Clock repair blog

Clock Repair Archive – –     

Many of the modern triple chime / westminster chime wall clocks available today that use popular european mechanisms have the mechanism mounted to the dial with threaded studs that are fastened to the wooden dial back by screws from the front , hidden behind the dial face. This in itself is not a problem if the dial face comes off easily .However this is not usually the case. Often the dial faces are glued on and will be destroyed or disfigured in the attempt to remove them. In most cases the dial face does not have to be removed. First ; LET THE MAINSPRINGS DOWN. Then loosen the movement mounting studs attached to the threaded posts on the back of the mechanism. Do not take them all the way off ; but allow enough slack for the movement post to be turned freely. Now , simply unscrew the movement posts from the studs mounted to the back of the dial. The bolt in the middle of the mechanism will hold the mechanism together while the posts are being turned.Take care to make sure the posts that are mounted to the dial don’t move while you are loosening the movement posts; they are attached under the dial face and may be impossible to tighten up if they come loose.

Clock Repair Archive – –     Dead Beat escapement ( Graham escapement ):


The gear train applies power to turn the escape wheel in the direction indicated. At A and B, the working face consists of the areas marked 1 and 2. When power is applied to the escape wheel through the gear train causing the escape wheel to rotate in the direction indicated, the verge is given a gentle push as the escape wheel tooth slides on area 2, after it locks on area 1. The amount of “lock” varies from clock to clock. The escape wheel should not rotate during the lock portion of the operation. The power transfer occurs during the slide operation. The escape wheel picture is for illustration only. Escape wheels like this always have gear teeth all the way around the gear! 

This dead beat escapement, also known as the graham escapement, is characterized by its action of lock and slide as it operates. There is no recoil of the escape wheel as the verge moves back and forth. When properly adjusted the escape wheel moves in one direction only. This type of system can be recognized by looking at the verge. Pay particular attention to the working faces of the verge, there will be a flat edge where the escape wheel tooth hits upon releasing from the opposite side and a sharp edge that the tooth drops off from the flat part and an angled surface that the tooth slides along as it gives the pendulum an extra push until it lets go and the whole thing starts again on the other side. This type of system is very accurate when properly adjusted, because the verge has significant control over how much power is delivered to the pendulum. If however there is too much lock or not enough lock the accuracy and dependability will be questionable at best. The depth setting is not the same for all clocks although the principle is the same. Generally speaking weight drive clocks with heavy pendulums are more sensitive and require somewhat shallow depth settings keeping in mind not to completely eliminate the lock segment of the operation. The lock is the amount of distance past the edge between surface 1 and 2 that the escape wheel tooth first makes contact on each tick. The following is a list of some of the sensitive clocks:

1. Seth Thomas #2 regulators : Slight lock– .005 inch
2. Most vienna regulators : Very slight lock– .0025 inch
3. most french clocks Slight lock– .003 inch
4. jewelers regulators (large wall clocks and floor clocks with mercury filled pendulums): Extremely slight lock– .002 inch.

The above information is intended as a guide. In each one of those groups there have been hundreds of thousands of clocks made over the years with hundreds of variations on each style. These names are general catagories of types of clocks. Even the Seth Thomas #2 regulators have some variations. On all of the above clocks watch the motion of the pendulum. Vienna regulators often do not have a large arc ( swing of the pendulum ). One inch is not unusual. The Seth Thomas #2 regulator usually has a large arc ( 3 inches is not uncommon ) and a very heavy pendulum.

Clock Repair Archive – – Date Codes:

date codes for some of the popular European clocks : 1990 – A1991 – B 1992 – C 1993 – D 1994 – E 1995 – F 1996 – G

Cuckoo clock repair:

Determining the correct type of chain:

