This article is for all you clockists out there who love their grandfather clock but cant afford to get a professional clock repairer in to stop it running fast or slow. You just live with it dont you. Well you dont have to. Its inhumane to have to bear this burden mild irritation caused by a favourite family heirloom looking like a inefficient ancestor. Like having Baldrick from Blackadder shouting the time out incorrectly in the corner of the hallway “its 63 minutes past the turnip and Im related to you”.
Well stop blaming the clock and do something to help it!. For gods sake whats wrong with you. How can you live with that “clock” telling you the wrong time when its the single and only thing its supposed to get right. Its no good just having a pretty face. A clock should have the brains too.
Well heres a surprise. Its your fault clock owner. Youve just put up with it thinking nothing can be done and let a fantastically clever device fall into retardation or hyperactivity. Your a sinner but redemption can be yours if you follow the light shone in the dark by Braintree Clock Repairs. Which is me, Justin. And some people. Important people. Sorry. Anyway.
This is how its done.
First you need to understand the importance of the seconds hand in this rapid regulation method. The seconds hand you see ticking away on the face is connected and driven directly by the escape wheel. The escape wheel has 60 teeth. There is no gearing. The seconds hand is going round at exactly the same rate as the escape wheel because the seconds hand is mounted on an extension of the escape wheel pinion. What you are seeing in the seconds hand is the heart of the clock, the escapement wheel, beating at one revolution per minute at 60 beats / wheel teeth (providing the clock is correctly regulated). Its the cog that has one job; to give the pendulum a push and keep it running against the very slight frictions invloved in its swing. Its where the pedal hits the metal so to speak. In doing this it is keeping track of the swing rate and displaying this directly through the seconds hand.
So the the escape wheel drives the pendulum, and the seconds hand is just like a hub cap on a wheel. It is connected to the wheel directly and goes round at exactly the same speed unless your a “gangsta rapper with spinning hubs”. Incidentally, if you are actually a gangsta rapper I mean no disrespect, its just that the analogy wont work for you and you might..shoot me or something. Anyway.
The escapement cogs 60 teeth pass the pendulum pallets at a rate defined by the time it takes the pendulum to swing once back and forth. One swing, one movement forward of the escapement wheel teeth. Therefore if the clock is to be entirely accurate then the pendulum will be swinging back and forth exactly once each second. In short, each tick tock is supposed to be one second long. So, what is going on is that the rate the pendulum swings at is being displayed on the front of the clock by the seconds hand.
Now, the lower the centre of gravity a pendulum is, the slower it swings back and forth. Therefore if you have the pendulum bob set too high up the clock will tick tock away every, say, 0.9 seconds. This will therefore give you a clock that is 6 seconds fast per minute because its running and 110% of the speed of a second. Or to put it another way, if you pendulum is swinging at 1.1 beats per second its adding .1 second to its time keeping every second which means .1 x 60 seconds which is 6 seconds. Actually, dont get caught up with the maths bit here, you dont have to understand the maths to regulate a clock – Im just giving those with a mathematical mind a frame or reference. All you need to know is that lowering the pendulum bob will make the pendulum run faster and heightening it will speed up the pendulum, and therefore the seconds hand. Regulation is simply a process of synchronising the pendulum swing frequency to exactly one second.
To move the pendulum bob up and down you use the screw that should be supporting it at the base of the pendulum rod. This is square normally so you can easily perform a quarter turn accurately (and an eighth). The bob should be sitting firmly on this. If you screw it upwards the pendulum bob rises and the clock runs faster. Unscrew it and the pendulum bob lowers and the clock runs slower.
So how do you find exactly the right height for the pendulum bob to be for the pendulum to swing at exactly one second per swing?
You use the dividing halves rule.
This is how it works.
The clock will either be running fast or slow otherwise you wouldnt be reading this. This is because the pendulum bob is not in that “sweet spot” where it will cause the pendulum to swing once a second. You have to find the sweet spot by manually mathematically searching for it. Maths truly applied.
Get an accurate clock such as a chronograph or quartz watch.
If the clock is running fast turn the nut at the bottom through ten full rotations downwards. The opposite if its running slow.
Time the clock over 5 minutes against your reference time piece
If it is stilll running fast then go another 10 turns down.
Keep going ten 10 turns per 5 minute measurement until the clock is running incorrectly in the opposite fashion i.e. it has gone from fast to slow or slow to fast.
