ST124 : fluctuating speed

DanGrayson

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A Seth Thomas 124 mantel clock, which I've refurbished, has serious problems with speed control. The rate of ticking varies during the week by up to 25 seconds per hour. The strange thing about the timings is that the wide swings in speed go both ways: In the second week it fell behind on Sunday, Monday, and Tuesday, then on Wednesday, Thursday, and Friday it sped up, and then on Saturday it slowed down. The rate varies in a continuous fashion, without sudden jumps. I can't imagine any mechanism that would explain that, since the tension on the spring is decreasing constantly during the week.

I peered closely at the escape wheel and verge, and the teeth are landing in the landing zone, not on the impulse face.

Does anyone have any theories that could explain it?
 
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Dick Feldman

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You said you refurbished the ST 124. What was done with that refurbish?
124’s are notorious for wear. Did you do anything to solve the wear in the movement?
You mentioned springs and the escapement. Unless the escapement has been “adjusted” by a novice, you can usually assume everything to be OK there. Springs seldom go bad. The problem is most likely between the spring and the escapement.
It is also common to not have the plate over the springs to be parallel with the clock plates. This problem arises from (necessary) small spacers being eliminated when assembling the movement by inexperienced repair people.
Pictures from all vantage points may be helpful.
And,
More information needed

Dick
 

Jeff T

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possibly the main spring is sticking to itself ...sometimes they get tacky and the coils stick to each other varying the power. if so clean and lube but I figure you already done that though
 

DanGrayson

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I like the theory about the mainspring, because that could explain variation that expresses itself over the entire week.
Anything involving the other wheels and gears could only explain variations over a 12 hour period.

I'm attaching some photos.

Here is some info about the refurbishing:

-----------------------------------------------------------------------------

Your service record:

Repairs done, Dec 6, 2015:

- modified chime correction mechanism to prevent bouncing (shortened the
chime correction arm by 0.15 mm, so it would slip off the pin sooner)
- modified the speed adjustment mechanism so it wouldn't bind
- replaced broken mainspring (time chain)
- replaced leather hammer tips
- replaced broken chime silencer shaft (someone must have forced it,
breaking off the tip)
- made the slit restraining the pendulum suspension spring narrower to
prevent flexing, which was making noise and wasting energy

Remaining faults:

- I've heard it stop once in three days in the middle of the chiming of the
3/4 hour, with one hammer raised; lifing the hammer allowed it to
continue, so there's not enough force. Next summer I should replace that
mainspring and see if that fixes it.

Repairs done: Fall, 2017 and Spring, 2018:

- Replaced all mainsprings
- Disassembled clock completely, cleaned, polished all pivots
- Installed one bushing. Its inner diameter is 2.0mm, and it leaves the
arbor a bit loose, but it's too late to retreat to 1.9mm, since that one
has a smaller outside diameter. At least it's new, circular, and strong,
so that is an improvement.
- The chime train mainspring was touching the time train mainspring, which
intrudes into its space. Next time I should just order a narrower
mainspring, but I fixed it this time by having 14" of one side of the
spring ground down by 2mm. I've also noticed that after letting the
strike train mainspring down all the way, it was coiled badly, taking up
too much space and putting a large longitudinal force on the wheel,
reducing all lateral play and probably making it hard to turn. So perhaps
that spring is too wide, too. If the clock stops, try fixing that.

Repairs done: Winter, 2018-19:

- December 22, 2018: Asked the clock club what might be wrong with the
movement. They marked a few pivot holes that might need rebushing, and
adjusted the verge away from the escape wheel by adjusting the placement
of the brackets under the screws. I used a screw driver to amplify the
effect by pushing the brass tab holding one pivot of the verge arbor, just
slightly. There seems to be an improvement, tests are underway... Well,
the clock stopped ticking after 6 1/2 days, too bad. The next thing to do
is to get a slightly thicker mainspring for that time gear train, namely:
11/16" x .015" x 54".
- One thing I forgot to do earlier was to replace the leather strip serving
as a cushion for the butts of the chime hammers. I've replaced it, and
that should eliminate hammer bounce and mute the chiming a bit.
- April, 2019: changed the lubrication on the time chain mainspring from
STP to Keystone Light, as an experiment, to see if it will help it tick
for a complete week. Nope, it ticks only for a few minutes.
- April, 2019: my latest observation is that the hanger spring from which
the pendulum hangs is biased toward one side, and that that was aggravated
by shimming one side of the clock movement to get it in beat. I've
corrected that and we'll see. (See the picture "hanger spring.jpg",
showing the corrected spring.)

Repairs done, Spring 2020:

- disassembled, cleaned, polished the pivots, straightened the arbors,
looked at it with Bruce Hannon's help, replaced a bushing, reassembled.
Ticks now for more than a week, replaced the floppy leather backstop I put
in before (for the feet of the chime hammers) with a new stiffer, more
uniform one, so it chimes uniformly now. The main problem now is that it
doesn't keep good time, and adjustment doesn't ever seem to have the
desired effect.

