Drill shear attachment clamps for a shear attachment with shear blades connected to a chuck of a portable drill includes left and right rails extending from and secured to the left housing side of the shear attachment along the drill body to a point beyond the rear of the drill body to a rear end. A connector adjustably is fastened to the rear ends of the rails to adjustably draw the ends together for nonrotatable securing of the shear attachment to the drill for one-handed operation of the drill with the shear attachment in either a right side up or upside down drill orientation.