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What's holding Fen End Pit up?


Fen End Pit

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This is not one of those blog entries about 'lost modeling mojo' or real life getting in the way but rather, hopefully, some useful ideas on layout support.

 

Many years ago a company called IKEA introduced Britain to the delights of IVAR shelving. This simple system used pine uprights and pine shelves, and to keep everything upright steel cross-braces needed to be purchased. The first usage I can remember for layouts was on Middlepeak wharf and several other people copied the idea! To complicate things IKEA changed the design of the braces slightly and there are now two lengths 100mm and 80cm.

 

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The standard 100mm brace is probably at its maximum with a distance of 75-80cm between the leg uprights.

 

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Now that distance was fine on the original, two baseboard, version of Fen End Pit. Using four upright leg units I could support the layout. However as Fen End Pit grew and more legs were added the displacement between the position of the legs and the area of the baseboards which needed support became more problematic. We ended up with one baseboard supported by a leg almost in the centre and the two boards either side. This needed to be the last board put in place when we put the layout up and it was always a bit of a faff to get it into place.

 

So when I started to plan the revised Fen End Pit I knew I needed to come up with some way to make the legs and the baseboards match. The difficulty was getting around the limitations of the, otherwise ideal, IVAR cross-brace. The solution came to me while on my way back from one of our Friday nights out, luckily John was driving so the eureka moment didn't have any unfortunate side effects (or impacts). The load on the actual cross-brace isn't particularly heavy, so if I simply got a second cross-brace I could do a 'cut-and-shut' job. Joining the two lengths of brace with a length of brass tube and cyano.

 

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The resulting structure now has legs which match with the ends of the frames of each baseboard. Ignore the book case, in the railway room each unit has a bookcase underneath but it isn't structural!

 

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Originally the leg uprights on Fen End Pit sat inside the baseboard framing and the top of the leg rested on the bottom of the baseboard. This isn't ideal as the strength is obviously in the framing. However, balancing baseboard frames on the top of legs isn't really a good idea, particularly at a public exhibition with children (though somehow in my experience it is often people who should know better who rock the layout).

 

My solution to this is to use a simple ply shape at the top of the leg to provide positive location for the baseboard frame. The slot in the ply needs to be wide enough to take the thickness of two frame thicknesses (in my case 12mm each) plus, and this is critical, the space needed for the baseboard alignment dowels to come apart.

 

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As you can see this gives a secure 'seat' for the end of the baseboard to sit in. I can now sit any baseboard in place, in any order, and should sit firmly.

 


Just a few words about how the baseboards get put together. As you can see the laser cut ply frames had holes cut in it and was made double thickness to give a total 12mm of material. You can see that there are 'bullet' type connectors of 9mm diameter and a hole for an M6 bolt (these are cut at about 8mm diameter because I use a threaded 'pronged T' on each side. This means I can just carry the bolts and not have to mess about with wing-nuts to hold the boards together. A socket spanner makes light work of tightening the boards together.

 

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The 2-pin connector takes the DCC power to the rails and the other RJ-45 connection takes the rest of the control and power for the MERG CBUS control system.

 

I hope all of this is of interest to someone, if you want a closer look at the real thing then see you at Ely on the 19th May.

 

David

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"Ignore the bookcase"...............

Certainly not!

Always interesting to see what other people have on their bookshelves!

 

Might see you at Leighton Buzzard if not Ely.

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