Bounce in gravity arm


bailey.services@...
 

How much bounce should you expect in the gravity arm, I am occasionally seeing a double impulse where it fails to latch. Reducing the current to slow things down gives unreliable advance of the pilot dial.

The latch and leather wing had been crushed together and gripped the catch on the gravity arm, I have straightened these but think the leather wing looks a bit high, bending it down so it meets the rising catch sooner and at a more acute angle would presumably slow the motion.

The leather is replaced wasn’t sure how thick it should be.

Any thoughts?
Howard


 

Is there enough weight in the gravity arm?  It looks like it bounces on the slope.  However, to get your question should there not be a light return spring that returns the catch to its slot?  I do not see it cleanly latching.

Simon


John Hubert
 

This is mine (note that mine doesn’t have the ‘advance’ loop fitted)




On 29 Jun 2021, at 18:53, bailey.services via groups.io <bailey.services@...> wrote:

How much bounce should you expect in the gravity arm, I am occasionally seeing a double impulse where it fails to latch. Reducing the current to slow things down gives unreliable advance of the pilot dial.

The latch and leather wing had been crushed together and gripped the catch on the gravity arm, I have straightened these but think the leather wing looks a bit high, bending it down so it meets the rising catch sooner and at a more acute angle would presumably slow the motion.

The leather is replaced wasn’t sure how thick it should be.

Any thoughts?
Howard <IMG_0075.MOV>


 

These videos really do help diagnose issues.  You can swipe the video back and forwards.  It is very tricky when you wait 30 seconds for the action to start again and it is all over in a quarter of a second.

Simon

On Wed, 30 Jun 2021 at 10:01, John Hubert <jfphubert@...> wrote:
This is mine (note that mine doesn’t have the ‘advance’ loop fitted)




On 29 Jun 2021, at 18:53, bailey.services via groups.io <bailey.services@...> wrote:

How much bounce should you expect in the gravity arm, I am occasionally seeing a double impulse where it fails to latch. Reducing the current to slow things down gives unreliable advance of the pilot dial.

The latch and leather wing had been crushed together and gripped the catch on the gravity arm, I have straightened these but think the leather wing looks a bit high, bending it down so it meets the rising catch sooner and at a more acute angle would presumably slow the motion.

The leather is replaced wasn’t sure how thick it should be.

Any thoughts?
Howard <IMG_0075.MOV>



--
Simon


John Hubert
 

There are several differences visible that may be significant.

On my clock, the ‘peg’ for the latch on the gravity arm is a solid item (looks like a steel peg with a shim soldered on!), whereas yours is a sprung folder arrangement.  Comparing your with another clock I have with your type pf latch, yours looks quite thin material - my other one is 0.6mm thick.  I will try and film it.

My clock has a notably ’snappy’ action - and gives a very short impulse.  I don’t know why, but the gravity arm has had a few variations/modifications in its life (before my time) and may be a bit lighter that it should be.  I should have thought that is marginal, but it is very ’snappy’, even running at a lowish current (from memory, about 280 mA) as it does.  Note that because it runs a Synchronome distribution board, the master movement coils are able to have their current set independently.  

Mine is an early clock without the buffer stop to the left of the vertical part of the gravity arm.  As early clocks do, it has a different profile on the impulse pallet slope.  I don’t see why this should make any difference to ‘bounce’.

I will try and film the later clock.

On 30 Jun 2021, at 10:20, Simon Allen <simon.sallen@...> wrote:

These videos really do help diagnose issues.  You can swipe the video back and forwards.  It is very tricky when you wait 30 seconds for the action to start again and it is all over in a quarter of a second.

Simon

On Wed, 30 Jun 2021 at 10:01, John Hubert <jfphubert@...> wrote:
This is mine (note that mine doesn’t have the ‘advance’ loop fitted)




On 29 Jun 2021, at 18:53, bailey.services via groups.io <bailey.services@...> wrote:

How much bounce should you expect in the gravity arm, I am occasionally seeing a double impulse where it fails to latch. Reducing the current to slow things down gives unreliable advance of the pilot dial.

The latch and leather wing had been crushed together and gripped the catch on the gravity arm, I have straightened these but think the leather wing looks a bit high, bending it down so it meets the rising catch sooner and at a more acute angle would presumably slow the motion.

The leather is replaced wasn’t sure how thick it should be.

Any thoughts?
Howard <IMG_0075.MOV>





-- 
Simon


John Hubert
 

And here is a later clock with a folded sheet metal type of latching piece on the gravity arm - and it does also bounce quite a lot.



