Sources of Mechanical Power Loss in Synchronome Movement
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Dear All, I recently replaced my home-crafted gathering jewel arm with an after-market one - whereupon I could not get the clock to run; it was constantly losing power. This prompted me to compile a list of places and settings where energy would be lost or gained in the system. I found this a useful 'checklist' of things to fix, or not. The good news is that the clock is now running, the bad news is that I don't know which of these things did the trick - I suspect a combination. The position of the pendulum on the trunnion is the most critical. All this may well be in a book somewhere, but I share it here as it may be of some use to someone. It is also quite likely that some of the things I have done are contra-indicated, but all are reversible. Note that the curved back of the gathering jewel I purchased is quite rough and could be heard scraping on the teeth tips on the backswing. Best regards, Grant
Factors
Affecting Synchronome Running Impulse Friction in gravity arm pivots - oiled Stiffness of wire to gravity arm - light wire now, correct curve to match diagram Lateral position of pendulum/roller slope - adjusted to match resting jewel position in diagram Height of impulse arm w r t roller - minimum clearance as before Position of reset contact gap - adjusted as per diagram: 1.8mm forward, 5.4mm back
Pendulum Loss Stiffness of suspension spring - unchanged Vibration in pendulum rod -
rod is 6mm Invar instead of 8mm, shivers on impulse Friction in impulse roller bearing - oiled Roughness of impulse slope - has been moved but not polished Friction on catch leaf - oiled slightly Friction in catch pivots - oiled Strength of catch return spring - unchanged Friction of vane tip on catch tip - oiled slightly Friction in gathering jewel arm pivot - corrected wire fit, not oiled Friction of back of gathering jewel on teeth slope - oiled back of jewel slightly Friction in index wheel pivots - oiled Friction in detent roller bearing - unchanged, not oiled Weight of detent roller arm/counterbalance
- replaced
similar to
original broken arm Friction in detent arm pivots - oiled
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John Hubert
A few ideas.
toggle quoted messageShow quoted text
Occasionally, the ‘length’ of the gathering wire can be troublesome, so a small adjustment may be needed to the settings to optimise if the new one is a little different to the old one. John
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Hi John, Yep, all good. See note on jewel back surface roughness, no oil on front face. Grant
On 17/10/2021 6:15 pm, John Hubert
wrote:
A few ideas.
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Ian Richardson
Hi Grant,
Further to what John said about the gathering jewel being clean and dry (which I fully endorse!), the glass back-stop roller should be similarly clean and dry. The gathering action of the jewel should be to JUST gather the tooth sufficient for the wheel to just tip over aided by the back-stop roller finally making it drop into place. Also, make sure that as the jewel approaches the tooth to be gathered that it doesn't catch the one before en route.
Otherwise, a good check list.
Best regards,
Ian R
-----Original Message-----
From: Grant Griffiths <grantgriffiths@...> To: synchronome1@groups.io Sent: Sun, 17 Oct 2021 9:34 Subject: Re: [synchronomeelectricclock] Sources of Mechanical Power Loss in Synchronome Movement Hi John,
Yep, all good. See note on jewel back
surface roughness, no oil on front face.
Grant
On 17/10/2021 6:15 pm, John Hubert
wrote:
A few ideas.
Occasionally, the ‘length’ of the gathering wire
can be troublesome, so a small adjustment may be needed to the
settings to optimise if the new one is a little different to
the old one.
John
Dear All,
I recently
replaced my home-crafted gathering jewel arm with
an after-market one - whereupon I could not get
the clock to run; it was constantly losing power.
This prompted me to compile a list of places and
settings where energy would be lost or gained in
the system. I found this a useful 'checklist' of
things to fix, or not. The good news is that the
clock is now running, the bad news is that I don't
know which of these things did the trick - I
suspect a combination. The position of the
pendulum on the trunnion is the most critical.
All this may well be in a book somewhere, but I
share it here as it may be of some use to
someone. It is also quite likely that some of the
things I have done are contra-indicated, but all
are reversible. Note that the curved back of the
gathering jewel I purchased is quite rough and
could be heard scraping on the teeth tips on the
backswing.
