How to calculate volume for casting

[theresa]

This may sound like a daft question, but here goes anyway - how do you calculate the amount of metal needed when casting, eg to pour into a 10mm ring shape gouged out of charcoal. Is there a formula?:confused:

[Dennis]

No formula, but just an experienced eye. If pouring by gravity, at least twice the volume, but someone who has done Delft clay, cuttlefish casting, or similar, will know.

If I had to invent a method, I would fill the mould with something mouldable and non destructive, such as BluTack, and submerge that in a measuring cylinder of water. The amount the water rises is the volume. Dennis.

[theresa]

Thank you Dennis