-----------------------------------------------------------------------------

P1030785.JPG P1030792.JPG P1030791.JPG P1030789.JPG P1030788.JPG P1030787.JPG P1030786.JPG
 

Vernon

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Hello Dan, Check for good end-shake with the springs let down. I notice the strike (barrel/cup) is bulged up at the anchor point for the spring. Did you check this (all 3) to see that they were still tight to the cup? I found on the one that I repaired, a cracked cup where the pin fell out after the spring was let down and a bulged one like yours with a loose pin.
 

Bruce Alexander

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Hi Dan,

replaced broken mainspring (time chain)
Is it possible that there was some damage or bending done to any of the pivots here. It would have to be pretty slight if you missed it but such damage might cause periodic depth problems.

- The chime train mainspring was touching the time train mainspring, which
intrudes into its space.
How did you solve this problem again? Did you grind/narrow the spring?

Bruce
 

Dick Feldman

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The hands on the clock only follow the action of the escapement.
If the escapement runs fast, the hands run fast and visa versa.

I think your problem may be operator error.
When adjusting the rate on a clock, one should compare to a known good timekeeper, operate it for three days or more and make a SLIGHT adjustment.
In another three days, a comparison should be made again and maybe another adjustment.
The second adjustment should be 1/2 or less of the first adjustment and so on till the clock keeps good time.
It is common for people to over adjust and not wait enough time between adjustments.
Hence a clock that runs fast and slow.
It is not uncommon for proper rating of a clock movement to take a month or so.
The rating system used on 124's is especially unforgiving of over adjustment.

I am dismayed that your clock or any other would only wear in a couple or a few places and only get a minimum amount of bushings.
Many years experience (and the laws of physics) tell me that clock movements will wear throughout.
A clock can be made to run by only addressing a few wear points but it is only a matter of time before another wear point fails, making the clock unreliable.

I also question the practice of polishing pivots with abrasives.
What will happen to the abrasive material left behind and that imbedded in the pivot metal?
A nice shiny pivot that will actually accelerate wear?
I feel pivots should be metal burnished.

Many clock repair people will attempt to treat the symptoms of the failure and overlook the root cause.
If your springs do not fit properly or are interfering, they are likely the victims of rather than the cause of the problem.
I have owned plenty of those movements and have had many more apart.
I have never found a reason to modify mainsprings from the original design.

Think also about what a sticky mainspring will do.
The power is interrupted when the leaves stick.
The clock then stops.
It is wishful thinking that the spring will supply less power and slow the escapement or supply excess power to make the clock run fast.
You have the cart pushing the horse.

Best Regards,

Dick
 

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You're winding every week, correct? It looks like this one has been an issue several times. It's costing you money. One check - when the clock stops, start at the EW and wiggle each wheel up and down. When you get to the one that doesn't wiggle, that's the problem, either in the wheel or it's driving pinion. It sounds like you have an issue in one of the lower wheels. Maybe a bent pivot, a bad pinion, a meshing (depthing) issue, an end shake issue, a too tight bushing or the need for a new bushing.
 

DanGrayson

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Hi Dan,

"The chime train mainspring was touching the time train mainspring, which intrudes into its space."

How did you solve this problem again? Did you grind/narrow the spring?

Bruce
Oops, it was actually the wheel that was touching the spring. And yes, I had a friend with a grinding wheel narrow part of the spring. Here are photos, before and after:

wheel touches spring - problem.jpg wheel touches spring - solved.jpg
 

Bruce Alexander

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I'm not sure that you have adequate clearance there Dan. I'm sorry if you've touched on this above, but do you know what the proper mainspring sizes are? Also, I think that grinding a mainspring to reduce its width may leave very sharp edges. Whether or not that will affect the torque curve as it unwinds I don't know but I don't think that is an ideal situation. I don't think I'd be very comfortable cleaning, lubricating and otherwise handling a mainspring with a sharp edge to it.

What Shutterbug said above. That's what I was asking about since you had a Time Train Mainspring Failure early on. Are you certain that there are no bent components in the Time Train?

I think that these movements may actually speed up temporarily as the torque drops.

Good luck with it.

Bruce
 

DanGrayson

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possibly the main spring is sticking to itself ...sometimes they get tacky and the coils stick to each other varying the power. if so clean and lube but I figure you already done that though
I liked this theory at first, but now I doubt it: can variation in mainspring force cause ticking to vary by 20 seconds per hour? That's a lot.
 

Uhralt

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I liked this theory at first, but now I doubt it: can variation in mainspring force cause ticking to vary by 20 seconds per hour? That's a lot.
Does the clock have a recoil escapement? If so, maybe. If it has a dead beat escapement, this would be very unlikely. I have a clock that had a very unstable speed and I tried to regulate it for months. I found that the suspension spring had small kinks. My Theory was that the area in which the spring flexes changed form time to time based maybe on temperature changes. This means a change in the effective pendulum length. I replaced the suspension spring and since then the clock keeps time very well.

Uhralt
 

DanGrayson

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Does the clock have a recoil escapement? If so, maybe. If it has a dead beat escapement, this would be very unlikely. I have a clock that had a very unstable speed and I tried to regulate it for months. I found that the suspension spring had small kinks. My Theory was that the area in which the spring flexes changed form time to time based maybe on temperature changes. This means a change in the effective pendulum length. I replaced the suspension spring and since then the clock keeps time very well.

