A bell made with cement cinder blocks covered in cob

[dustinmattison]

Dear All,



Can I use cement cinder blocks instead of cob bricks for the perimeter of the bell chamber, and then cover the inside with a an inch or two of cob? Would the cob without straw be enough to protect the cinder blocks from heat damage?



Dustin

[peterberg]

You could build the bell out of cinder blocks, yes. Those blocks can withstand heat in the range of 400 to 500 C. But you need to line the inside of the bell with refractory material like fire bricks everywhere above the level of the riser. You could even use split fire bricks for that purpose, has been done before with good results.
Don't apply cob on the inside, there's a good chance it will come loose and fall down.
My opinion, of course.

[ronyon]

Would a sheet metal lining work as well as a refractory lining in the areas above the riser? The metal barrels survive direct blasts from the riser.