Die for cutting screw-threads

A die for cutting external taper screw threads into tapered ends of externally ribbed steel for reinforcing concrete with an external thread-cutting machine to which the die is operatively connectible, said die comprising:

• a cutting portion of finite length and having a plurality of first cutting teeth arranged in a cutting plane, said cutting plane having a finite length measured in the longitudinal direction of said die, said first cutting teeth having a tooth depth increasing within said cutting plane rearwardly to final depth;
• and
• a guide portion adjacent said cutting portion, said guide portion having a predetermined length measured in the longitudinal direction of said die and having a plurality of second cutting teeth arranged in a guide plane, said predetermined length of said guide portion corresponding to about 3 to about 6 times the magnitude of said infinte length of said cutting portion, and said predetermined length of said guide portion being of from about ten to about twenty times the magnitude of said finite length of said cutting plane, said second cutting teeth in said guide portion having a constant tooth depth corresponding to the final tooth depth in said cutting portion.