Uhralt
It's a deadbeat.

Maybe I should chart the temperature as well as the speed in another experiment!
 

DanGrayson

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I'm not sure that you have adequate clearance there Dan. I'm sorry if you've touched on this above, but do you know what the proper mainspring sizes are? Also, I think that grinding a mainspring to reduce its width may leave very sharp edges. Whether or not that will affect the torque curve as it unwinds I don't know but I don't think that is an ideal situation. I don't think I'd be very comfortable cleaning, lubricating and otherwise handling a mainspring with a sharp edge to it.

What Shutterbug said above. That's what I was asking about since you had a Time Train Mainspring Failure early on. Are you certain that there are no bent components in the Time Train?

I think that these movements may actually speed up temporarily as the torque drops.

Good luck with it.

Bruce
Yes, the sizes are specified in Conover's book, they agreed with what I pulled out of the clock originally, and Timesavers offered those exact sizes, so I bought them.

It's conceivable that the time mainspring, rather than being too wide, was just seated off center in the box. That could be caused by an asymmetric end hole, or a pin that is not in the right position.

I'm normally careful to check for bent arbors and pivots, by spinning them in the lathe, so there shouldn't be anything bent.
 

R. Croswell

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A Seth Thomas 124 mantel clock, which I've refurbished, has serious problems with speed control. The rate of ticking varies during the week by up to 25 seconds per hour. The strange thing about the timings is that the wide swings in speed go both ways: In the second week it fell behind on Sunday, Monday, and Tuesday, then on Wednesday, Thursday, and Friday it sped up, and then on Saturday it slowed down. The rate varies in a continuous fashion, without sudden jumps. I can't imagine any mechanism that would explain that, since the tension on the spring is decreasing constantly during the week.

I peered closely at the escape wheel and verge, and the teeth are landing in the landing zone, not on the impulse face.

Does anyone have any theories that could explain it?
First of all, the variation in rate is relative. I doubt that the clock is speeding up but rather something is slowing the clock down more at certain times. In a case like this one needs to be careful not to introduce additional problems. Several times you used the word "modified" which sends up red flags. Unless the problem is the result of a previous modification, we can usually assume that the clock did once run properly without modifications. The 124 can be a finicky movement and pretty much has to be near perfect to run well. Here are a few questions and comments:

* The 124 used a deadbeat escapement but there were two different types. One is the usual Graham deadbeat style and the other used two diamond shaped pallets pressed into a brass holder as the verge. Can you please post a close up picture showing the escapement? The important thing with a deadbeat escapement is that the escape wheel teeth must land on the dead face - not on the impulse face or the line of separation between the dead and impulse faces. Is the escapement adjusted for a dead face lock?

* You said, "....Installed one bushing. Its inner diameter is 2.0mm, and it leaves the arbor a bit loose, but it's too late to retreat to 1.9mm, since that one has a smaller outside diameter". The 124 does not tolerate loose pivot holes and that includes the pivot holes that hold the verge. Because the pivots are tiny and the gear teeth fine, it also does not tolerate bushings that are at all off center. You may need to install a much larger bushing at this location and install a small bushing in the larger one.

* You said, "modified the speed adjustment mechanism so it wouldn't bind". I believe you also said at some point that the rate adjustment didn't seem to make any difference. Can we see a closeup of the rate adjuster. Do you have a pin or wire through the suspension spring and the upper support? It is unusual that the adjustment would have no effect. It is important that the "chops" not be too tight. That is, if you tilt the clock forward or backward a little, the pendulum must be free to continue to hang straight down. If the chops pinch too tight it can cause the suspension spring to be twisted is the clock is tilted causing unpredictable rate control and pendulum wobble.

* Related to the above, the pendulum leader rod must be centered in the slot in the crutch foot. If it touches either end of the crutch foot slot the clock will stop of be unpredictable. Is the suspension rod centered in the crutch foot?

* You said "...made the slit restraining the pendulum suspension spring narrower to prevent flexing, which was making noise and wasting energy". Do you mean the chops in the rate adjuster or the slot in the crutch foot? The space between the suspension rod and the slot in the crutch foot should be minimal but must not be zero or operation will be erratic. At least 0.002".

* You said "..The next thing to do is to get a slightly thicker mainspring for that time gear train, namely: 11/16" x .015" x 54". The information I have is 11/16" x .014: x 54" for the ST 124. The clock should operate properly with the original size spring. What size spring is in the clock now?

* You said "..."changed the lubrication on the time chain mainspring from STP to Keystone Light, as an experiment, to see if it will help it tick for a complete week. Nope", This is not surprising. Keystone medium would be more appropriate, or a 75W-90 gear oil, or even a light grease, but that's not the problem here. Make sure the spring is clean and smooth and almost any oil will do in the short term

* You said "...disassembled, cleaned, polished the pivots, straightened the arbors, looked at it with Bruce Hannon's help, replaced a bushing, reassembled. Ticks now for more than a week,........... The main problem now is that it doesn't keep good time, and adjustment doesn't ever seem to have the
desired effect
". The part about straightened the arbors concerns me. Did you find arbors that were bent? Which arbors? How did you determine that the arbors were bent? How did you straighten them and how do you know that they are straight now? The rate adjuster pretty much has to work even if the clock does not keep good time.