If you have a cuckoo clock that does not
have any chains or has chains that do not work correctly there is a way to determine
what chain to use. First ,count the number of teeth on the sprocket and measure
the effective diameter of the sprocket. Keep in mind that most cuckoo clocks
sprockets / chains use every other link , so the distance between sprocket teeth must
match the distance between 3 centers of links. Use the formula to find the circumference
of a circle; to find the distance around the sprocket exterior ; then divide that by the
number of teeth to determine the required distance between every other link ie: the
distance between sprocket tooth ends. The wire diameter must be such that the links will
set in the saddle of the sprocket enclosure without climbing out as the sprocket turns as
the clock is running or when the clock is being wound. The links should sit approximately
50% of the way down on the tooth. The final test, however, is whether or not the chain
pulls through without any places that bind up. The chain must run though SMOOTHLY or the
clock will not work. If the links climb up on the sprocket teeth when the chain is pulled
though, then the chain is not the correct link per foot count or the wire diameter is wrong.
Many times the chain will climb up on the sprocket teeth on the side opposite the weight (the
loose end side). You will not see this if it is up inside the clock. Sometimes the chain
will climb only intermittantly. This is a very difficult thing to catch. It will happen
when the customer has the clock at home. They take it off the wall , bring it back in to
you and by the time you get it the chain problem has vanished. You will hang the clock up
and it will perform perfectly. I am not suggesting that you check each link on every chain
on every cuckoo you repair. What I am saying is to check each chain by pulling it through
the sprocket and watching it carefully. If you have a cuckoo come back and there appears to
be nothing wrong , then you need to check the chain VERY carefully. This is also true for
most chain drive clocks. Brass chain does stretch more than steel chain , but it tends to
wear the sprocket teeth less. It is usually easier to replace a chain than a sprocket.

Most cuckoo clocks do not have suspension springs. They depend on
gravity and the power in the gear train to make the pendulum move. They do ,
however have a suspension. It consists of 2 loops and one hook. The hook is on the
end of the suspension rod. Always check this system. The loops get grooves worn
in them and this is enough to stop the clock. Also check the top loop on the
suspension post to be sure they are not loose. The clock will stop if either one of
these are loose. They must be tight, absolutely tight. If the post is threaded in the
threads can be tightened by closing the hole in the plate slightly with a hole closing
punch. This will adequately tighten the suspension , providing the hole is not closed
too tightly. These loops in my opinion are best served by light oiling. Light meaning very
small amounts of oil , and a very light weight oil. Only enough oil to cover the friction
points with a thin film of oil should be used.

Many of the cuckoo clocks you see will have music mechanisms in them. They
will usually be weight drive. watch for worn governor assemblies, worn bushings on
the player drum assembly, and missing or ineffective dampers on the sounding fingers.
the governor assemblies that have plastic worm drive gears often have cracked gears;
and will make a clicking sound as the cracked part of the gear passes the worm gear.
these must be replaced once the gear cracks.
An irritating squeaking noise as the music plays is often caused by bad or

missing dampers on the music sounding fingers, to fix this simply glue
new tiny plastic pieces on
the inside bottom of the fingers. The originals are glued on. The plastic you
use to dampen the vibration must not be too stiff or too flexible. If there are any
of the originals left you can tell from them what the required flexibility must be. If not you may
have to order a new mechanism and take the dampers off of the new one. Why would you
want to do this, you may ask? Because the customer may not want to change the tune
and you may not be able to find a replacement mechanism with the same tune. I have been
through this hundreds of times.
The squeak can also be caused by loose hardware in the
clock anywhere. Check very carefully for loose screws or wood parts.
The governor assemblies can be rebushed if they aren’t worn too badly, and
this is preferable , because the original tune can then be saved. There are some
replacement governor assemblies available, but quite ofter the correct gear ratios are
not included. Also, it is possible to rebush the player drum assembly. Use the appropriate
reamer and very carefully, by hand , open the holes on the frame and press the bushing
in with a pair or flat parallel jawed pliers. Make sure the bushing fits the shaft before
it is pressed in.
DO NOT EVER PUT ONE OF THESE IN AN ULTRASONIC CLEANING
MACHINE , THE DAMPERS WILL BE BOILED OFF AND IT WILL BE RUINED.
There are music mechanisms that have only the tune part separate , and the gear
train is in the main mechanism. The usually have large vertically mounted governors,
with adjustable fan blades . Watch out for these ; if the worm gear has worn teeth , it
will never work correctly . On music cuckoos , if the return spring on the side mount
music mechanism it too tight; the entire time/strike mechanism will bind up and stop.