On 30 Jun 2021, at 10:39, John Hubert via groups.io <jfphubert@...> wrote:

There are several differences visible that may be significant.

On my clock, the ‘peg’ for the latch on the gravity arm is a solid item (looks like a steel peg with a shim soldered on!), whereas yours is a sprung folder arrangement.  Comparing your with another clock I have with your type pf latch, yours looks quite thin material - my other one is 0.6mm thick.  I will try and film it.

My clock has a notably ’snappy’ action - and gives a very short impulse.  I don’t know why, but the gravity arm has had a few variations/modifications in its life (before my time) and may be a bit lighter that it should be.  I should have thought that is marginal, but it is very ’snappy’, even running at a lowish current (from memory, about 280 mA) as it does.  Note that because it runs a Synchronome distribution board, the master movement coils are able to have their current set independently.  

Mine is an early clock without the buffer stop to the left of the vertical part of the gravity arm.  As early clocks do, it has a different profile on the impulse pallet slope.  I don’t see why this should make any difference to ‘bounce’.

I will try and film the later clock.

On 30 Jun 2021, at 10:20, Simon Allen <simon.sallen@...> wrote:

These videos really do help diagnose issues.  You can swipe the video back and forwards.  It is very tricky when you wait 30 seconds for the action to start again and it is all over in a quarter of a second.

Simon

On Wed, 30 Jun 2021 at 10:01, John Hubert <jfphubert@...> wrote:
This is mine (note that mine doesn’t have the ‘advance’ loop fitted)




On 29 Jun 2021, at 18:53, bailey.services via groups.io <bailey.services@...> wrote:

How much bounce should you expect in the gravity arm, I am occasionally seeing a double impulse where it fails to latch. Reducing the current to slow things down gives unreliable advance of the pilot dial.

The latch and leather wing had been crushed together and gripped the catch on the gravity arm, I have straightened these but think the leather wing looks a bit high, bending it down so it meets the rising catch sooner and at a more acute angle would presumably slow the motion.

The leather is replaced wasn’t sure how thick it should be.

Any thoughts?
Howard <IMG_0075.MOV>





-- 
Simon



Ian Richardson
 

Hi All,

There is video on YouTube of my Synchronome No.40:

https://www.youtube.com/watch?v=Rna3Ak2W7yA

I have not watched this in slow motion until this thread started, and it is interesting to see that the action is very "snappy" with almost no bounce at all!!

Best regards,
Ian R
Auvergne,
France



-----Original Message-----
From: John Hubert <jfphubert@...>
To: synchronome1@groups.io
Sent: Wed, 30 Jun 2021 11:49
Subject: Re: [synchronomeelectricclock] Bounce in gravity arm

And here is a later clock with a folded sheet metal type of latching piece on the gravity arm - and it does also bounce quite a lot.



On 30 Jun 2021, at 10:39, John Hubert via groups.io <jfphubert@...> wrote:

There are several differences visible that may be significant.

On my clock, the ‘peg’ for the latch on the gravity arm is a solid item (looks like a steel peg with a shim soldered on!), whereas yours is a sprung folder arrangement.  Comparing your with another clock I have with your type pf latch, yours looks quite thin material - my other one is 0.6mm thick.  I will try and film it.

My clock has a notably ’snappy’ action - and gives a very short impulse.  I don’t know why, but the gravity arm has had a few variations/modifications in its life (before my time) and may be a bit lighter that it should be.  I should have thought that is marginal, but it is very ’snappy’, even running at a lowish current (from memory, about 280 mA) as it does.  Note that because it runs a Synchronome distribution board, the master movement coils are able to have their current set independently.  

Mine is an early clock without the buffer stop to the left of the vertical part of the gravity arm.  As early clocks do, it has a different profile on the impulse pallet slope.  I don’t see why this should make any difference to ‘bounce’.

I will try and film the later clock.

On 30 Jun 2021, at 10:20, Simon Allen <simon.sallen@...> wrote:

These videos really do help diagnose issues.  You can swipe the video back and forwards.  It is very tricky when you wait 30 seconds for the action to start again and it is all over in a quarter of a second.

Simon

On Wed, 30 Jun 2021 at 10:01, John Hubert <jfphubert@...> wrote:
This is mine (note that mine doesn’t have the ‘advance’ loop fitted)




On 29 Jun 2021, at 18:53, bailey.services via groups.io <bailey.services@...> wrote:

How much bounce should you expect in the gravity arm, I am occasionally seeing a double impulse where it fails to latch. Reducing the current to slow things down gives unreliable advance of the pilot dial.

