It is not an issue of relative materials hardness.
It is about technique.
The question is...
How can the cutting stone expand inside the borehole in order to enlarge the borehole out to within a few mm of the outside diameter?
CUTTING STONE INSERTED
DRIVESHAFT/STICK INSERTED, ENGAGED WITH CUTTING STONE
CUTTING STONE MIRACULOUSLY EXPANDED?????????
TOTALLY, PHYSICALLY IMPOSSIBLE
Edited 3 time(s). Last edit at 07-May-16 02:18 by Jon Ellison.