Service Work-Flow of an 8 Day Long Case or Grandfather Clock
The clock is completely dismantled then cleaned and rinsed ultrasonically in top brand none water based propriety fluids and then attended to in stages.
Stage 1
1. All internal items i.e. between the plates are laid to one side and checked for wear.
2. These items are then brightened up by hand and any rust removed from steelwork paying particular attention to the escape wheel for bent or short teeth.
3. Next we burnish any worn pivots and replace those that are badly worn.
4. The barrels are assembled noting any excessive wear and removing any old clock line knots left in the barrels as these can come out and trap the great wheel when winding. We have had as many as 23 knots in one clock
Stage 2
1. Attention is now turned to fitting all the newly treated internals into the clock plates marking all worn bushes including the pallet arbor and back cock.
2. We then make sure that any oval holes are pulled back on centre and then the clock is bushed where needed after checking that no one has inadvertently moved over the rear centre arbor bush in the past. This causes the hands of the clock to become in near contact with the dial face at some point; we also check that the centre arbour extension itself is not bent as this can cause the same problem. Custom made bushes are installed on clocks of high quality Bergeon brass bushes using Bergeon bushing equipment are installed to others.
3. The internals are again installed and new bushes are broached. The clock trains are then spun and tested: face up, face down, noting any stickiness and ensuring that the trains are free running.
4. The pallets and back cock are fitted in place and the escapement is roughly examined and noted for its drops and wear.
5. We remove the pallets again and clamp a gauge to the inner side of a clock plate to test the escape wheel for concentricity and make any corrections in situ with very fine needle files and papers. Doing this in situ instead of using the jewellers lathe is a slower process but we find it to be more accurate if the escape wheel is only a small amount out of true or has a couple of high teeth.
6. Next the pallets and faces are attended to, polished and/or rebuilt as required, so that when the escapement is correctly adjusted the pallet arbour is horizontal to the clock plates. If the back cock has had its screw holes elongated then it is pinned to stop it moving.
7. When all is satisfactory the clock is dismantled again and the clock plates are brightened up, the trains refitted, and the strike train is timed.
8. The gathering pallet is left on in its correct position and the plates are pinned.
9. At this stage the clock is oiled with quality clock oil.
Stage 3
1. Next all items belonging to the front plate are brightened up and any rust removed.
2. The front pivots or stub arbors are refitted, then the minute wheel with its thrust.
3. We then refit the hour wheel bridge making sure that the bridge pipe is not binding on the minute wheel extension.
4. Next the minute hand and collet is fitted and checked for the correct amount of tension applied to the thrust washer; also that the hand collet is of the correct thickness so that the front of the minute wheel is not binding on the back of the bridge.
5. We also check that the reverse minute wheel is in mesh and in line with the minute wheel. The hand is removed and the hour wheel fitted checking for wear and alignment.
6. All the strike levers have their working faces smoothed and polished and the rack and tail is checked for any movement.
7. All items on the front plate are then fitted including hands, noting the striking sequence with its snail and correcting any misalignment.
Stage 4
1. When all is to our satisfaction the gut line is fitted whilst carefully ensuring not to score the clock line.
2. The seat board is fitted followed by the bell stand and bell.
3. The crutch is checked to the suspension block and bridge.
4. The clock is now set up on a test stand and run.
5. After approximately thirty minutes the clock is checked for recoil and the amount of pendulum swing.
6. The dial is fitted a day or so later after ensuring that the movement is correct and running properly.
All clock repairs are treated in similar manor.
Saturday, June 7, 2008
Thursday, June 5, 2008
Care and Maintenance of Grandfather Clocks
Longcase clocks, are known as Grandfather clocks, and tall case clocks in the USA. If properly cared for, longcase clocks will give hundreds of years faithful service. Their value can only increase if they are looked after, and by seeking the services of a competent horologist, it is possible to maintain a clock in near original condition for a very long time indeed.