Best
regards,
Grant
Factors Affecting
Synchronome Running
Impulse
Weight of gravity arm - unchanged Friction in gravity arm
pivots
- oiled
Stiffness of wire to gravity
arm
- light wire now, correct curve to match
diagram
Lateral position of
pendulum/roller slope -
adjusted to match resting jewel position in
diagram
Height of impulse arm w r t
roller
- minimum clearance as before
Position of reset contact gap
- adjusted as per
diagram: 1.8mm forward, 5.4mm back
Pendulum Loss
Stiffness of suspension
spring
- unchanged
Vibration in pendulum rod
- rod is 6mm Invar instead of 8mm, shivers
on impulse
Friction in impulse roller
bearing
- oiled
Roughness of impulse slope
- has been moved but not
polished
Friction on catch leaf
- oiled slightly
Friction in catch pivots
- oiled
Strength of catch return
spring
- unchanged
Friction of vane tip on
catch tip
- oiled slightly
Friction in gathering jewel
arm pivot
- corrected wire fit, not oiled
Friction of back of
gathering jewel on teeth slope -
oiled back of jewel slightly
Friction in index wheel
pivots
- oiled
Friction in detent roller
bearing
- unchanged, not oiled
Weight of detent roller
arm/counterbalance - replaced similar to
original broken arm
Friction in detent arm
pivots
- oiled
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Thank you Ian, Johnny and John, I have had a crash course in Synchronome
setting recently, so I was across those things - but always
useful to re-iterate! This clock is a mixture of very old parts
and very new parts that arrived in bags - the older glass roller
detent was mangled beyond use, so I have used a more recent one
with a steel roller. I added a removable brass tube over the
counterbalance arm to check if it required increased
counterbalance - it didn't. I have also installed 10V
back-to-back Zener diodes across the coil for spark suppression,
which I can recommend. The clock was running well for months until
I added the 'correct' gathering jewel wire. The subsequent
refusal to operate prompted me to think through the mechanical
system a bit more thoroughly. My conclusions were confirmed by
Johnny, it is the position of the pendulum on the trunnion
within fractions of a millimeter that is most critical for
correct impulse. Best regards, Grant
On 17/10/2021 7:34 pm, Ian Richardson
via groups.io wrote:
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Morris Odell
Hi all,
My introduction to synchronomes came when I helped a friend restore a genuine one that had some parts missing. I have since made my own pretty much from scratch after starting with only the A frame. In both of those I had to use whatever was to hand and make other parts. I have not been able to find jewels so both synchronomes just use a stainless steel gathering wire with a right angle bend to engage the teeth of the count wheel. Adjusting the shape and position is quite an art! The impulse roller in my synchronome consists of a couple of 6 mm ball races next to each other on a steel arbor. The back stop roller is brass rather than glass. Mine has been working continuously now for almost a year and since I did manage to obtain a genuine slave clock, I know it keeps good time. I have also made an electronic monitor with a microcontroller and quartz reference to keep track of the timing, a bit like the power station comparison clock. I can echo Grant's comments about power loss. When I was making mine I learnt a lot about how the energy budget is distributed and how important it is to lubricate the appropriate points and keep other clean. The various stops and gaps are quite critical. Taking a close up video of the impulse mechanism with my phone and playing it back frame by frame was invaluable in adjusting the various points. I did that many many times. I also have a dual dial power station synchronome here that belongs to another friend. I've been keeping it for him until the lockdown situation here in Australia eases and it can be collected. I will be very interested to see how it goes once he sets it up. Cheers, Morris
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Howard
I would add that where the count wheel has been damaged it may be necessary to set the jewel slightly deeper so that it properly catches the lower teeth. This will mean that the higher teeth show some recoil but unavoidable without re-shaping the count wheel.
