... and finally...

This is a multi-part casting. Each rib was a separate part, cast as a 'set' and linked by sprues. With any enclosed mold, you have to pay attention to both where the molten metal enters the mold and where the hot gases exit. A good cast seems to be 90% about the preparation of the mold, so hats off to the guys who helped me with this, as the number of pieces meant a complex mold. The individual pieces were created out of polysterene using a hot-wire and encased within the mold for a 'lost' pour. Always make sure you've bribed the pour crew with a few beers, as they tend to end up wreathed in noxious smoke when the metal enters the mold!

Cheers to Stuart McWilliams for the photos - and a chance for a quick public plug! - http://www.stuartmcwilliamphotography.co.uk/