Clock repair blog

Clock Repair Archive – –     
The sessions westminster chime mechanism with only 2 mainsprings can be

recognized by the silver colored large hammer lift assembly on the back plate that is

quite obvious when you open the back door. This is not present on time and strike
mehanism. The assembly is spring loaded . If there is not a coil spring in the cap
on the end, there should be! This mechanism has 2 racks and 2 snails. The front rack
and snail controls the hour count, the rack and snail behind these control the quarter
hour chime. the two racks work together, in other words they both always drop, and
the gathering pallet cam picks both of them up together. They are offset from each
other, that is they drop to different levels. The snail for the hour has 12 levels;
the one for the quarter hour has four levels. Behind the hammer lift assembly on the back
plate is a fixed indexing pin permanently attached to the plate; it should not move,
or be moved unless someone has tampered with it. the hammer lift assembly has a
hole in it that snaps onto the indexing pin at the end of the hour chime sequence ,
allowing the hour count to finish the remaining gear travel allowed for by the hour
strike rack action.

The power to run the chime and strike is transfered through the
long shaft that runs through the hammer lift assembly. The cap on the back end of
the hammer lift assembly has a pin that catches either all the discs in the hammer
assembly, or just the hour strike disc depending on the position of the assembly
as determined by the fixed pin on the outside for the back plate.

To set these mechanisms up after rebushing them, first set up the snails
and racks on the front plate to the 12 o’clock position with the trip cam on the inside
of the plate with the high side having just released the trip lever. The quarter hour
snail should be set so the corresponding rack drops to the deepest spot. Set the hour
snail to the 12 o’clock position of course. The hour snail has a set screw on it so when
the snails are set on the front very carefully tighten that setscrew; be absolutely
certain nothing moves when you do (except the set screw, of course!). Be absolutely
certain that the hour tube still has endshake after this cam is secured. Now move
your attention to the back plate. There is a cam friction fit on the back of the
centerpost that needs to push the hammer lift assembly out (via the swivel lever
on the back plate) far enough to clear the indexing pin so the hammer lift assembly
is in position to lift the hammers that will sound the quarter hour chime after the trip
lever releases. On the hour this cam must just be starting to lift the swivel lever in
order for the hammer lift assembly to be in the correct position when the quarter
hour chime starts. This mechanism can take as long a 1 and a quarter hours to self
correct.

There is an idler gear on the front that meshes with the gear on the quarter hour
snail. This gear is often friction fit on. It should be absolutely tight. It must not
move or the clock will never work. What usually happens if this gear is too loose is that
the clock will mysteriously keep getting out of sequence. It needs to turn of course , but
it must be tight on the shaft. this idler gear, as you will probably notice turns the
quarter hour snail.

There are usually 2 setscrews on the cap on the back of the hammer lift
assembly; be sure to loosen these when you set the chime sequence at the hour.
There is not a lot of spin on the governor before the first hammer picks up on this
clock. The sequence of the hammers is the 1,2,3,4 down the scale at quarter after
similar to the modern german w.c mechanisms.

