Much of the skill acquired in clock repair comes from seeing and hearing things happen. This acquired skill must be accompanied by strong deductive, inductive, and abductive reasoning ability. Having something written is very helpful however, your main focus should be with "hands on experience". There is no magic information guru that can instantly make you a clock repair genius. You can read every book ever written, but if you can't apply that information to the real world, all your reading will be akin to useless rhetoric. Spend 20 percent of your time reading, and 80 percent of your time doing. The information presented here is meant as a guide. It has worked for the author. It may not work for you. This is not the "know all", "see all", supreme authority manifesto on clock repair; clock repair is a combination of art and technology. For example; you will need a good "ear" for music to be able to make sure chime melodies sound right; however what is "right" to one person may not be right to someone else. If you are tone deaf, you will not be able to fix the sound of chimes without help of some sort. It is absolutely imperative that a repair person have excellent hearing in addition to knowing what to listen for, because listening to the sound of the mechanism working will be the key to whether or not a problem is discovered or missed.PUTTING A CLOCK IN BEAT back to top
All clocks must have maximum power transfer to the pendulum or they will not run dependably. This means they must be in beat. What does this mean? Some call this "setting the balance". Try to imagine the pendulum and verge as a swing and the person pushing as the escape wheel. When the clock is in beat the escape wheel gives the pendulum a push at just the right time in the same way as a person gives the swing a push just as it arrives back and at the instant it starts back on its return trip. When a clock is not in beat the situation is similar to the person pushing the swing taking five or six steps forward before the person on the swing starts on their way back. What happens? There is a collision and the arc of the swing is disturbed. If a clock is out of beat the verge collides with the escape wheel teeth, and the clock eventually stops before it is run down.
The verge clutch will usually allow the beat to be set by adjusting the position of the impulse arm until it is at the true center at rest with the mechanism and case set level and plumb. Be very careful when setting the beat; sometimes the verge clutch is set so tight that the escape wheel teeth can be bent without realizing it. If the clock is "in beat" then as you watch the pendulum swing you will hear a "tick" or "tock" precisely at the point when the pendulum passes the center ( true center as mentioned above) of its arc. This must be its characteristic arc , not the one you give it when you swing the pendulum. How do you know its "true arc" ? Do this with the clock perfectly level while you can see the escape wheel and verge: starting with the pendulum at rest move it slowly until you hear a tick or a tock which is the sound of the escape wheel releasing.(You must know which way to move the pendulum of course because the escape wheel will only release once on each side of the arc. If you are doing this for the first time it would be a good idea to be able to watch the escape wheel and verge interaction so as to know which way to move the pendulum to allow the verge to release the escape wheel. To get an idea how this works, take the pendulum off and GENTLY move the suspension arm back and forth to observe and learn the action of the escape wheel / verge combination, then put the pendulum back on and continue.) As soon you hear the tick or the tock release the pendulum. DO NOT PUSH IT. If the clock is in beat you will hear the other side tick when the pendulum gets to the other side of its arc.
If the beat is set, but the clock gets in beat and they out of beat; check for bent escape wheel teeth if the "in beat and out of beat" sound has a regular repeating pattern. If there is not a regular pattern then the problem is probably a loose verge. The clutch can be ok but the verge can be loose on the shaft. when setting the beat on a clock, if possible do it by sight and sound.
