Sunday, 25 November 2012

Internal Divisions

I am hoping that I have now designed the last bit of the 3D jigsaw that is the NG Y ballast wagon kit - save for the brass bits which I shall entrust to Narrow Planet.

This last piece is perhaps the most complicated and ambitious on the wagon. It is the internal sections which guide the payload to the eight doors at the bottom of the hopper.

(The irony is not lost on me that all this effort will be wasted on buyers who choose to model their wagons loaded!)

As I have done all the way through the project I am trying to cast this in the least amount of pieces possible, which in this case means dividing it in half into two mirror image sections which meet in the middle.

Being mirror-image, of course, means I only have to make one master.

What makes it particularly challenging is the way the main sloping section rises up into the body of the hopper and joins with the sloping ends, which has been achieved by means of the small triangles at the top corners.

The three dividers have also had to be shaped to fit into the angles inside the wagon and have a triangular section along the top which protrudes to rest on the top of the frames,

It is these which concern me most.  I am hoping they will cast OK in the mould.

Here's how the master sits inside the wagon.

If - and it's always a big if - I have measured and made it accurately enough, two of the casts should fit neatly in the hole and meet in the middle.

The silicone mould is setting as I type, so I'll find out soon enough...

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