The latch and leather wing had been crushed together and gripped the catch on the gravity arm, I have straightened these but think the leather wing looks a bit high, bending it down so it meets the rising catch sooner and at a more acute angle would presumably slow the motion.

The leather is replaced wasn’t sure how thick it should be.

Any thoughts?
Howard <IMG_0075.MOV>





-- 
Simon



Darren Conway
 

Hi

I inserted a small piece of shoe inner sole to absorb the shock and reduce the bounce.    The piece was inserted as shown in red on the attached image (OPs clock).

The silicone gel type soft material is good for absorbing energy.  I did it to reduce the noise.

If you want to keep to traditional materials, a piece of felt would be OK as well.

The aim is not to stop the tab flexing.  The aim is to absorb the energy to reduce the bouncing. 


Regards

Darren Conway
Lower Hutt
New Zealand


On 30.06.21 9:49 pm, John Hubert wrote:
And here is a later clock with a folded sheet metal type of latching piece on the gravity arm - and it does also bounce quite a lot.



On 30 Jun 2021, at 10:39, John Hubert via groups.io <jfphubert@...> wrote:

There are several differences visible that may be significant.

On my clock, the ‘peg’ for the latch on the gravity arm is a solid item (looks like a steel peg with a shim soldered on!), whereas yours is a sprung folder arrangement.  Comparing your with another clock I have with your type pf latch, yours looks quite thin material - my other one is 0.6mm thick.  I will try and film it.

My clock has a notably ’snappy’ action - and gives a very short impulse.  I don’t know why, but the gravity arm has had a few variations/modifications in its life (before my time) and may be a bit lighter that it should be.  I should have thought that is marginal, but it is very ’snappy’, even running at a lowish current (from memory, about 280 mA) as it does.  Note that because it runs a Synchronome distribution board, the master movement coils are able to have their current set independently.  

Mine is an early clock without the buffer stop to the left of the vertical part of the gravity arm.  As early clocks do, it has a different profile on the impulse pallet slope.  I don’t see why this should make any difference to ‘bounce’.

I will try and film the later clock.

On 30 Jun 2021, at 10:20, Simon Allen <simon.sallen@...> wrote:

These videos really do help diagnose issues.  You can swipe the video back and forwards.  It is very tricky when you wait 30 seconds for the action to start again and it is all over in a quarter of a second.

Simon

On Wed, 30 Jun 2021 at 10:01, John Hubert <jfphubert@...> wrote:
This is mine (note that mine doesn’t have the ‘advance’ loop fitted)




On 29 Jun 2021, at 18:53, bailey.services via groups.io <bailey.services@...> wrote:

How much bounce should you expect in the gravity arm, I am occasionally seeing a double impulse where it fails to latch. Reducing the current to slow things down gives unreliable advance of the pilot dial.

The latch and leather wing had been crushed together and gripped the catch on the gravity arm, I have straightened these but think the leather wing looks a bit high, bending it down so it meets the rising catch sooner and at a more acute angle would presumably slow the motion.

The leather is replaced wasn’t sure how thick it should be.

Any thoughts?
Howard <IMG_0075.MOV>





-- 
Simon



Virus-free. www.avast.com


bailey.services@...
 

The return spring is a spiral spring around the arbor that hooks into the frame, same as in your video. Yours looks to have extra weight added via brass nut and bolt which maybe necessary with earlier pallet shape. Interesting to see other videos.
Howard


John Hubert
 

Early clocks have a spiral spring as you describe.  See immediately below;

Later clocks have a separate spring set to the right side which has a few turns and a long ‘arm’.  Again, see immediately below;

Apologies for the photo quality, the light is poor and the ‘flash’ on my phone camera has a mind of its own.



On 30 Jun 2021, at 13:18, bailey.services via groups.io <bailey.services@...> wrote:

The return spring is a spiral spring around the arbor that hooks into the frame, same as in your video. Yours looks to have extra weight added via brass nut and bolt which maybe necessary with earlier pallet shape. Interesting to see other videos.
Howard


Ian Richardson
 

Further to my posting of the YouTube video on Synchronome No40, note that the latch assembly is quite different from more modern versions.  The moving latch has an agate piece let in which actually forms the latch and the post on the gravity arm is a rigid hardened steel half-round piece.  This rigid construction avoids the springiness in more modern designs - but it's a bit more noisy!  Over-run is prevented by the leather lined curved part of the latch, rather than the later buffer stop mounted lower down to buffer the vertical part of the "L" shaped gravity arm.

