Machine for continuous casting of a lead alloy for forming a continuous strip of grids for plates of electric storage batteries, which comprises: - a support structure abutted against the ground; - a rotary drum rotatably mounted on said support structure around a rotation axis, provided with an external peripheral surface with a plurality of grooves obtained according to the grid design to be made; - a sliding block fixedly mounted on said support structure, having an internal surface of curved shape adapted to be coupled in sliding relation with the external surface of said rotary drum, and provided with means for distributing molten lead intended to receive a flow of molten lead from feeding means and adapted to insert said molten lead within the grooves of said external peripheral surface, filling said grooves during the rotation of said rotary drum, in order to form a continuous strip of grids made of lead; said plurality of grooves comprising: - at least two circumferential notches spaced from each other and intended to form, by means of the lead of the distribution means of said sliding block, two first longitudinal sides of at least one first succession of grids of said continuous strip of grids made of lead; - at least one plurality of transverse notches parallel to the rotation axis of said rotary drum, spaced from each other and intended to form, by means of the lead of the distribution means of said sliding block, two second transverse sides of each grid of said at least one first succession of grids; wherein said circumferential notches and said transverse notches meet at a plurality of vertices intended to form the corners of the first succession of grids of said continuous strip of grids made of lead; wherein said machine comprises a plurality of studs placed within at least one of said at least two circumferential notches at said vertices to interrupt the circumferential continuity of said circumferential notch, intended to shape the corners of the first succession of grids of said continuous strip of grids made of lead in smoothed form; said machine being characterized in that said sliding block comprises at least one extension portion which is arranged at said at least one circumferential notch provided with said studs and is circumferentially extended in the sense opposite the rotation sense of said rotary drum. - a support structure abutted against the ground; - a rotary drum rotatably mounted on said support structure around a rotation axis, provided with an external peripheral surface with a plurality of grooves obtained according to the grid design to be made; - a sliding block fixedly mounted on said support structure, having an internal surface of curved shape adapted to be coupled in sliding relation with the external surface of said rotary drum, and provided with means for distributing molten lead intended to receive a flow of molten lead from feeding means and adapted to insert said molten lead within the grooves of said external peripheral surface, filling said grooves during the rotation of said rotary drum, in order to form a continuous strip of grids made of lead; said plurality of grooves comprising: - at least two circumferential notches spaced from each other and intended to form, by means of the lead of the distribution means of said sliding block, two first longitudinal sides of at least one first succession of grids of said continuous strip of grids made of lead; - at least one plurality of transverse notches parallel to the rotation axis of said rotary drum, spaced from each other and intended to form, by means of the lead of the distribution means of said sliding block, two second transverse sides of each grid of said at least one first succession of grids; - at least two circumferential notches spaced from each other and intended to form, by means of the lead of the distribution means of said sliding block, two first longitudinal sides of at least one first succession of grids of said continuous strip of grids made of lead; - at least one plurality of transverse notches parallel to the rotation axis of said rotary drum, spaced from each other and intended to form, by means of the lead of the distribution means of said sliding block, two second transverse sides of each grid of said at least one first succession of grids;