Ceramic Spheres: a Work in Progress

I am currently preparing to make a series of fired ceramic masonry spheres, around 3 feet in diameter.   These spheres will utilize the interlocking triangular design which I’ve developed over the years.  The image below is from an electronic file created by my business partner, Mike Wong.  This same file will be used to produce the master shape from which molds are made.

I plan to produce the ceramic shapes from plaster molds.  These molds will be made from a CNC (computer numerically controlled) machined master shape.  I expect the master shape to be made from wood.  The key to doing this efficiently is to cast the ceramic parts from a simple two-piece plaster mold.  More than two parts for a mold makes production difficult, time consuming and expensive.  Below are images of blocks made from a two-piece mold for a kiln I made, as discussed here.

The geometry I’ll be using for this sphere is that of an icosahedron.  There are twenty pieces in an icosahedron, each is an equilateral triangle.  The shapes will be curved, like those on the right, below:

I’ll probably use a series of thin metal bands on the outside of the sphere to help hold the sphere together and make them easy to transport.  I expect these to look pretty cool, like a modular spherical UFO of a barbeque!

These complete spheres will have a rectangular door on the side.  I plan for this door to be a simple hinged arrangement, with a hinge at the bottom. 

These spheres can be used for pizza ovens, barbeques, smokers, or simply as ovens.  I’m curious if anyone reading this can think of another use for this sized sphere?

I plan to configure these so that they can run on propane, natural gas, wood or charcoal.  I plan to have the burner port on the bottom and the vent/chimney on the top.  I also plan for the flame to be slightly tangential (offset from center) so that a swirling vortex is developed within the firing space.  This extends the flame path, creates more even temperatures, and increases efficiency.

The thermal mass effect of the ceramics will help provide radiant heat and even temperatures throughout the firing space.

I will post additional entries on this forum as the project moves along.  Right now I have around 25 tons of clay sitting in my driveway, which I’ll be using to make these spheres (right now I'm racing against winter!).  If all goes well, I should be able to make between 500-1,000 of these spheres.  This should be fun!

[Here is an update on this project]