Setting the beat on a balance wheel is just as important as the beat on the pendulum units. The hairspring collar can usually be moved if need be, it is a delicate operation. Practice on spare parts! back to top
WHAT WILL CAUSE A CLOCK TO STOP ? ( You may have to check all of these if you have problems after moving a clock ) It doesn't take much to stop a clock. The most common problem is failure to wind the mainsprings up all the way! This is a user/owner problem. Generally speaking if a clock is stopping after it has been rebuilt check the following: Check the beat setting check endshake check for tight bushings check the position of the impulse arm vs susp rod check for bent escape wheel teeth check for bent teeth (even slightly) every where in the gear train check for a mounting bind (with the mechanism is mounted in the case if one of the mounting feet is even slightly bent it can cause any one or all of the gear trains to bind) check for barrell teeth hitting #2 wheel teeth on endshake minimum or maximum. check for worn gear teeth check for proper gear depthing are the mainsprings the correct strength? is the suspension the correct strength? possibly the pendulum is the wrong weight Hands rubbing on the glass at any point in the 360 degree rotation? (put your finger on the glass over where the minute hand is located and if the hand looks closer to your finger than the glass is thick then the hand is probably hitting on the glass.) check for a bushing not oiled are the hands touching each other at all anywhere? when the clock stops , very carefully check to determine if there is any power to the escape wheel; if there is power then be more concerned about pendulum friction, sympathetic vibration, or suspension problems. If there is absolutely no ; or very little then there is probably a gear train problem. is there any air circulation around the pendulum? are the weights magnetized and is the pendulum brass plated steel? is the pendulum touching the back of the clock ? Is the clock case sitting on a solid surface? is the clock hanging plumb on the wall? Is the hour tube binding? are the chime or strike levers binding because of lack of oil or rough edges? check the suspension post to see if the suspension is loose--- If it is loose the clock will probably stop. check for pallet face wear check all lubrication points. back to top WHAT WILL CAUSE TIMEKEEPING PROBLEMS: There are a number of things that will cause timekeeping problems. Some are true generally speaking and some are specific to certain clocks. The following is a list of the generally speaking problems: a "set" mainspring improperly lubed mainspring damaged mainspring--- scratched ,rusted or pitted spring : or a spring with lumps caused from the shape of the spring upon itself being wound for years and years. worn weight pulley gummy oil worn or loose bushings loose suspension post incorrect mainspring sympathetic vibration damaged threads on the pendulum adjusting nut regulator end of key damaged bent suspension spring loose verge worn gear teeth worn roller pinions and or worn roller pinion bushings incorrect weight on time gear train loose hand clutch scored pivots or pivot too much play in impulse loop incorrect gear ratio incorrect center of gravity on the pendulum bob incorrect pendulum weight incorrect suspension spring thickness mainspring run down unstable running position out of beat mainspring catching on gear teeth or click rivet or click spring hooks damaged escape wheel teeth moon dial gear binding incorrect verge escape wheel depth (shallower depth will generally make the clock run faster because the swing is reduced making less time between ticks.
This is a phenomena that sounds unbelievable at best, but it does exist and is a common cause of many clocks stopping. Sympathetic vibration can be described as the transfer of energy from one object moving with a steady frequency to another object (initially not moving) connected to it. The objects will transfer energy very efficently if they are the same length; however, they do not have to be exactly the same length to transfer energy . A classic example is a large grandfather clock with a heavy pendulum and a case that is set up on a rug. When the weights travel downward and get even with the pendulum bob, the weights will absorb enough energy from the pendulum to either stop the clock and or start the weights swinging and stop the clock. Also the clock case can absorb energy from the pendulum because the case is not solid on the rug. Even the slightest instability can cause the clock to stop. On old cases ; if they are loose, if the case is not solid, the pend moving will cause the case to oscillate (this may or may not be visible) and the case will absorb enough energy to stop the clock. correct this by securing the case to the wall. be sure the case is solid.
If there are several clocks running on a shelf with similar pendulum lengths , and the shelf appears solid it still may be possible that the clocks on this shelf will transfer energy back and forth. The result may not be just stoppage. One or both of the clocks may not keep time or may be un-regulatable because they will affect each other.
