FilFiles are used to shape metal parts, adjust fits, clean up castings, remove excess solder, and refine surfaces before assembly or finishing. They offer control and precision where cutting tools or abrasives would be too coarse or inconsistent. A small number of high-quality files, chosen and maintained carefully, can meet almost all modelling requirements.
Classifying Files
Files are classified by length, cut, and cross-section.
- Length refers to the cutting portion only, excluding the tang.
- Cut describes the type and density of teeth—whether single-cut, double-cut, or another variant, and how coarse or fine the teeth are.
- Cross-section defines the file’s shape, which affects its suitability for different tasks.
Shorter files tend to have finer teeth for a given cut grade. For example, a cut #2 file at 4 inches will have more teeth per inch than a cut #2 file at 8 inches. This makes shorter files more suitable for detail work.
[Diagram: Figure showing file length measurement and difference between hand and flat files.]
Tooth Types
- Single-cut files have a single row of teeth, usually cut at about 25° to the file axis. They produce a smoother finish and are ideal for draw-filing, finishing strokes, and use on soft materials.
- Double-cut files have two intersecting sets of teeth, usually at 25° and 45°. These cut more rapidly and are used for general shaping on harder materials. Most modelling work relies on double-cut files.
- Curved-tooth or Dreadnought files are intended for heavy removal on soft or fibrous materials such as wood, Tufnol, Ebonite, and aluminium. They are too coarse for modelling but can be useful for roughing out jigs or stock material. The smallest available is typically a 6″ hand file.
[Diagram: Comparison of single-cut and double-cut teeth patterns.]
Common File Shapes
| Shape | Description |
|---|---|
| Flat | Tapered in width and thickness. Cut on both faces and both edges. Suitable for general work. |
| Hand | Parallel in width, tapered in thickness. Cut on the faces and one edge only; the other edge is safe (no teeth). Useful when filing up to shoulders or internal corners without damaging adjacent surfaces. |
| Square | Used to enlarge or true internal corners and slots. |
| Triangular | For cleaning out angles and working into tight spaces. |
| Half-round | One flat face and one curved. Useful for concave shapes or irregular surfaces. |
| Round | Tapered cylindrical profile. Used to enlarge holes and shape curved recesses. |
| Barrette | Triangular with one wide cutting face and two safe sides. Ideal for edge work. |
| Warding | Thin and flat, often tapered. Originally for lock work, but suitable for fine slots and grooves. |
[Diagram: Cross-sections of common file shapes.]
Hand files are especially useful where a safe edge is required. When filing into a rebate, shoulder, or close to a finished surface, the safe edge allows material to be removed from one side only, protecting the adjacent face. The straight edge of a hand file can also be used to check flatness or act as a guide.
File Cuts and Grades
Files are graded by the spacing and size of their teeth. The most common grading system for precision files is the Swiss cut system, used by manufacturers such as Vallorbe and Grobet. Higher numbers indicate a finer tooth.
| Swiss Cut | Approx. Teeth per Inch | Typical Use |
|---|---|---|
| #0 | ~50 | Heavy stock removal |
| #2 | ~79 | General-purpose shaping |
| #4 | ~117 | Finishing brass or nickel silver |
| #6 | ~160 | Fine adjustment and clean-up |
| #8 | ~260 | Ultra-fine finishing |
The same cut number will differ in absolute coarseness depending on the file’s length. For example, a 4″ cut #2 file will have finer teeth than an 8″ cut #2 file.
Swiss pattern files are all double-cut and are produced to high standards of consistency and sharpness. The cut number is typically stamped on the tang of the file, making identification straightforward. Swiss files also offer a broader range of profiles than standard engineering files, and the finer cuts produce a cleaner finish with less need for subsequent polishing.
Tapered shapes in Swiss files are generally sharp-pointed, unlike many Sheffield pattern files which taper more gradually. Blunt or parallel files are also available and are usually marked or catalogued separately. Like Sheffield files, Swiss files vary in width, thickness, and available cuts according to their length.
