Basic Clock Design

[AjohnwParticipant @ajohnw51620]

There isn't much room around them Russel. I have seen various sizes at the odd clock fair I go to but the colour of the "new" ones is hopeless and would never match. The seller pointed out that it would be a problem, Easy to make a replica but he reckoned I would never match the colour. The alternative would be to put something entirely different there but I don't think that would work in the case. It didn't on the one in the hall but that is a very cheap old clock. The colours don't match and the addition looks cheaper than the clock.

Following Michael's comments I had a look around at true regulators. One thing that surprised me was that they date from 1800 plus or minus rather a lot and scarcely any example photo's about at all. Just shots of the face showing the separate hour, mins and seconds dials. The mention of this one earlier in the thread has fascinated me

2 aspects. The general construction and the use of dural. Interesting to note that it uses an electric remontoire that winds every 30 sec. That seems to be done by the wheel that looks like it's the escapement but that seems to be behind it.

Also serves as a shot of a real regulator but the hour dial is rather unusual.

John

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Edited By Ajohnw on 17/04/2016 13:31:09

[John HaineParticipant @johnhaine32865]

Well that's Burgess' Clock B at the Greenwich Observatory, hardly 19th century as it was finished in 2013! Has been running for 2 years in the Clock Workshop and has never been more than a second adrift from exact time. It demonstrates what Harrison's grasshopper escapement is capable of when properly implemented. There have been two seminars held at the RGO on the clock and I had the chance to have a close up look at the second. However it isn't perhaps a "basic clock design"!

[jaCK HobsonParticipant @jackhobson50760]

Posted by Ajohnw on 17/04/2016 13:28:31:

That seems to be done by the wheel that looks like it's the escapement but that seems to be behind it.

Edited By Ajohnw on 17/04/2016 13:31:09

I seem to remember the electric drive to the remontoire was really simple – no clever escapement. Are you looking at the right thing – I think the remontoire weight is brass lump at bottom left of picture.

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Ajohnw on 17/04/2016 13:28:31:

There isn't much room around them Russel. I have seen various sizes at the odd clock fair I go to but the colour of the "new" ones is hopeless and would never match.

The ones I bought from M & P for the Vienna clock I restored came unfinished and I stained and varnished them to match. I agree that matching staining is not easy but it can be done.

Russell.

[John HaineParticipant @johnhaine32865]

Jack, John, the brass weight drives the great wheel through (IIRC) a differential arrangement so it can be lifted by the winding motor every 20 minutes (this is from Frodsham's website). The remontoire is essentially a spring arrangement behind the escape wheel (at the top of the clock) which is itself rewound every 30 seconds. The main rerason for the remontoire here is to keep the drive torque to the 'scape wheel, and hence the pendulum impulse, as constant as possible and isolated from variations introduced by inaccuracies and stiction in the train.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by John Haine on 17/04/2016 17:21:47:

(this is from Frodsham's website)

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**LINK**

MichaelG.

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Edit: This page may also be of interest

… 'though we have strayed rather a long way from 'basic clock'

Edited By Michael Gilligan on 17/04/2016 18:02:47

[brickyParticipant @bricky]

Books by John Wilding have all you need to know about the basic clock designs,his straight foreward approach to his text is easy to follow.I started out by reading a book of his from the library and built two astronomical regulators.The first to my own design to take account of my lack of equipment and knowledge.I had to fix the wheel sizes on a needle file for tooth and space,I set out the teeth with a disc of paper glued to the blank and carefuly set out the divisions,filed out the teeth and with with a pattern filed the crests.wooden pendulem rod and lead weight and bob.They needed to be heavy to overcome any discrepencies.Why I am saying this is that there is nothing wrong with your design and they don't have to be perfect to work ,this clock when finished kept time after much regulation to two seconds a week.My second clock [by now I was tooled]was a near copy of a Riefler regulator and has a 2degree of arc on the pendulem and is driven by a 1.5lb weight .Don't get bogged down with to many technicalities get stuck in.

Frank

[AjohnwParticipant @ajohnw51620]

I thought from comment in the thread that it was obviously not an 18 – 19 century design. The method of CONSTRUCTING it is interesting and personally I think the use of dural is too. The mechanisms are not really related to that. Trying to find out how it works is another matter. I take the hefty weight as relating to the unusual hour dial. Also there are other pictures about and some show the other wheel behind what appears to be the escapement wheel. There are is an interesting series of 13 video's on youtube of some one building a replica of one of Harrison's clocks which suggest a simple weight isn't used as well.

