Question: what is the difference between unc and unf thread?
Answer: UNC: Is the symbol for Unified coarse pitch threads. UNF: Is the symbol for Unified fine pitch threads. UNEF: Is the symbol for United extra fine pitch threads. ... As an example, a 1/4"-20UNC thread has a 1/4" major diameter, with 20 threads per inch (TPI) and is a UNC coarse pitch thread.