Turning 2 stone

["Simon Brown" <moonsong@zzzzzzzzzzzzzzz>]

Hi Bob,

I've got some photos of my home-made lathe that I could send to you. I now
use a CNC bridge saw with a turntable in a training workshop for a similar
use. I also use a brick saw with a potter's turntable under it for turning
simple bowls. A stone mill that I deal with uses a reverse blank wrapped in
diamond tape to hone out a positive blank.

Diamond saw blades are meant to be stressed and worn from the periphery in,
not from the side - there is a risk of losing segments and wearing the blade
out inefficiently - but you may consider this acceptable to achieve your end
result.

I imagine that a cup wheel would be too slow, instead, use the saw blade
(cutting at right angles to the axis of rotation) to provide a series of
concentric rings, then 'wipe' the blade sideways along the piece to clean it
up.

The saw blade can cut as deep as you like, but don't wipe the blade sideways
any deeper than the depth of the cutting segment.

I think the key is first getting the penetration through the waste using the
saw blade, then using the blade to clean up. I don't think that drilling and
splitting would work because of the risk of splitting right through the
stone, as well as leaving a rough surface inside ( I'm assuming you mean
inside a bowl?). Use the diamond blade for waste removal is surprisingly
effective if the cut is reasonably smooth, not lumpy.

The other thing to be careful of is to make sure the saw is firmly mounted
so the cutting action is free from vibration.

Simon