A tool for attaching a suture (20, 84) to a needle barrel (14, 82), the needle barrel having a first radially defined portion (86) in a 12 o'clock position in the circumference of the section transverse of the needle barrel, a second radially defined portion (88) in a 6 o'clock position on the circumference of the cross section of the needle barrel and the first and second lateral portions (90, 92) in a position at 9 o'clock and 3 o'clock respectively in the circumference of the cross section of the needle barrel, and a hole (18, 96) that is formed at one end of the needle barrel (14, 82) and it is at least partially defined by opposite inner surfaces (94), and the end of the suture (20, 84) being positioned in the hole (18, 96), said tool comprising: a first set of dies (22) that includes the first (24) and second (26) dies, at least one of said first (24) and second (26) dies being mobile in relation to the other of said first (24) and second (26) dies, said first die (24) having a first slot (40) therein to receive the barrel of the needle (14, 82) and said second die (26) having a flat surface (30) opposite and separate from the first die (24), such that when said at least one of said first (24) and second (26) dies moves to said other of said first (24) and second (26) dies during a first compression stroke, said second die (26) compresses the first radially defined portion (86) of the needle barrel (14 , 82) to compress the suture (20, 84) against the opposite inner surfaces (94) of the hole (96), said first groove (40) being at least partially defined by a cylindrically curved surface (42) with a constant radius r1 on a longitudinal axis A1 on an arc of about 180º, the axis A1 is or separated from a flat surface (28) of the first die (24) by a distance d1, wherein the radius r1 of the curved surface (42) and the separation distance d1 are selected so that the needle barrel (14, 82) is contained laterally in the first and second opposite lateral portions (90,
