Re: Count wheel & backstop roller & Pendulum length to bob?

John Hubert

You will have to try it.  It is entirely possible the bob is a replacement, but the weight is not ‘critical’.  The rod itself is quite light, so the bob dominates the CoG.  You might have to extend the threaded section at the rating nut end if it has been snapped short, but that is easy.  I believe it is 4 BA threaded rod/stud/bar - widely available in longish lengths quite cheaply.  6 inch and 12 inch lengths of 4 BA threaded bar (note bar or stud is a better search term) are available on eBay for under £10.


On 23 Feb 2021, at 16:05, Chris Wollaston <chris@...> wrote:

Hi, well, I may be in a bit of a pickle here with this pendulum and bob. The facts are:
Bob weight = 9.25lbs, dimensions of bob: Ht = 15.4cm,  Dia = 6.2 cm
Invar steel rod length - w/o threaded adjuster, just rod to steel top clamp, not with suspension spring = 102cm
So, is it likely that the CofG is going to be very much different to a 16lb bob on a standard Invar rod of say 108cm that an acquaintance has on a Synchronome master and hence the time period for each swing way out of standardisation?
i.e. Is it likely that this pendulum and bob are for a different clock altogether?
If it isn't going to keep anywhere like correct time then how do I source the correct pendulum and bob?

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