Clock Running Slow

sandy06230

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Feb 24, 2021
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Hi,
This is my first time owning a key wound clock and first time on the forum. I recently purchased a Seth Thomas, 1962 Woodbury Mantle clock A401. I cleaned and oiled the pivots and got the clock in beat. The clock now runs and chimes ok but it seem to be losing time. In the last 12 hours, the clock has slowed by 7 minutes. The pendulum bob weighs 2.44 oz and the pendulum leader is approximately 1.75" long. I've played around with the adjustment nut on the bottom of the bob and find that even when it's in the highest position possible, the clock still seems to lose time. I'm wondering if I should try purchasing a lighter bob or short leader. Any help would be greatly appreciated.

UNADJUSTEDNONRAW_thumb_1a69.jpg UNADJUSTEDNONRAW_thumb_1a68.jpg
 

shutterbug

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Hello Sandy, and welcome to the forum!
It looks like everything is right. You might check out a thicker suspension spring. Also look to see if there's anything preventing the pendulum bob from going any higher. It looks like there's plenty of room there.
Have you done anything else to it? It may just need a full service ... polishing pivots and installing bushings.
 

sandy06230

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Feb 24, 2021
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Hi Shutterbug,
Thanks for the quick reply. I just moved the bob up to it's highest point so I'll monitor it for a few hours and see what happens. Is the suspension spring what the pendulum leader sits on? If yes, I'm trying to understand how a thicker spring would speed up the clock. When I first got the clock all 3 arbors wouldn't wind. I spent hours reading posts on this forum and learned so much which is how I got the clock running...thank you all for sharing your expertise! The only thing I did was remove the brass mechanism (not sure that's what it's called) and cleaned the pivots on both sides and oiled all pivots and arbors with clock oil. I also adjusted the beat so the clock would stay running.
 

R. Croswell

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If you didn't disassemble the movement then you didn't really clean it sufficiently. Considering the age of the movement, I suspect you will find that it has considerable wear to some of the pivots and pivot holes. A thorough cleaning and inspection should be the first step, and that includes removing the main springs. Unless someone has messed with this clock and substituted parts there should be no need to change parts. The weight of the pendulum has very little to do with how fast or slow the clock runs. The length of the pendulum is the primary regulating variable but lack of power will also affect how the clock runs. This isn't really the best clock as one's "first clock service".

RC
 

Willie X

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Welcome to the MB,

Your pendulum finish doesn't match the clock, so you could have a replacement pendulum there. Or, someone may have simply polished the old one?

I would take the pendulum off, remove the rating nut (at the bottom) completely and slide the bob completely off. A good look at the threaded part will tell you what you need to know. Your pendulum bob needs to go about 1/8" higher.

I have some of these clocks and can post a photo of an original pendulum, if necessary.

Willie X
 

sandy06230

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Feb 24, 2021
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I didn't disassemble the movement after reading about the dangers of the mainspring power. The mainsprings on the clock are contained in a brass enclosure so if the clock is wound down, not sure if it's still a safety issue as opposed to mainsprings not enclosed? If I wanted to play around with the length of the pendulum and shorten it, could you recommend which leader would work with my clock and where to purchase? Thanks!
 

sandy06230

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Willie,
If I remove the nut and slide the bob off completely, please let me know what I should be looking for (newbie here).
 

Willie X

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Without the nut, the pendulum bob should slide off easily and also slide up, all the way the the square hanger part. There should be enough threads to get it about 1/8" higher than it is now. If you find something that is blocking/limiting further upward movement, thar's yer problem. Willie X
 

sandy06230

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Feb 24, 2021
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Willie,
I was able to slide the pendulum up about 1/8" as seen in the pic so I guess time will tell:) You can see the backside of the pendulum isn't so pretty. I hadn't considered the pendulum may not be original. UNADJUSTEDNONRAW_thumb_1a6a.jpg
 

Willie X

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For a test, just run it in that 'full up' position for a while. It should go fast. Willie C
 

R. Croswell

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I didn't disassemble the movement after reading about the dangers of the mainspring power. The mainsprings on the clock are contained in a brass enclosure so if the clock is wound down, not sure if it's still a safety issue as opposed to mainsprings not enclosed? If I wanted to play around with the length of the pendulum and shorten it, could you recommend which leader would work with my clock and where to purchase? Thanks!
Mainsprings always pose a potential danger. When the clock runs down and stops there is still considerable power left in the springs. One would use a letdown tool to hold back the power of the spring while releasing the click (the gizmo that clicks when it is wound and what keeps it from unwinding) and slowly allowing the spring to totally unwind until it is completely "let down". At that point you can rock the main wheel (gear) back and forth and it will feel loose. All three springs need to be let down, then it will be safe to disassemble the movement (after taking pictures and notes so you get everything back).

Removing the springs from the brass barrels is best accomplished using a spring winder tool. The spring will expand several times the diameter of the barrel and can pose a danger if you loose control of it, but it is important to remove and clean the springs. This may be a good time to read a couple books on basic and chime clock repair. For this one, I recommend Steven Conover's books; Clock Repair Basics and Chime Clock Repair.

RC
 

sandy06230

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Thanks for the book recommendation...I would love to be able to service my own clock. Is there a clock you would recommend to start out with before jumping into the Woodbury for the first time disassembling?
 

Kevin W.

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Hi Sandy. The best clock to learn on in my opinion is a 30 hour Ogee clock movement. No main springs to contend with.
 

sandy06230

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Thanks Kevin...I'll look on FB Marketplace for that type of clock. In the meantime I just ordered the Clock Repair Basics book that RC recommened. I'll report back as to how the Woodbury is running since moving the pendulum bob to the highest position (fingers crossed).
 
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Thomas Sanguigni

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I don't know what part of the country you live in, but you can still attend the school of Horology at Gem City College in Quincy, IL. I enjoy working on clocks, and have for some time now.
 

sandy06230

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Thomas,
I'm in CT...I didn't realize you could take classes on the subject. I'll look to see if there's any classes nearby since it's something I would enjoy. Thanks!
 

sandy06230

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Unfortunately it looks like there's only jewelry and watch repair classes in my area:(
 

R. Croswell

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Thanks for the book recommendation...I would love to be able to service my own clock. Is there a clock you would recommend to start out with before jumping into the Woodbury for the first time disassembling?
An American made time and strike (no qtr hr chimes) with open springs (no spring barrels). A so called kitchen clock that has the escapement outside the frame An OG 30 hour is simple to work on but not so easy to setup on the bench with the weights.

RC
 
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sandy06230

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Thanks RC...I'll keep that in mind when selecting a first clock to work on. I'm going to start out reading the books you recommend first.
 
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disciple_dan

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I post #9 it looks like your pendulum has been rubbing up against something. Can you see any worn places on the back of the movement?
 

sandy06230

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Hi,
There's no wear on the movement. Not sure why, but the 'brass' is flaking off the backside of the bob.
 

sandy06230

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Moving the bob up to the top solved the problem...the clock is running a little fast now but that's easily fixed. Thanks everyone for your help!
 

shutterbug

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If you want to look into an online course, Tascione has one that's pretty reasonable and very thorough. Click on his name.
 

disciple_dan

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Hey, Sandy. I think you may still have the rubbing issue when you lower it down to slow it. It looks like it has been rubbing a screw or a pivot on the chime housing. I can see that even on the front of the bob there is a rub mark. It was probably on with the shiny side in at some point. It's worth checking out. You'll get it. Danny
 
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