* You mentioned having to grind down the width of one of the springs to keep it from hitting the wheel. I ran into that problem on only one ST-124. Seems the radius at the bottom of the drum can was too large (perhaps an incomplete drawl at the factory). I had to grind down the outer coils to get the spring to settle into the can. Any sharp edges can be smoothed while the spring is out of the can, As long as the spring isn't contacting the wheel that isn't your problem.

If you did have bent arbors, the force sufficient to bend the arbor may have damaged the wheel and/or pinion teeth. I suggest a careful inspection of all the teeth. This clock isn't a precision time keeper, but everything does need to right or you will be disappointed.

When the clock is running, what is the total pendulum swing?

RC
 
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Bruce Alexander

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I'm normally careful to check for bent arbors and pivots, by spinning them in the lathe, so there shouldn't be anything bent.
Are you just eye-balling these parts? If there was a mainspring failure in the gear train, you should be very careful to check for any eccentricities. Even minor ones could be significant.

You might also want to check to make sure that there is no "sway" in the regulation chops. Any slop in the suspension can result in issues.
 

DanGrayson

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* The 124 used a deadbeat escapement but there were two different types. One is the usual Graham deadbeat style and the other used two diamond shaped pallets pressed into a brass holder as the verge. Can you please post a close up picture showing the escapement? The important thing with a deadbeat escapement is that the escape wheel teeth must land on the dead face - not on the impulse face or the line of separation between the dead and impulse faces. Is the escapement adjusted for a dead face lock?

RC
Here are some pictures. I've looked closely at it, and the teeth are landing on the dead face, with no visible recoil.

View attachment 616192 View attachment 616193

P1030804.JPG P1030803.JPG
 

DanGrayson

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* You said, "modified the speed adjustment mechanism so it wouldn't bind". I believe you also said at some point that the rate adjustment didn't seem to make any difference. Can we see a closeup of the rate adjuster. Do you have a pin or wire through the suspension spring and the upper support? It is unusual that the adjustment would have no effect. It is important that the "chops" not be too tight. That is, if you tilt the clock forward or backward a little, the pendulum must be free to continue to hang straight down. If the chops pinch too tight it can cause the suspension spring to be twisted is the clock is tilted causing unpredictable rate control and pendulum wobble.

RC
I've just tested it, and the chops are loose enough so the pendulum can hang straight down.

Here are some pictures.

P1030793.JPG P1030794.JPG
 

DanGrayson

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Thanks for all the tips!

* Related to the above, the pendulum leader rod must be centered in the slot in the crutch foot. If it touches either end of the crutch foot slot the clock will stop of be unpredictable. Is the suspension rod centered in the crutch foot?

RC
Well, not centered, but "far enough" from the ends. I've just centered it.


* You said "...made the slit restraining the pendulum suspension spring narrower to prevent flexing, which was making noise and wasting energy". Do you mean the chops in the rate adjuster or the slot in the crutch foot? The space between the suspension rod and the slot in the crutch foot should be minimal but must not be zero or operation will be erratic. At least 0.002".

RC
"The slit" I referred to was the space between the chops, which is still large enough to allow the pendulum to swing freely.

I've just measured the space between the rod and the side of the slot in the crutch foot -- it's between 0.002" and 0.004".

I'm beginning to think the next experiment is to simply replace the suspension spring. (I can trade it with one from one of my other ST124 clocks.)
 

DanGrayson

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Are you just eye-balling these parts? If there was a mainspring failure in the gear train, you should be very careful to check for any eccentricities. Even minor ones could be significant.

You might also want to check to make sure that there is no "sway" in the regulation chops. Any slop in the suspension can result in issues.
Not just eyeballs -- usually I wear my 4x magnifiers on my head when peering closely at such things, and I position an object behind the pivot so
I have a reference point for wobble detection.

I did narrow the chops early on, as the suspension spring was flexing. I suppose that by "sway" you mean excessive space between the chops.
 

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I keep thinking about how the clock only needed one bushing. I checked my records on one that I repaired and I put in 17. Maybe have another look with better lighting and magnification to see if there are any more issues besides the one that you did. I use an eye loop by itself or in concert with my optivisor. If you had a clock timer, that may help too.
 

R. Croswell

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About 27mm, measured at the side of the bob.
27 mm is a little on the weakfish side. I agree with Vernon, a ST-124 requiring only one bushing is a little unusual. Eyeballing isn't always the best. Try placing just one arbor in the bottom plate, then place the top plate in position but don't allow the pivot to enter the pivot hole. "Tilt" the arbor so it travels 360 degrees around the pivot hole. The pivot should be the same distance all the way around the pivot hole. If not, then the pivot hole is worn eliptical or a bushing was installed crooked. The pivot should be about one to two pivot diameters from the edge of the pivot hole. Check every arbor.

When adjusting the rate make the last adjustment in the "fast" direction to take up any slack in the adjuster. Then give the pendulum a little tug downward. Wind the clock to one turn short of a full wind, set the clock, and then let the clock run for seven days without being disturbed. Each day record the indicated time and the number of minutes fast or slow but do not reset the clock. This will give a better picture of how the clock is running.

