DTH Drill Bis Grinder Sharpening Machine BTON200, BTON500, AGM18, etc...are pneumatic models, called air grinder. Our Air Grinders require a clean and dry air supply of a minimum 80 psi and 29 cfm passing through an in-line oiler to supply lubrication to the grinder. Also, a supply of water from a mains supply or a sump is required to act as a coolant during the grinding process.