Advice required regarding escapements

[murrmacParticipant @murrmac]

Hi, I didn't know whether to post this in the clock making forum ( where all the escapement experts probably hang out) or on here, but since it isn't to do with clockmaking, I decided to put it here.

Basically (very basically) imagine if you will that you have a pendulum with a bob weighing 14lb, swinging at a radius of 500 mm.

I want to create an escapement mechanism which has to be powered by a weight rather than a spring, which will impart a constant periodic motion to the pendulum.

There is no requirement for huge accuracy … I have the necessary machining capabilities and facilities to do whatever is necessary … welding and angle grinding will suffice …I just need an expert to tell me what to do.

If the expert advising me were based in or around Edinburgh, that would be a bonus … viva voce discussion would be a huge plus …however, if you are an expert in escapement mechanisms and feel able to offer advice, then please do so, no matter where your location.

I will add that this is for a commercial venture, and any advice received and accepted will be eligible for a remuneration on completion of the project.

The pendulum will be swinging "cantilevered" with an axle supported by two bearing blocks … the axle will extend beyond the furthest bearing block to enable fixing of any necessary cogs/gear wheels/ whatever.

[murrmacParticipant @murrmac]

[Ady1Participant @ady1]

You can get loads of horology books from xxxbay. 70 books for less than a tenner on a dvd and all fully searchable

[roy entwistleParticipant @royentwistle24699]

Murrmac Just put clock escapements into Google

Roy

[murrmacParticipant @murrmac]

Thanks for replies … I am now engaged in much googling, reading and Youtube viewing … I think I can crack it .

I will also try to make contact with any local clockmakers who would probably know instinctively what would be the most effective way to construct what I am after.

[Neil WyattModerator @neilwyatt]

Darn you Ady, that cuts off when it gets interesting… is that available on google books?

Neil

[Stephen BensonParticipant @stephenbenson75261]

Posted by murrmac on 15/06/2014 01:35:40:

Basically (very basically) imagine if you will that you have a pendulum with a bob weighing 14lb, swinging at a radius of 500 mm.

As a clockmaker the proportions are all wrong for any escapement that I know of (pendulum too heavy and radius too small) you either have to increase the radius or decrease the weight significantly in my opinion.

However have a look at Grasshopper / gravity escapement as this style works better with heavier pendulums

[Ady1Participant @ady1]

Darn you Ady, that cuts off when it gets interesting… is that available on google books?

I get my stuff from xxxbay, before the government bans it

The book is "Watch and clock escapements (1904)"

Edited By Ady1 on 16/06/2014 18:33:57

[Neil WyattModerator @neilwyatt]

> I want to create an escapement mechanism which has to be powered by a weight rather than a spring, which will impart a constant periodic motion to the pendulum.

From that can we assume the point is to impulse the pendulum and keep it swinging, rather than the pendulum keeping an escapement moving in time?

If so, then a simple electromagnet on synchronome lines would be enough, with optical sensors to judge when it needs a boost (and when to apply it). Only one moving part (the pendulum) required.

Neil

[murrmacParticipant @murrmac]

Thanks again for all replies …Stephen, I did have a kind of apprehension that the weight/radius relation was slightly out of kilter and I am going to look at that again.

Neil, you have got it in one … the point is indeed just to keep the pendulum in motion …your idea of the electromagnet sounds extremely promising, but I have no idea how it would work … I will try some googling but in the meantime do you have a link I could check out just to see how it might work ?

[Michael GilliganParticipant @michaelgilligan61133]

The Hipp toggle is probably the simplest, and most appropriate, arrangement.

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Neil Wyatt on 16/06/2014 18:38:12:

… a simple electromagnet on synchronome lines would be enough, with optical sensors to judge when it needs a boost (and when to apply it). Only one moving part (the pendulum) required.

.

Sorry, Neil, but that's not how the Synchronome works.

… What you are describing is much more like Hipp.

MichaelG.

[NJHParticipant @njh]

Hi Murrmac

I had assumed from your original post that electrical involvement was not appropriate. If you will allow this then Michael is of course spot on, The master clock principle, as well as being the basis for driving clocks in large buildings, was also employed to drive all the pulse generation for telephone exchanges. Click HERE to see an explanation. I seem to recall seeing second hand Gents master clocks and slaves in surplus shops.

( Best not to re-invent the wheel unless you need to!)

Regards

Norman

[murrmacParticipant @murrmac]

Thanks again to all who have replied .. I think it best if I come clean here and explain exactly what it is I am trying to achieve.