Moving the clock
Firstly, remove the pendulum and weights. This is crucial because otherwise the delicate suspension spring at the top of the pendulum rod will bend, or break. Remove the hood and gently lift the pendulum rod from inside the trunk. Check that the brass piece at the top of the thin suspension spring lifts completely clear of the bracket in which it sits, and let the pendulum down gently, making sure the large brass block at the bottom of the suspension spring passes through the slotted part through which it goes, called the crutch. The pendulum should descend freely. If it seems to stick, don't pull, just gently move the pendulum from side to side a little, making sure that the pendulum rod is not twisting, and it should come out.
The weights unhook from their pulleys. Winding the clock before removing the weights limits the degree of unravelling of the lines around the barrels.
If it is necessary to touch the movement (the works), wash and dry your hands thoroughly, because any fingerprints you leave behind will contain natural oils which will cause corrosion over time. For this reason horologists wear white cotton gloves when handling clock parts.
Cleaning
Cleaning should be confined to the dusting of the exterior of the clock case. In particular you should avoid dusting a dial. If a cleaning cloth catches the tip of one of the hands, it will bend the hands when pulled away. Once a hand has been bent it is seriously weakened and may break when it is bent back into place. Moreover, depending on the type of dial, a wiping action may smudge any ink (due to dampness in a cloth) or remove lacquer.
Setting the time
Use the tip of a finger to move the clock's minute hand. It is unsafe to turn the hands backwards past the hour. Avoid touching the surface of the dial. Acid from your hands will tarnish the brass. This may not be strictly true for a lacquered dial, but even if the dial is lacquered, the lacquer will eventually wear off. For clocks with rack striking, if it is necessary to turn the clock past 12 o'clock, pause at just after 12 and let it strike. Ideally this precaution is not necessary, because there is a mechanism in the clock to allow this to happen safely, but in my experience it is rarely set up correctly. If in doubt, wait until the striking has finished.
Clocks with count wheel striking should be advanced one hour at a time, to allow the striking to keep up with the indicated time. If the time indicated is between about 5 to the hour and the hour, the strike will have warned, and turning the hands back will allow the strike to run. This can be used to advantage where the clock has count wheel striking, which can get out of step with the time indicated. The striking can be advanced by turning the hands to 2 minutes to the hour and then turning them back to about quarter to the hour. This will trigger the next strike. With repeated steps the striking will eventually fall back into sync. Clocks with rack striking can never get out of sync.
The process of setting the time on a clock is formally known as hand-setting.
Winding
Winding thirty-hour clocks
Thirty-hour clocks do not have winding squares and are not wound with a key. When winding a 30-hour clock it is necessary to pull down on the rope (or chain). The rope goes around the pulleys in an endless loop. Pull one of the sides that goes through the counterweight. Take some of the weight with the other hand as the rope/chain is pulled, to relieve the winding mechanism of some of the strain.
Winding eight-hour clocks
For 8-day clocks use a cranked winding key and wind more slowly as the weights approach the seat-board. Stop winding just before the weights touch the underside of the seat-board. If the clock will not go for 8 days, the lines may be too short. Even worse, the clock may not be in its original case, which would have been taller and provided a longer drop for the weights. Note whether the 2 weights are level at the end of the week - if not then this may indicate there is a problem with the striking. The left hand weight is for the striking. If it is lower than the going weight on the right then this indicates that the strike train is not locking correctly and striking too many blows; if it is higher than the going weight then this indicates that the striking is not delivering the correct number of blows. It is worth placing a cushion (or other such shock absorber) in the bottom of the case. One day a line may break and the weight will drop to the bottom of the case. A shock absorber will minimise damage to the case, and soften the sound of the thud.
Winding clocks with maintaining power
If the winding holes in the dial are obscured by brass shutters, then the clock has maintaining power. Maintaining power keeps the clock going during winding. There will be a cord or lever, which must be pulled before winding can take place.
Clocks with a deadbeat escapement will have automatic maintaining power, in a form known as Harrison's maintaining power. This is an essential feature of such clocks because the escape wheel teeth are so delicate that it cannot be left to chance that the winder will apply the maintaining power.
