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4rd March 2012 Time for a clock

Bob's Clock
The inspiration behind my model was Bob Palmer's pre-war model shown at the January meeting of SELMEC

The end of January saw the first meeting of the year for the South East London Meccano Club (SELMEC).  At that meeting, new member Bob Palmer showed his version of a clock based on a pre-war manual model. For years I have thought about building a clock but never got around to it. This little model captured my imagination and I decided to have a go. A discussion with Bob followed and I discovered that he had incorporated certain modifications…

Using old manual instructions to build models can be fun but can also be full of pit-falls. The detail that caught me out with this model was the circular strip. I did not realise at the time but the circular strip used in the pre-war plan is the old, 7 inch diameter, obsolete version - I wondered why it wouldn’t fit! We have several circular strips in our collection but they are all the latter 7½ inch diameter part.  It wasn’t too much trouble to accommodate the larger piece requiring only minor changes to the ‘case’ and a few spacer washers here and there to get the clock spindle in the correct (central) position relative to the new larger circular strip.

Clock
The 'case' takes shape

The other major change is to the gearing. Since the model was designed, a 4:1 (15t pinion and 60t gear) ratio has become available meaning the drive between the minute and hour hand can be simplified to just two pairs of gears 3:1 + 4:1 giving a total of 12:1. At the time of writing 4:1 was only achievable by using two pairs of 2:1 (25t pinion and 50t gear) gears. This also put the axles out of position so a further pair of 1:1 (2 x 30t gears) is incorporated to get all the gears and axles in such a position to drive the hands. With all those unnecessary gears removed and replaced with the single set of 4:1, the gear-chain is much easier to understand for a novice clockmaker like me.

Gearing
Using the 4:1 ratio gears removes a lot of the clutter

The rest of the model is straightforward. I have made a few cosmetic changes to the design by adding feet made from socket couplings and modern tyres. I also had to replace the curved strips that link the frame to the circular strips to accommodate my use of the larger ring.

A few hours after beginning this little project the clock ticks away and seems to keep reasonable time although I can only get it to run for an hour or so at the moment. I think this is because I have built it using the first parts that came to hand. In future I will be selective about which gears I use looking for true running coaxial items (or at least as near as I can find). Sue and I have also taken on a new hobby – axle rolling – in an effort to find the straightest Meccano rods we can find in our collection. Failing that I might resort to using stainless steel compatible axles.

It Works!
It worked - First time! now for the clock face and some hands...

For now, I will play around with this little clock to get the best out of it I can and I am working on a face. It may not be a John Harrison regulator but it is mine, I built it and it works (after a fashion). Very satisfying!

I will post some pictures of the finished model soon...

Ralph

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