Sympathetic vibration may be demonstrated by a little device with weights and strings. Suspend 2 weights ( at least 8 ounces ; fishing weights would work nicely ) from a small frame like a scale model of a swing set with strings. Make the strings the same length. Start one weight swinging and very soon the other one will be swinging, and the first one will be stopped. This is sympathic viabration. The less solid your frame the quicker the energy will bea transferred. The frequency with which the energy is transfered back and forth ( the weights will start and stop alternately) is related to the length of the strings and the amount of friction present and the time it takes to transfer the energy.WHAT ABOUT THE IDEA THAT THE WEIGHT HAS NOTHING TO DO WITH THE PERIOD OF A PENDULUM? back to top
Well you can believe what you want. And if you are a physics major you may say that this is true. In theory you are correct. In clock repair not true at all. There are several reasons for this. First, the "center of gravity" of a pendulum determines its effective length as far as the clock is concerned. This has been determined by exaustive empirical study. So if you put a "different" weight on a pendulum the timekeeping will change. In other words if you change the pendulum bob you will probably change the timekeeping characteristics of the clock. It is important to understand here that if you "add" weight to a pendulum, you will change its effective center of gravity. To better understand this concept; think about it this way: How do you determine how long a pendulum is? Is it the pendulum rod, the suspension, the pendulum stick, or the pendulum bob? If you were doing a physics experiment, how would you make the pendulum shorter? You would probably shorten the string holding the weight. To adjust the timekeeping of a clock you move the bob up or down depending on whether or not it is running slow or fast. This changes the effective length of the pendulum, thereby changing the period. If you add weight to a clock pendulum, you will change the period of the pendulum and you will change the characteristic timekeeping of the clock, unless you add the weight in such a manner so as to NOT change the center of gravity, and you add enought power to the mainspring or or weight that supplies power to compensate EXACTLY for the weight you have added. Consider this: Lets say you have a wall clock that has a pendulum that produces one tick per second ( This is typical of many large wall clocks ). How many seconds in a day? 60 * 60 * 24 = 86,400. Now take that times 7 and you have 604,800 seconds in a week. In most repair situations and customer service situations, if a clock is more that 5 minutes a week off, you will get a call from your customer. This error is not acceptable to most people. Lets say you change the length of your pendulum so the period is one tenth of one percent slower that it should be on each swing. That is .001. One thousandth. Doesn't seem like much? Better think again. 604,800 * .001 = 604 that is 604 seconds in a week. Depending on the gear ratio, the clock could be ten minutes off or more. Ok, lets say the error was only .0001 one ten thousandth. That would still be a minute a week. Annoying, but ok. However, lets say you had a 30 day clock ( there are clocks designed to run for 4 weeks on one winding ). That would be a half hour in a month. Probably not acceptable to most people. A tiny set screw on a small wall clock pendulum will make more difference than the .001. This does, as you can see, illustrate the fact that a heavier pendulum will be more accurate, because adding a small amount of "change of center of gravity" will have less overall effect on a heaver pendulum. Clock timkeeping error is additive in a way most people do not consider, and weight change on a clock pendulum does make a difference; sometimes a large difference. This theory mentioned above is precisely why clocks have been designed with temperature compensating pendulums, and suspension springs. If the temperature changes 10 degrees and the suspension rod expands say .01%, it will change the timekeeping. If the pendulum bob expands, and does so in a non-uniform way, the timekeeping will change, because the center of gravity will be altered by the changing shape of the pendulum bob.
Second: If you put a heavier weight(pendulum bob) on a pendulum the pendulum arc will decrease because you have not changed the amount of power that is pushing the pendulum yet you have added to the friction. With a shorter arc there will be less time between ticks. The escape wheel will move faster and the clock will run faster. Too much weight here and the clock will stop. This problem is worse with spring drive clocks than with weight drive clocks because of isochronal error. That is a fancy way of saying there is less power available from a mainspring when it unwinds. The reduction in power is not linear. Generally speaking the mathematics needed to design a clock was available many years ago. Most clocks have been designed well and the "stock" pendulums and mainsprings are crucial in providing good timekeeping. For this reason, I recommend when ever you can, keep the clock as original as possible. Unless you are a skilled mechanical engineer with years of experience in designing slow moving grear trains, you probably will not be able to improve much on the design of an old clock.
