Thread file
The thread file is a special version of the file . It is used for the manual reworking of external and internal threads on technical components such as screws , bolts , shafts or axles .
Like ordinary files, the thread file is made of suitable tool steel . The files bat , however, the cutting "teeth" consists of several parallel rows of teeth in the form of standardized cross-section ISO - thread have. The distance between the rows of teeth always corresponds to a standardized thread pitch . A thread file is therefore only suitable for one pitch and a small range of thread diameters. That is why several slopes are usually combined in one tool. Square files with a square cross-section, each with four pitches on either side of the center, and sometimes also one on each end are common.
Thread files are mainly required when parts that are expensive or complex to manufacture, such as special screws, shafts or axles, have suffered slight damage to the thread as a result of assembly or disassembly, or in order to remove other irregularities ( burr formation, etc.) from manufacture. In the case of inexpensive standard parts such as ordinary screws, the effort is usually not worth it. They are replaced by new parts.
So-called thread chasers are used for manual reworking of external or internal threads on larger nuts . They have a comb-like row of individual teeth at the end of a shank and correspond to a lathe tool ground in ISO thread form . They can also be used on lathes .