An underground drilling machine comprising: a rotational driver including a rotationally driven rod coupler adapted for connection to an end of a drill rod , the rod coupler being rotatable about a drive axis , the rotational driver being mounted to move back and forth along the drive axis ; a drill rod storage structure positioned alongside the drive axis ; a rod handling device for conveying drill rods back and forth between the drive axis and the drill rod storage structure along a rod transfer path; a first rod vise positioned along the drive axis ; and a second rod vise positioned along the drive axis , the second rod vise being positioned between the first rod vise and the rotational driver , the second rod vise being movable along the drive axis relative to the first rod vise between a first axial position and a second axial position, the first axial position being located such that the second rod vise is not intersected by the rod transfer path when the second rod vise is in the first axial position, the second axial position being located such that the second rod vise is intersected by the rod transfer path when the second rod vise is in the second axial position, the second rod vise being pivotally movable about the drive axis between a first pivotal position and a second pivotal position; and characterized by further comprising an up-hole rod centering member corresponding to the second vise and a down-hole rod centering member corresponding to the first vise , the first and second vises being positioned between the up-hole and down-hole centering members , the up-hole and down-hole centering members being configured for centering drill rods relative to the first and second vises while the first and second vises are open. a rotational driver including a rotationally driven rod coupler adapted for connection to an end of a drill rod , the rod coupler being rotatable about a drive axis , the rotational driver being mounted to move back and forth along the drive axis ; a drill rod storage structure positioned alongside the drive axis ; a rod handling device for conveying drill rods back and forth between the drive axis and the drill rod storage structure along a rod transfer path; a first rod vise positioned along the drive axis ; and a second rod vise positioned along the drive axis , the second rod vise being positioned between the first rod vise and the rotational driver , the second rod vise being movable along the drive axis relative to the first rod vise between a first axial position and a second axial position, the first axial position being located such that the second rod vise is not intersected by the rod transfer path when the second rod vise is in the first axial position, the second axial position being located such that the second rod vise is intersected by the rod transfer path when the second rod vise is in the second axial position, the second rod vise being pivotally movable about the drive axis between a first pivotal position and a second pivotal position; and characterized by further comprising an up-hole rod centering member corresponding to the second vise and a down-hole rod centering member corresponding to the first vise , the first and second vises being positioned between the up-hole and down-hole centering members , the up-hole and down-hole centering members being configured for centering drill rods relative to the first and second vises while the first and second vises are open. <EOS>