**LINK**

 

John

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Edited By Ajohnw on 17/04/2016 19:35:12

[John HaineParticipant @johnhaine32865]

The weight drives the hour wheel, which drives the minute wheel, which drives the remontoire input, which drives the scape wheel through a spring mechanism. Actually it's quite a simple clock apart from the grasshopper escapement. The dural is I think mainly the dials and large wheels, the backplate is a massive 1 inch thick mild steel plate and the cocks and bridges also steel IIRC. The construction was described at the seminars by a man from Frodshams but for some reason the RGO has chosen not to publish the slides. It's a big clock too, must be a metre and a half tall.

Edited By John Haine on 17/04/2016 22:49:27

[James AlfordParticipant @jamesalford67616]

Posted by bricky on 17/04/2016 18:48:23:

.Why I am saying this is that there is nothing wrong with your design and they don't have to be perfect to work ,this clock when finished kept time after much regulation to two seconds a week.My second clock [by now I was tooled]was a near copy of a Riefler regulator and has a 2degree of arc on the pendulem and is driven by a 1.5lb weight .Don't get bogged down with to many technicalities get stuck in.

Frank

Frank: thank you.

I am currently redrawing the design using 0.6 mod wheels and pinions instead of 1 mod. One result of this, without increasing the tooth count, is that I will need to make pinions with 10 leaves and an outside diameter of 6mm, another with 8 leaves and OD of 4.8mm. Are these realistic sizes for pinions or are they likely to be too weak?

Regards,

James.

 

Edited By James Alford on 17/04/2016 22:57:18

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by James Alford on 17/04/2016 22:56:55:

I am currently redrawing the design using 0.6 mod wheels and pinions instead of 1 mod. One result of this, without increasing the tooth count, is that I will need to make pinions with 10 leaves and an outside diameter of 6mm, another with 8 leaves and OD of 4.8mm. Are these realistic sizes for pinions or are they likely to be too weak?

Well Thorntons sell pinion cutters down to 6 leaves for 0.6 mod so it should be no problem. Bear in mind though that the pinion cutters are different for each number of leaves and are rather expensive. The wheel cutter covers all numbers of teeth. It may be more economical to purchase lengths of pre-cut pinion rod and bore and cut to the required lengths.

Russell.

[Martin KyteParticipant @martinkyte99762]

Missing Eagles

Regarding ornamentation on Vienna Regulators, many were supplied originally with an eagle on the top plinth. At the outbreak of the war with Germany most households removed the eagle for obvious 'patriotic' reasons which is why there are a huge number of these clocks now with empty plinths. My grandfather actually stored his eagle away but as it was 'off the clock' for so long the colour is now slightly different.

Regarding the main part of this thread, go for lantern pinions.

regards Martin

[speelwerkParticipant @speelwerk]

Posted by James Alford on 17/04/2016 22:56:55:

I am currently redrawing the design using 0.6 mod wheels and pinions instead of 1 mod. One result of this, without increasing the tooth count, is that I will need to make pinions with 10 leaves and an outside diameter of 6mm, another with 8 leaves and OD of 4.8mm. Are these realistic sizes for pinions or are they likely to be too weak?

No, that is not to weak but these smaller diameters are more critical, best is to do trail cuts first in brass until set-up is correct. I leave the blanke diameter a little oversized (0.2 mm) to make sure to get the full tooth profile. You will have to harden, polish and temper the pinion to get maximum strength. Niko.

[James AlfordParticipant @jamesalford67616]

Thank you Nico and Russell. I was considering whether to use pinions or lantern pinions, but am not sure whether they will be too fiddly to do.

Edited By James Alford on 18/04/2016 12:47:14

[jaCK HobsonParticipant @jackhobson50760]

Posted by John Haine on 17/04/2016 17:21:47:

Jack, John, the brass weight drives the great wheel through (IIRC) a differential arrangement so it can be lifted by the winding motor every 20 minutes (this is from Frodsham's website). The remontoire is essentially a spring arrangement behind the escape wheel (at the top of the clock) which is itself rewound every 30 seconds.

I was wrong. But, the motor driven weight could be a nice simple solution for Jame's clock.