Clock Repair Archive – –   

Clock Repair Archive – –     

Clock Repair Archive – –

Repivoting skills are a must. The only way to become proficient at this is
practice; lots of practice. Accuracy to within +- .0005in. is absolutely necessary if
repivoting jobs in clock repair are to be done properly. With the piece in the lathe,
perfectly centered, bring the point of the graver SLOWLY to the center of the work as
it is spinning. The graver must be sharp. Razor sharp. In the instant before the end
of the graver contacts the end of the spinning stock, holding your breath is a good
way to steady your touch because you must be absolutely steady or the first cut will
be off. Of course, using the steady rest as a solid anchor for the graver is a must.
In order to make the stock end true center visable; square off the end with a file as
it is spinning in the lathe again makeing sure it is running absolutley true before
you do this. The resulting circular pattern will appear to come to a point like a
bullseye; the point is the true center of the spinning stock. If the true center is
struck, there will be a cone shaped indentation in the end of the stock. If there
is a tiny protruding dimple in the middle of the cone, then center has not been
properly struck. Do not attempt to “drill away” this imperfection, that will not work.
You will have to start over with a flat surface again. You must either have exceptional
vision, or learn to use a magnifier. Drilling the center of a shaft that is .040 of
an inch in diameter is routine. This must be second nature for you. A sharp graver is
needed. Continue to practice striking center and avoid the small dimple in the middle.
When you drill the stock go slowly and use a pivot drill whenever possible, and use oil.
Do be sure, however to get ALL of the oil out before you drive the new pivot in. The
hole that is drilled should be about .001in. smaller than the stock you intend to use.
Be certain you know how the drill bits you are using react. Most high speed drill bits
drill a hole slightly larger than the size stamped on them. This is true for most
repivoting work in clocks on straight shafts larger than .020in. . Use the lathe and
wire chucks to install (drive in) the new pivot. It should not be necessary to strike
the pivot end very hard to get the pivot to seat properly. If possible the hole for
the pivot should be twice as deep as the pivot is long. This is not always possible,
however. If you are drilling into a shaft that has a gear over where the pivot is located ;
be very careful not to drill into the gear so as to weaken it. Check this out in advance.
In order to drill hard steel properly , you will have to draw the temper on it do the
work, and then re-temper the piece when you are done (before you install the new pivot.
This is the correct way to fix a bad pivot in almost all cases. Repivoting may seem
impossible when you first start; but it will get easier with practice. There will
indeed be times when it may not be practical to repivot. For example : a french clock
with the pinion gear as an integral part of the shaft with a bad pivot in the opposite
ind: the shaft will be very hard steel , and it will be very difficult to strike center.
Sometimes repivoting is not the correct solution. For, example, repivoting a mainspring
arbor is not a good idea usually. By the time you get the arbor drilled for the new
pivot, you most likely will have taken off too much metal and the arbor would likely
break when the full power of the mainspring is applied. Knowing when and when not to do
this comes with experience. This is part of that section in the essay where I describe
how a person must know the meaning of differences in power like what is 10 times, and
what is 100 times, and so forth. You must know by the feel of the power of the mainspring
if a repivoting will hold up. All the more reason to practice your repivoting skills.
Know what will break and what will not break with a given force.

Clock Repair Archive – –      

QUAIL CUCKOO CLOCKS:

Quail cuckoos are quite involved and can be very challenging repair items. Have
a test rack set up to run and observe them on. Spend a siginficant amount of time
inspecting the mechanism before you take it apart. Check the bellows for tears or worn spots.
They contain of course 3 bellows and usually have the strike controlled by count wheels. The
quail gear train usually trips the cuckoo train . The quail is tripped at the quarter hour
(every 15 minutes). The quail sounds once at quarter after , twice at half past the hour ,
three times at quarter to the hour , and four times at the hour. Immediately after this
the cuckoo gear train is released and and allowed to count the hour.
Always check for worn pinions on these clocks . They will have to be replaced
if they are worn., That is it ; the clock will not work dependably if they are not fixed.
Also check for worn ratchets; this is a common problem on the older cuckoos. Some of these
clocks have hard steel in the pivots and pinions. Be careful ; they can break easily because
they are very brittle.
The shutoff cams in the quail and cuckoo gear trains can be quite difficult to
set. They must be set so that they they don’t lift the shutoff lever too high to cause it to
jump over the stop pin, but enough so that they still shut off. Do not try to bend the
shutoff lever too far; it is usually very hard brass and will break quite easily.
The brass in the plates of these clocks is usually very high quality (IE: very
hard and wears well ) so only rebush them with bronze bushings and if the bushing
has marginal wear ; it is best to leave it just a tiny bit on the loose side. Be very
cautious of the bushings that are near to the edge of the plate ; the edge of the plate
is very easily broken if a bushing of too large a diameter is used. If you are not sure ;
use the smallest bushing that can be drilled out to fit the pivot. It would be well to
check for this type of situation before you get too far into the repair job.
The count wheel is critical to the proper operation of the bird action. The
shutoff lever where it rides on the surface of the count wheel
must bot be allowed to bounce at all, or the bird will flop in and out
of the little door. The lever must ride solidly on the count wheel without making it
bind. Be sure the count wheel is mounted securely. The looser the count wheel the
more chance of failure. Do not, however, make the count wheel so that it puts even
the slightest undue pressure on the gear train’s ability to move.
The hands on these old cuckoos are brittle and will break very easily. It is
best to look for cracks or places where the hands have been glued before you even
start the repair. This is very important. Check the clock when you first get it ;
and do this in front of the customer. If you find a crack or a place where the
hand has been glued point it out tactfully to the customer and make a note of this
condition on the repair order paper work that the customer signs.
Many of the hands on these old clocks are made of ivory and are
impossible to replace. If the hand is cracked or if you break it during the repair
you will have more trouble that you care to deal with.

