Rather than relying on channel action like normal bits core bits have a central pilot bit that holds the bit in place while the outer sections of the bit cuts a hole through stone.
Marble hole drill bit.
These core bits are made up of a concentration of diamonds and metal bonds in order to cut the hard surface of the granite.
It leaves a cylinder shape which often is used as sink holes or to feed lines and pipes.
Hole bits or core bits are specially designed drill bits that are tipped with either diamond or carbide.
Marble drilling bit self centering marble drilling bit creates the perfect indentation to keep marbles in place on a board.
Sunjoyco diamond drill bits 30 pcs glass hole saw drill bit set cutting remover tools for glass porcelain tile ceramic marble granite bottles diy 6mm 50mm 4 1 out of 5 stars 208 18 99 18.