Facing and boring head

A facing and boring head comprising a supporting member in the form of a circular disc to be secured by its back to the spindle of a lathe or the like, a slide which is displaceable radially at the front of the supporting member in a guide extending perpendicularly and symmetrically with respect to the axis of rotation and to which a tool holder can be secured, a counterweight which is displaceable in a guide in the opposite radial direction between the front of the supporting member and the slide and the mass of which corresponds to that of the slide including tool holder and tool, and a gear which causes an opposite and equal radial movement of slide and counterweight depending on a positioning element, wherein the improvement comprises a cylindrical housing which surrounds the slide, the counterweight, their guides and the gear and is flanged-mounted on the supporting member, the housing including, at its front adjacent to the tool holder, a cover with a plane end face and an elongated slot extending in the displacement direction of the slide for the passage of a portion of the slide, and a cover plate which covers the elongated slot completely and bears with a plane face against the end face of the cover, said cover plate being provided on said portion of the slide.