Weights
The going weight should weigh about 12 lbs and the striking weight around 14 lbs. The going weight is always on the right and the striking always on the left. If the going and striking weights are the same size, it would be wise to weigh them. A going weight of 14 lbs would eventually do a lot of damage to the clock. Furthermore, the amplitude of the swing of the pendulum may increase to the point where the pendulum hits the side of the case. The size of weight for a regulator is usually less than half that for a Longcase clock.
Setting up a clock
All longcase clocks should be fixed securely to a wall to avoid the possibility that the case might move due to the swinging of the pendulum. Such movement will reduce the amplitude of the pendulum's swing and may loosen the joints of the case over long periods of time. A clock whose case is free to move may also exhibit a phenomenon known as Thursday disease (see below). Any movement of the case, however slight, will be transmitted to the weights. When the weights have descended to the point where the length of the lines supporting the them is the same as the length of the pendulum, the weights will swing in sympathy with the pendulum (but back to front rather than side-to-side). They will then hit the pendulum and stop the clock. This is known as Thursday disease, because the clock would traditionally have been wound on a Sunday and it would take until Thursday for this phenomenon to reveal itself.
Ensure the clock is vertical in both planes by using a spirit level. This ensures that the pendulum is clear of the backboard and allows the weights to descend without making contact with the case.
Calendars
Some calendars advance twice a day, half a day at a time; others change once a day. The time at which they change varies from maker to maker. Once-a-day calendars may well start to change at 1am and complete the change two or three hours later. Twice a day calendars may change at about 3 am and then again at 3 pm. This means that the correct date is shown for most of the daylight hours. Whilst the change is still in progress it will show half way between the correct date and the date of the next day.
At the end of a month with fewer than thirty-one days, it will be necessary to advance the calendar manually to the correct date. Depending on the mechanism, there may be a risk of touching the dial with your fingers. The same care should taken as when changing the time to avoid tarnishing the dial by touching it.
Timekeeping
Typically an average longcase clock should keep time to an accuracy of about 10 seconds a day which is roughly equivalent to a minute a week. The rate is likely to decrease in summer and increase in winter, due to the expansion and contraction of the pendulum rod with temperature.
The clock can be made to run faster or slower by adjusting the rating nut found under the pendulum bob. However, achieving the right setting can be a frustrating process for those who have not had much practice. Whilst a trained horologist can calculate the exact adjustment required, most clock owners perform this task by trial and error, and in so doing they often achieve equally good results. By keeping a record of how fast/slow the clock is running and of what adjustment is made, one can gain a feel for what effect a particular change to the rating nut will have. Note that as you home in on the desired rate, the clock will appear to become more sensitive to small changes.
If it gains, turn the nut looking from the front, to the left, which will lower the pendulum to make it go more slowly. If it loses time, turn the nut looking from the front to the right, which will raise the pendulum to make it go more quickly. Note that the pendulum bob must be free enough to descend of its own accord when the rating nut is lowered.
Keys
If there is a lock on the door and/or the hood and you have a key then use it. Keep mice and children at bay!
Servicing
In times gone by, it used to be necessary to service a clock every three years or so, because the air was so dirty from coal smoke and smog in the atmosphere which would cause the oil to thicken more quickly and cause the clock to stop. With cleaner air and synthetic oils, a clock may well now be capable of running for decades without servicing. However, you would be well advised to have your clock serviced every ten years whether your clock stops functioning or not in the intervening period; if you leave your clock until it stops functioning altogether then the work required will be much more extensive. The popular view that a clock which has stopped "only needs a clean" may have been true in days gone by (when the intervening period between services was much shorter by necessity), but this will not be the case for a clock which has not been serviced for thirty years!
Conservation and Restoration
It is important that the restoration of the clock is done in a way that has minimal impact on the clock, having due regard to maintaining the clock in as near original condition as possible.
A gloriously polished and brilliant restoration may make the owner feel proud of his clock and want to show off how well it has scrubbed up. But beware; it certainly didn't leave its maker polished to a mirror finish. Such a clock is in anything but original condition!
