A method of forming a radial array of overlapping blades comprising: a first stage of advancing a tool towards a workpiece in a direction towards the face of the workpiece to remove material from said workpiece by inducing a change of state of the material by proximity of said tool to produce a partially finished bladed disc; and a second stage of removing further material from said workpiece to finish said blades, this removal also being effected by a change of state of the material induced by proximity to a second advancing tool, wherein said second advancing tool comprises: a first side opposite a second side and third and fourth side surface regions extending between said first and second sides; and a top and a bottom, wherein: either said first side is adapted to be supported with said second side being unsupported or said top is adapted to be supported with said bottom being unsupported; said third side surface region is concave and corresponds to a desired convex face of the blades and said fourth side surface region is convex and corresponds to a desired concave face of the blades; and said bottom corresponds in shape to a desired surface of a hub at a blade root region of the workpiece, said second stage comprising: machining the convex face of one blade as said second advancing tool is advanced radially towards the partially finished bladed disc into a gap between respective blades; rotating the disc slightly on its axis; and machining the concave face of an adjacent blade as said second tool is withdrawn. a first stage of advancing a tool towards a workpiece in a direction towards the face of the workpiece to remove material from said workpiece by inducing a change of state of the material by proximity of said tool to produce a partially finished bladed disc; and a second stage of removing further material from said workpiece to finish said blades, this removal also being effected by a change of state of the material induced by proximity to a second advancing tool, wherein said second advancing tool comprises: a first side opposite a second side and third and fourth side surface regions extending between said first and second sides; and a top and a bottom, wherein: either said first side is adapted to be supported with said second side being unsupported or said top is adapted to be supported with said bottom being unsupported; said third side surface region is concave and corresponds to a desired convex face of the blades and said fourth side surface region is convex and corresponds to a desired concave face of the blades; and said bottom corresponds in shape to a desired surface of a hub at a blade root region of the workpiece, said second stage comprising: machining the convex face of one blade as said second advancing tool is advanced radially towards the partially finished bladed disc into a gap between respective blades; rotating the disc slightly on its axis; and machining the concave face of an adjacent blade as said second tool is withdrawn. a first side opposite a second side and third and fourth side surface regions extending between said first and second sides; and a top and a bottom, wherein: either said first side is adapted to be supported with said second side being unsupported or said top is adapted to be supported with said bottom being unsupported; said third side surface region is concave and corresponds to a desired convex face of the blades and said fourth side surface region is convex and corresponds to a desired concave face of the blades; and said bottom corresponds in shape to a desired surface of a hub at a blade root region of the workpiece, said second stage comprising: machining the convex face of one blade as said second advancing tool is advanced radially towards the partially finished bladed disc into a gap between respective blades; rotating the disc slightly on its axis; and machining the concave face of an adjacent blade as said second tool is withdrawn. machining the convex face of one blade as said second advancing tool is advanced radially towards the partially finished bladed disc into a gap between respective blades; rotating the disc slightly on its axis; and machining the concave face of an adjacent blade as said second tool is withdrawn.