Re: Bounce in gravity arm

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 <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.


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, via <> 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>


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