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29th April 2010 A bridge too far…

This year has been one mad panic after another and the Meccano time has been suffering. For the past couple of weeks Sue and I have been trying to complete a model of a transporter bridge for display this bank holiday weekend at the Meccanuity 10 exhibition in Ironbridge. The theme of the show this year is bridges, shame it wasn’t last year as we had our 16½ foot long model of the forth bridge on display, see HERE. It is now Thursday, the day before the show set up and it is becoming obvious the transporter bridge is just not going to be finished in time…

Tower Bridge
The finised model

Time to implement Plan B. What’s plan B? I hear you ask. It is now that I should be answering with a well-defined fallback plan, trouble is there is not one. At this point the immortal words of Douglas Adams (or for that matter corporal Jones) come to mind  “DON’T PANIC!”  What we need here is a bridge, any bridge, nothing enormously complicated but something recognisable as a bridge. My first thought was the swing bridge from the 1960s No 6 set in silver/black/yellow. I can remember wishing I had enough Meccano to build it when I had expanded my collection to a set No 5. More than forty years later I happen to have a French No 7 set (equivalent to that original No 6 set) and that same bridge is featured in the manual. In the cold light of day that model is not up to much and even if a do spend some time improving it will still not be recognisable to non Meccano people. However while flicking through the pages of said instruction manual I spotted a reasonable looking representation of probably the most famous bridge in the whole world, Tower Bridge. That was it, Plan B had arrived and was about to get implemented. 

Instruction boof from French No 7 set

The model in the manual was severely compromised by the lack of parts available in the set. Luckily we don’t have that problem any more. The result of many years of searching the boot fairs and jumble sales as well as auctions and even ebay in recent years we have amassed a goodly amount of what has become known as common parts. This will enable me to build a pretty good representation of Tower Bridge based on the original model in the instruction book.

Walkway
Doubled up single braced girders look much better

Our favoured colour scheme at the moment is Silver/Red so I managed to find enough red plates in good condition and some single braced girders that were doubled up to give the look of double braced girders. Building commenced and before long the familiar shape was beginning to take shape. Areas of multiple plates were substituted with solid plates and infill was added where it was not used on the original plan. This all helps to make the bridge look more substantial. The catenary and its suspension cables were represented in the original model with string. On our model the catenary was made from 3 and 4 hole narrow strips that had initially been bolted loosely together. This was to prove a disaster, as it was impossible to get a convincing catenary without leaving the nuts so loose that they would fall off. Lock-nutting would have solved the problem but that would have been laborious as well as not looking very neat. The Meccano locking nuts came to the rescue and prove a very satisfactory solution.

Catenary
Modem locking nuts allows the catenary to form on the suspension chains

The top of each tower had a 2½ x 2½ inch perforated plate fitted, one hole down and onto this four red trunions were mounted. The top of each tower was finished off with a zinc strips bolted inside and out and a screw rod adapter in the centre onto which the flag pole is attached using a metal rod connector.

Having started this model on Thursday afternoon It was a late night and then an early morning to get it finished in time. Set up was Friday and we had to get there first but that is another story…

Ralph.

 

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The top of each tower has strips lining the inside to add strength and create a solidity to the structure
 
 
 

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