Question: is bsw the same as unc?
Answer: The Unified thread angle is 60° and has flattened crests (Whitworth crests are rounded). From ​1⁄4 in up to ​1 1⁄2 in, thread pitch is the same in both systems except that the thread pitch for the ​1⁄2 in bolt is 12 threads per inch (tpi) in BSW versus 13 tpi in the UNC.