Help with clock escapement

[John ReeseParticipant @johnreese12848]

There are several good You Tube videos on clock repair, some dealing with escapements. As I understand it the position of the pallets with respect to the wheel is critical. If it is not right on the wheel will not give the pallet the proper nudge to keep the pendulum moving. DISCLAIMER: I am not knowledgeable about clocks except what I learned from the videos.

[Tim StevensParticipant @timstevens64731]

One test you might do is to assemble the pendulum as normal, and swing it slowly and gently by hand past the central position. You should see that as the scape wheel is released by the edge of the half-cylinder, this is not exactly a sudden process, rather that the scape moves gradually at the end of the swing and is then released. This is necessary so that the scape tooth gives the pendulum a small nudge to keep it going. Then at the end of movement the other way, a further gradual release nudges the pendulum the other way. These little nudges are critical, and the surface conditions of the ends of the teeth, and the ends of the half-circle, as well as the shape of both, must be correct. This means very smooth as well as the right shape.

In a conventional 'cylinder escapement' the scape teeth end in little blades like shoes, just long enough to fit exactly inside the cylinder as it rotates, and the outer face (the sole) of each shoe is bevelled to give the cylinder a push as it arrives and leaves. With your design, the edges of the cylinder seem to provide the slope, rather than the teeth of the scape wheel. If you look at the first pictures you include, the fifth shows the edge of the cylinder, and a distinct groove can be seen in the edge. I suspect that this is a wear mark, and may be one of the causes of your problem, as it means the shape is wrong. It may be possible to move the scape wheel along its shaft so that it bears on a new area both sides. If this proves difficult (depending on how tight the fit is) then an alternative would be to make up a packing piece to fit between the (black) pendulum bracket and the (brass) main plate of the movement. I guess that 1mm should be enough to move the cylinder enough to put the teeth on an unworn surface. And if it does not help, you can remove the packing without having spoiled anything. I am assuming in this dodge that both sides of the pendulum pivot are held in the black bracket.

I do hope this helps.

Cheers, Tim

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Tim Stevens on 21/11/2017 10:40:12:

… I am assuming in this dodge that both sides of the pendulum pivot are held in the black bracket.

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Tim,

Whilst I accept that there is no guarantee that Ian's clock exactly corresponds to the patent drawing; I think your assumption is likely to be invalid.

MichaelG.

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[Michael GilliganParticipant @michaelgilligan61133]

Ian,

I am a little wary of suggesting this, so please go gently …

Your video of stopping the 'scape wheel with a slip of paper seems to support my hypothesis that there is excessive friction somewhere in the train.

If it was mine [which of course it is not], I would re-fit the pendulum and add some extra weight to the clock, to see if that makes it run. … If it does, you have excess friction : If it does not, then the problem may lie elsewhere.

MichaelG

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael Gilligan on 21/11/2017 18:00:09:

Posted by Tim Stevens on 21/11/2017 10:40:12:

… I am assuming in this dodge that both sides of the pendulum pivot are held in the black bracket.

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Tim,

Whilst I accept that there is no guarantee that Ian's clock exactly corresponds to the patent drawing; I think your assumption is likely to be invalid.

MichaelG.

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Tim,

I think I must retract my comment ^^^

I have been looking at some other pictures, and it now seems clear that the pendulum is supported entirely by the 'black bracket'. … But note that the holes are [intentionally] greatly oversize and the pivots roll in the bottom curve of them.

The logic of your 'dodge' is probably sound; 'though I can't quite see how the end float of the pendulum arbor is controlled in this clock.

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

Here is the companion video to the one I linked before: **LINK**

The rolling action of the pendulum pivot is very nicely shewn.

MichaelG.

[Neil WyattModerator @neilwyatt]

Posted by Michael Gilligan on 21/11/2017 23:52:32:

The logic of your 'dodge' is probably sound; 'though I can't quite see how the end float of the pendulum arbor is controlled in this clock.

MichaelG.

Looking at the video, the pivots roll on a convex curved surface, like a ball race to give a self-centring action and the pallets are more than wide enough to allow for he potential difficulty of ensuring an exact position.

[Tim StevensParticipant @timstevens64731]

Looking again at the youtube video M Gilligan links to, it is clear that as the scape wheel moves it starts slowly and then clicks round. This is the effect I refer to above, with the movement of the scape pushing the pendulum to keep it going.

Looking at the pivots, as MG also reminds us, there is a rolling action rather than sliding at the pivots. Therefore it is clear that the exact shape of the rolling surfaces is important. The pivot must be smooth, and more important, I think, the base of the large hole in which it rolls must not have any groove or roughness. This applies to both sides of the pivot, of course. It may be that the clock in question is worn in these areas, forcing the pivot to slide rather than roll, and so increasing the friction.

I don't think (and I have not suggested) that the exact position of the pivot is critical. The only other factor I can think that would increase friction here is the need for some end float of the pivot. If this is eliminated (perhaps by adjusting too far in, ?) then this will add friction to the movement of the pendulum.

Finally I note from the video that the scape wheel shown there is held by a set screw on its arbour. This may be a clue to the option of moving the scape so that it contacts a unworn area on the pendulum.

Cheers, Tim

[CirclipParticipant @circlip]

Shouldn't (?) make a difference but the scape wheel exhibits "flywheel wobble" when free running.

Regards Ian.

[Ian ParkinParticipant @ianparkin39383]

Right. I’m getting fed up of taking this to bits and trying things…

Does anyone fancy having a look? I’ll post it to them and pay for advice/adjustment services

I’m sure there’s nothing worn in it it looks hardly used

I’ve printed copies of the patent papers.

