Automatic water slot milling machine also for drilling ventilation holes on PVC profiles. The machine features 3 cutter heads with pneumatic feed and traversing on recirculating ball slideway packs which can be selected independently. The cutter heads are provided with memorizable adjustments through 6 stops on the stroke and 6 stops for head positioning. Tilting of the cutter heads is adjustable thanks to the angular references. Milling is performed via three high frequency electrospindles; four adjustable pneumatic vices ensure clamping of the profile, even large size one. Four excludable stops (two pneumatic) speed up workpiece positioning.