Monday, May 31, 2010

How I cast cattle/loading docks from concrete

Given that my railway is inspired by the Welshpool and Llanfair and similarly based in a rural location (in the heart of Cheshire) and, like the W&L, the line terminates beside a Smithfield Market, it's inevitable that livestock will become a mainstay of the goods traffic on the line. Having already constructed two cattle vans (based loosely on W&L prototypes - see How I constructed two cattle wagons), with more planned, I realised I would have to construct the means by which the wagons could be loaded at each station on the line. Having gained some experience of casting overbridges in situ (see How I cast two concrete overbridges), I decided to use the same approach.

Firstly, a mould was constructed out of off-cuts of timber:

Having unsuccessfully tried scribing the stonework by removing the mould when the concrete was still in its partially dried (green) state, I decided to use an approach I'd used successfully on one of the bridges - I used a hot glue gun to create mortar courses inside the mould:

A site was selected alongside a siding and some hardcore (rubble) was put into a trench beneath where the dock would sit:

The mould was then put in place and filled with a stiff mix of concrete (2 parts sand, 1 part gravel, 1 part cement) to which had been added some red dye to simulate the local red sandstone.
While the concrete was wet. I added some square posts (mahogany) to eventually support the railings to guide the livestock up the ramp:

Lolly sticks were trimmed to fit in between the posts to mask the surface when sprinkling coarse sand on the surface. 

When the concrete was nearly dry (12-24 hours), the lolly sticks were removed so the tops of the stonework could be scribed on.

When the concrete was completely dry (3 days) the mould was carefully dismantled by unscrewing the screws which hold it together.

Railings made from coffee stirrers were then glued on to the posts with exterior PVA and treated with Cuprinol.
A mix of concrete (4 parts builders' sand + 1 part cement + brown dye) was smeared on the trackwork and then stippled with an old paintbrush. As you can see, I have a bit of tidying-up to do - remodelling the corner nearest the camera and colouring the mortar-courses - but the overall effect seems OK.

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