Westclox Big Ben Alarm Clock

[watchtinker]

I recently bought a Westclox Big Ben alarm clock and for some reason at random times the hands will stop moving. The clock continues to run but the hands don't move. So for instance, for the last 25min the clock has been stuck on 3:55. Does anyone know what could cause this, and is it a simple fix?

 

[RJSoftware]

The mechanism that allows a clock's hands to be set independently from linkage to the time train is called the clutch. The time train is the series of gears starting from mainspring and ending at the escape wheel and anchor which rotates the balance wheel back and forth The pinion acts like a stop for the spring to push tight against washer/pin.

If the pinion is not split then one can often reach inside the clock with a pair of needle nose pliers and adjust tightness without disassembling the alarm clock. Sometimes scooting the pinion or bending additional bend in cupped washer works well. Basically adding more resistance.

One good way to tell is how easy the hands move when setting the clock's time. There should be some resistance felt, not a real struggle to change the time, but some resistance. If it's way too easy then your probably on the right track.

RJ

 

[bangster]

Can you show us a picture? There are many different models of Big Ben.

 

[watchtinker]

Here are the photos.

 

[R. Croswell]

Here's a picture of a typical Big Ben "clutch" assembly close up. I agree that something wrong in this area is likely the problem. Note that the three-finger 'copper' spring element provides the pressure. It is held by a pressed on brass collar. It is important to determine what is slipping and why before attempting a "fix" by bending stuff. Perhaps there is just accumulated wear, perhaps the spring element is broken, perhaps the brass collar has slipped, perhaps it has been apart and the collar not pressed on far enough. If the collar is loose, bending the spring 'tabs' will only be a temporary fix. This issue can best be addressed and repaired with the movement disassembled.

RC

 

[RJSoftware]

If after examining carefully, you may have success inserting a semi wide flat blade screwdriver and with twisting motion get the brass bushing that the arrow is pointing at to slide. I am only guessing as I can only sort of see it.

Turn the time setting knob and see where it slips on center minute arbor.

But if I am correct and that bushing is working like a stop, then inserting a screwdriver blade between the plate and bushing and with a twisting action you might be able to scoot the bushing over making it tighter. You would do this equally on both sides. Hopefully that bushing is not cracked. Cracked bushings can have a hairline crack which is hard to spot sometimes.

Taking an alarm clock apart is not good for a first clock as some of the pieces are threaded on (some left handed threads too) and others are peened/friction fit. Some require pinion gear pullers and are a bit rough to deal with. That and the balance wheel cup assembly is not as service friendly as watches are.

Another option (highly discouraged) is if you have a split pinion/bushing is to super glue it. If you do so, try to go sparingly on the super glue by applying drop to a plate or something and then use a small screwdriver tip to apply tiny amount. Super glue can make a heck of a mess.



Later you can restore the bushing/pinion properly if you wish.

RJ

 

[watchtinker]

Thank you for all the advice. I don't really want to take the whole thing apart right now so I just bent the tabs a little more. It seems to be working now. Now the clock is just fast.

 

[R. Croswell]

Thank you for all the advice. I don't really want to take the whole thing apart right now so I just bent the tabs a little more. It seems to be working now. Now the clock is just fast.

Glad your clock is working again. If the problem should come back, another issue with these is the cast 'bright metal' lantern pinion shroud (and other cast 'bright metal' parts) sometimes slip on the arbor. The metal is very soft and does not grip the arbor very well. If the lantern shroud slips it can relieve the spring tension on the clutch parts.

RC

 

[bangster]

In which case, apply Loc-Tite.

 

[R. Croswell]

In which case, apply Loc-Tite.

Yes, that can work if one can get into the joint. Usually works best in the parts to be locked are separated and cleaned first. 609 Loctite I have used

RC

 

[RJSoftware]

Cool beans. It usually makes sense that it now is too fast as the previous owner may have adjusted the regulation to faster to try to compensate for the clock running slow/behind but now understood as most likely slipping. Try to avoid pushing the regulation adjustment fast. While movement is out of the case examine the regulation loop adjustment and set to approximate middle. The middle position is where it should have been when out of the factory. But nothing is perfect.

The concern is what often happens when the regulation loop is not proper it can snag the hairspring of the balance wheel and bend it up. You can straighten a bent up hairspring with tweezers but you don't get too many forgiveness bends. Eventually the thin little strip of metal bust.

The hairspring regulation loop should slide smoothly in a small arc of only a small amount of degrees over a small portion of the hairspring near it's terminal end.

When the hairspring is adjusted from it's full + or -, the regulation loop should not deform/push the main body of the coil. This may mean adjusting the loop to better accommodate the hairspring or adjusting the bends at the end of the hairspring to accommodate the regulation loop. The bend of the hairspring at the termination point that provides the gliding portion of the hairspring to the regulator is called the "dog leg". Another term for "offset bend".

