saw blades

Quoted text begins.What points do I look for in deciding on a blade?
End of quote.

Hi Norman,

Balancing price against performance means talking to your supplier, and then
developing your own experience.

Different stones require different blades. Sandstone can be cut using almost any
blade, wet or dry. Brittle marble needs to be cut with a continuous rim wet
blade. Granite can be cut wet or dry, but you must be particular about the type
of blade.

Your euipment wil determine what blade you can use. If you have air-powered
saws, you can use wet blades, if you have only electric, stick to dry cutting.
If dust is a problem (working indoors) use dust suppression (hold a wet sponge
against the blade) or dust extraction (vacuum cleaner nozzle near the dust exit
point).

Dry blades (turbo blades) are 'turbinated' - they have ridges along the face of
the blade to widen the cut. Widening the cut stops the stone rubbing on the
sides of the blade and overheating it, and the ridges draw cooling air into the
cut. Wet blades have slots in the rim to drag cooling water into the cut, or
have a continuous rim. Turbo blades produse a rougher cut than continuous rim,
sacrificing quality for convenience. Delicate marbles cannot be cut accurately
using turbo blades, they just fall apart.

The performance of a blade is determined by what type of matrix holds the
diamond borts in place. The tungsten carbide matrix is inversely matched to the
hardness of the material to be cut, soft matrix for hard stone, hard matrix for
soft stone. Put a little too simply, a hard, resistant stone will wear the
matrix, exposing the diamonds for cutting, and a soft stone will preserve the
matrix, holding the diamonds in place.

Heat is the enemy of diamonds. Being the hardest known substance, they just
don't wear. They shatter when heated and cooled suddenly. Something like 186
times every second, spinning in a grinder. So let the coolant, whether it's air
or water, run freely over the blade and don't force the blade too hard. The
blade can distort if it gets too hot, turning into a saucer shape. Even dry
blades can burn, and need to be sharpened by running through abrasive stone.

Some pictures here:
http://www.mkdiamond.com/stone/bld_00.html

Good luck with your reactions...

Simon