Also weight of pendulum bob was a factor in getting an older clock to run reliably. Did clocks have different weights? Swapping the usual heavy 16lb (?) for 12lb brass sorted the issue, I could have added weight to the gravity arm but this was original and clock was bought minus the bob. Howard
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Ian Richardson
Hi All,
At the risk of "teaching my grandmother to suck eggs", it may be worth pointing out that the only source of input energy is the falling gravity arm. After that, everything else is draining energy from the system. Putting more energy in (e.g. by adding weight to the gravity arm) is the wrong approach unless and until all forms of energy loss have been eliminated or at least minimised. If the countwheel has been damaged, surely it should be "topped off" to ensure that all teeth tips are level.
The point that was made about the sideways location of the pendulum is valid (provided that the clock is vertical) but it should be positioned such that the gravity arm roller sits just near the top of the impulse pallet and then the length of the gathering arm should be fixed such that the jewel sits midway between two teeth when at rest. That position in turn can, to some extent, be moved by adjustment of the backstop glass roller.
Incidentally most supply houses will provide a ruby Brocot jewel which works for the gathering jewel.
Best regards,
Ian R
-----Original Message-----
From: bailey.services via groups.io <bailey.services@...> To: synchronome1@groups.io Sent: Sun, 17 Oct 2021 11:09 Subject: Re: [synchronomeelectricclock] Sources of Mechanical Power Loss in Synchronome Movement I would add that where the count wheel has been damaged it may be necessary to set the jewel slightly deeper so that it properly catches the lower teeth. This will mean that the higher teeth show some recoil but unavoidable without re-shaping the count wheel.
Also weight of pendulum bob was a factor in getting an older clock to run reliably. Did clocks have different weights? Swapping the usual heavy 16lb (?) for 12lb brass sorted the issue, I could have added weight to the gravity arm but this was original and clock was bought minus the bob. Howard
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Howard
Hi Ian
Does topping off require any specialist equipment? Howard
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Ian Richardson
Howard,
Basically, you need a lathe. You need to be able to rotate the arbor with its wheel at fairly high speed on a fixed axis, and JUST touch the tips of the teeth with a fixed tool. I say "fixed" in both cases because if you stick the wheel in the chuck of a drill and run a file round it, it will end up eccentric!
I have done this in a Myford lathe with a plain tool in the toolpost. You only need to make the merest contact with the tips of the teeth, and only run until all the teeth touch the tool equally. After topping off this way, there may be a very slight burr on the trailing edge of the teeth, which you will have to remove with a very fine file. I would add that it is not difficult to ruin the wheel, so if you're not confident - don't do it!
Hope this helps,
Ian
-----Original Message-----
From: bailey.services via groups.io <bailey.services@...> To: synchronome1@groups.io Sent: Sun, 17 Oct 2021 14:56 Subject: Re: [synchronomeelectricclock] Sources of Mechanical Power Loss in Synchronome Movement Hi Ian
Does topping off require any specialist equipment? Howard
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One thing that has come our way in recent years is the ability to use a smartphone to video the operation of the mechanism as the gravity arm is unlatched. It only requires about 10 seconds of video starting about 5 seconds before the unlatch. You can play it back a frame at a time and see what is going on. I have used it on several occasions to help diagnose problems. If you can do that and share it here I am sure we can help. Also, what are you seeing on the beat plate 3.6 is good but lower than that indicates loss of energy or insufficient energy into the pendulum. Simon
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Simon
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Andrew Nahum
For sideways location of the pendulum and the relationship of the gravity arm roller to the impulse ramp I use the very helpful 1982 set-up diagram of L Paton (detail extracts attached). I assume everyone has got this drawing? Note also the instruction to polish the ramp occasionally. Has anyone got an extra glass back stop roller they could spare? Best regards Andrew  
On 17 Oct 2021, at 13:18, Ian Richardson via groups.io <irichar361@...> wrote:
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John Hubert
I don’t have an extra glass backstop, but have successfully used perspex (very easy to buy a rod and to drill/machine) and works perfectly - looks like glass.
