivalent to a chord of 11.23mm (0.442in) on a crutch length of 100mm (3.937in) as shown in Fig 7. A chord measurement of between 9.5mm (0.375in) and 12.5mm (0.5in) is acceptable with this crutch length.

Fig 7

Any correction of the pallets is best carried out by drawing the pallets on card, using the wheel diameter and centre distance between the wheel and pallet arbors. If the wheel diameter or the centre distance has been altered from the original, use the new dimensions. The instructions for constructing recoil and dead-beat pallets are detailed in Chapters 5 and 6 respectively. When taking the centre distance remember that the arbors are not necessarily parallel and make the measurement by means of a vernier calliper held close against the escape wheel and pallets and making allowance for the diameters of the arbors.

After drawing the pallets, punch a hole on the escape-wheel centre so that the card can be slid over the pallet arbor and you can judge how far the pallets need to be bent and how much needs to be added to the impulse surfaces for them to match the drawing. If additions are to be made to the pallet faces, shape them before attachment so that little work needs to be done after soldering; harden them by heating to red heat and quenching in water in order to make the cleaning for soldering easier; tin the surface using solder, flux and a soldering iron and then tin the old surface of the pallets. Put the new piece in position on the pallet, tinned surface to tinned surface, then bring to soldering temperature by resting a hot soldering iron on the new piece or slowly heating with a gentle (quiet) gas flame. The soldering temperature will temper the new pieces to blue and make them sufficiently soft for a saw-sharpening file to shape them to suit the drawing. Polish after filing with emery and crocus paper.

SIMPLE RE-FACING OF PALLETS

A more common repair than the rather complex matter of turning the escape wheel and re-shaping the pallets, is straightforward compensation for the wear that takes place on recoil pallets. The evidence for this is a visible pit in the impulse face and the failure of the escapement to move the crutch through an acceptable angle (Fig 6). The wear can be corrected by removing metal from the impulse surface until a slip of spring steel can be soldered on and restore the original level of that surface.

Before you start, make sure that the remains of the original surfaces would give an even drop and the correct angle of crutch movement. If the drop is the same for both sides and the thickness of the spring steel that you have available is, for instance, 0.5mm (0.02in), it is only necessary to soften the pallets and file away 0.5mm (0.02in) from them. Do not worry about removing all evidence of the pits. If the original drop was uneven, now is the time to correct it by filing. Checking this matter of the original drop can be done quite simply by using feeler gauges to bridge the pit and discover the drop on each pallet; do not forget that the actual drop will be 1.4 times this measurement (Fig 8). Tin and solder the spring-steel pieces as before.

Fig 8

Measurement of the amount of metal being removed is difficult. You can do it by putting the work back into the movement plates and using the feelers, or by measuring from impulse face to some other part of the anchor. A third method is to lay the anchor on a piece of scrap brass plate, locate it in place with a peg through the arbor hole and two other pegs registered on the outside, and record the starting position of the impulse faces by clamping two small strips of metal on the plate and resting against the faces.

CRUTCH COLLET

It is always a good idea to check the firmness of the attachment of the crutch to the pallet arbor. A slight failure of riveting or solder will allow movement of the crutch and prevent the full impulse being transferred to the pendulum.

Going train

Remove the escape pallets and try the freedom of the train. Do this by applying pressure to the teeth of the great wheel or going barrel until the train just turns, then very lightly touch the escape-wheel arbor with the tip of a finger so that there is the sort of back pressure on the train that the escapement would give. You will feel an unevenness to the rotation of the train, but it must not be such that would require much increase in drive (from the great wheel), to keep the escape wheel turning. If the train is alternatively hard and easy to keep going, the mesh or the pivots are at fault.

PIVOTS AND PIVOT HOLES

If the movement of the train is difficult, turn the train until the stiffest part of the rotation is found, stop turning and gently tip the plates to the horizontal. All the arbors of wheels and pinions that are meshing freely and have unbent pivots, should drop so that their shoulders rest on the movement plate. Turn the movement over so that the arbors fall in the opposite direction. Those arbors that failed to move on either of the tilts are suspect, mark them and the position of the teeth that are in mesh at the time and dismantle the movement. You can expect to find bent pivots, or gummed up or damaged teeth. This same tilting test that finds arbors that will not drop but do not show any significant variation in rotating, should reveal worn pivots and/or holes, or gummed up pivot holes.

Having checked the pivots for freedom, test the wear between pivot and hole. Inspect the holes for ovality and try to judge the amount of movement