Basic Clock Design

[James AlfordParticipant @jamesalford67616]

One day, I should like to build a clock and have drawn out this design, using a detailed guide for designing the escapement. I propose to use a 1 mod cutter and all measurements shown are both the number of teeth and the pitch diameter. It will have a one metre (or thereabouts) pendulum and be spring driven. I have made no attempt yet to design the cosmetics, just the basic gearing.

Can anyone see any glaring errors in my plans?

Thank you.

James.

James.

Edited By James Alford on 11/04/2016 07:39:38

[James AlfordParticipant @jamesalford67616]

[Sam Longley 1Participant @samlongley1]

Yes— You will need some hands on the front

[Michael GilliganParticipant @michaelgilligan61133]

James,

Is there a good reason why you have chosen to use spring drive ?

MichaelG.

[Russell EberhardtParticipant @russelleberhardt48058]

Just a suggestion: With a one second pendulum you have a long case so why not make it weight driven. That will give a constant driving force unlike a spring.

Russell.

[James AlfordParticipant @jamesalford67616]

Posted by Michael Gilligan on 11/04/2016 07:53:35:

James,

Is there a good reason why you have chosen to use spring drive ?

MichaelG.

Michael. The overall design that I have in my mind uses a quite delicate and thin skeleton frame. If I use weights, which was my first thought for simplicity, the frames would need to be somewhat chunkier, I imagine.

Posted by Sam Longley 1 on 11/04/2016 07:49:03:

Yes— You will need some hands on the front

Doh! I knew that I had forgotten something!

[Michael GilliganParticipant @michaelgilligan61133]

Posted by James Alford on 11/04/2016 08:02:50:

Posted by Michael Gilligan on 11/04/2016 07:53:35:

James,

Is there a good reason why you have chosen to use spring drive ?

MichaelG.

Michael. The overall design that I have in my mind uses a quite delicate and thin skeleton frame. If I use weights, which was my first thought for simplicity, the frames would need to be somewhat chunkier, I imagine.

.

James,

A spring would need to have the same stored energy, to drive the clock for a given duration.

You would also [assuming it is to be a useful timepiece] need to consider including a fusee.

If the overall construction is to be light, then an electrically wound remontoire [which could be weight or spring] might be the answer.

MichaelG.

[James AlfordParticipant @jamesalford67616]

Michael,

With a spring drive, would not the force of the spring be contained within the barrel, rather than being supported by the actual frame?

Regards,

James.

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by James Alford on 11/04/2016 08:57:30:

Michael,

With a spring drive, would not the force of the spring be contained within the barrel, rather than being supported by the actual frame?

Regards,

James.

No, it will be balanced by a ratchet mounted on the frame.

Russell.

[Michael GilliganParticipant @michaelgilligan61133]

James,

My understanding is that the driving force from the spring is applied to the train through the barrel teeth, and reacted on the barrel arbor … effective loading being the same as a weight.

Someone please correct me if I am wrong !!

MichaelG.

.

Edit: … I note Russell's mention of the Ratchet [Pawl]; which does change the vector, but not the total force.

Edited By Michael Gilligan on 11/04/2016 09:09:00

[Russell EberhardtParticipant @russelleberhardt48058]

The driving force is required to overcome friction, to accelerate the wheels on each beat, and to overcome the pendulum losses (mainly air resistance). You can reduce the force required for acceleration of the wheels by using lighter wheels, perhaps go to 0.6 mod rather than 1 mod?

Russell

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael Gilligan on 11/04/2016 08:51:03:

If the overall construction is to be light, then an electrically wound remontoire [which could be weight or spring] might be the answer.

.

Useful notes here: **LINK**

MichaelG.

[Neil WyattModerator @neilwyatt]

Possibly the frame only needs to be robust in the area between the spring arbour mounting and the ratchet, with a weight the whole bottom part of the frame needs to be beefed up.

Neil

[Russell EberhardtParticipant @russelleberhardt48058]

For a reasonably well made 8 day movement with a one second pendulum the weight required will be between four and five kg. Not really a lot for the frame to support. No beefing up should be required even for a relatively light frame.