toggle quoted messageShow quoted text
John
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Andrew Nahum
Dear John,
toggle quoted messageShow quoted text
Many thanks for the tip. A friend in fact kindly made made me a Delrin (engineering nylon) roller and it does work fine. I run it dry. I just wonder (maybe a superstition) whether the glassiness of glass might give lower friction in that application, given there is so little energy to spare. Andrew
On 17 Oct 2021, at 18:01, John Hubert <jfphubert@...> wrote:
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John Hubert
Perspex is quite a hard shiny surface and works well
toggle quoted messageShow quoted text
John
On 17 Oct 2021, at 18:16, Andrew Nahum <andrew.nahum@...> wrote:
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Odell, Edward
There is a video of correct gathering jewel set up on clockdoc https://clockdoc.org/default.aspx?moid=58095
Eddy Odell
From: synchronome1@groups.io <synchronome1@groups.io>
On Behalf Of Simon Allen via groups.io
Sent: 17 October 2021 17:16 To: synchronome1@groups.io Subject: Re: [synchronomeelectricclock] Sources of Mechanical Power Loss in Synchronome Movement
One thing that has come our way in recent years is the ability to use a smartphone to video the operation of the mechanism as the gravity arm is unlatched. It only requires about 10 seconds of video starting about 5 seconds before the unlatch. You can play it back a frame at a time and see what is going on. I have used it on several occasions to help diagnose problems. If you can do that and share it here I am sure we can help. Also, what are you seeing on the beat plate 3.6 is good but lower than that indicates loss of energy or insufficient energy into the pendulum.
Simon
On Sun, 17 Oct 2021 at 14:34, Ian Richardson via groups.io <irichar361=aol.com@groups.io> wrote:
-- Simon
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Peter Torry
I have found that the local craft shop has many varieties of glass bead including clear glass so have a search for suitable shops in your area. Kind regards Peter
On 17/10/2021 18:01, John Hubert wrote:
I don’t have an extra glass backstop, but have successfully used perspex (very easy to buy a rod and to drill/machine) and works perfectly - looks like glass.
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Darren Conway
Hi If materials like Delrin were available when the clock was made, it may have been chosen. When I purchased my clock it was missing the ruby on the gathering arm. Impossible to obtain here. I made one from graphite impregnated bearing plastic, designed to
run dry. It has the same friction coefficient as ruby (low) and
works perfectly. SWMBO is noise sensitive so I replaced the felt buffer pads with
soft rubbery gel type material punched from innersoles. Noise is
noticeably reduced. I use modern materials where there is good reason for doing so,
without degrading the aesthetics of an old clock. Regards
Darren Conway Lower Hutt New Zealand On 18.10.21 6:16 am, Andrew Nahum
wrote:
Dear John,
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Graham Mitchell
HI Grant,
Here's a link to Grant's presentation on his Synchronome extracted from the latest EHG Zoom here in Australia last month. That's before his latest fiddlings, https://youtu.be/6UuUjaAmYdU I put the EHG zooms in an unlisted category on youtube and circulate locally as well as to the AHSoc EHG via James Nye which some of you may have already seen, Regards Graham Sydney
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Thanks Graham and everyone else, This has been a very interesting and useful
discussion! A couple of points to add: although the only energy input to the system is the falling of the gravity arm, there are losses that occur before that energy reaches the pendulum. In particular, having too stiff a wire connecting the gravity arm to the thumbnut is not helpful, as are gunked up pivots. I purchased a commercially-made gathering-jewel arm because I was in lockdown and couldn't nip out and scrounge a Brocot jewel from a fellow Chapter member. My pivot steel and paperclip one worked well but was a bit embarrassing :-) However, as I said before, the commercial one could be heard scraping the tooth tip on the backswing (and my clock room is noisy). https://www.ebay.com.au/itm/293928399806 Finally, the impulse causes the pendulum rod to vibrate, being 6mm not 8mm, and this definitely takes energy from the system. This can be seen in the jerky motion of the rod in the slo-mo video on my YouTube channel: https://www.youtube.com/watch?v=3_HVCrjTXfE Best regards, Grant
On 18/10/2021 7:41 am, Graham Mitchell
wrote:
HI Grant,
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