My granny's old clock. Fired up after at least 15 years languishing in an attic. Cleaned by a professional its runs like er...clockwork.
It has lost 5 minutes in a week or so....it has a pendulum and a regulator at its six o clock position.....the regulator is graduated but which way to turn to let it keep time.
Any ideas >
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Turning the adjustment beneath the pendulum bob clockwise will effectively shorten the pendulum and make it run faster. Actually 5 mins in a week is not too bad so don't move it too much.
Clocks tend to speed up and and slow down dependant on the temperature so don't expect quartz accuracy unless you have a very fancy clock
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Is there no way to shorten or lengthen the pendulum?
Shortening it will make it run faster - lengthening it slower.
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I guess that's what the regulator does.....I identified that it was losing more when it was hot here.....may leave well alone. It's a battleworn but nice clock, has character...
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Trial and error? Move it a notch one way, see if it improves or worsens, then try moving it two notches the other way (ie, one notch back to the starting position, and then one notch the other way)
edit:- by 'notch' I'm referring to however the adjuster is graduated.
Last edited by: VxFan on Sun 14 Aug 11 at 20:59
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>> It has lost 5 minutes in a week or so....
>>
>> Any ideas >
So it's only telling the correct time .. err .. very rarely? You should just stop it completely, then it's right twice a day.
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It must be a railway clock. Apparently if a train arrives within 5 minutes of its advertised time its considered "on time"
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Funny you should say that - My maternal gran had a collection of what would be now called Railway memorabilia in her home. My Grandad worked with the bus company...:-)
An interesting and very understated man - served with the Royal Horse Artillery in WW1.
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My grandad was a docker.
Whatever you wanted....
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Flash player for your iPad guv ?
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>> Flash player for your iPad guv ?
ave a zoom to go wiv it, go on, plenty where that came from mate.
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>> My grandad was a docker.
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>> Whatever you wanted....
>>
Diesel fitter? (Liverpudlian accent).
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Try adding or removing weights, a piece of solder for example.
I've a 400 day clock (one of those that sits inside a glass dome, with four weights that slowly rotate back and forth) and It's neigh on near impossible to regulate the damn thing accurately because of variations of temperature and humidity.
I love it because of it!
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>> Try adding or removing weights,
About 20 years ago I got roped into cleaning out the belfry of the local church. Dead pigeons, the nests and other mess they left that clogged up the ringing mechanism. Will have to wait and see if I suffer any medical problems from all the pigeon faeces and other mess left behind because I didn't wear a face mask when clearing it out.
Anyway, I digress. On the way up the rickety ladder to the belfry I had a good look at the clock mechanism. On the shelf nearby were several old coins. Their purpose was to regulate the clock by adding or removing some from the ledge of the pendulum weight. It was a fine art by the old boy who used to look after it by all accounts. When he died no one else could maintain the accuracy of it. All since ripped out and an electronic mechanism installed in its place with only the original hands and face of the clock remaining.
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Weights on a pendulum make no difference. The frequency of oscillation is solely dependent on the length.
Is it a 7-day clock? Wind it once a week on the same day, and don't be tempted to wind it more frequently. Cheaper clocks often run slower (or perversely, sometimes faster) as they run down, so you need to average out that error.
Don't keep making adjustments during the week - it may gain/lose during the course of the week. You can't help that, it's the weekly result you need to be minimising.
5 minutes is pretty poor for an averagely decent clock. You ought to be able to get it down to about a minute with careful adjustment. As you get closer, and are down to making 1/2 or 1/8 turns, it is vital to keep a detailed record, not just twiddle it up and down.
At a certain point you will find you can't improve it any more, because the uncontrollable factors like temperature and inherent clock quality and design become significantly larger than the variations you are measuring.
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>> Weights on a pendulum make no difference. The frequency of oscillation is solely dependent on
>> the length.
Weight AND length. Otherwise all clocks would have exactly the same weight on the end of their pendulum.
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Pendulum clocks have an adjustment on the pendulum whereby a a small weight can be wound up and down a screw to adjust the timekeeping. The length of screw and therefore the length of the pendulum remains unchanged. The duration of the swing on where the mass of the pendulum is located not its absolute length.
If you were to tape a paper straw to the end of a heavy pendulum it would make virtually no difference even though you had considerably extended its length.
As far as accuracy is concerned this of course depends on the quality and age of the clock. I have several and the typical 1920s wall clock in the hall is accurate to about 2 or 3 mins a weeks at best .
Temperature makes a lot of difference and I have another clock with a compensated pendulum designed to counteract the effect of expansion and lengthening of the pendulum in warm weather. This is much more accurate- within a minute or so per week.
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See www.physicsforums.com/showthread.php?t=517659.
Sorry, there are various error factors, like amplitude, air resistance, temperature, but the frequency is independent of the weight.
The only consequence of increasing the weight would be to increase the pressure on the escapement wheel - like the person pushing a heavier child on the swing in the example above.
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>> Sorry, there are various error factors, like amplitude, air resistance, temperature, but the frequency is
>> independent of the weight.
