Abstract: A surfacing plate for a boring and milling machine comprising a hollow cylindrical body provided with a rear end fixed to the milling spindle and a head on which a radial guide is formed for a tool holder slide. The movement of the slide is controlled by the boring spindle through a control unit located inside the body and comprising a central part sliding longitudinally in the body under the action of the spindle and having two longitudinal racks. The slide bears two radial racks connected respectively to the two longitudinal racks through two independant transmission trains, and is provided with means for adjusting the relative radial position of the two radial racks for taking up the play in the transmission.