Russell.

[James AlfordParticipant @jamesalford67616]

Thank you for all of the replies. I do not know anything about remontoires, so shall look into these.

I can see how the frame would need to be beefed up to brace a pawl if mounted on it. However, I have seen a number of designs, like this one where the pawl is mounted on either the main wheel or the back of the barrel itself. In this case, would not the stored force be contained within the barrel and the wheel, rather than the frame?

Regards,

James.

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by James Alford on 11/04/2016 22:02:26:

I have seen a number of designs, like this one where the pawl is mounted on either the main wheel or the back of the barrel itself.

That is the barrel from a weight driven clock – not a spring barrel. In fact it is from this clock. Is that the sort of thing you were thinking of making?

Russell.

[James AlfordParticipant @jamesalford67616]

Posted by Russell Eberhardt on 11/04/2016 22:37:59:

Posted by James Alford on 11/04/2016 22:02:26:

That is the barrel from a weight driven clock – not a spring barrel. In fact it is from this clock. Is that the sort of thing you were thinking of making?

Russell.

Russel,

That is a good point, one that I had not considered. Yes: the picture in the link is the type of thing that I am thinking of building, albeit without the shelf on which it is sitting.

Regards,

James.

[Russell EberhardtParticipant @russelleberhardt48058]

A book describing how to make that clock is available here.

I would also recommend looking at Ian Cobb's site.

Russell

[Stephen BensonParticipant @stephenbenson75261]

I would rethink the 1 module cutter it would make the timepiece too large 0.6 module would better for that style of movement

[James AlfordParticipant @jamesalford67616]

Stephen: I have also come around to that way of thinking and am in the process of doing so.

Russell: thank you for the links.

JAmes.

[AjohnwParticipant @ajohnw51620]

There is a mechanical remontoire here that looks like it may be achievable

**LINK**

By a Frenchman called Robin. There are odd bits on the web about it. The general idea is that this drives the escapement directly and is rewound via some other source of power. The aim should be to minimise the friction etc variations on the drive to the escapement to get round the usual regulation problems with weight driven clocks.

Must admit I am not sure if does that but thought it might be of general interest.

John

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[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Ajohnw on 12/04/2016 10:51:10:"to get round the usual regulation problems with weight driven clocks."

What might those problems be John? Weight driven clocks are certainly easier to regulate than spring driven ones. Even with a fusee it's difficult to get constant driving force with a spring. With a weight it is always constant although does depend on altitude!

Russell.

[AjohnwParticipant @ajohnw51620]

Friction variations Russel especially over time.

This confused me. We have a Viena type old wall clock and what ever I did it wouldn't hold time as well as expected. Turns out that the wrong weights were fitted or the clock is too old and has varied somewhat somewhere to how it should be so the weight need adjusting. I mentioned it to a tat shop that sold old clocks and they reckoned it was a common problem on any weight driven clock.

A remontoire is reckoned to get round part of the problem by applying the weight further down the gearing but some people reckon that they aren't worth using in anything other than tower clocks. I'd guess they may be well worth using on spring driven clocks.

A problem though – figuring out how remontoires work for a none clock maker isn't a trivial task. Not for me anyway. Some are simpler than others. One which might be of interest is the Magnier. It can be found on the web.

John

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[Michael GilliganParticipant @michaelgilligan61133]

Posted by Ajohnw on 13/04/2016 12:55:54:

… I mentioned it to a tat shop that sold old clocks and they reckoned it was a common problem on any weight driven clock.

.

John,

I would recommend that you find a different 'tat shop' to deal with.

MichaelG.

[AjohnwParticipant @ajohnw51620]

Why Michael ? They got clocks in and they were fine when they sold them which strongly suggests that they do know what they are doing and even had repeat business. Gone now. They owned the shop and had been their for rather a long time. They decided now was a good time to sell and retire some years ago. They sold a lot of old clocks too of all sorts of styles.

The shop sells wedding dresses now or did last time I noticed. Sad really I lot of interesting shops fairly close to where I live have gone now usually down to retirement and no one prepared to continue with the business.

John

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