Third: If you put a lighter weight on a clock pendulum ( that is to say if you put a pendulum that is lighter on the clock ) the arc on the swing of the pendulum will increase slightly because you have reduced the amount of friction on the pendulum. Maybe I shouldn't call it friction. As the weight of the pendulum increases it takes more energy to push it. As the weight of the pendulum decreases, it takes less energy to push it. Then there will be more time between ticks. The escape wheel will move more slowly and the clock will run slower. Remember that this effect is additive here; most clocks will tick hundreds of times in one day.
The strength of the suspension spring will also determine the arc of the pendulum. A thicker (stronger) suspension spring changes the arc , or swing of the pendulum ; it usually makes it shorter. Too thick (strong) and the clock will stop. Too thin (weak) and the clock will stop. A thinner (weaker) suspension spring changes the arc , it usually makes the pendulum arc increase. Remember, when the pendulum arc (swing) increases there is more time between ticks and the escape wheel turns more slowly which makes the clock run slower. All of these factors interact in a very complex way mathematically. Sometimes timekeeping is affected in ways that seem illogical at best. If a clock has an excess of power , sometimes you can get away with putting a stronger suspension spring on it. The key word here is sometimes. As soon as you start changing things you will need to be very careful. I strongly advise against changing a clock suspension spring or pendulum unless you use an exact replacement. If you have a clock that has no suspension or pendulum this may help you devise one by emprical study. back to top
WHAT ABOUT THE SAYING THAT "THE CLOCK IS WOUND TOO TIGHT"?
You can only wind a spring drive clock so far and then either the spring will break, or the key will break, or one of the gears will be ripped loose. I have seen some clocks that have been forced so hard that the arbor actually has snapped. The old Urgos spring drive clocks have an arbor that has a small groove cut in it for assembly convvenience that will snap if you force it. If a clock needs repair and it is wound fully many times the mainspring will stick. This gives the appearance of the clock being wound too tight. Essentially , from the users perspective , it is. From the repairperson's point of view it needs cleaning. Each coil of the mainspring has only a fraction of the power of the total power of the mainspring so if the surface tension of the mainspring grease is to the point where it does not allow the spring to release ( because oil / grease thickens up over time and becomes "sticky") then when the mainspring is wound FULLY all the coils stick together and give the illusion that the mainspring or clock is broken. It sort of is, but not from over winding. If you overwind a clock and break it , believe me you will know. You may loose finger nails faster that you can see , there will be noise with a volume directly perportional to the size of the spring.
On weight drive clocks, often the pulley/pulleys will catch on part of the mechanism or mechanism mounting hardware if the clock is fully wound and give the impression of the clock being wound too tight. Also, the cable can come off the pulley and get stuck between the pulley frame and the pulley this may prevent the associated gear train from functioning. These are things to look for.
A note about timekeeping with the stock pendulum that is designed to be used with a given clock: Shorten this pendulum and the clock will run faster. Lengthen this pendulum and the clock will run slower. In other words turn the adjusting nut to your left to make the pendulum longer so the clock will run slower. Turn the adjusting nut to the right to make the pendulum shorter so the clock will run faster. One full turn. (Make sure the pendulum actually moves when you do the adjusting; sometimes the part inside the pendulum bob is loose and slips when you try to make an adjustment.) Make note of the time. Check the clock in 2 days. Make the adjustment again of one full turn. Make note of the time. Check the clock in 2 days. Keep this up until you have done two things: Acquired a record of how many turns it takes to make a specific change in timekeeping ; and have the clock keeping time. A useful formula for calculating timekeeping data is: L = Li*(1±E/R)². L is correct length, Li is incorrect length, E is error in hours, and R is length of test run in hours.
