# Slotted spring pin (ISO 8752 / DIN 1481)

Heavy-duty slotted spring pin (roll pin), d 1 to 50 mm, any length, with catalogue sizes as presets.

## Geometry

The pin in its free state, before fitting: a tube of outside diameter **d1 max** and wall **s**, both ends tapered
over the length **a min** to the end diameter **d2** (the wall keeps its thickness through the taper), and an axial
slot. ISO 8752 leaves the slot's width to the supplier (Table 2: "Form and width of slot at the discretion of the
supplier") and sets one rule (clause 4): mounted in the smallest permitted hole (diameter d, tolerance class H12), the
slot shall not fully close. The slot is drawn at that limit, π × (d1 max − d) wide at the outside: the circumference
a pin of d1 max gives up when pressed into a hole of diameter d. A real pin's slot is wider by the supplier's margin. One end is on the XY plane at the origin, the pin along +Z, the
slot at the +X side.

## Parameters

| Parameter | Meaning |
|---|---|
| `diameter` | Nominal diameter d (the hole it fits), mm |
| `length` | Length l, mm |
| `material` | `spring-steel`, `stainless` (martensitic) |

## Source

ISO 8752:2009, *Spring-type straight pins — Slotted, heavy duty*, Table 1, pp. 2-3: d1 max before mounting, d2
before mounting (for reference), a min, s (mm); clause 4 and Table 2 for the slot (above). Read from the official
preview (<https://cdn.standards.iteh.ai/samples/40658/df4caae79e6b4325b3bc70097ffa4274/ISO-8752-2009.pdf>) and checked against fasten.it's DIN EN ISO 8752:2009-10
(<https://fasten.it/en/Norms/Norm/DIN%20EN%20ISO%208752>). ISO 8752:2009 was confirmed in 2024 and is current. The
2009 edition calls the nominal diameter d1 nom; here it is d.

| d | d1 max | d2 | a min | s |
|---|---|---|---|---|
| 1 | 1.3 | 0.8 | 0.15 | 0.2 |
| 1.5 | 1.8 | 1.1 | 0.25 | 0.3 |
| 2 | 2.4 | 1.5 | 0.35 | 0.4 |
| 2.5 | 2.9 | 1.8 | 0.4 | 0.5 |
| 3 | 3.5 | 2.1 | 0.5 | 0.6 |
| 3.5 | 4 | 2.3 | 0.6 | 0.75 |
| 4 | 4.6 | 2.8 | 0.65 | 0.8 |
| 4.5 | 5.1 | 2.9 | 0.8 | 1 |
| 5 | 5.6 | 3.4 | 0.9 | 1 |
| 6 | 6.7 | 4 | 1.2 | 1.2 |
| 8 | 8.8 | 5.5 | 1.6 | 1.5 |
| 10 | 10.8 | 6.5 | 2 | 2 |
| 12 | 12.8 | 7.5 | 2 | 2.5 |
| 13 | 13.8 | 8.5 | 2 | 2.5 |
| 14 | 14.8 | 8.5 | 2 | 3 |
| 16 | 16.8 | 10.5 | 2 | 3 |
| 18 | 18.9 | 11.5 | 2 | 3.5 |
| 20 | 20.9 | 12.5 | 3 | 4 |
| 21 | 21.9 | 13.5 | 3 | 4 |
| 25 | 25.9 | 15.5 | 3 | 5 |
| 28 | 28.9 | 17.5 | 3 | 5.5 |
| 30 | 30.9 | 18.5 | 3 | 6 |
| 32 | 32.9 | 20.5 | 3 | 6 |
| 35 | 35.9 | 21.5 | 3 | 7 |
| 38 | 38.9 | 23.5 | 4 | 7.5 |
| 40 | 40.9 | 25.5 | 4 | 7.5 |
| 45 | 45.9 | 28.5 | 4 | 8.5 |
| 50 | 50.9 | 31.5 | 4 | 9.5 |

Corrected in this audit: d 8 a 2.0 -> 1.6 (2.0 is a max; every other row uses a min); the slot width is now
explained by the clause it comes from.

Preset list: sizes of the step.parts catalogue (MIT), see `library/NOTICE.md`.