Punch Cutting
Part of Printing
How to engrave steel punches — the master letter forms from which all movable type is derived.
Why This Matters
At the root of every letterpress printing system is a set of steel punches — hardened steel rods with a letter engraved in relief on one end. These punches are struck into copper to create matrices, and from matrices, type is cast by the thousands. The punch is the ancestor of every printed character.
Punch cutting is the most demanding skill in the printing process chain. It requires the finest degree of hand control, the sharpest tools, and the most thorough understanding of letterform. A punch cutter in a rebuilding community becomes the bottleneck and the foundation for everything else: no punches means no matrices, no matrices means no type, no type means no press output.
However, a determined craftsperson who can work metal to fine tolerances can learn punch cutting. The historical punch cutters of the 15th–17th centuries were not a priestly caste — they were skilled artisans who learned through practice, experience, and careful observation. The same path is open to anyone who chooses it.
Understanding Letterform
Before cutting a single punch, the punch cutter must deeply understand the letters they intend to cut. Every letter has:
Strokes: The principal lines that compose the letter. Thick strokes and thin strokes have a specific ratio determined by the typeface design.
Serifs: Terminal finishing strokes at the ends of main strokes. Serif forms vary enormously between typefaces — bracketed, hairline, slab, and many others.
Counters: The enclosed or partially enclosed white spaces within letters (the inside of ‘o’, ‘e’, ‘a’, ‘p’, etc.). Counter shapes are as defining as stroke shapes.
Proportions: The width-to-height ratio of each letter, and the relationship between uppercase and lowercase height (x-height).
Before cutting, draw each letter at an enlarged scale — at least 5–10× the intended printed size. Work out the proportions carefully. Only when the drawn letter looks correct should cutting begin. The drawing stage is not optional; it is the design stage, and design errors discovered in steel are very expensive.
Steel Selection and Preparation
Punches are cut from tool steel — a high-carbon steel that can be hardened and tempered to hold a sharp edge. Spring steel, bearing steel, or repurposed files all work if they are high-carbon.
Punch blanks: Cut steel rod to length (typically 50–80mm long). The working end will be the engraved punch face. The other end is struck with the hammer during matrix striking.
Annealing for cutting: Before engraving, anneal the punch blank by heating to a dull red heat and allowing to cool very slowly in sand or ashes. Annealed steel is soft enough to cut cleanly with gravers and files.
Punch face preparation: File and stone the punch face flat and polished. Polish to a mirror finish if possible — the punch face becomes the printing surface of the letter, and the quality of finish directly determines the quality of the type cast from the resulting matrix.
Engraving the Punch
Tools
Gravers (burins): Small hardened steel tools in various profiles used to remove steel. Essential profiles:
- Flat graver: cutting broad strokes and flat counters
- Lozenge graver: fine lines and serifs
- Round (ball) graver: curved counters and bowls
- Square graver: right-angle corners
Gravers must be razor-sharp. A dull graver tears rather than cuts, leaving rough edges. Sharpen on oilstones before each working session.
Needle files: For smoothing and refining surfaces after rough graving.
Magnification: A loupe or magnifying glass (5–10×) is essential for working at type sizes. Without magnification, fine details cannot be seen accurately enough to cut correctly.
Linseed oil: Applied to the punch face while cutting to prevent gumming and to help the graver slide cleanly.
The Cutting Sequence
1. Transfer the design Apply a thin coating of beeswax or pencil graphite to the polished punch face. Scratch the letter outline into the wax with a needle, using the drawn design as reference. This gives a visible guide for the graver.
2. Cut the counters first Begin with the enclosed spaces (counters). On letters like ‘o’, ‘e’, ‘b’, ‘p’, ‘d’, the counter must be cut to the correct shape before the outer stroke forms are defined. Use a counter punch for circular or near-circular counters: a separate, smaller hardened steel punch shaped like the interior space, struck into the soft steel of the main punch face. This is faster and more consistent than cutting each counter by hand.
3. Define the main strokes Use flat and lozenge gravers to cut the main letter strokes. Work from the center of each stroke outward toward the edges. Strokes should be slightly narrower than intended at this stage — edges will be refined in later steps.
4. Refine the serifs Serifs are the most difficult part of punch cutting. They are very small, very precise, and must be consistent across all letters in the font. Cut each serif in two or three controlled movements — the vertical element, the bracket, and the foot or cap. Use a very sharp lozenge graver.
5. True the edges With the major forms established, carefully true all straight edges with a flat graver held against a small steel straightedge. Curved edges are refined by comparing frequently to the design drawing.
6. Check by test striking At intervals during cutting, test the punch by striking it lightly into soft lead and examining the impression under magnification. This reveals problems that are difficult to see directly in the steel — reversed forms, unequal stroke widths, asymmetric counters.
7. Final refinement Compare the lead test impression to the design drawing. Note all discrepancies and correct them on the punch. When test impressions match the design consistently, the punch is complete.
Hardening the Finished Punch
Once engraving is complete and test impressions are satisfactory, the punch must be hardened so it can strike copper matrices without deforming.
Hardening:
- Heat the punch face end to a bright cherry red (not orange, not yellow).
- Quench in a bucket of clean water or oil. Plunge straight down, without moving.
- The steel is now fully hardened — hard enough to engrave glass, brittle enough to shatter if dropped.
Tempering: Hardened steel is too brittle to use safely as a punch — it may shatter when struck. Tempering reduces brittleness while retaining most of the hardness.
- Polish the hardened punch face bright with fine abrasive.
- Gently heat the punch shank (not the face) with a small flame. Watch the color that progresses along the steel toward the face.
- Temper colors appear in sequence: pale yellow → golden yellow → brown → purple → blue.
- Quench when the color reaches the punch face as a pale to mid-golden yellow. This leaves the punch face at approximately 60–62 HRC (Rockwell hardness) — hard enough to strike copper repeatedly, tough enough not to shatter.
Quality Standards
A finished punch should produce:
- Clean, sharp impressions in lead test strikes
- Consistent results in 10 successive strikes into the same lead piece (if the impression varies, the punch is not stable)
- All serif forms intact and undamaged after hardening and tempering
- No visible file or graver marks on the letter face — only the intended form
Producing a complete alphabet of 26 uppercase letters, 26 lowercase, digits 0–9, and common punctuation represents approximately 70–90 individual punches. For an experienced punch cutter, this is several months of work. For a beginner, it may take much longer. The investment is worthwhile: the resulting punches, carefully stored, can supply a print shop with new type indefinitely.