This is needed because often the arc of the regulator loop does not match the radius of the hairspring coils. When this is not attended to new owners will unknowingly bend the hairspring when they adjust the regulation.

The regulation is fine tuning of only minutes a day, it can not overcome major tuning of much more. This is a general description so first regulate as best you can with the regulator.

If the farthest setting does not do enough then it is time to re-vibrate the spring. Not easy for beginners and this is often why hairspring length should never be cut. For once you remove you can't add unless you cheat and use a portion of hairspring attached by super glue. No guarantee how long it will hold.

That is another reason why clocks and watches that run slow is good and fast is bad. If it has short hairspring with no extra after the terminal pin.

RJ

 

[R. Croswell]

......... It seems to be working now. Now the clock is just fast.

As with the 'slipping problem' it is best to determine why it is running fast before messing with stuff. That's a common problem with these old Big Bens. First, how much total rotation do you have of the balance wheel from when it stops in one direction to where it stops in the other? Goal is about 360 degrees but it may run OK with 270. Weak balance rotation almost always results in the clock running too fast, especially if the rotation is less than 270 degrees. Weak rotation can be caused by many things including general wear, dirt, lack of lubrication, too much lubrication, oil that's too heavy, 'messed up' hair spring and/or regulator loop. A very common cause is worn points on the balance staff and/or worn balance screws.

If you have good balance rotation, then take a good look at the regulating loop where the tail of the hair spring passes through. With the clock running, the hair spring should be centered in the opening of the loop. That is, as the balance rotates back and forth the tail of the hair spring should touch first one side of the loop and then the other. If the hairspring tail is in continual contact with just one side of the loop opening the regular is likely pulling the hairspring off center. The shape of the outer coil of the hairspring is important as is the position of the regulating loop. You want to have the hair spring tail centered in the loop through out the range of the regulator.

If you don't have good balance rotation find and fix that problem before messing with the regulator and hair spring. You can't regulate a clock that isn't otherwise running properly.

RC

 

[RJSoftware]

I have found that 3/4 turn (210 degrees) is generally good enough for alarm clocks. More is better. As mentioned the less the wheel turns the FASTER the escapement. This is because the less the balance turns the faster it can return back. So you don't want a weak rotation, more robust the better. A lot depends on how fast it is and how well the balance is turning.

But, adjusting the regulation loop is a good first step. If problem solved, then problem solved.

RJ

 

[watchtinker]

Well the Balance appears to be rotating somewhere between 270 and 360 deg. One thing I noticed though is that when the regulator is pushed all the way to the slow end, the hairspring is in the center of the regulator loop, but as I push it toward the fast end it rests on the outer edge of the Regulator loop. Also the inner edge of the regulator loop touches the main body of the hairspring when it is toward the fast end.

 

[RJSoftware]

The only real concern when it comes to alarm clocks is that they fall within a couple minutes a day. So the hairspring resting on the regulation loop outer/fast position is only of concern if it's effect is noticeable in the body of the hairspring. If it pushes those coils noticeably. There is also not suppose to be any portion of the coil touching other coil. There should be airspace between even if only miniscule. If they touch each other that is the same effect as shortening the hairspring which drastically increases the speed.

How fast is it per the day?

Well the Balance appears to be rotating somewhere between 270 and 360 deg. One thing I noticed though is that when the regulator is pushed all the way to the slow end, the hairspring is in the center of the regulator loop, but as I push it toward the fast end it rests on the outer edge of the Regulator loop. Also the inner edge of the regulator loop touches the main body of the hairspring when it is toward the fast end.

 

[R. Croswell]

..........Also the inner edge of the regulator loop touches the main body of the hairspring when it is toward the fast end.

It should not do that. Is it possible that the inner edge of the regulator loop also touches the main body of the hairspring momentarily when the regulator is in mid-range as the hair spring expands or "breathes"? It sounds as if the hair spring is distorted or off center or the portion that passes through the regulator loop has the wrong shape, or perhaps the regulator loop is bent inward toward the main body of the hairspring. These can be frustrating to work on and get right.

RC

 

[watchtinker]

How do you work on it? Also the regulator doesn't seem to do anything. The clock still seems to gain the same amount no matter where the regulator is.

 

[R. Croswell]

The barrel and its arbor should run properly. This is after you have ascertained that the mainspring works well within the barrel. Now follow down all the wheels and pivots. All should run smoothly before you enter comprehending faults within the escapement.