You then know you have passed the sweet spot on the pendulum within 10 turns.
You then change to five turns in the opposite direction of rotation. If the clock is still running incorrectly in the same direction (slow or fast) you know the sweet spot is within 5 turns in the rotation you are currently proceeding in (up or down).
Now proceed 2.5 turns in the direction of the sweet spot.
If you overshoot it then reverse back 1.25 turns. If this is still overshot then half a turn forwards or backwards.
- Just keep halving the rotations and chasing in the upward or downward direction of the sweet spot.
This is a great method and quickly allows you to regulate a clock quite accurately very quickly. It can be done in a couple of hours if you pay attention. Once you have done a few “ups” and “downs” searching for the sweet spot by effectively passing it within a know margin you can then half reverse to see which side, up or down, the sweet spot is. By reducing by half, very quickly, you are passing the sweet spot by fractions of a turn on each 5 minute test run.
A few hints and tricks.
Write down and draw what you are doing. So the first entry on your sheet should note that the clock is running “x” minutes fast and that you have changed the pendulum bob level ten turns down. Each ajustment you make, take a note of it. So your second entry might be “clock went from running fast to slow after 10 turns down. It was running 10 seconds fast but is now 7 seconds slow”. Be as literal as that – it only takes a little longer. The thing is because you are going to be going up and down searching for the sweet spot its really really easy to forget how many turns you are on and in which direction you are searching. These notes are a godsend and remember this is a two hour process. Imaging getting mixed up after one and a half hours. Michael Finnnegen begin again. Grrrrr.
Each time you run your five minute (or 20 minute if you have the time) measurement session you are going to have reset it against the control clock / watch. This is more difficult than you think because when you watch says its exactly on the minute you have to have the seconds hand on the 60 postion and then swing the pendulum. If you stop the pendulum swinging on each test run its very hard to set it swinging with exactly the same arc as it will setttle into after its running in perpetual motion aided by the escapment pushing it. This means that at first the swing will be slightly longer than it settles into, and innacurate. Ideally you just want the pendulum to keep swinging and the clock to be frozen in time until you press a magic button to start it running. Thats what this method is.
If you simply stop the seconds hand going round with your finger the clock will stop but the pendulum will continue to swing for quite a while. This means that you can advance the clock to say exactly 6pm (assuming the actual time is 5.59.45 pm) and stop the seconds hand until the control clock has caught up to 6pm. At the exact second of 6pm you simply pull you finger off the seconds hand and you will find the clocks are so closely synchronised you can hold one and the other in field of view and see they are ticking the seconds away at the same initial rate (well they are not but it takes 5 minutes for the difference to be perceptible via accumulation). The great thing here is that you can just watch your control time piece without looking at the grandfather clock at all with this little gem of a trick. If it were not for this, the dividing halves method would only be accurate to 1 or two seconds per 5 minutes which amounts to around 5 minutes loss or gain a day coincdentally. Too much. With this fast method you can get it down to 1 minute a day with a couple of hours work.
With grandfather clocks its all about the accuracy of the test runs, which in turn, is about an efficient method of sychronisation with your control clock. After you have that sorted with the finger stop method your realy just lowering and heightening the bob to a lesser and lesser degree past an invisible sweet spot which you find by testing against a control clock.
You can only get so far on 5 minute tests. To increase the accuracy of this method each test should really be a week but then you are talking about fine tuning almost beyond the clocks capacity for accuracy. There is varying friction with temperature and even humidity so its never going to be atomic clock accurate but I would say you should be able to get a grandfather clock as accurate as a decent mechanical watch. Apart from the really good grandfather clocks costing a lot of money you can expect a gain or loss of a few minutes a week. Variations in temperature can do that because the pendulum rods tend to be made of steel which expands and stretches as it becomes warmer, so in reality you are never going to get second accurate time out of your clock. Having said that your winding it once a week so you can correct it at that point. Electric clocks are never entirely accurate and because you dont wind them there is actually far more risk of these clocks accruing a time lag or gain over time, than there is for a grandfather clock. The mechanical clock, is by it nature, a more reliably accurate every day time keeper with the right treatment.
Easy really, but you have to know how.
Now you do.
If you dont get this then read it again more slowly. It does make sense and you will eventually have a eureka moment and it will all seem so obvious. Your Baldrick will turn into Blackadder the III and you will have an efficient and smart companion. And absolution sinner.