Can the motor driving the brass weight be considered a form of remontoire or are there some conditions it doesn't meet in order to be considered one? e.g. does it have to be supplying power closer to the escapement?

Edited By jaCK Hobson on 18/04/2016 13:56:08

[Michael GilliganParticipant @michaelgilligan61133]

Posted by jaCK Hobson on 18/04/2016 13:54:28:

Can the motor driving the brass weight be considered a form of remontoire or are there some conditions it doesn't meet in order to be considered one? e.g. does it have to be supplying power closer to the escapement?

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"a form of remontoire" … I would say Yes

[Note: I did try to keep that broad definition when I mentioned it earlier]

A good recent example is included in John Reynolds' "new design of" Regulator which is being published in EiM and has been completed in HJ.

MichaelG.

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P.S. … Harrison did not have the luxury of electrical rewinding available to him … but I'm sure he would have used it if he could !!

Edited By Michael Gilligan on 18/04/2016 14:48:48

[AjohnwParticipant @ajohnw51620]

While nosing around one the web I came across something that confused me so as this is basic clock question I may as well clarify it 'cause my assumption may be wrong which is

That a 1 second period pendulum with completely rotate a 60T escape wheel in 60 secs / 1min, ???

Not a so called seconds pendulum but one which is circa 248mm long.

John

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[Michael GilliganParticipant @michaelgilligan61133]

John,

Have a look at the other recent clock thread … particularly my post on 03-April

MichaelG.

[AjohnwParticipant @ajohnw51620]

Posted by Michael Gilligan on 18/04/2016 16:47:53:

John,

Have a look at the other recent clock thread … particularly my post on 03-April

MichaelG.

LOL that thread doesn't help in places a 1 sec pendulum based on my sums which should be correct reckon that it will be circa 248mm long. I notice that you used the more correct term SECONDS and the s on the end infers a 2 sec pendulum which will be circa 1/2 a metre long and will tic tock at 1 sec intervals with tooth released by a "1/2 a tooth" on each tick and tock.

So a true 1 second period pendulum without the s on the end will need a 60T escape wheel to revolve once per min.

maths L= g*T/(2*pi)^2

If I have anything wrong please point out where. To be honest I never worried about it to date. I am pretty sure I have something wrong because my impression is that a seconds pendulum is circa 1m long.

John

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[jaCK HobsonParticipant @jackhobson50760]

I think at one time it was proposed to define the meter as the length of a pendulum with a half period of one second. That didn't stick but it isn't far off.

[Michael GilliganParticipant @michaelgilligan61133]

John,

It's confusing, but a long-established 'fact of life'

Physicists work with the [full cycle] period of a pendulum

Horologists work with the [half cycle] beat of a pendulum

MichaelG.

Edited By Michael Gilligan on 18/04/2016 19:23:04

[BazyleParticipant @bazyle]

Does a pendulum go tic as it swings to the left and toc on the right or the other way round? And is it reversed in the southern hemisphere? Perhaps some of our Australian forum members could confirm.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Bazyle on 18/04/2016 19:23:01:

Does a pendulum go tic as it swings to the left and toc on the right or the other way round?

.

NO … it's the escapement that makes the noises.

[AjohnwParticipant @ajohnw51620]

Posted by Michael Gilligan on 18/04/2016 19:22:06:

John,

It's confusing, but a long-established 'fact of life'

Physicists work with the [full cycle] period of a pendulum

Horologists work with the [half cycle] beat of a pendulum

MichaelG.

Edited By Michael Gilligan on 18/04/2016 19:23:04

So working it out as I type a 4 sec period pendulum 1m long has a 2 sec beat so for each 2 sec interval the escape wheel advances by 1/2 a tooth. But if it did that a 30T wheel would take 60*2= 120 sec to revolve completely so I'd suspect that it actually advances a whole tooth. If it did that a hand attached to it would have 2 sec jumps and not indicate seconds really, just 2 second intervals. That still sounds wrong.

John

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Edited By Ajohnw on 18/04/2016 20:34:27

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Ajohnw on 18/04/2016 20:33:25:

So working it out as I type a 4 sec period pendulum 1m long has a 2 sec beat …

.

As they chant in the Panto:

Oh no it doesn't

Nominal 1m pendulum has a period of 2s and a 1s beat.

… Try it with a 'plumb line'

MichaelG.

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