RC
 

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When adjusting the rate make the last adjustment in the "fast" direction to take up any slack in the adjuster. Then give the pendulum a little tug downward. Wind the clock to one turn short of a full wind, set the clock, and then let the clock run for seven days without being disturbed. Each day record the indicated time and the number of minutes fast or slow but do not reset the clock. This will give a better picture of how the clock is running.

RC
That's what I did, except that it was a full wind, I omitted the little tug, and the test was for 2 full weeks. There hasn't been any adjustment to the rate in months. And any settling caused by missing the little tug could only have decreased the speed of ticking, whereas I observed both increases and decreases.
 

Bruce Alexander

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In the second week it fell behind on Sunday, Monday, and Tuesday, then on Wednesday, Thursday, and Friday it sped up, and then on Saturday it slowed down.
Hi Dan,

In terms of minutes, how far does it deviate from the correct time in one direction or the other before it reverses? How often are you taking notes?
Are the Chime and Strike Trains operating as they should without fail?
Did this behavior only begin after your most recent servicing in the Spring of this year? If so, was the problem immediately evident?

Thanks,

Bruce
 

DanGrayson

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Hi Dan,

In terms of minutes, how far does it deviate from the correct time in one direction or the other before it reverses? How often are you taking notes?
Are the Chime and Strike Trains operating as they should without fail?
Did this behavior only begin after your most recent servicing in the Spring of this year? If so, was the problem immediately evident?

Thanks,

Bruce
The clock is near where I work, so I can record the time it starts chiming the hour 4 to 6 times per day -- it's enough to see that the rate of ticking doesn't seem to suddenly jump. The week of 9/18 it started out on time, got up to 11:38 after the hour in 3 days, then backtracked to 7:27 after the hour. The second week it started out 0:59 after the hour, got up to 4:36 after the hour on the second day, backtracked, got down to 2:47 before the hour on the 5th day, reversed again, and got up to 1:19 before the hour.

Chiming and striking work without fail.

Yes, this behavior is recent and was immediately evident in the spring, but I'm not sure I would have been able to observe earlier, in light of other problems. Hard to tell.
 

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Dan, you are apparently judging the accuracy of the clock by the moment it chimes/strikes. I think we need to confirm the time by the position of the minute hand. I can think of a few things that could cause the strike to be delayed or erratic, but we don't need to go down that trail if the times indicated by the clock's hands are the same as what you report by when it chimes.

Assuming that the time of day and time of chime are identical, I would have a closer look at that deadbeat escapement. Make sure that you understand what the dead face and the impulse face are. It isn't easy to see where the escape wheel teeth land on the face of the verge. If the teeth of the escape wheel clearly land on the dead face as they should its operating characteristics will be quite different that if they land on the impulse face. If the line of demarcation between the dead face and impulse face is worn or rounded off and the EW teeth land on the rounded line of demarcation operation will be erratic at best. The characteristics of the escapement may not be completely dead beat and changing as the spring runs down. If the line of demarcation is rounded the verge will need professional work to sharpen the line and maintain the angles and spacing of the pallets. You might try setting the verge for a bit more lock (closer to the the escape wheel) and see if there is any better regulation.

In solving such a mystery I believe Sherlock said something like after all possibilities have been eliminated, whatever is left is the solution.

RC
 

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I'm sorry, I'm a little confused by your mathematical terminology/reference so I'm just going to review the most recent isochronal error that you're reporting.

Please correct me if I don't have this right...after a full winding for a post overhaul, 2nd week run, your movement gained about 3 minutes 30 seconds in two days (0:59 -> 4:36) in the first two days, then lost about 2 of those minutes (4:36- 2:47) over the next three days and then ended up about about 20 seconds fast (2:47 -> 1:19) in reference to the starting time of 0:59.

Personally, I could see a pattern more clearly if you stated error on a daily basis, but by the end of the week it would seem that your movement was pretty well calibrated to keep decent time, albeit with a pretty fast start which I wouldn't expect with a deadbeat escapement.

Before I go much further though, have I understood your error reporting or do I have it all screwed up? :???:

Ultimately the question is "What was changed?" during your latest overhaul.


Edit:
straightened the arbors
I see that RC asked you about the specifics behind this statement Dan. Did you respond? If so, I've somehow missed it. Perhaps indirectly via my "eyeballing" question?
 
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DanGrayson

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I'm sorry, I'm a little confused by your mathematical terminology/reference so I'm just going to review the most recent isochronal error that you're reporting.

Please correct me if I don't have this right...after a full winding for a post overhaul, 2nd week run, your movement gained about 3 minutes 30 seconds in two days (0:59 -> 4:36) in the first two days, then lost about 2 of those minutes (4:36- 2:47) over the next three days and then ended up about about 20 seconds fast (2:47 -> 1:19) in reference to the starting time of 0:59.

Personally, I could see a pattern more clearly if you stated error on a daily basis, but by the end of the week it would seem that your movement was pretty well calibrated to keep decent time, albeit with a pretty fast start which I wouldn't expect with a deadbeat escapement.

