ER16 collets
ER16 body geometry, bore and collapse ranges, accuracy grades, assembly interfaces and an inch-versus-metric gripping example.
Tags: tooling, interfaces, collets, toolholding
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A nominal 1/4-inch (6.350 mm) shank exceeds the 5.0–6.0 mm range of REGO-FIX's standard ER16 1116.06000 by 0.350 mm. Its 1 mm collapse extends toward smaller shanks. The standard and UP 6 mm products list 10 µm and 5 µm TIR respectively, as collet specifications. Assembly runout depends on seating, holder, shank and projection. REGO-FIX, 1116.06000, REGO-FIX, ER16-UP Ø6.0 mm.
REGO-FIX lists a 17 mm outside diameter and a usual 27.5 mm length. Its 9.5–10 mm row lists a shorter 26 mm body, with up to 27.5 mm possible depending on production. REGO-FIX, ER System catalog, collet dimensions, printed page 155.
Body size, nominal bore and gripping range
Three quantities have different meanings:
| Quantity | Meaning | Example |
|---|---|---|
| ER size | Body and mating-family designation | ER16 |
| Nominal bore | Marked upper tool-shank diameter | 6.0 mm |
| Clamping range | Documented diameters one collet can grip | 6.0–5.0 mm for the named product below |
Match the body to the holder and nut, then check the individual bore range.
For example, REGO-FIX 1116.06000, ER16 Ø6.0 mm, lists a 6.0–5.0 mm clamping range. Its 1116.01000, ER16 Ø1.0 mm, lists 1.0–0.5 mm. The first range spans 1 mm; the smaller example spans only 0.5 mm. A blanket “every ER collet collapses 1 mm” rule would misdescribe the second product. REGO-FIX, 1116.06000; REGO-FIX, 1116.01000
Collapse range extends toward smaller shanks, not above the stated maximum. A diameter that appears close in everyday unit descriptions can still fall outside the documented interval.
Accuracy grade is a separate product property
REGO-FIX lists 0.010 mm TIR for standard 1116.06000 and 0.005 mm TIR for its 1116.06001 ER16-UP Ø6.0 mm product. Both pages list a 6.0–5.0 mm clamping range. The smaller TIR value is a property of the specified accuracy grade, not a consequence of the ER16 body size or nominal bore alone. REGO-FIX, standard Ø6.0 mm; REGO-FIX, ER16-UP Ø6.0 mm
Those product-page values do not supply an assembled spindle-to-tool runout guarantee or a measurement distance. Holder condition, nut, collet seating, shank geometry, projection and the machine contribute to the actual assembly. A catalog collet TIR value is not a finished-hole tolerance or a prediction of surface roughness.
Collet, nut and holder form one gripping system
In REGO-FIX notice 0361.0002, marked 01/2021, the collet's extraction groove engages an eccentric ring in the nut before the nut/collet assembly is mounted on the holder. The document relates incorrect engagement to damage and poor concentricity. The ring is therefore a functional assembly feature, rather than a sign that the nut's opening should be concentric when empty. It also relates contamination to lower clamping force and accuracy. REGO-FIX, ER Precision Tooling-System notices, pages 1–2
The same notice describes full-length shank engagement where possible, with a minimum of two-thirds of collet length, and explains that inadequate insertion can deform the collet. A tool bottoming against a back-up screw during tightening can impair runout and holding force. These are the manufacturer's assembly conditions; they do not establish a universal nut torque or qualify a different holder system. REGO-FIX, notice 0361.0002, page 2
Check nut thread and external clearance as well as collet fit.
Coolant capability is independent of bore range
The cited standard Ø6.0 mm and ER16-UP Ø6.0 mm pages both mark their products “Coolant-thru Capable: No.” Neither an ER16 label nor the UP accuracy designation implies a sealed through-coolant arrangement. A compatible fluid route also depends on the holder, nut and cutting tool; ordinary collet slots are not evidence of a sealed delivery path. REGO-FIX, 1116.06000; REGO-FIX, 1116.06001
Worked example: 6 mm and 1/4 inch are different shanks
This original calculation compares ideal nominal diameters only. Assume a cylindrical 1/4-inch shank and the named Ø6.0 mm collet's 6.0–5.0 mm range. It does not predict deformation, clamping force or actual tool tolerances.
1/4 inch = 0.250 × 25.4 = 6.350 mm
Oversize relative to 6.0 mm = 6.350 − 6.000 = 0.350 mm
The 6.350 mm shank exceeds this collet's stated maximum by 0.350 mm. The 1 mm collapse span does not help: it describes the interval down to 5.0 mm, not an additional 1 mm above 6.0 mm.
By contrast, a hypothetical 5.500 mm shank lies inside that 5.0–6.0 mm interval, 0.500 mm below its upper bound. Range membership addresses only diameter; it does not establish adequate gripping length, straightness, surface condition or cutting-load capacity. A purpose-marked inch collet and a metric collet are not interchangeable solely because their labels are near the same nominal size.
Coverage and limitations
These references establish ER16 dimensions and selected REGO-FIX product properties. They do not establish universal gripping torque, nut torque, spindle speed, pullout resistance, coolant pressure or assembled runout. Shank tolerance, engagement length, nut/holder design and condition remain specific to the actual assembly.
The mounting notice displays 01/2021 despite the later dates in its URL. The dimension catalog's issue date is not established here. The cited product pages show no issue date in the content reviewed on November 2, 2026; copyright and crawl dates are not treated as publication dates.