Xem Studiomeasured geometryLibrary › Hardware › Machine tool tapers & collets ·
ER collets ER8, ER11, ER16, ER20, ER25, ER32, ER40, ER50: collet diameter, length, clamping range and nut thread (DIN 6499 / ISO 15488)
What are the dimensions of ER11, ER16, ER20, ER25, ER32 and ER40 collets and their nut threads? · Standard part · basis: cgtk.co.uk (holder-side taper and nut thread), Little Machine Shop and RicoCNC (collet OD, length, clamping range, agree with each other), AIMS Industrial (ER8 / ER50 and maximum shank); numbers only
Also called: er11 collet dimensions, er16 collet dimensions, er20 collet size, er25 collet diameter, er32 collet dimensions, er40 collet size, er collet size chart, er32 nut thread, er collet clamping range, din 6499 er collets, er collet length, er collet nut thread size, er40 nut thread M50
Exact dimensions. True size, with no tolerance added.
- sizes
- 8 in table
Notes
- ER collets (DIN 6499, ISO 15488) are slotted spring collets that close in a nut; AIMS gives a nominal 1 mm clamping range for most sizes. The number is the nominal taper size in mm: ER16 sits in a holder whose taper OD is 16 mm (the cgtk column). The collet body itself is slightly larger: 11.5, 17, 21, 26, 33, 41 mm (ER32 is printed as 33 in all three sources that list lengths; one AIMS paragraph says 32), and the lengths are 18, 27.5, 31.5, 34, 40, 46 mm. Little Machine Shop, RicoCNC and AIMS agree on diameter and length for every size.
- Clamping range: Little Machine Shop and RicoCNC print 0.5–7, 0.5–9, 1–13, 1–16, 1–21, 3–26 mm for ER11 to ER40; AIMS prints a maximum shank of 7, 10, 13, 16, 20, 26 mm. The two differ at ER16 (9 / 10) and ER32 (21 / 20); both are shown and not averaged. Check your collet's own marking. The cgtk column 'taper OD / bore / minimum bore length' is the holder side as published there; the nut thread column is its nut thread diameter × pitch and thread length. cgtk notes that some ER sizes have different nut styles, so their thread need not match. ER8 and ER50 are in AIMS' table only.
- Why no files: the collet body is a slotted spring shape whose slot pattern and taper angle are not published as numbers in the sources read; a plain tube would not be a collet. Makers (Kennametal, Hoffmann, Rego-Fix, Schunk) carry 3D data on their own product pages.
- Not here: ER nut dimensions (width across flats, height, bearing-nut styles), collet slot pattern, sealed (ER-GB) collets, ER holders and tool holders per taper (see steep-taper-7-24-cat-bt-nmtb-30-40-50), and runout grades.
ER collets ER8, ER11, ER16, ER20, ER25, ER32, ER40, ER50: collet… size chart
| size | collet OD (mm) | collet length (mm) | clamping range (mm), Little Machine Shop / RicoCNC | max shank (mm), AIMS | cgtk: taper OD / bore / min bore length (mm) | nut thread (mm), cgtk | nut thread length (mm) |
|---|---|---|---|---|---|---|---|
| ER8 | 8.5 (AIMS) | 13.6 (AIMS) | — | 5 (AIMS) | — | — | — |
| ER11 | 11.5 | 18 | 0.5 – 7 | 7 | 11 / 8 / 17 | 14 × 0.75 | 8 |
| ER16 | 17 | 27.5 | 0.5 – 9 (LMS, Rico) | 10 (AIMS) | 16 / 11 / 22 | 22 × 1.5 | 12 |
| ER20 | 21 | 31.5 | 1 – 13 | 13 | 20 / 14 / 27 | 25 × 1.5 | 13 |
| ER25 | 26 | 34 | 1 – 16 | 16 | 25 / 18 / 37 | 32 × 1.5 | 13 |
| ER32 | 33 (a 32 appears once in AIMS' text) | 40 | 1 – 21 (LMS, Rico) | 20 (AIMS) | 32 / 24 / 42 | 40 × 1.5 | 15 |
| ER40 | 41 | 46 | 3 – 26 | 26 | 40 / 31 / 47 | 50 × 1.5 | 16 |
| ER50 | 52 (AIMS) | 60 (AIMS) | — | 34 (AIMS) | — | — | — |
Where the files are
Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.
| cgtk.co.uk (A. S. Budden) | ER collet dimensions: taper OD, bore, minimum bore length, nut thread diameter, pitch and length for ER11 to ER40 | web | Publisher's page; dimensions are facts |
| Little Machine Shop | ER collet sizes: length, diameter and clamping range, ER-11 to ER-40 | web | Publisher's page; dimensions are facts |
| RicoCNC | ER8 to ER40 collets, DIN 6499: OD, length, clamping range (agrees with Little Machine Shop) | web | Publisher's page; dimensions are facts |
| AIMS Industrial | ER collet guide: ER8 to ER50 major diameter, length and maximum shank capacity | web | Publisher's page; dimensions are facts |
| Kennametal | ER standard collets, metric and inch (maker product pages) | web | Maker product page |
| Hoffmann Group | ER collet ER 16 and ER clamping nuts (maker product pages) | web | Maker product page |
Xem scan
File coming
No downloadable true-size file yet: the published figures do not fix the whole shape, and Xem never guesses a number. A measured scan is planned; request it and it moves up.
https://xemstudio.com/mcp to Claude, ChatGPT, Cursor or any MCP client (free, no account, one minute) and it can look up exact sizes, mating fits and free STEP/STL from every chat.Plain text: sheet.txt · JSON: /api/geometry?object=er-collets-er8-er50
Fits with
Questions
What is the outside diameter of an ER32 collet?
33 mm (the nominal size is 32; the collet body is 33 mm in the lists read) and 40 mm long.
What is the nut thread of an ER16 collet nut?
M22 × 1.5 in the cgtk table.
What range does an ER20 collet cover?
1 to 13 mm, each collet closing over about 1 mm.