Before I go much further though, have I understood your error reporting or do I have it all screwed up? :???:

Ultimately the question is "What was changed?" during your latest overhaul.

Edit:

I see that RC asked you about the specifics behind this statement Dan. Did you respond? If so, I've somehow missed it. Perhaps indirectly via my "eyeballing" question?
Maybe I didn't make clear that during the time when the rate of ticking was going up and down by up to 15-20 seconds per hour, I was not adjusting the rate or trying to calibrate it. So, no it's not "well calibrated", its rate is all over the place during the week. I attach a photo of a note card on which I recorded some of the times it chimed during a week.

IMG_20201015_065937388.jpg
 

DanGrayson

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Dan, you are apparently judging the accuracy of the clock by the moment it chimes/strikes. I think we need to confirm the time by the position of the minute hand. I can think of a few things that could cause the strike to be delayed or erratic, but we don't need to go down that trail if the times indicated by the clock's hands are the same as what you report by when it chimes.

Assuming that the time of day and time of chime are identical, I would have a closer look at that deadbeat escapement. Make sure that you understand what the dead face and the impulse face are. It isn't easy to see where the escape wheel teeth land on the face of the verge. If the teeth of the escape wheel clearly land on the dead face as they should its operating characteristics will be quite different that if they land on the impulse face. If the line of demarcation between the dead face and impulse face is worn or rounded off and the EW teeth land on the rounded line of demarcation operation will be erratic at best. The characteristics of the escapement may not be completely dead beat and changing as the spring runs down. If the line of demarcation is rounded the verge will need professional work to sharpen the line and maintain the angles and spacing of the pallets. You might try setting the verge for a bit more lock (closer to the the escape wheel) and see if there is any better regulation.

In solving such a mystery I believe Sherlock said something like after all possibilities have been eliminated, whatever is left is the solution.

RC
Yes, the hands seem to be in the right position when it chimes. You make a good point, though -- ideally I would have a machine counting and timing each tick of the clock.

When I had the clock on the bench, I checked, and the impulse faces are clearly delineated from the dead faces, and the teeth are clearly landing on the dead faces, with no recoil. It's hard to those tiny things though, so maybe, the next time I have it on the bench, I should try for a bit more lock. (The current experiment to see if using a different suspension spring will help.)
 

Simon Holt

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ideally I would have a machine counting and timing each tick of the clock.
How tech-savvy are you? There's a member of this forum who has developed a simple application that runs on a Raspberry Pi microcomputer that will monitor both beat and striking and show them as a graph. For example, here's the striking record one of my mis-behaving clocks:

problem clock.png
Simon
 
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DanGrayson

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How tech-savvy are you? There's a member of this forum who has developed a simple application that runs on a Raspberry Pi microcomputer that will monitor both beat and striking and show them as a graph. For example, here's the striking record one of my mis-behaving clocks:

View attachment 617033
Simon
I'm tech savvy. I started a project a few years ago to write code (at DanGrayson/PendulumTimer) for a simple microprocessor (ATmega32U4) so it could use an infrared LED to watch the pendulum pass back and forth. I made progress, but then there were some glitches and I put the project aside. Maybe I should try it again! Or just pull out my raspberry pi and put your friend's code on it.
 

Bruce Alexander

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Maybe I didn't make clear that during the time when the rate of ticking was going up and down by up to 15-20 seconds per hour,
That was clear enough, but then you went to what seemed to be a totally different description in post #28. I asked you to verify or correct my attempted summary of what you were reporting at that point.

I'll assume that I did not have it right otherwise it would seem as though you and I are just going in circles.

I attach a photo of a note card on which I recorded some of the times it chimed during a week.
I really couldn't care less when it chimes at this point. If the clock were in my shop, I'd work on the Time Train's BPH and then worry about the chime points, which can typically vary a minute "fast" or "slow" according to the time shown by the minute hand. These Chime/Strike points often need to be adjusted to re-sync the Trains.

So, no it's not "well calibrated"
Okay. Well, it would seem that you need to figure out what changed during your overhaul since the clock was working in terms of the Time Train's rate before you fixed it. A Seth Thomas 124 Westminster Movement should be able to maintain a rate of 10584 beats per hour.

I've worked on a number of 124s but I've never seen this kind of problem before. Good luck with it.
 

R. Croswell

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Dan, maybe brain fog but I'm still not clear about what you are observing and how. You keep referencing seconds per hour but this clock has no seconds bit and cannot display that that kind of resolution. In a clock like this it is normal for the BPM to change over the course of an hour as the time train interacts with the chime/strike trains.

Are you using an electronic timing device? If so, keep in mind that the rate indicated is only the rate at the moment sampled. Unless the optical sensor is used even an extended sample time period will yield incorrect results because of the extraneous sounds made by the chime and strike trains.

It isn't clear to me how you are determining the rate and how much it is fast or slow.

You cannot read or accurately estimate seconds from the position of the minute hand, and the moment of chiming/striking can fluctuate +/- a minute or so and in as much as the chimes at 12:00 take several seconds to run out the strike is delayed.