Swiss pattern needle files are essential for detailed work and are available in an even wider range of shapes than larger Swiss precision files. The cut numbers bear the same relationship to length and are marked on the shanks. These files are measured overall, usually in centimetres, and the finer cuts are excellent for finishing. A practical selection includes a coarser file (cut #0 or #2) for roughing out and a finer one (cut #6) for finishing. While handles or pin vices can be used, many prefer to use these files unhandled for better tactile control. Additional profiles are available under watchmakers’, clockmakers’, and escapement files from specialist suppliers.
Escapement files have a much smaller cross-section than needle files and are particularly useful in confined or delicate areas. They are available in the same profiles and cut ranges and allow precise work in tight spaces.
Riffler files have curved ends and are useful for reaching into recessed or enclosed spaces where conventional files will not fit. They are not often needed, but when they are, nothing else will do the job as effectively. A small set of good-quality rifflers, such as those used by woodcarvers or jewellers, is worth considering for occasional use.
[Diagram: Comparative chart of Sheffield vs. Swiss cut systems with typical tooth counts and lengths.]
Filing Technique
Use the full length of the file with each stroke, applying moderate pressure on the forward stroke only. Lift the file on the return stroke to prevent dulling the teeth. File at a slight angle and slide the file laterally with each pass to avoid wearing a groove in one spot. Work at a steady, even pace and check progress frequently—particularly when working on thin or detailed parts where over-filing can cause damage.
Clamp or stabilise the workpiece whenever possible. For flat or large parts, use a smooth-jawed vice. For small or delicate items, a bench pin or cork-covered filing board may be more appropriate. Thin wires or rods can be held in shallow grooves carved into a filing board.
Matching Files to Materials
- Brass/Nickel Silver: Cut #2 for shaping, #4 or #6 for finishing
- Whitemetal: Cut #0 or a worn #2 file. Use light pressure—soft alloys clog easily
- Plastic: Avoid fine files. Use coarse files sparingly or finish with abrasive paper
- Steel: Use only high-quality files. Expect accelerated wear
Use chalk on the file to help prevent clogging when working with soft materials.
Storage and Maintenance
Store files so that cutting surfaces do not touch. File rolls, lined trays, or fitted boxes are best. For needle files stored in portable kits, insert each into a plastic straw trimmed to length. Colour-coded bands on the handles help with quick identification.
Avoid leaving files near acidic fluxes or damp areas. Clean fine-cut files using a strip of Tufnol, copper, or a brass brush. Pinning can be reduced by rubbing chalk on the file before use.
Mark any file used on hardened steel or piano wire, and reserve it for rough use only.
Old or damaged files can be ground into scrapers or custom-shaped tools. Grind in short bursts and quench frequently to avoid softening the steel.
Summary
A small number of high-quality files, chosen to match the work at hand, will outperform a large collection of cheap ones. Proper technique, thoughtful storage, and occasional maintenance will extend their life and deliver consistently clean results in model work..
More Information
- Brook Smith, Joe. “Joe’s Jottings… 29: Files for Modelling.” Scalefour News, no. 117, May 2000, pp. 10-11.
- Burgess, Jack. “The Tool Shed: Files, Rifflers, and Reamers.” Model Railroad Hobbyist Magazine, no. 57, November 2014.
- Griffin, Laurie. “Cleaning-Up Etched Parts.” Model Railway Journal, no. 212, 2012.
- Jones, Geoff. “The Basic Skills – 1: Of Saws and Files and Clamping Things.” The 2mm Magazine, March 1965, pp. 34-35.
- Jones, Geoff. “The Basic Skills – 1: Of Saws and Files and Clamping Things (Part II).” The 2mm Magazine, May 1965, pp. 68-70.
- Shackle, Bob. “Storing Needle Files: Particularly Those That Go Travelling in Small Tool Kits.” The 2mm Magazine, February 2005, p.6.
- Webster, Andrew. “Files and the 2mm Modeller – Part One.” The 2mm Magazine, December 1999, pp. 74-77.
- Webster, Andrew. “Files and the 2mm Modeller – Part Two – Care and Use of Files.” The 2mm Magazine, February 2000, pp. 7-9.