Casting a venturi
Just testing to see if I can do this!
This method of venturi manufacture comprises casting lead into a copper pipe mould using cores which create the specially shaped internal voids.
These cores can be made from several materials, steel, aluminium, wood or even plaster. Each has its benefits and drawbacks:
Steel ... will give an excellent finish to the internal faces of the venturi and is durable. It requires the use of a release agent without which there is risk the lead adhering, making it impossible to remove the cores. A lathe will be required to manufacture steel cores.
Aluminium ... will give a reasonable finish but may degrade with multiple use. It doesn't require a release agent and a lathe will be required to make the cores.
Wood ... will give a poor finish and can only be used once. Charring may evolve gas as the molten lead is pored worsening the finish. Wood cores do not require any special tools and can be made quite simply by whittling, filing and sanding.
Plaster ... I haven't tried this yet but if a wood core is pushed into some Plasticine, plaster can be poured into the mould to create a core. Plaster cores will probably not give a smooth finish and will most likely be destroyed when removed.
Core geometry
--Bio-rich-time-poor 12:25, 13 November 2010 (UTC)
