Collet system
ER16 collets: shank range to 3/8 in, mini nuts and spindles
ER16 ranges by maker (to 10 mm, 0.375 in, Somma to 13/32 in), why 1/2 in is out of range, nut threads and Carbide 3D's ER16 65 mm spindle.
Also listed as ER-16, ER 16 collet, ER16M
Short answer
ER16 collets in the catalogs checked reach 10 mm, or 3/8 in (Somma lists up to 13/32 in), so ordinary ER16 does not hold a 1/2 in shank. Carbide 3D's 65 mm VFD Spindle Kit has used ER16 since May 2025, with an ER16M mini nut on an M19 thread.
Key facts
- Type
- ER spring collet with an 8-degree setting angle, held in the spindle taper by a threaded nut[1][2]
- Standard
- ISO 15488, Collets with 8 degree setting angle for tool shanks: collets, nuts and fitting dimensions. It defines Form A (hard bore, h10 clamping range) and Form B (extended clamping range) collets.[1]Scope from the Standards Norway listing; we state no edition status.
- Collet dimensions
- D 17.0 mm, length 27.0 mm per Galaxy's drawing fields[3]Galaxy does not label D as the outside diameter.
- Shank range makers list
- Galaxy: 1.0-1.5 mm (ER16-015) to 9.0-10.0 mm (ER16-100). Command Tool: 0.5-1.0 mm to 9.0-10.0 mm. Somma: 1-10 mm and 1/16-13/32 in.[3][4][5]
- Largest inch size listed
- Command Tool's ER16-F375 clamps 0.336-0.375 in (3/8 in). Somma lists up to 13/32 in (about 10.3 mm, calculated from 25.4 mm per inch).[4][5][6]A 1/2 in (12.7 mm) shank is outside the ER16 ranges published by Galaxy, Command Tool and Somma.
- Range per collet
- PreciseBits: 0.039 in (1 mm) per ER16 collet. Somma: 1/32 in for its non-sealed ER collets, except ER8, ER11 and ER12.[7][5]This is the range of one collet, not the range of the whole series.
- Nut thread
- Hex, standard and UM nuts M22 x 1.5; mini nuts M19 x 1.0 (PreciseBits). Carbide 3D's ER16M nut has an M19 thread.[8][9]M19 matches PreciseBits' ER16 mini-nut thread diameter.
- Spindles and routers that use it
- Carbide 3D 65 mm VFD Spindle Kit, updated to ER16 in May 2025 (earlier kits used ER11)[9]
- Sizes supplied in kits
- Carbide 3D 65 mm VFD kit: 1/8, 1/4 and 3/8 in ER16 collets with an ER16M nut[10]Carbide 3D also lists a 22 mm wrench for the nut and a 16 mm wrench for the spindle shaft.
- Runout claims (maker's)
- PreciseBits grades its ER collets by TIR at the collet face and 1 in down a calibration blank, for example Precision-Grade at 0.0004 in and 0.0008 in. REGO-FIX lists 10 um TIR for its ER standard line without a measuring point.[11][12]Maker claims, not measurements of ours.
- Makers' clamping rules
- REGO-FIX: never clamp a shank larger than the collet's nominal size; use the next larger collet. Insert the tool over the full collet length where possible and never less than two-thirds of it. Carbide 3D: snap the collet into the nut before inserting the tool.[12][2]
- Not confirmed
- Not confirmed
Watch out for
- Ordinary ER16 does not hold a 1/2 in shank: Galaxy and Command Tool stop at 10 mm and Somma at 13/32 in.
- Carbide 3D's ER16 spindle uses an ER16M mini nut (M19); a standard ER16 nut is M22 x 1.5 per PreciseBits, so the two are not interchangeable.
- Somma's 13/32 in top size is Somma's own listing; Command Tool's ER16 page stops at 0.375 in.
- Carbide 3D's maximum cutter diameter for the current 65 mm kit is 3/8 in (10 mm).
Carbide 3D's ER16 kit is covered on the Shapeoko 5 Pro and Shapeoko 4 and Pro records. For 1/2 in bits, see ER20.
Questions
Can an ER16 collet hold a 1/2 in bit?
Not in the catalogs checked. Galaxy and Command Tool list ER16 up to 10 mm (Command Tool to 0.375 in), and Somma lists up to 13/32 in, about 10.3 mm, still below 12.7 mm.[4][3][5]
What nut does the Carbide 3D ER16 spindle use?
Carbide 3D's 65 mm ER16 VFD spindle uses an ER16M collet nut with an M19 thread, which matches PreciseBits' ER16 mini-nut thread diameter.[9][8]
Which collets come with the Carbide 3D ER16 kit?
Carbide 3D lists 1/8, 1/4 and 3/8 in ER16 collets and an ER16M collet nut.[10]