Concentric graining on the chapter ring (which makes it look like a gramophone record) may be thought to be attractive, but it will detract from its value and it will remove the surface metal causing the engraving to disappear. Graining is a 20th century fashion, which has no place on an antique clock. Contrary to intuition, the ideal comment from a clock owner following the restoration of a clock should be, "Well it's been to the clockmaker but apart from the fact that it now goes, you can't tell by looking at it". The only exception to this is if work has been done to the dial.
The policy of the National Trust, is not to have any cleaning or polishing work done. Their attitude is that it removes the history of the clock. That is not to say the clock shouldn't work. The British Museum's attitude is that whatever condition an artefact came in, it should stay that way. Any artefact suffering from deterioration or corrosion will be conserved and stabilised to prevent further deterioration.
Not many of us have clocks that are worthy of a place in the British Museum, but the principle still applies. If repair work is restricted to making it go, then any restoration work can be undertaken after doing some research. Once restoration is done, it can't be undone, so think carefully before commissioning any work on your clock.
In particular, you should ask your horologist about his attitude to conservation. Repairs should be undertaken in such a way that the minimum quantity of original metal is removed and, any materials used should be of the correct type. For example bushes should be fitted without the need to file down the surplus on the inside of the plate, which inevitably removes metal from the plate. Where the presence of a bush can be detected, the old bush can easily be removed without any damage to the clock plate, and a new one inserted. Re-conversion to an earlier form of escapement, particularly verge escapements, must never involve drilling of new holes.
Before commissioning a horologist to restore your clock, ask about the methods used, and their attitude to conservation. A horologist should be BHI qualified (Grad. BHI, MBHI or FBHI). The West Dean College Diploma in Antique Clock Restoration is widely considered to be the best qualification available to a horologist working on antique clocks.
Longcase clocks, are known as Grandfather clocks, and tall case clocks in the USA. If properly cared for, longcase clocks will give hundreds of years faithful service. Their value can only increase if they are looked after, and by seeking the services of a competent horologist, it is possible to maintain a clock in near original condition for a very long time indeed.
Moving the clock
Firstly, remove the pendulum and weights. This is crucial because otherwise the delicate suspension spring at the top of the pendulum rod will bend, or break. Remove the hood and gently lift the pendulum rod from inside the trunk. Check that the brass piece at the top of the thin suspension spring lifts completely clear of the bracket in which it sits, and let the pendulum down gently, making sure the large brass block at the bottom of the suspension spring passes through the slotted part through which it goes, called the crutch. The pendulum should descend freely. If it seems to stick, don't pull, just gently move the pendulum from side to side a little, making sure that the pendulum rod is not twisting, and it should come out.
The weights unhook from their pulleys. Winding the clock before removing the weights limits the degree of unravelling of the lines around the barrels.
If it is necessary to touch the movement (the works), wash and dry your hands thoroughly, because any fingerprints you leave behind will contain natural oils which will cause corrosion over time. For this reason horologists wear white cotton gloves when handling clock parts.
Cleaning
Cleaning should be confined to the dusting of the exterior of the clock case. In particular you should avoid dusting a dial. If a cleaning cloth catches the tip of one of the hands, it will bend the hands when pulled away. Once a hand has been bent it is seriously weakened and may break when it is bent back into place. Moreover, depending on the type of dial, a wiping action may smudge any ink (due to dampness in a cloth) or remove lacquer.
Setting the time
Use the tip of a finger to move the clock's minute hand. It is unsafe to turn the hands backwards past the hour. Avoid touching the surface of the dial. Acid from your hands will tarnish the brass. This may not be strictly true for a lacquered dial, but even if the dial is lacquered, the lacquer will eventually wear off. For clocks with rack striking, if it is necessary to turn the clock past 12 o'clock, pause at just after 12 and let it strike. Ideally this precaution is not necessary, because there is a mechanism in the clock to allow this to happen safely, but in my experience it is rarely set up correctly. If in doubt, wait until the striking has finished.