I have to agree this is important, but watchtinker stated "Well the Balance appears to be rotating somewhere between 270 and 360 deg." No guarantee but with that kind of balance rotation there's a pretty good chance that the going train from the main spring to the balance wheel is in pretty good order. One other issue with Big Ben's that have the "alternating"alarm feature where the alarm cycles on and off every few seconds instead of sounding until the spring runs down is even when the alarm is not sounding the time train has to lift the alternating control lever every few seconds. This can load the going train and result in a decrease in balance rotation briefly every time the alternating lever is lifted. Make sure the lever moves freely. Other issues such as rough suggested of an intermittent nature in the going train can be a problem as well.

RC

 

[RJSoftware]

The situation you described below is proof that the hairspring dog leg is not following the curve of the regulation loop. But it is usually the extreme ends (full fast or full slow) when the clock is out of the case, that is not normal operation. When the clock is in the case fully assembled the regulation sweep is shortened.

But, you have not answered the question of how fast the clock is running. So if it's only minutes a day off then , hey it's an alarm clock, not a astronomical time keeper.

If your a beginner I would not recommend hairspring work till you get more experience with more disposable clocks.

If it's much faster per the day then you may have to restore the hairspring.

The rule for bending is for "out of round", 90 degrees before the error result is seen. So if a coil is obviously wide or narrow (touching another) then go 90 degrees before that and bend there.

The rule for bending "out of flat" is 180 before.

For the bending of out of round, the bend happens where you grip the spring with the tweezers. You can use any object to bump when the spot you desire to bend is held next to tweezer tips. So basically grab where you want it bent and use your finger tip to flex the result.

For bending out of flat you use 2 tweezers. Grab 180 degrees before the result with one tweezer and next to that with other tweezer roll the one tweezer so that it bends a twist. This twist action is harder to do than out of round but with enough practice you can get errant coils to lay flat.

There are only two other hairspring modification tricks. One is the untangle of a cross over loop. The cross over loop happens when an outer coil works it way by accident in between inner coils.

This can be easily solved by grabbing terminal end of hs, stretch moderately and orbit in figure 8. Sometimes it works -sometimes not. Sometimes you have to work the errant coil outward with needle working the coil to outer coils. Then try the 8.

The next trick is for coned hairspring coil. A cone happens by accident when a hairspring is stretched and forms a cone. This is fixed by stretching the hairspring cone in opposite cone. Test stretch and take small measures first for results.

Beat:
The hairspring collet that connects to the balance wheel arbor is friction fit to the arbor. The collet has a slit that you can insert a small watchmaker flat blade screwdriver into.

If the hairspring has descent form, coils are in-line from side view (called true in the flat) and coils are not touching and the coil is evenly spaced (called true in the round) and the dog leg (bend that conforms to regulator and is staked at the terminal) is reasonable, then you may need to work on the beat.

The beat of the balance wheel has to do with the balance working equal distances on both entrance and exit. Look and see the small pin that is on the side of the balance wheel. This pin interacts with the palette fork.

If you can, look at movement from side view and examine the rotation of the pin while the balance turns back and forth. If you draw a straight line between the lever arbor and the balance wheel, you should see the pin appear in equal amounts on both sides of that line.

To be in beat the pin pushes the lever in equal amounts for the entrance palette and exist palette. If you find that the pin favors one side you can change this in the following way:

Insert a flat blade screw driver into the hairspring collet. You may have to rotate it with a finger to an accessible position. Insert the blade holding with one hand, with other hand/finger CAREFULLY, SLOWLY rotate the balance forcing the friction fitted collet of the hairspring to give and allow the balance to turn. Rotate till the pin is in a better position.

The evidence of a good beat is evenly spaced "tick-tock-tick-tock". Unevenly spaced "tick-tock...... tick-tock......tick-tock is evidence of not being in beat.

Though this expression may seem crude it points out that there is a different sound between entrance palette(tick) and exit palette(tock). So you understand.

After you have established the clock to be in beat, check and see what the results are. Beat however is not really related to time keeping but more to keeping movement working.

The other thing left is to re-pin the hairspring at the terminal. If you are lucky you will have extra length left over after the termination. You will most likely see a taper pin inserted in the termination block.

So, you want to terminate at a longer point. Depending on how much extra you have left you can experiment at about 1/8th inch intervals.

But understand, when you re-pin the hairspring at the terminal, making the effective area of the hairspring longer, you will have to re-establish the beat. You can get away with some re-pinning without losing the beat too much, but, the more you add the farther the pin moves out of the alignment for equal "tick-tock".

In the probability matrix of cause and effect, I would suspect out of round, out of flat and maybe touching coils.

RJ

Well the Balance appears to be rotating somewhere between 270 and 360 deg. One thing I noticed though is that when the regulator is pushed all the way to the slow end, the hairspring is in the center of the regulator loop, but as I push it toward the fast end it rests on the outer edge of the Regulator loop. Also the inner edge of the regulator loop touches the main body of the hairspring when it is toward the fast end.