... : 60mm·Shank Diameter:6mm·Model:C6·Design For CNC Milling Machine, Engraving marble ,granite ,sandstone ,stone, tile ,bluestone, glass·High ... engraving bit is most important for working with CNC Router Machine. How to select a good engraving bit supplier???1. Select good quality engraving ... supplier can test bit with CNC Machine. If Bit supplier can't operate CNC Machine, bit quality not be approved.3 ...