Clocks with count wheel striking should be advanced one hour at a time, to allow the striking to keep up with the indicated time. If the time indicated is between about 5 to the hour and the hour, the strike will have warned, and turning the hands back will allow the strike to run. This can be used to advantage where the clock has count wheel striking, which can get out of step with the time indicated. The striking can be advanced by turning the hands to 2 minutes to the hour and then turning them back to about quarter to the hour. This will trigger the next strike. With repeated steps the striking will eventually fall back into sync. Clocks with rack striking can never get out of sync.
The process of setting the time on a clock is formally known as hand-setting.
Winding
Winding thirty-hour clocks
Thirty-hour clocks do not have winding squares and are not wound with a key. When winding a 30-hour clock it is necessary to pull down on the rope (or chain). The rope goes around the pulleys in an endless loop. Pull one of the sides that goes through the counterweight. Take some of the weight with the other hand as the rope/chain is pulled, to relieve the winding mechanism of some of the strain.
Winding eight-hour clocks
For 8-day clocks use a cranked winding key and wind more slowly as the weights approach the seat-board. Stop winding just before the weights touch the underside of the seat-board. If the clock will not go for 8 days, the lines may be too short. Even worse, the clock may not be in its original case, which would have been taller and provided a longer drop for the weights. Note whether the 2 weights are level at the end of the week - if not then this may indicate there is a problem with the striking. The left hand weight is for the striking. If it is lower than the going weight on the right then this indicates that the strike train is not locking correctly and striking too many blows; if it is higher than the going weight then this indicates that the striking is not delivering the correct number of blows. It is worth placing a cushion (or other such shock absorber) in the bottom of the case. One day a line may break and the weight will drop to the bottom of the case. A shock absorber will minimise damage to the case, and soften the sound of the thud.
Winding clocks with maintaining power
If the winding holes in the dial are obscured by brass shutters, then the clock has maintaining power. Maintaining power keeps the clock going during winding. There will be a cord or lever, which must be pulled before winding can take place.
Clocks with a deadbeat escapement will have automatic maintaining power, in a form known as Harrison's maintaining power. This is an essential feature of such clocks because the escape wheel teeth are so delicate that it cannot be left to chance that the winder will apply the maintaining power.
Weights
The going weight should weigh about 12 lbs and the striking weight around 14 lbs. The going weight is always on the right and the striking always on the left. If the going and striking weights are the same size, it would be wise to weigh them. A going weight of 14 lbs would eventually do a lot of damage to the clock. Furthermore, the amplitude of the swing of the pendulum may increase to the point where the pendulum hits the side of the case. The size of weight for a regulator is usually less than half that for a Longcase clock.
Setting up a clock
All longcase clocks should be fixed securely to a wall to avoid the possibility that the case might move due to the swinging of the pendulum. Such movement will reduce the amplitude of the pendulum's swing and may loosen the joints of the case over long periods of time. A clock whose case is free to move may also exhibit a phenomenon known as Thursday disease (see below). Any movement of the case, however slight, will be transmitted to the weights. When the weights have descended to the point where the length of the lines supporting the them is the same as the length of the pendulum, the weights will swing in sympathy with the pendulum (but back to front rather than side-to-side). They will then hit the pendulum and stop the clock. This is known as Thursday disease, because the clock would traditionally have been wound on a Sunday and it would take until Thursday for this phenomenon to reveal itself.
Ensure the clock is vertical in both planes by using a spirit level. This ensures that the pendulum is clear of the backboard and allows the weights to descend without making contact with the case.
Calendars
Some calendars advance twice a day, half a day at a time; others change once a day. The time at which they change varies from maker to maker. Once-a-day calendars may well start to change at 1am and complete the change two or three hours later. Twice a day calendars may change at about 3 am and then again at 3 pm. This means that the correct date is shown for most of the daylight hours. Whilst the change is still in progress it will show half way between the correct date and the date of the next day.
At the end of a month with fewer than thirty-one days, it will be necessary to advance the calendar manually to the correct date. Depending on the mechanism, there may be a risk of touching the dial with your fingers. The same care should taken as when changing the time to avoid tarnishing the dial by touching it.