Note also the snub nosed impulse pallet - quite different from the later curved impulse pallet face.

Don't know if this helps, but it does show an early stage of the Synchronome's evolution.

Cheers,
Ian R
France



-----Original Message-----
From: Ian Richardson via groups.io <irichar361@...>
To: synchronome1@groups.io <synchronome1@groups.io>
Sent: Wed, 30 Jun 2021 13:09
Subject: Re: [synchronomeelectricclock] Bounce in gravity arm

Hi All,

There is video on YouTube of my Synchronome No.40:

https://www.youtube.com/watch?v=Rna3Ak2W7yA

I have not watched this in slow motion until this thread started, and it is interesting to see that the action is very "snappy" with almost no bounce at all!!

Best regards,
Ian R
Auvergne,
France



-----Original Message-----
From: John Hubert <jfphubert@...>
To: synchronome1@groups.io
Sent: Wed, 30 Jun 2021 11:49
Subject: Re: [synchronomeelectricclock] Bounce in gravity arm

And here is a later clock with a folded sheet metal type of latching piece on the gravity arm - and it does also bounce quite a lot.



On 30 Jun 2021, at 10:39, John Hubert via groups.io <jfphubert@...> wrote:

There are several differences visible that may be significant.

On my clock, the ‘peg’ for the latch on the gravity arm is a solid item (looks like a steel peg with a shim soldered on!), whereas yours is a sprung folder arrangement.  Comparing your with another clock I have with your type pf latch, yours looks quite thin material - my other one is 0.6mm thick.  I will try and film it.

My clock has a notably ’snappy’ action - and gives a very short impulse.  I don’t know why, but the gravity arm has had a few variations/modifications in its life (before my time) and may be a bit lighter that it should be.  I should have thought that is marginal, but it is very ’snappy’, even running at a lowish current (from memory, about 280 mA) as it does.  Note that because it runs a Synchronome distribution board, the master movement coils are able to have their current set independently.  

Mine is an early clock without the buffer stop to the left of the vertical part of the gravity arm.  As early clocks do, it has a different profile on the impulse pallet slope.  I don’t see why this should make any difference to ‘bounce’.

I will try and film the later clock.

On 30 Jun 2021, at 10:20, Simon Allen <simon.sallen@...> wrote:

These videos really do help diagnose issues.  You can swipe the video back and forwards.  It is very tricky when you wait 30 seconds for the action to start again and it is all over in a quarter of a second.

Simon

On Wed, 30 Jun 2021 at 10:01, John Hubert <jfphubert@...> wrote:
This is mine (note that mine doesn’t have the ‘advance’ loop fitted)




On 29 Jun 2021, at 18:53, bailey.services via groups.io <bailey.services@...> wrote:

How much bounce should you expect in the gravity arm, I am occasionally seeing a double impulse where it fails to latch. Reducing the current to slow things down gives unreliable advance of the pilot dial.

The latch and leather wing had been crushed together and gripped the catch on the gravity arm, I have straightened these but think the leather wing looks a bit high, bending it down so it meets the rising catch sooner and at a more acute angle would presumably slow the motion.

The leather is replaced wasn’t sure how thick it should be.

Any thoughts?
Howard <IMG_0075.MOV>





-- 
Simon



John Hubert
 

From the serial number records we have available, the change from the steel half round piece to the springy latch seems to have occurred around 1925.  It is not really possible to put an exact date and many earlier clocks have been updated over the years.  Between the earliest clocks (circa 1908) and the mid 1920s it is fair to say that the design of the clock was evolving and a number of changes to the latch, pallet, advance mechanism and backstop occurred.  No definitive records are known to have survived, and the knowledge we have comes from observations of surviving clocks - many of which have had a 100 year life - much of which would probably have been in an industrial, or institutional environment where reliability was prized over originality!

For those interested, the Synchronome, Masters of Electrical Timekeeping book by Bob Miles covers all of this material, but new pieces to the jigsaw surface from time to time.

John

On 1 Jul 2021, at 01:16, Ian Richardson via groups.io <irichar361@...> wrote:

Further to my posting of the YouTube video on Synchronome No40, note that the latch assembly is quite different from more modern versions.  The moving latch has an agate piece let in which actually forms the latch and the post on the gravity arm is a rigid hardened steel half-round piece.  This rigid construction avoids the springiness in more modern designs - but it's a bit more noisy!  Over-run is prevented by the leather lined curved part of the latch, rather than the later buffer stop mounted lower down to buffer the vertical part of the "L" shaped gravity arm.