Now this interesting question. What do you compare the clock to ? You would be surprised what I have found customers comparing their clocks to for timekeeping adjustments. The TV (the TV is the best one I have heard), a digital clock,( a digital clock without a number for seconds will drive you nuts if you want to get more than plus or minus 1 minute accuracy), the clock on the town hall, my cuckoo clock, the computer clock, the clock in my car, the list goes on. My point here is be sure you are using an accurate comparison, and only ONE clock for comparison, or you will be spinning your wheels - - literally! The big mistake most people make is assuming that all clocks in the realm of TV, government, business, and technology, are somehow all set to exactly the same time, so they compare to a different clock every time they make an adjustment. If you are a clock repair technician, this is obvious to you, but to the average person it may not be so obvious.HOW DO I FIX THE CHIMES?
Now a little bit about chime adjustment. I have had numerous requests about this topic. First lets get on the same page, so to speak, about the meaning of chime, and stike, and gong. For our purposes here the chime will mean the melody that plays on the quarter hours. The strike will mean the hour count. Gong will mean what ever is the sound making device. Things such as bells, wires, rods, steel rods, or steel coils are included. If there is an issue with a specific type of gong material it will be indicated. Hammer will mean the device that hits the gong. It usually looks like a miniture hammer.
There are several aspects to chime and strike. One is volume. Another is tempo. A third is the actual pitch of the notes and whether or not the chord on the hour strike is "in tune" and whether or not the melody sounds in tune.
Volume can mean different things to different people. Here we are talking about amplitude, not frequency. A higher pitch may sound louder to some people, depending on their hearing, so if you are in business, be aware of this. As you might guess the amplitude or volume is pretty much directly related to how hard the hammer hits the gong. Consider a hammer that is solid brass (or steel) hitting a gong; the frequency spectrum of sound produced will be on the high end making a "tinny" sound. You can change the volume of this by reducing the impact of the hammer hitting the gong. To do this change the return spring to one with less strength, move the hammer away from the gong so it hits with less force, or reduce the distance the hammer travels ( reduce the throw ) before it hits the gong. The last two methods are the best choices. The first method is a last resort and one must be very careful when altering a clock's design. So reducing the throw or moving the hammer away from the gong are the best methods for changing volume. DO NOT BEND THE GONG, EVER. A good general rule ( when making an adjustment in clock repair ) is that if you saw it move it moved too much. Adjusting hammers that produce sound for the chime or strike is very difficult unless you have lots of experience. The above gives you one perspective.
SOME FACTS ABOUT THE SOUND OF CHIMES:
One: If you hit a gong hard it will produce a loud sound and will produce a different frequency spectrum of sound with more amplitude than if you hit it with less force.
Two: A hard substance on a hammer such as steel or brass will make a high pitched sound when it hits the gong, and will be percieved as loud to many people.
Three: A soft substance on a hammer such as cloth, or plastic, or rubber, will fail to produce high amplitude high frequency vibrations. This will be percieved as soft by many people.
Four: A longer gong rod, or larger bell does not necessarily produce a lower pitch than does a slightly shorter rod or smaller bell.
Five: The more substance ( mass ) a given gong material has the lower the frequency produced when it is hit by the hammer.
Six: The design of the gong where it attaches to the mounting screw will affect the frequency of vibration along with the size and length.
The tempo of the strike or chime is directly related to adjustment. This is a very complicated subject and is different for every clock. The tempo is determined by the actuating mechanisms that lift the hammers. These usually consist of pins, or cams, or star wheels, or drums with lift pins in specific areas attached to gears.
There is also the issue of sequence. Most modern clocks are self correcting. For example, the "Westminister" chime has a melody that plays four notes on the quarter hour, eight notes on the half hour, twelve notes on the three quarter hour, and sixteen notes on the hour followed by the hour count. These mechanisms are set up so as to self correct if they get out of sequence. If one of these clocks is allowed to run down and stop, the sequence will probably be off for at least one hour. If the hour count rack is stuck behind the snail, it may take up to 12 hours to correct itself. If, when the clock stops, the owner forces the minute hand ahead, in an attempt to reset it, there will usually be damage to the trip lever inside and the clock will not work right until the correct angle is restored to this lever. If the owner moves the hour hand to make it match the count, the clock will be off permanently and they will not even realize what they have done. If they are lucky they will not break the hour hand when they try to move it.
