ASME B18.29.1 pdf download Helical Coil Screw Thread Inserts— Free Running and Screw Locking (Inch Series) 1.4 Class of Fit Since helical coil inserts are flexible, the class of fit of the final assembly is a function of the size of the tapped hole. Helical coil STI taps are available for both tolerance Classes 2B and 3B tapped holes. Tolerance...