The clock should be wound fully wound and set to the correct time of day as close as possible. (set the minute hand 5 minutes fast and turn the hand backward to the left to exactly the correct time. The last movement of the hand should be to the left to take up any slack or backlash in the gears). Record the time. Leave it alone for 24 hours, then compare the indicated time to the time of day and record the difference as; day one + 2 min. (or whatever it is), Do not reset the clock, Check and record the the time again after another 24 hour period, etc. The results will be to the nearest minute indicated by the hands; do not try to record seconds. For the purpose of optimizing this clock, we are first interested in the total time gained or lost over a 1 week period. Then we are concerned with the daily trend - both direction and magnitude to the nearest minute. We need to be sure that extrapolating data to a higher resolution than the clock is capable of yielding isn't the tail wagging the dog.

We really need to get the 7-day start of week - end of week times to be close to the same before we evaluate the daily deviation.

RC
 
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Simon Holt

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Or just pull out my raspberry pi and put your friend's code on it.
If you want to go that route you'll need a USB microphone. Let me know and I'll put you in touch with him.

Simon
 

Bruce Alexander

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What RC said.
Mathematically speaking...
10584 beats per hour
... is an average.

Do a search on "Clock Timer" there are pages of Threads on the subject in the Archives. You'll find anything from manufactured to home-made to downloadable apps that you can use with a Mic or IR beams as sensors. Just make sure your movement is in beat first.
 

Carl Alelyunas

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So the time train is varying 25 second per hour? So early in the week, it gains or loses 10 minutes in 24 hours, then changes to 20 minutes in 24 hours later in the week? That's amazingly bad. My worn out ST124's are good to within +/- a minute over the whole week, and should only get better when I rebuild them. One thing I can think that would cause that is if the escape wheel skips teeth occasionally. So I'd suggest looking very closely at the escapement. Both entry and exit should drop just barely on the dead faces.
 

DanGrayson

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So the time train is varying 25 second per hour? So early in the week, it gains or loses 10 minutes in 24 hours, then changes to 20 minutes in 24 hours later in the week? That's amazingly bad. My worn out ST124's are good to within +/- a minute over the whole week, and should only get better when I rebuild them. One thing I can think that would cause that is if the escape wheel skips teeth occasionally. So I'd suggest looking very closely at the escapement. Both entry and exit should drop just barely on the dead faces.
Yes, looking at the escapement was the first thing I did a few weeks ago. It all looks okay to me.
 

Carl Alelyunas

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Yeah, I figured that you probably did that first, about 30 seconds after I posted.

Anyway, if you have an iphone or ipad, a $30 app called clockmaster is extremely useful for determining problems with regulating pendulum clocks. It shows a running detection of beats per minute over a period of hours using the built-in microphones. As a signal processing engineer, I can say that the algorithms it uses are top-notch; noise gates for when the clock is chiming, missing pulse tolerance, that sort of thing. (I don't have any association with the folks who programmed it; I just think it's well worth the money). By looking at the variance, you can tell how sensitive the beat frequency is to hand position, etc. Here's a typical trace of one of my clocks, with a recoil escapement that hasn't been cleaned or oiled in a while. Its variance over an hour is 3 minutes per day over an hour, with a slight drift of a few seconds per day for spring power. Most of the variance comes at twice per hour, as the minute arbor lifts the gong lever (yeah, I don't know the proper terms), once for the hour gong and once for the half-hour strike lever on the bell. I'd be really interested to see a similar trace of your clock- a true deadbeat escapement on an ST124 movement should be 20 times better- maybe 10 seconds per day variance over an hour with a fraction of a second per day per hour slope due to spring power variance.

IMG_1153.JPG
 

Carl Alelyunas

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I guess you don't drop your ipad enough :D That's how I usually get a new one. Well, actually my wife gets the new one and I get hers.

Speaking of planned obsolescence, did you know that there used to be an app that measured how high you could toss your iphone? I think it was free, too.
 

DanGrayson

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Dan, maybe brain fog but I'm still not clear about what you are observing and how. You keep referencing seconds per hour but this clock has no seconds bit and cannot display that that kind of resolution. In a clock like this it is normal for the BPM to change over the course of an hour as the time train interacts with the chime/strike trains.
Thank you for the advice!

I observe the time of starting to strike the hour.

Are you using an electronic timing device? If so, keep in mind that the rate indicated is only the rate at the moment sampled. Unless the optical sensor is used even an extended sample time period will yield incorrect results because of the extraneous sounds made by the chime and strike trains.
No, I have no electronic device.

It isn't clear to me how you are determining the rate and how much it is fast or slow.
I observe the time of starting to strike the hour.

You cannot read or accurately estimate seconds from the position of the minute hand, and the moment of chiming/striking can fluctuate +/- a minute or so and in as much as the chimes at 12:00 take several seconds to run out the strike is delayed.
Yes, but if I observe the time of chiming at two separate times separated by 24 hours, then any fluctuation on the order of a minute will amount to about 2 seconds per hour (divide by 24), and the fluctuations observed are much greater than that, up to 24 seconds per hour.