Note also the snub nosed impulse pallet - quite different from the later curved impulse pallet face.

Don't know if this helps, but it does show an early stage of the Synchronome's evolution.

Cheers,
Ian R
France





James Nye
 

Just to pick up on John’s final comment on Bob’s book, there was a first edition of 500 copies in 2011, and then the (slightly) revised second edition of 300 copies in 2019. A reprint of the second edition, again in 300 copies, is currently in press. It should be available in October. This is identical to the second edition, save for the fact that we are changing the colour of the cloth for the binding, and the background colour for the dustjacket. It will still be £25 plus postage and packing.

 

All the best

 

James

 

From: synchronome1@groups.io <synchronome1@groups.io> On Behalf Of John Hubert
Sent: 01 July 2021 09:04
To: synchronome1@groups.io
Subject: Re: [synchronomeelectricclock] Bounce in gravity arm

 

From the serial number records we have available, the change from the steel half round piece to the springy latch seems to have occurred around 1925.  It is not really possible to put an exact date and many earlier clocks have been updated over the years.  Between the earliest clocks (circa 1908) and the mid 1920s it is fair to say that the design of the clock was evolving and a number of changes to the latch, pallet, advance mechanism and backstop occurred.  No definitive records are known to have survived, and the knowledge we have comes from observations of surviving clocks - many of which have had a 100 year life - much of which would probably have been in an industrial, or institutional environment where reliability was prized over originality!

 

For those interested, the Synchronome, Masters of Electrical Timekeeping book by Bob Miles covers all of this material, but new pieces to the jigsaw surface from time to time.

 

John



On 1 Jul 2021, at 01:16, Ian Richardson via groups.io <irichar361@...> wrote:

 

Further to my posting of the YouTube video on Synchronome No40, note that the latch assembly is quite different from more modern versions.  The moving latch has an agate piece let in which actually forms the latch and the post on the gravity arm is a rigid hardened steel half-round piece.  This rigid construction avoids the springiness in more modern designs - but it's a bit more noisy!  Over-run is prevented by the leather lined curved part of the latch, rather than the later buffer stop mounted lower down to buffer the vertical part of the "L" shaped gravity arm.

 

Note also the snub nosed impulse pallet - quite different from the later curved impulse pallet face.

 

Don't know if this helps, but it does show an early stage of the Synchronome's evolution.

 

Cheers,

Ian R

France



 


cicastol@...
 

Hi,
i've taken a slow mo  vid of my gravity arm, that little bouncing is not visible by naked eye, really smooth operation.

Ciro


Eric Scace
 

   It’s pretty easy to adjust to eliminate almost all of the bounce, which helps quiet the clock.

   Another helpful step is to place a small dense foam pad on the stop for the gravity arm (located behind the pendulum rod). I used a hole punch to cut one from a pad of neoprene; e.g., a computer mouse pad. Of course one must back out the screw to compensate for the presence of the foam pad. This pad acts to decelerate the gravity arm, eliminate the bounce, and cut down the noise (acoustic and vibration).

   Similarly, neoprene pads around the armature that shoves the gravity arm will cut down the noise. Spring tensions and voltages can be reduced significantly for the armature as well, if one uses a regulated DC supply rather than a battery, whilst still maintaining reliable (but much quieter) reset of the gravity arm.

   Lastly, the click jewel that drops between the teeth of the count wheel can be quieted by adding a bit of weight on its counterbalancing arm. I used a piece of heatshrink, experimenting to find the length and position that resulted in the quietest, yet reliable, operation… and then locking the heatshrink in place with the heat gun.

   All of the above steps are completely reversible to restore the clock to as-built condition.

   A more aggressive step is to remove the solenoid entirely, replacing it with a length of nichrome wire attached to the reset armature. Current flow heats the nichrome, expanding it so that a tensioning spring causes the armature to reset the gravity arm during the time allotted by the pendulum movement. Interrupting the current when the gravity arm has latched up (using a pair of leaf contacts opened by the armature travel) causes the nichrome to shrink, with the spring returning the armature to its resting position. I haven’t built this (yet). It’s not a Synchronome design, but still electromechanical, FWIW.

— Eric

On 2021 Jul 05, at 12:59 , cicastol@... wrote:

Hi,
i've taken a slow mo  vid of my gravity arm, that little bouncing is not visible by naked eye, really smooth operation.

Ciro


bailey.services@...
 

Interesting use of computer mouse pad, I will have to keep one back before they become obsolete!
My clock doesn’t have the gravity stop but all suggestions welcome and would like to see clock with nichrome wire operation.
Howard