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Steel Stamp Set Sizes: How to Read 80*10*5, 105*10*4 and More
A steel stamp set is sold by a three-number code, and once you can read it the choice becomes simple. The code on a set such as 80*10*5, 105*10*4, 100*10*10 or 125*12*5 describes the body and the character, and those numbers decide what the mark will look like on the work. Sets in this range run from 14 pieces up to 27, so the code also tells you how complete the kit is.
This guide explains what each part of the code controls, how character size changes legibility, and how to strike a mark that stays square and readable on steel, aluminium and cast iron.
What the three numbers mean
The three figures follow a fixed order: overall length, the width of the stamp body, and the height of the character. On a 100*10*10 stamp the body is 100 mm long, 10 mm across the shank, and the character stands 10 mm tall. On a 125*12*5 stamp the body is longer and heavier but the character is smaller, because that set is built for repeated strikes on harder material rather than for large lettering.
| Part of the code | What it controls | In this range |
|---|---|---|
| First figure | Body length, and therefore how much you can grip and how much force reaches the face | 80 mm, 100 mm, 105 mm, 125 mm |
| Second figure | Shank width, and the amount of steel standing behind the character | 10 mm or 12 mm |
| Third figure | Character height, measured from the base of the letter to its top | 4 mm, 5 mm or 10 mm |
| Piece count | How many characters come in the box | 14, 18, 20 or 27 |
Read this way the code answers the two questions that matter before you buy: can I hold and strike this comfortably for a whole job, and will the mark still be legible after the part has been painted or buried under a component.
Character size and legibility
Character size is the number most buyers get wrong. A stamp only has to be read once, but it has to be read by whoever inspects the part years later, and that often means reading a photograph or a scanned drawing. The working rule is to choose the smallest character that will still be legible after the surface has been finished, because a large character spreads the same striking force over a bigger area and therefore cuts less deeply.
| Character height | Best for | Trade-off |
|---|---|---|
| 4 mm | Small parts and thin sections where a deep mark would weaken the part | Hard to read once painted; needs a firm single strike |
| 5 mm | General workshop marking on brackets, plates and light fabrications | The usual compromise between depth and legibility |
| 10 mm | Large fabrications, crates, jigs and anything read from a distance | Needs more force and leaves a heavy impression in thin plate |
In practice a workshop keeps two sizes: a 5 mm set for everyday marking and a 10 mm set for anything that has to be found quickly on a big assembly. A 4 mm set is kept for small parts and for places where a heavy impression would count as a defect rather than a mark.
How the pieces in a set add up
The piece count decides whether a set can write what you need or only part of it. A 14-piece set is normally a numeric selection or a partial alphanumeric one; 20 pieces covers a fuller character range; 27 pieces is the practical full set that lets you stamp a complete part number, a date code and an operator mark without borrowing from another box.
It is worth buying the fuller set even when today’s work only needs digits. Characters are the part that gets lost, and replacing one character costs far more than the difference between the two set sizes at the start. The heavier sets here also carry a longer body, which is why the price follows the piece count as much as the character size.
Steel stamp sets in this range
Every option in this range
Four codes, from a compact 80 mm body up to a 125 mm body, in sets of 14 to 27 pieces. Prices are per set.
| Code | Pieces | Typical use | Price |
|---|---|---|---|
| 80*10*5 | 14 | Small parts and light workshop marking | $8.99 |
| 105*10*4 | 27 | Full alphanumeric marking with a small character | $14.38 |
| 125*12*5 | 18 | Heavier body for repeated strikes on hard material | $14.98 |
| 100*10*10 | 20 | Large, easily read marks on fabrications | $19.48 |
The pattern is worth noting: the cheapest set is the short one with the fewest pieces, and the dearest is the one with the largest character. For mixed work the 105 mm set covers the most ground for the least money, because the long body keeps the strikes accurate while the small character keeps the mark neat.
Striking a mark that stays square
- Set the stamp on the surface and check it against a square before striking; a stamp that leans cuts a letter with an uneven base.
- Use one firm blow rather than several light taps; repeated light blows bounce the face and produce a double image.
- Hold the body low and close to the surface so the force travels down the axis instead of tipping the stamp.
- Support the back of thin material with a block so the impression does not distort the other face.
- Work from one end of the mark to the other so a long part number does not drift out of line.
- Re-check alignment every few characters, because each strike nudges the stamp slightly off position.
Faces, hardness and wear
The face of a stamp is hardened to resist the blows, while the body is left softer so it absorbs shock instead of cracking. That is why a stamp should never be struck with a hardened hammer: hard face on hard face chips the stamp and the hammer together. A copper, brass or soft-faced mallet is the right tool, and it also stops the head of the stamp from mushrooming.
Wear shows up first on the edges of the character, which round over and start to produce a mark with soft corners. A worn stamp can be dressed flat and re-cut, but in most workshops it is cheaper to replace the single character. Keeping the set in its box under a light film of oil prevents the rust that spoils legibility just as thoroughly as wear does.
Frequently Asked Questions
What does the middle number on a stamp mean?
It is the shank width. A 10 mm code has a body 10 mm across; a 12 mm code puts more steel behind the character so the stamp stands up to harder strikes.
Is a bigger character easier to read after painting?
It is easier to see but harder to cut deeply, so paint can fill a shallow impression. For painted work a medium character struck firmly reads better than a large character struck lightly.
How many pieces do I need?
Digits are enough for date codes and sequence numbers. A 27-piece set covers the full alphabet plus punctuation, which is what real part numbers and asset tags need.
Can I stamp stainless steel?
Yes, with a heavier body and a firm single strike. Stainless work-hardens, so several light blows on one spot are less effective than one decisive blow.
Where should the set be kept?
In its box, lightly oiled, with every character back in its marked slot. A set that lives loose in a drawer loses characters and rusts on the faces.
Choosing the right set
Match the character size to how the mark will be read, then match the body length to how hard the material is. The steel stamp range covers a short 80 mm body through to a 125 mm body in sets of 14 to 27 pieces.