The clock should be wound fully wound and set to the correct time of day as close as possible. (set the minute hand 5 minutes fast and turn the hand backward to the left to exactly the correct time. The last movement of the hand should be to the left to take up any slack or backlash in the gears). Record the time. Leave it alone for 24 hours, then compare the indicated time to the time of day and record the difference as; day one + 2 min. (or whatever it is), Do not reset the clock, Check and record the the time again after another 24 hour period, etc. The results will be to the nearest minute indicated by the hands; do not try to record seconds. For the purpose of optimizing this clock, we are first interested in the total time gained or lost over a 1 week period. Then we are concerned with the daily trend - both direction and magnitude to the nearest minute. We need to be sure that extrapolating data to a higher resolution than the clock is capable of yielding isn't the tail wagging the dog.

We really need to get the 7-day start of week - end of week times to be close to the same before we evaluate the daily deviation.
RC
Hmm : I'm assuming that we should first get the rate of ticking to be constant, and then get the rate of ticking to be correct.
 

Bruce Alexander

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Please correct me if I don't have this right...after a full winding for a post overhaul, 2nd week run, your movement gained about 3 minutes 30 seconds in two days (0:59 -> 4:36) in the first two days, then lost about 2 of those minutes (4:36- 2:47) over the next three days and then ended up about about 20 seconds fast (2:47 -> 1:19) in reference to the starting time of 0:59.
Hmm : I'm assuming that we should first get the rate of ticking to be constant, and then get the rate of ticking to be correct.
That would really depend on what your base of reference is. As I stated early, based on a one-week run time, your movement is well calibrated in that it runs fast after a winding and gradually slows down until it's almost accurate by the end of the week. For poor time-keepers, this is one way to "calibrate" them to keep decent time on average. Often one may find a recoil escapement in need of service with a tired mainspring resulting in a weekly isochronal error of more than 3 minutes per week. You can either wind the mainsprings more often or set the rate to run fast anticipating that it will lose time by the end of the week so that, on average, it will keep decent time. That is what I was trying to get at before.

You've presented us with a math word problem and it's still not clear to me when the variance is fast or slow based on the hourly strike over a 24 hour period of time. Generally speaking, I guess that's useful. As mentioned by RC earlier, your Seth Thomas 124 is not a high precision movement but it does use a Deadbeat Escapement and is very capable of proving much better time-keeping than what you've achieved after servicing it.

Since you did not observe this behavior prior to your service, you have obviously damaged or altered something. Assuming that the mainsprings are not the source of the problem, something is interfering with the smooth transfer of power from the Mainspring of your Time Train through the train to the Escapement. It's not rocket science. Is there a noticeable difference in the pendulum's amplitude during your test periods? What about the volume of the Escapement's ticking sounds?

No one seems to recognize this behavior and there are many moving parts to consider so it looks like you're just going to have to go back through the movement and eliminate all possibilities. If the movement was on my bench, I'd let the power down and look for end shake. If every bearing looked to be within acceptable tolerances, I'd go through everything with a fine toothed comb.

Perhaps some mechanical genius here can discern the problem from your description. Perhaps you'll just have to go back over your steps and find the problem on your own.

In any case, I look forward to finding out what has caused your problem. Don't feel bad. These movements can be very tricky and difficult to diagnose. In my experience they are not as bad as three train cuckoos but minor things are a little "off", they are no walk in the park either.

Good luck.

Bruce
 

DanGrayson

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...

In any case, I look forward to finding out what has caused your problem. Don't feel bad. These movements can be very tricky and difficult to diagnose. In my experience they are not as bad as three train cuckoos but minor things are a little "off", they are no walk in the park either.

Good luck.

Bruce
I love a challenge. I look forward also to eventually finding out the single item that causes this strange behavior, and will report back here. Step by step, following all the advice offered here.
 

R. Croswell

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Re: the "Clockmaster" app.

Sadly, I don't have an iPhone and it isn't available for Android phones. I wish it were!
If you have an Android "smart phone" there is an app called "Clock Tuner" that works pretty well. It does not display a graph over a long period of time but it does display over a few second when the sample is taken.

All clocks of this type will have some variation in rate during the course of an hour, day, or week, the question is whether the variation you are seeing is normal. I do not believe that you can answer that question by observing the strike point. For most folks, the important thing is how well the clock keeps time over the week run. If you fully wind the clock on day-1 and set the time of day, then once or twice each day at the same time record on a graph the number of whole minutes fast or slow to the nearest minute. Do not reset or rewind during the week. Connect the dots on the graph and after 8 days you will have a pretty good indication of what's going on.

As for a couple more possible causes for variations, temperature affects this clock, and did you lubricate the springs well, and with what? If the springs are sticking and then slipping the power curve will be all over the place.

RC
 

Bruce Alexander

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Dan,
The good thing, obviously, is that your movement isn't stalling. I've completed overhauls after which I couldn't make that claim. :chuckling:
I think you're very close to getting things where you want them to be to the degree of accuracy this movement is capable of achieving.
Keep in mind that it may not be a single factor. If you have to split the plates again, double-check everything. :thumb:
A nice thing about these movements is that you can look at and work with the Mainsprings, as RC suggests, without having to open up the entire movement.
I definitely agree that you should start with the mainspring(s).

Bruce
 
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