Sovereignty Module: Cut the Tooth
Complete File Making: From Bar to Cutting Tool
Files are essential for shaping metal, wood, and other materials. This campaign covers file types, tooth cutting, hardening, handle fitting, and file care.
Chapter 1: File Types and Profiles
| Profile | Cross-Section | Primary Use | Common Sizes |
|---|---|---|---|
| Flat file | Rectangular | General purpose, flat surfaces | 6-14 inches |
| Half-round | One flat, one curved | Concave and flat surfaces | 6-12 inches |
| Round (rat-tail) | Circular | Holes, concave curves | 4-10 inches |
| Square | Square | Slots, corners, keyways | 4-8 inches |
| Triangle (three-square) | Triangular | Angles, corners, saw teeth | 4-8 inches |
| Knife | Thin wedge | Narrow slots, fine work | 4-8 inches |
| Needle files (set) | Various | Fine detail work | 4-6 inches |
Chapter 2: Cut Types
| Cut | Teeth Pattern | Aggressiveness | Finish | Use |
|---|---|---|---|---|
| Bastard (coarse) | Single row, wide spacing | High | Rough | Heavy material removal |
| Second cut (medium) | Single row, medium spacing | Moderate | Medium | General shaping |
| Smooth (fine) | Single row, close spacing | Low | Smooth | Finishing |
| Dead smooth (very fine) | Single row, very close | Very low | Very smooth | Final finishing |
| Double cut | Two rows crossed at angle | High | Rough | Fast removal, soft metals |
| Rasp cut | Individual raised points | Very high | Very rough | Wood, leather, soft materials |
Single cut: teeth run in parallel diagonal lines across the face. Double cut: two sets of teeth cross each other at an angle, creating diamond-shaped cutting points.
Chapter 3: File Making Process
Tooth cutting: 1) Start with flat bar of high-carbon steel (W1 or 1095). 2) Dimensions: 1 inch wide, 3/16 inch thick, desired length. 3) Anneal steel (heat to non-magnetic, slow cool). 4) Grind or file blank to desired profile. 5) Taper tang end (for handle). 6) Secure blank on lead block or hardwood (supports teeth during cutting). 7) Use sharp chisel (file-cutting chisel: narrow, very sharp). 8) Hold chisel at 60-70 degree angle to file face. 9) Strike chisel with hammer: one blow per tooth. 10) Move chisel width of one tooth, strike again. 11) Work from tang end toward tip. 12) Each blow raises a small ridge of metal (the tooth). 13) Spacing determines cut: coarse (12 teeth/inch), medium (20/inch), fine (30/inch). 14) For double cut: cut second set of teeth at 45 degrees to first.
| Step | Tool | Action | Critical Factor |
|---|---|---|---|
| Blank preparation | Grinder, hammer | Shape steel to profile | Uniform thickness |
| Annealing | Forge | Soften for cutting | Must be fully soft |
| Tooth cutting | Chisel + hammer | Cut teeth one at a time | Consistent angle and spacing |
| Hardening | Forge + quench | Heat to non-magnetic, quench | Even heat, fast quench |
| Tempering | Oven | 375-400°F for 1 hour | File must be very hard |
| Handle fitting | Drill, tang | Fit wooden handle | Tight, secure |
Chapter 4: Hardening and Tempering
Hardening: 1) Heat file evenly to non-magnetic (cherry red, ~1475°F). 2) Quench in brine (salt water) for maximum hardness. 3) Brine quench: 10% salt by weight in water. 4) Submerge file completely, move in figure-8 pattern. 5) File should be glass-hard after quench (60-65 HRC). 6) Test: file should scratch glass.
Tempering: 1) Files require minimal tempering (they must stay very hard). 2) Heat to 375-400°F (light straw color). 3) Hold for 1 hour. 4) Air cool. 5) File should still scratch glass after tempering. 6) Too much tempering softens the teeth (file won't cut).
| Hardness | HRC | Temper Color | Temper Temp | Result |
|---|---|---|---|---|
| Maximum (glass hard) | 63-65 | No temper | None | Too brittle, teeth chip |
| File hard (ideal) | 60-63 | Light straw | 375-400°F | Hard teeth, slight toughness |
| Too soft | Below 58 | Dark straw-brown | Above 450°F | Teeth dull quickly |
Chapter 5: File Care and Restoration
| Problem | Cause | Solution |
|---|---|---|
| Clogging (pinning) | Soft metal fills teeth | Use file card (wire brush), chalk teeth |
| Dulling | Normal wear | Re-cut teeth or retire file |
| Rust | Moisture | Oil after use, store dry |
| Chipping | Excessive pressure or lateral force | Use less pressure, file in one direction |
| Handle loose | Wear | Replace handle, tighten |
File restoration: 1) Anneal old file (heat to non-magnetic, slow cool). 2) Grind off old teeth. 3) Re-cut new teeth. 4) Re-harden and temper. 5) A good file blank can be re-cut several times.
Reference Card
- Files cut in one direction only (push the file forward across the work; lift on the return stroke; dragging the file backward dulls the teeth). 2. Chalk prevents clogging (rubbing chalk on the file face fills the spaces between teeth and prevents soft metals like aluminum from clogging the teeth). 3. A file card is essential (a file card (short-bristle wire brush) cleans clogged teeth; brush along the tooth lines, not across them). 4. Files must be very hard (file teeth must be harder than the material being filed; a properly hardened file is 60-63 HRC, hard enough to scratch glass). 5. Never use a file without a handle (the tang of a file is a sharp spike that can impale the hand if the file catches; always fit a handle before use). 6. Consistent chisel angle makes consistent teeth (the angle and force of each chisel blow must be identical; inconsistent teeth produce a file that cuts unevenly). 7. Brine quench for maximum hardness (salt water quenches faster than plain water, producing maximum hardness; this is critical for files, which must be extremely hard). 8. File making is precision blacksmithing (cutting hundreds of identical teeth by hand, each at the correct angle and spacing, then hardening to exact specifications, requires the highest level of skill and patience).