The escape spindle revolves 1800 times in a 30 hour period that involves the clock dropping 4 inches on its racks ….if the escapement is removed it drops in 5 seconds so that means the spindle is going at 21,600 rpm. I just cant see how the escapement wheel can give an impulse to the pendulum with that gearing.. But then again i know really nothing much about clocks…

So before i fit a quartz mech to it does anyone fancy taking it on?

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Neil Wyatt on 22/11/2017 08:56:02:

Looking at the video, the pivots roll on a convex curved surface, like a ball race to give a self-centring action and the pallets are more than wide enough to allow for he potential difficulty of ensuring an exact position.

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Neil,

Sorry to be pedantic, but:

1. surely the pivots are rolling on a concave surface.
2. my comment about end-float related specifically to Tim's suggestion of relocating the support.

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Ian Parkin on 22/11/2017 12:25:21:

Right. I’m getting fed up of taking this to bits and trying things…

Does anyone fancy having a look? I’ll post it to them and pay for advice/adjustment services

[ … ]

So before i fit a quartz mech to it does anyone fancy taking it on?

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Ian,

If no-one 'qualified' steps forward … I would be delighted to look at it, if you cover the postage & such.

No promises, and certainly no charge for my 'services' !

MichaelG.

[Ian ParkinParticipant @ianparkin39383]

Thank you michael

Can you pm me your address and I’ll get it sent to you

Ian

[Michael GilliganParticipant @michaelgilligan61133]

P.M. sent, Ian

MichaelG.

[Dick HParticipant @dickh]

Did you see these threads on the NAWCC? Some nice pictures.

**LINK**

**LINK**

You don´t seem to be the only one having fun with this escapement.

Dick.

[Neil WyattModerator @neilwyatt]

Posted by Michael Gilligan on 22/11/2017 13:18:07:

Posted by Neil Wyatt on 22/11/2017 08:56:02:

Looking at the video, the pivots roll on a convex curved surface, like a ball race to give a self-centring action and the pallets are more than wide enough to allow for he potential difficulty of ensuring an exact position.

.

Neil,

Sorry to be pedantic, but:

1. surely the pivots are rolling on a concave surface.
2. my comment about end-float related specifically to Tim's suggestion of relocating the support.

MichaelG.

Yes I have convex and concave in a tizzy.

This is my crude drawing of my impression of the spindle. You can see how it would self-centre so end-float would not be an issue. It also gives the desirable point contact:

Edited By Neil Wyatt on 22/11/2017 14:49:21

[Ian ParkinParticipant @ianparkin39383]

Neil

That’s how the spindle is but with longer small ends about 2.5mm long and overall its 10mm long

[Michael GilliganParticipant @michaelgilligan61133]

Neil,

'tis as Ian describes ^^^

Here is Ian's photo, cropped and brightened a little:

If you watch the two videos I linked, you will see one in action.

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

As an amusing digression … here is a 'compound pendulum' conversion of a Turret Clock.

**LINK**

https://www.tapatalk.com/groups/modelsteam/setting-up-a-turret-clock-movement-with-a-compound-t48059.html

… That's a clever way of domesticating it.

MichaelG.

[Neil WyattModerator @neilwyatt]

Posted by Michael Gilligan on 23/11/2017 21:27:29:

As an amusing digression … here is a 'compound pendulum' conversion of a Turret Clock.

**LINK**

https://www.tapatalk.com/groups/modelsteam/setting-up-a-turret-clock-movement-with-a-compound-t48059.html

… That's a clever way of domesticating it.

MichaelG.

Before I clicked I assumed you meant one of these – an interesting way to keep random time…

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Neil Wyatt on 24/11/2017 16:45:03:

Before I clicked I assumed you meant one of these –

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Ah ! … as specified by Mrs May, for the Brexit Bill

MichaelG.

[Fiona WilliamsonParticipant @fionawilliamson98389]

Hi. Very new to this and a bit lost really!! I have an identical gravity clock, to the one you have photographed, that up until recently has worked well. However, it was knocked on the floor and now rattles! I cannot find anyone local to look at it for me and have become very interested in trying to repair it myself. Just not sure where to start! The weight has obviously become unattached but I don't know how to get behind the black face plate. Any advice gratefully received!

[Michael GilliganParticipant @michaelgilligan61133]

Welcome, Fiona

Have a look at the 'slideshow' that I referenced in my first reply to Ian

Here's a direct link: **LINK**

http://s1251.photobucket.com/user/cazboy5525/slideshow/English%20Gravity%20Clock_1

That should get you reasonably acquainted with the construction.

I'm currently investigating Ian's clock, so I can post a few pictures at the weekend.

MichaelG.

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P.S. … the weight in the bottom of the 'can' is only secured by one screw.

[V8EngParticipant @v8eng]

Looking at the progress of this thread the following comment might be surplus to requirements, here goes anyway.

The BHI keeps a record of professional repairers, listed under areas / counties, etc.

Might be useful for future reference:-

**LINK**

Edited By V8Eng on 03/01/2018 21:18:43

Edited By V8Eng on 03/01/2018 21:19:08

[Fiona WilliamsonParticipant @fionawilliamson98389]

Thank you Michael, they are great photos and certainly gives me plenty to refer to, however, I don't even know how to get the hands off to enable me to remove the black plate!

Thank you v8Eng, I have had a look at the record that the BHI keeps but not sure how up to date it is as I had no luck with the couple of local numbers I tried. I really want to have a go myself now!

[Author]

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