# Spring plunger (Elesa+Ganter GN 615-K / GN 615.1-B)

Threaded spring plungers with a ball (GN 615-K, M3 to M10) or a bolt (GN 615.1-B, M4 to M10). Presets cover the
catalogue's ball plungers and spring plungers.

## Geometry

Envelope: the threaded body as a cylinder at the thread's nominal diameter **d1**, length **l**, axis along +Z from
the XY plane, centred on the origin; at its top the plunger stands out by **w**: a ball of diameter **d2** (its top at
l + w) or a bolt of diameter d2 to l + w. The thread, the screwdriver slot and the bolt's rounded end are not
dimensioned and not modelled (the bolt is drawn flat-ended).

## Parameters

| Parameter | Meaning |
|---|---|
| `size` | Thread d1: M3 to M10 (bolt: M4 to M10) |
| `style` | `ball` (GN 615-K) or `bolt` (GN 615.1-B) |
| `material` | `steel` (black-oxide body) |

## Sources

- Elesa+Ganter, **GN 615** "Ball spring plungers, Steel", sheet dated 11/2025, table GN 615-K (d1, d2, l ± 0.1, w,
  spring preload and max load): https://www.elesa.com/siteassets/PDF/PDF_EN/GN%20615.pdf
- Elesa+Ganter, **GN 615.1** "Bolt spring plungers, Steel", sheet dated 10/2025, table GN 615.1-B (d1, d2 −0.1,
  l ± 0.1, w; w tolerance +0.3/−0.4): https://www.elesa.com/siteassets/PDF/PDF_EN/GN%20615.1.pdf

| d1 | Ball d2 | l | w | Bolt d2 | l | w |
|---|---|---|---|---|---|---|
| M3 | 1.5 | 7 | 0.4 | – | – | – |
| M4 | 2.5 | 9 | 0.8 | 1.8 | 9 | 1.5 |
| M5 | 3 | 12 | 0.9 | 2.4 | 12 | 2 |
| M6 | 3.5 | 14 | 1 | 2.7 | 14 | 2 |
| M8 | 4.5 | 16 | 1.5 | 3.8 | 16 | 2 |
| M10 | 6 | 19 | 2 | 4.5 | 19 | 2.5 |

Not covered: the M3 spring (bolt) plunger (GN 615.1 starts at M4) and the indexing plungers (Elesa+Ganter's GN 617
indexing plungers use fine threads M10 × 1 and up; no coarse-thread M3 to M10 series was found).

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