What are the different types of files used in fitting?

Short Answer:

Files are hand tools used in fitting work to smooth, shape, or remove small amounts of metal, wood, or plastic. In mechanical workshops, files are very important for giving the final shape, removing sharp edges, or adjusting the size of a part. They have a hardened steel body with small cutting teeth and are used by moving the file back and forth over the material.

There are different types of files based on shape and cut. Common types include flat file, round file, half-round file, square file, and triangular file. Each type is made for a specific purpose, like enlarging holes, filing corners, or smoothing flat surfaces. Using the correct file ensures clean and accurate finishing.

Detailed Explanation:

Types of files used in fitting

In a mechanical workshop, fitting is the process of shaping, finishing, and assembling parts to meet required measurements and tolerances. Files are one of the most important tools used in fitting operations. They are made from high-carbon steel and have sharp cutting teeth arranged in rows. These teeth help in removing small chips of material when rubbed against a surface.

Files come in different shapes, sizes, and cutting styles. The correct type of file is chosen based on the material being filed and the nature of the work — whether it’s smoothing, shaping, enlarging holes, or cleaning sharp edges.

Based on Shape – Common Types of Files

  1. Flat File
  • Shape: Rectangular in cross-section with flat surfaces.
  • Use: Used for general-purpose filing of flat surfaces. It can also be used for finishing corners and external curves.
  1. Round File (Rat-tail File)
  • Shape: Circular in cross-section, tapers to a point.
  • Use: Used to enlarge round holes and for curved surface filing. It is very helpful in shaping internal curved areas.
  1. Half-round File
  • Shape: Flat on one side and curved on the other.
  • Use: Used for filing both flat and curved surfaces. It is useful in shaping internal round areas like pipe ends.
  1. Square File
  • Shape: Square cross-section.
  • Use: Used to file square corners, slots, and keyways. Also helpful in internal corners where round files can’t reach.
  1. Triangular File (Three-square File)
  • Shape: Triangular in cross-section.
  • Use: Used for filing sharp corners and angles, such as grooves and notches. Also used to sharpen saw teeth.
  1. Knife-edge File
  • Shape: Very thin with sharp edge like a knife.
  • Use: Used for filing narrow grooves and fine corners.
  1. Barrette File
  • Shape: Flat on one side and tapers to a narrow edge on the other.
  • Use: Used for finishing delicate and fine surfaces like slots or small edges.
  1. Needle File
  • Shape: Small-sized files of various shapes.
  • Use: Used in fine work, such as in jewelry making or miniature mechanical parts.

Based on Cut – File Cutting Styles

Files are also classified by the way their teeth are arranged:

  • Single Cut File:
    Teeth run in a single direction. Used for smooth finish and light filing.
  • Double Cut File:
    Teeth are cut in two directions crossing each other. Used for faster material removal.
  • Rasp Cut File:
    Has large, widely spaced teeth. Mostly used for wood or soft materials.
  • Curved Cut File:
    Teeth are arranged in curved lines. Used for automotive and bodywork jobs.

How to Use a File Properly

  1. Secure the Workpiece: Clamp the material firmly in a vice to avoid movement.
  2. Choose the Right File: Select the correct shape and cut according to the job.
  3. Hold the File Correctly: Use one hand on the handle and the other at the tip.
  4. Apply Even Pressure: Push the file forward while applying gentle pressure, and lift it slightly on return stroke.
  5. Clean Regularly: Use a file card or wire brush to clean metal particles from the teeth.

Safety Tips While Filing

  • Always wear safety goggles to protect eyes from metal chips.
  • Do not use files without a handle — it may hurt your hand.
  • Do not use excessive force; it can damage the file and the workpiece.
  • Keep the file teeth clean to maintain smooth operation.
Conclusion

Files are essential tools in mechanical fitting work. They help in shaping, finishing, and adjusting parts to exact sizes. Different types like flat, round, half-round, and triangular files are used for different jobs. Choosing the correct file and using it properly ensures smooth finishing, accurate results, and long-lasting tools. A good fitter always understands the use and care of different files for perfect fitting work.