Determining the correct type of chain:

If you have a quail 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. Also, check to be sure the sprocket teeth are all
straight and uniformly spaced; significant amounts of wear or damage will prevent even a
chain of correct dimensions from functioning properly. 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
It is not possible  the clock is running or when the clock is being wound. Cuckoo clock chain is catagorized
by the number of links per foot and wire diameter, so it will be necessary to remember
that you will need to calculate the center to center distance between links before you
will know which chain will be the closest fit to your sprocket tooth pattern. Keep in
mind that where the links hook together there are two thicknesses of wire diameter.
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 (theloose 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.

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.
The escape wheel/verge depth on this type of escapement in not as critical as
the dead beat escapement. On most cuckoo clocks the depth should be set so that the
escape wheel is 80% of the way from completely missing ; to actually hitting on the
edge of the verge on both sides(binding up). Generally speaking, the lighter the
pendulum, the deeper the setting on this type of system, up to the 80% amount.
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.

Clock Repair Archive – –     

To calculate the required length for a pendulum you can use this formula: 
where Li is the incorrect length, L is the correct length, E is the error in timekeeping, and R is the length of the test run. Use + if the timekeeping is fast and – if the timekeeping is slow. This is an approximate formula and the results will be as good as your measurments and mathematics. Unfortuantely it is not possible to get an exact answer; but what you will get will be close enough to allow for regulation.
Be sure your error E and length of test run R are in the same units. For example if the clock is 1 minute slow in 3 days you will need to convert the days to minutes or the minutes to fractions of a day before you plug the values into the formula.

Clock Repair Archive – –     

Clock Repair Archive – –     New Haven mainsprings: 

Clock Repair Archive – –   

Most barrel caps are friction fit into the barrel. Installing a barrel cap on a
mainspring barrel can be a frustrating experience if the cap does not fit snugly. Here
is one way to install barrel caps if they are loose. Many times you will notice
that the caps have been forced or gouged and distorted from mis-handling. More often
the barrel itself has been distorted where the cap fits on. This often happens when
the arbor is struck on the end opposite the barrel cap to remove it. This works, but
it will cause the cap to become slightly distorted so it won’t fit tightly when reinstalled.
Most, but not all, barrells are put together this way, so it is necessary to use force to
get the cap off. If the person who removed it does not know about this situation, they
will probably try to tighten up the fit by modifying the edge of the barrel, causing
damage. There is usually a small groove with a shoulder on the inside of the barrel
that keeps the cap from sliding too far into the spring. If the barrel has been soldered;
expect the cap to be loose. If you see scratches and deep gouges around the edge; this
is another warning sign. If the cap has been removed and installed too many times, the
barrel and / or the cap will get warped and the cap will not fit tightly. The diameter
of the barrel cap must be uniformly between 2 and 3 thousandths of an inch larger than
the opening in the barrel, depending on the thickness of the walls of the barrel.