Most cuckoos have what is sometimes called an “Anchor escapement” system or a “Recoil
escapement”. This type of system does not have a lock action , it is simply impact, slide ,
and release. The recoil escapement is less critical to adjust, and generally speaking ,
is more efficient in that it does not take as much power to run. However this type of
system is less accurate because the motion of the pendulum is less isolated from the
gear train. The escape wheel tends to bounce backwards at each impulse ; and as the
spring runs down the arc of the pend slows causing less bounce or recoil in a nonlinear
manner. In the case of weight drive cuckoos this is not as much of an issue.
Make sure that the verge-escape wheel depth is set such that the pendulum will not
swing far enough to hit the sides of the case enclosure. The depth settings will vary
from clock to clock. If the original depth setting is lost; a general rule I use is
this: the working surfaces of the escape wheel tooth contact with the verge surfaces
( the slide and release ) should be 20 percent of what the total depth would be if it were
taken all the way to the point at which the verge surfaces would not release the escape wheel
teeth.
If possible the escape wheel should move equally on each
side of the tick. Often the verge has either been bent or replaced and the escape
wheel will impact,slide and release further on one side than the other; and in many
cases the clock will run. My experience has taught me that this is not an extremely
critical adjustment on this type of verge with respect to whether or not the clock will
run.If the goal is just to get it to run ; then don’t be fussy. To charge a customer a
premium price for this kind of work , however is quite another matter. The majority of
clocks (excluding cuckoos) that I have seen over the years have an even release distance
on the impact ,slide , and release. If you want to do accurate, original , restoration;
then set both sides of the sequence equal.

 Cuckoo Clock chain fitting: 

Chain problems: 

Clock finishes:

In 25 years of repairing clocks some facts about old clock finishes became
painfully obvious. First if you are not a wood worker do not attempt to “restore”
your clocks finish. There are thousands of clocks that have had their antique value
completely ruined by well meaning owners.

By value I mean two things from the perspective of a collector, or a museum :

A. The “market” or monetary value.

B. The value that you cannot put a “price” on; that value that brings something out
of the past of society and its creations of manufacture to us here in the present.
What an old clock usually means is a piece of the past here in front of us now. The
fact that it is a time piece increases this feeling. The industrial revolution
was part of this. Many factories made millions of clocks. As a society we like to
be able to see part of our past. If you take this past and destroy it or change it
you are in effect cheating society out of their ability to see the past. Altering
an old timepiece by painting it or changing its finish is an example of this.

Clocks that have been in families for multiple generations are an exception to this.
An example would be “Great Grandfather made this clock and this is the finish that is
supposed to be on it”. How can you argue with this? You can’t. At least not and be in
How can you tell someone that their ancestors destroyed the value of an
excellent antique clock? You can’t. My suggestion is don’t try. To them it doesn’t matter.
So value is relative. Be aware of this before you decide to do something to the finish of an old
clock, or any clock for that matter. Unless it is custom built from the ground up ;
do not alter the finish; and even then you are taking a chance.
If you have an old clock and you change its finish to make it
look like new; you will alter its value forever. The only time I would recommend
re-finishing an old clock case is if it is literally falling apart ; in other words it
is in pieces. Get a professional furniture refinisher with a good reputaion to do the work
for you.

There are things you can do to make a case look better without destroying it.
Lemon oil on a SOFT rag can work wonders. I have left the rest up to wood workers.
If you are fortunate enough to have 15 or 20 years of professional experience
in wood working and 15 or 20 years in clock repair then you are probably qualified to
do case work and mechanical clock mechanism repair. ( Lets see, if you were 21 when you
started you either worked 80 or 90 hours a week for 20 years or you worked two careers
back to back and you are now in your late 50’s. Well , any way you get my point.)
Usually clock repair shops will have someone they work with that knows case
repair. If you want to know what your particular old clock should look like you should
check with your local chapter of the NAWCC. They are
a non-profit organization. You will get your best information from them.

 Bushings:

Be very careful in your assumptions about the extent of our knowledge in this century compared to what has been known in the past. Society’s knowledge of gears, gear ratios, and mechanical devices goes back considerably longer in time than a few hundred years. The Greek scientists had built a bronze mechanical device similar to a clock in that it had gears using complicated ratios, sizes and combinations of gears. This device was built around 80 BC and was discovered in a shipwreck near Greece in 1900. For a long time the scientific community of the time refused to admit that the Greeks could have built anything like this mechanism, yet recently it has been shown to be authentic and has significantly altered established ideas of what the ancient people were capable of. The existence of this device, which was used to compute the seasons and positions of stars and possibly the passage of time in lunar units shows us that the art of brass and bronze gear making goes back thousands of years. . . but don’t take my word for it; here are some links to information about this fantastic discovery:

http://antwrp.gsfc.nasa.gov/apod/ap061205.html 

http://commons.wikimedia.org/wiki/Image:NAMA_Machine_d%27Anticyth%C3%A8re_1.jpg 

http://en.wikipedia.org/wiki/Antikythera_Mechanism 

http://www.nature.com/nature/journal/v444/n7119/abs/nature05357.html

http://ccat.sas.upenn.edu/rrice/apagadgt.html