Sorry, but I have taken a weight off a pendulum clock, the pendulum remained the same length and the clock shot off like a sprinter with the pendulum frantically nodding away.
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>>
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>> Sorry, but I have taken a weight off a pendulum clock, the pendulum remained the
>> same length and the clock shot off like a sprinter with the pendulum frantically nodding
>> away.
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>>
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That's because in removing the weight you have shortened the effective length of the pendulum. It's got nothing to do with the weight per se. The "length" of the pendulum is the distance from pivot to its centre of gravity.
If you had substituted a weight of identical size but lower density - aluminium for example, it would not have behaved like that.
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>> Weights on a pendulum make no difference.
Not so.
Have a quiet word with the bloke that looks after the Great Clock* at the Palace of Westminster. You will find that he has a supply of old penny pieces which are added to or removed from the weight on the pendulum, in order to maintain time.
* What ignoramuses would call Big Ben
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>> >> You will find that he has a supply of old penny pieces
>> which are added to or removed from the weight on the pendulum, in order to
>> maintain time.
>>
That's because it shifts the centre of gravity and hence the effective length of the pendulum.
If you added more weight at the centre of gravity it would make no difference.
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I was under the childhood impression that it is an 8 day clock - it gets wound every Sundy. It's mournful, but homely, hourly and half hourly "bong" gradually gets more stately towards the end of its week - It's seventy years old plus so I forgive its inaccuracy to a degree, but it would be nice to know if it was tweakable...
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>>but it would be nice to know if
>> it was tweakable...
>>
It may well be. Each Sunday when you wind it, write down by how much it is fast or slow, and then adjust the pendulum a guessed amount, writing it down - eg 1/2 clockwise.
Next Sunday, observe the effect, writing it down. If you have moved in the right direction, eg from 5 mins slow to 3 minutes slow, try another 1/2 turn.
If you overshoot, try 1/4 turn back.
Etc, you get the idea.
But of course it may not be consistent from week to week, because of design, wear, temperature, etc. There is not much you can do about that, but at least it will be the best it can be.
After you have finally tweaked it for optimum weakly timekeeping, you can start observing what happens during the week. Don't start fiddling, just note whether the error slowly increases, or swings about either way. An error that slowly builds up may still be adjustable.
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>> Have a quiet word with the bloke that looks after the Great Clock* at the
>> Palace of Westminster. You will find that he has a supply of old penny pieces
>> which are added to or removed from the weight on the pendulum, in order to
>> maintain time.
And a £5 coin. Keep up!
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>> >> Weights on a pendulum make no difference.
>>
>> Not so.
>>
>> Have a quiet word with the bloke that looks after the Great Clock* at the
>> Palace of Westminster. You will find that he has a supply of old penny pieces
>> which are added to or removed from the weight on the pendulum, in order to
>> maintain time.
>>
>> * What ignoramuses would call Big Ben
Another one who remembers John Noakes climbing the clock??
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Shep followed him up "Get down Shep!"
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>> Shep followed him up "Get down Shep!"
Pre Shep I have the relavant Blue Peter Book c1967/8. Patch and Petra were the dogs then.
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Major driftage here: I own an album by The Barron Knights, which contains their 'hit', 'Get Down Shep'.
Contains a useless impression of Noakes, a bit of a guitar riff, but generally pretty horrible. Takes me back to childhood though.
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I do. John Noakes engaged a generation into learning about "stuff" and being a non-Oxbridge type was unpopular with the BBC's hierarchy
Last edited by: R.P. on Mon 15 Aug 11 at 14:42
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>> a non-Oxbridge type was unpopular with the BBC's hierarchy
Ironic init.
IIRC Noakes started out as a ground tech with BOAC but jacked it in as he wasn't progressing to flight engineer. Probably forgot more about "stuff" than a PPE grad ever knew AND had the gift to explain it to kids without patronising.
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Do wear a mask where those pesky filthy Pigeons have been.
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Damn thing has just bonged nine, bang on time.
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But does the first bong signify 9pm, or is it the last one?
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>> But does the first bong signify 9pm, or is it the last one?
>>
The last. If you were counting the bongs you wouldn't know it was going to be 9pm until that point. Then you would say "Ah, nine o'clock, time for my Ovaltine".
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Ah! But! Big Ben counts the exact time as the first of the number bongs. You dont know what the exact time is unless you look at your watch. Or its 1 o'clock.
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Not that worried ! But I reckon the time slip was due the weather....
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So you've wasted 8 bongs when you could have been running for your train, or else you have been running needlessly only to find it's only 8 pm and you've an hour to wait anyway.
In the stories it's always the last bong that counts - the hero steps calmly into the Reform Club just before the clock stops chiming.
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Update - finally sorted it - now keeping good time after some tweaking of the pendulum - seems that good old fashioned analog actually beats digital as the mantlepiece clock a Seiko clock seems to be slightly less accurate consistently losing time....ho hum
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best time to set a pendulum clock is on the equinox , should be around 23 sept ....dont ask me why
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Clocking - a lost skill. - CGNorwich