WHAT IF THE CLOCK DOES NOT CHIME ( OR STRIKE ) EXACTLY WHEN THE MINUTE HAND REACHES THE 12, 3, 6, OR 9? ( 12 OR 6 IN THE CASE OF A TIME AND STRIKE CLOCK )
This can be caused by a number of different problems. The most common cause of this is that the minute hand gets forced ahead after the clock runs down and stops; or the minute hand gets moved while the clock is chiming or striking. Most of the time the owner won't realize the damage they have done. This is not the only aspect of this problem by any means. If the trip cam is loose, or if the trip lever is loose or bent at the incorrect angle the same problem may occur. If the trip cam is worn or if the pin used as the working surface on the trip lever is loose; again the same problem may occur. If the minute hand hub slips slightly, the chime or strike won't trip when the minute hand is at the corresponding 12, 3, 6, or 9. This problem can also be caused by too much oil on the trip lever, or trip lever axel or a broken or jammed return spring on the trip lever. This can be a very difficult problem to solve. This is where the repair person needs to have a lot of experience and a very sharp eye for things out of place in most every kind of mechanism. These are just some of the aspects of this problem.
WHAT ABOUT SOLDERING IN THE REPAIR OF CLOCKS?
If you don't absolutely have to DO NOT SOLDER ANYTHING ON A CLOCK. I say this because I have seen thousands of clocks with blobs of solder and acid flux all over them, many of them destroyed because of it. For example, simply tack soldering gear teeth on a gear to fix the gear is something one should never do. This is an insult to the owner, the maker, and the repair persona. What usually happens is it holds long enough for the owner to wind it up a few times then it lets go and destroys more that just the gear. Or worse yet, it may hold for several years, and then let go. This opinion is because of many bad experiences with clocks other persons have ruined. It is very discouraging to open up a pristine looking french clock, only to find it has been butchered with a punch and blobs of solder. Because of this, it is important to realize, that other repair persons may not be as negative about solder as I am; and it is true that it could have been repaired during the war when no brass was available for repairs, however, a good repair person can tell just by looking whether a clock has been repaired recently or not. How, you might ask? You look at the oil ( or lack of it ) on the verge, you look at wear spots with an eye loop, you look at the condition of the pivot ends, you look at the lustre of the entire mechanism, you look at the inside of the cabinet, you look for traces of dust, you listen very carefully to the mainsprings and pay close attention to their feel as you let them down. When you have done this many times on many clocks, you will be able to tell if a clock has been worked on recently or not; then you will know the reason why there may have been soldering where there was not an immediate necessity.
If you must solder a part on a clock, silver solder is ok but be careful because heating brass makes it very soft. You can ruin a gear or a barrell if you are not careful. If you see the brass get red hot, you have already ruined it. Right before the brass gets red hot you have already ruined it. Electronic solder will not work. It is not strong enough. There is solder available that requires only slightly more heat than a soldering iron, and is much sronger. It is available from most clock repair parts suppliers. It is possible to solder parts with this solder without ruining them, but you still must be very careful. Do not overheat the brass. Try a heating a piece of scrap brass and then hammering it and working with it before you ever try any soldering on a clock. This is the best way to learn for yourself how brass reacts to heat. Do keep in mind, however, that the size and shape of a piece of brass will affect how it reacts to heat.
Soldering in itself is somewhat of an art. If you have worked in electronics or plumbing and understand how solder works, then you have a head start, but you are not there yet. Brass does not react the same way as copper, or tinned copper wire, it is not as forgiving. Don't even attempt any kind of soldering on clocks until you fully understand the basics of it first.