# ER25 collets

ER25 body dimensions, bore ranges, nut compatibility and product-specific clamping limits.

Reviewed: 2026-11-02

Tags: tooling, collets, toolholding

## Identity and dimensions

Techniks lists two ER25 nuts with different holder threads and tightening torques. Its **41925** slot nut is **M32 × 1.5 at 77 ft·lbf**. Its **23125** mini nut is **M30 × 1.0 at 28 ft·lbf**. Use the tightening torque for the matched holder and nut. EROGLU's ER25 430 E-13 collet separately lists a 12–13 mm shank range. [Techniks catalog, printed pp. 62–63](https://www.techniksusa.com/downloads/catalogs/Collets_Nuts_Catalog.pdf#page=20), [EROGLU capacity and size table](https://www.eroglu.de/en/products/accessories/collets/collets-system-er-din-6499-b/iso-15488-b-er-25-b).

EROGLU identifies its ER25-B collets as DIN 6499 B / ISO 15488-B, order family 430 E.

REGO-FIX lists these body dimensions, distinct from holder nose diameters. [REGO-FIX main catalog, printed p. 295](https://regousa.com/wp-content/uploads/2022/04/REGO-FIX-Main-Catalogue-ENGLISH.pdf#page=299)

| Size | Outside diameter D1 | Overall length L | Catalog scope |
| --- | --- | --- | --- |
| ER16 | 17 mm | 27.5 mm; 26 mm variant | 9.5–10 mm bores include a shorter version; availability up to 27.5 mm depends on production |
| ER20 | 21 mm | 31.5 mm | Listed bores 1–13 mm |
| ER25 | 26 mm | 34 mm | Listed bores 1–17 mm |
| ER32 | 33 mm | 40 mm | Listed bores 2–22 mm |

ER25 and ER32 require different mating holders and nuts even at the same bore.

## Bore size and collapse range

EROGLU specifies 0.5 mm collapse for its nominal 1–2 mm bores and 1 mm for nominal 3–16 mm bores. Thus its 430 E-13, nominally 13 mm, covers a 12–13 mm shank interval; its 2 mm size covers 1.5–2 mm. A family-wide capacity is the union of multiple collets, not the travel of one collet. [EROGLU capacity and size table](https://www.eroglu.de/en/products/accessories/collets/collets-system-er-din-6499-b/iso-15488-b-er-25-b)

**Worked diameter example:** 1/2 inch × 25.4 mm/inch = 12.700 mm. This falls within the stated 12–13 mm interval, with 13.000 − 12.700 = 0.300 mm diametral collapse. That arithmetic establishes nominal range membership; it does not establish assembled runout or cutting performance. A 13.2 mm shank exceeds that collet's 13 mm upper limit.

Catalog coverage differs: Techniks' metric ER25 set 04204MS contains fifteen collets, 2–16 mm in 1 mm steps, for a stated aggregate 1–16 mm shank range. That set's 16 mm maximum does not contradict REGO-FIX's separate 17 mm catalog entry. [Techniks collets catalog, printed p. 46](https://www.techniksusa.com/downloads/catalogs/Collets_Nuts_Catalog.pdf#page=4)

## Nuts, engagement and torque

Techniks lists these two ER25 nut products. The common collet designation does not make their holder threads interchangeable. [Techniks catalog, printed pp. 62–63](https://www.techniksusa.com/downloads/catalogs/Collets_Nuts_Catalog.pdf#page=20)

| Product | Holder thread | Nut outside diameter | Listed torque |
| --- | --- | --- | --- |
| PowerCOAT slot nut 41925 | M32 × 1.5 | 42 mm | 77 ft·lbf |
| PowerCOAT mini nut 23125 | M30 × 1.0 | 35 mm | 28 ft·lbf |

REGO-FIX specifies 24 N·m for 1–3.5 mm and 104 N·m for 8–17 mm standard/ER-UP ER25 bores with ER/ERC nuts. Assembly requires nut-ring engagement before mounting and tool insertion of at least two-thirds collet length. [REGO-FIX catalog, printed pp. 290, 293](https://regousa.com/wp-content/uploads/2022/04/REGO-FIX-Main-Catalogue-ENGLISH.pdf#page=294)

Check clearance, coolant sealing and assembly speed for the specified nut and holder.

## Accuracy and coverage limits

Techniks describes its ordinary metric ER collets as averaging 0.0002 inch TIR. Conversion gives 0.0002 × 25.4 = 0.00508 mm, or 5.08 µm. An average is not a guaranteed maximum, and a collet figure is not a measured spindle–holder–collet–tool assembly result. [Techniks catalog, printed p. 46](https://www.techniksusa.com/downloads/catalogs/Collets_Nuts_Catalog.pdf#page=4)

This reference covers the named manufacturers' ordinary collets and selected nuts. It does not establish limits for sealed, tapping, extended-nose or pullout-resistant variants, nor installed equipment condition, tool overhang, cutting loads or a particular shop's acceptance criteria. Those properties remain specific to the actual assembly and application.

The EROGLU page and Techniks catalog provide no issue date in the cited material. REGO-FIX's cited main catalog carries document code 0362.00251 / ENG.1; no issue date was established. URL directory dates are not edition dates. The reviewed date records this article's research review, not publication of the source documents.

## Related reference

[Cutting tools and tooling references](../index.md)