A barrel cap can be installed by clamping the barrel and the cap at one
edge snugly, but not destructively, in a vise with SMOOTH jaws, and then with a
hardwood mallet, the other edge can be installed with some sharp tapping.
Do not squeeze the barrel/cap combination tight enough to distort or destroy the
small edge on the barrel that holds the cap. I have also installed the caps by holding
one end of the barrel/cap in my hand and tapping on the cap with a wooden mallet
with the tooth side of the barrel sitting on a SOLID spot on the bench. This is faster
but a little bit more difficult. If the cap is loose and doesn’t stay put DO NOT
START WITH TRYING TO MAKE THE BARRELL OPENING SMALLER. DO NOT TRY TO MODIFY THE BARRELL.
It is much easier to make a cap than a new barrel. Start with the cap. With a polished piece
of hard steel as an anvil; work the edges of the cap outward gradually by hitting the
cap evenly around the entire circumference of its outer edge with a polished hammer. This
is going to take some practice in order to get the edge even, but it can be done.
Stay as close to the edge as possible without actually hitting the edge. If the cap is
steel; this method will work; however it will take much longer to get the diameter
of the cap increased than if the cap is made of brass. If one is very careful the
diameter of the cap can be increased enough to make the cap stay put nicely. Be sure
to carefully check the barrel for cracks in the sides. As one can imagine; it will not
be possible to get the cap to fit tightly if the barrel is cracked. Again; do not try
to modify the barrel edge; the cap will hold if it fits snugly. Always check the barrels
before you take them apart. If there is evidence of butchery, plan on spending a lot of time
in trying to get the barrel caps to fit properly. Don’t forget to check the cap to be sure
it is flat and not cupped before installing it on the barrel. Remember that when
you hit the metal of the cap in a spot where the metal cannot expand out it will distort
the cap. This is one of those times when knowing how to work with metal in the same
fashion as an artist will be very necessary. This is a classic example of why clock repair is
part technical, part artistic.

If the barrel is cracked soldering may be the only way to fix it. This is one of
those rare occasions where soldering may be acceptable. It is a judgement call. It depends
on how bad the break in the barrel cylinder is. Usually if it is a hairline crack you will
be the first to notice it, which indicates you are a good repair person. In this case If the
spring is a small to average size you will probably be successful with soldering. Do not just
put blobs of solder on the crack and call it good. The barrel must be cleaned COMPLETELY and
ALL oil residue removed before you start. Be sure to remove ALL the flux and clean and polish
the barrel after you are finished. If the procedure is done correctly, the solder will not be
visible and the barrel will hold just fine. Be careful when you do this, because many
barrells are soldered already where the cylinder attaches to the gear. If you get the
barrel too hot, the whole thing will fall apart on you. The best, and the most expensive,
way to fix this would be to have a new barrel made; however If I were doing this repair
for a customer, I would discuss it with them before proceeding. They may want to keep it as
original as possible. You must be able to know from experience whether or not the crack in
the barrel will hold by taking into account the strength of the spring, the design and size
of the barrel, and the extent of damage from the crack. This goes back, again, to the
clock repair essay and knowing the feel of things. After you have wound enough mainsprings
and worked enough metal you will know what decision to make about a cracked barrel cylinder
edge. If you are not sure, replace it. Only experience, or someone experienced who can
look at it, can provide an accurate answer.

Clock Repair Archive – –     

#10 --- .669X .0177 X 58.6
#11 --- .669 X .0157 X 47.25
#20 --- .669 X .015 X 47.25
#21 --- .669 X .0157 X 47.25
#30 --- .472 X .0157 X 43.25
#31 --- .472 X .0134 X 45.25
#32 ---- .472 X .0165 X 43,25
#33 ---- .472 X .0126 X 45.25
#40 ---- .669 X .015 X 43.25
#41 ---- .827 X .0157 X 45.25
#42 ---- .669 X .0157 X 43.25
#50 ---- .669 X .0157 X 47.25
#52 ---- .669 X .0165 X 47.25
#54 ---- .827 X .0165 X 75
#55 ---- .827X .0177 X 71
#56 ---- .669 X .015 X 47.25
#57 ----.669 X .0126 X 59