I am in the fortunate position of having a courtyard which faces on to an extremely busy thoroughfare, and I wish to construct a kinetic sculpture similar (though not necessarily identical) to [url="https://www.youtube.com/watch?v=vh2a4a6JPM8"%5D this[/url] which will be installed at the front of the yard, in view of the public, and out of reach of poking hands.

The sculpture works pretty well as is, but I feel that some kind of escapememt mechanism would be both visually attractive, and would save me having to come out every ten minutes to give the pendulum a push.

From a visual, aesthetic point of view, the mechanical escapement route would be preferable, but this would have to be weighed up against the practical advantages of an electronic system (assuming there are in fact practical advantages to an electronic system). I am slightly loth to have a mains cable lying all the way from the back to the front of the yard … if an electronic system could be battery operated … that could be an option.

Like I say, I could construct it as is …without an escapement … the advantage of the escapement is that it would enable me to make the sculpture slightly more "chaotic" (which would be visually more exciting) … as it is, all the components are in equilibrium, and it is this equilibrium which enables the sculpture to swing for such a long time without any external force other than the initial push to the base sledgehammer.

Locating the axles and bearings slightly away from the theoretical centre of gravity on each component will lead to a more chaotic movement, but will also consume more energy, so that is why I would like the pendulum to have some kind of intermittent ( or constant) external impetus.

Edited By murrmac on 16/06/2014 22:29:10

[murrmacParticipant @murrmac]

sorry, the youtube URL doesn't appear to come up as a clickable link …

[NJHParticipant @njh]

These clocks were not mains powered – 50volts DC was the standard for telephone exchanges.

Norman

[Marcus BowmanParticipant @marcusbowman28936]

You might like to know (if you don't already have the information) that the East of Scotland branch of the British Horological Institute meets once a month in central Edinburgh (in a room in The Canon's Gate, 232 Canongate). There is always a good attendance, and lots of advice is freely available. They are a friendly lot. Next meeting is not until September, because of the summer holidays, but if you would like further details, just let me know, as I attend the meetings.

That would be an easy way to have a face-to-face discussion.

Marcus

[murrmacParticipant @murrmac]

**LINK**

Hopefully this will come up as a link … and thanks Marcus, i will definitely take you up on that offer

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Neil Wyatt on 16/06/2014 15:29:40:

… that cuts off when it gets interesting…

.

Neil,

Re: Huygens … Have a look here

[includes references and links]

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by murrmac on 16/06/2014 22:25:52:

Thanks again to all who have replied .. I think it best if I come clean here and explain exactly what it is I am trying to achieve.

I am in the fortunate position of having a courtyard which faces on to an extremely busy thoroughfare, and I wish to construct a kinetic sculpture < etc. >

.

murrmac,

Now that I see what you are trying to do … May I recommend using a Conical Pendulum

These are visually attractive, and very effective as a drive 'motor'

MichaelG.

.

Edit:  Here is a good video of the Bond Astronomical Regulator

… The Liverpool example is on display in the Museum.

 

Edited By Michael Gilligan on 17/06/2014 09:38:14

[speelwerkParticipant @speelwerk]

This is perhaps a bit of topic but on this site http://ckcc.huygens.knaw.nl/epistolarium/ you can search for correspondence between Dutch scholars in the 17th-century. If you search for "Pendulum" you get nice reading, including that of Robert Hooke. Niko.

[Michael GilliganParticipant @michaelgilligan61133]

Niko,

Very useful link, thank you.

MichaelG.

[Neil WyattModerator @neilwyatt]

> What you are describing is much more like Hipp.

Yes you are right, I got muddled.

On reflection, one opto detector which sent a reasonably well time pulse to an electromagnet to impulse the pendulum whenever the beam wasn't broken on a swing of the pendulum.

An even neater way would be to have a magnet on the pendulum and a soft-iron cored fixed coil.

On each swing the magnet induces a pulse in the coil, one way then the other. When this pulse is detected but falls short of a threshold, The coil is energised. A bit like detecting the speed of a BLDC motor using back emf.

Neil

[John McNamaraParticipant @johnmcnamara74883]

???

Are we building a time piece or are we building a piece of performance art?

It think the latter.

Thinking about this problem I am remained of the Foucault pendulum at the science museum London.

A long wire with a ball at the bottom **LINK** It is maintained in motion by a periodical electrical impulse. celestial rotation provides the circular motion, but that is a bit slow for an art work.

A little chaos could be introduced by using two impulse mechanisms at 90 degrees and driving them randomly. as extreme timekeeping is not required or desired a pair of solenoids could be used to apply a variable force to the wire. A small Arduino processor and a couple of drivers and the job is done,

Regards
John

PS Talking of clocks, here is a gear train clock that will take a while to roll over….

**LINK**

Edited By John McNamara on 17/06/2014 15:00:19

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