Machine designed for the removal of welds on the corners of tubular pieces at 90°, for example table legs, with processing of the four sides of the corner in a single work cycle. Composed of 4 grinder heads, two of which are vertical mirrors that work simultaneously on the upper and lower sides of the corner and two positioned horizontally for cleaning the sides. Pneumatic tension of the belts. Controlled by a touch screen PLC with the possibility of adjusting the individual heads and controlling the individual processing times according to the required finish. Movement of the lateral heads on the vertical axis to make the most of the entire surface of the abrasive belt.