Chamfering, immediately after drilling, with no changes either in job setting, spindle speeds or direction of spindle rotation. No special skill is required. the bottom side of a drilled hole is deburred or chamfered, after mounting the same job upside down. The automatic duplex deburring & chamfering tool, in one go, deburrs and produces a chamfer in a drilled hole both at the top as well as at the bottom. No change either in the spindle speed or in the direction of spindle rotation or in the job set-up is required.