Timekeeping
Typically an average longcase clock should keep time to an accuracy of about 10 seconds a day which is roughly equivalent to a minute a week. The rate is likely to decrease in summer and increase in winter, due to the expansion and contraction of the pendulum rod with temperature.
The clock can be made to run faster or slower by adjusting the rating nut found under the pendulum bob. However, achieving the right setting can be a frustrating process for those who have not had much practice. Whilst a trained horologist can calculate the exact adjustment required, most clock owners perform this task by trial and error, and in so doing they often achieve equally good results. By keeping a record of how fast/slow the clock is running and of what adjustment is made, one can gain a feel for what effect a particular change to the rating nut will have. Note that as you home in on the desired rate, the clock will appear to become more sensitive to small changes.
If it gains, turn the nut looking from the front, to the left, which will lower the pendulum to make it go more slowly. If it loses time, turn the nut looking from the front to the right, which will raise the pendulum to make it go more quickly. Note that the pendulum bob must be free enough to descend of its own accord when the rating nut is lowered.
Keys
If there is a lock on the door and/or the hood and you have a key then use it. Keep mice and children at bay!
Servicing
In times gone by, it used to be necessary to service a clock every three years or so, because the air was so dirty from coal smoke and smog in the atmosphere which would cause the oil to thicken more quickly and cause the clock to stop. With cleaner air and synthetic oils, a clock may well now be capable of running for decades without servicing. However, you would be well advised to have your clock serviced every ten years whether your clock stops functioning or not in the intervening period; if you leave your clock until it stops functioning altogether then the work required will be much more extensive. The popular view that a clock which has stopped "only needs a clean" may have been true in days gone by (when the intervening period between services was much shorter by necessity), but this will not be the case for a clock which has not been serviced for thirty years!
Conservation and Restoration
It is important that the restoration of the clock is done in a way that has minimal impact on the clock, having due regard to maintaining the clock in as near original condition as possible.
A gloriously polished and brilliant restoration may make the owner feel proud of his clock and want to show off how well it has scrubbed up. But beware; it certainly didn't leave its maker polished to a mirror finish. Such a clock is in anything but original condition!
Concentric graining on the chapter ring (which makes it look like a gramophone record) may be thought to be attractive, but it will detract from its value and it will remove the surface metal causing the engraving to disappear. Graining is a 20th century fashion, which has no place on an antique clock. Contrary to intuition, the ideal comment from a clock owner following the restoration of a clock should be, "Well it's been to the clockmaker but apart from the fact that it now goes, you can't tell by looking at it". The only exception to this is if work has been done to the dial.
The policy of the National Trust, is not to have any cleaning or polishing work done. Their attitude is that it removes the history of the clock. That is not to say the clock shouldn't work. The British Museum's attitude is that whatever condition an artefact came in, it should stay that way. Any artefact suffering from deterioration or corrosion will be conserved and stabilised to prevent further deterioration.
Not many of us have clocks that are worthy of a place in the British Museum, but the principle still applies. If repair work is restricted to making it go, then any restoration work can be undertaken after doing some research. Once restoration is done, it can't be undone, so think carefully before commissioning any work on your clock.
In particular, you should ask your horologist about his attitude to conservation. Repairs should be undertaken in such a way that the minimum quantity of original metal is removed and, any materials used should be of the correct type. For example bushes should be fitted without the need to file down the surplus on the inside of the plate, which inevitably removes metal from the plate. Where the presence of a bush can be detected, the old bush can easily be removed without any damage to the clock plate, and a new one inserted. Re-conversion to an earlier form of escapement, particularly verge escapements, must never involve drilling of new holes.
Before commissioning a horologist to restore your clock, ask about the methods used, and their attitude to conservation. A horologist should be BHI qualified (Grad. BHI, MBHI or FBHI). The West Dean College Diploma in Antique Clock Restoration is widely considered to be the best qualification available to a horologist working on antique clocks.
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