Shortlist · Collets and collet nuts
ER collet sets and single collets with the range stated
Approved ER11 and ER20 collet sets whose seller states the system and every size in the set, with how they compare to the ranges collet makers publish.
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Short answer
Two approved ER collet sets state their system and every size. Choose the 15-piece Genmitsu ER11 set for an ER11 spindle or router if you run inch and metric bits up to 1/4 in, or the 14-piece Genmitsu ER20 set for an ER20 spindle running bits up to 1/2 in. Neither fits an ER16 spindle.
How we chose
A set is on this list only if:
- It names one ER system. The system must match your spindle nose and nut. The ranges differ: Somma lists ER11 at 1/16-1/4 in and 1-7 mm, ER16 at 1/16-13/32 in and 1-10 mm, and ER20 at 1/16-1/2 in and 1-13 mm.[1]
- Every size in the set is listed. For comparison, Somma's metric ER11 set holds 13 collets from 1 to 7 mm in 0.5 mm steps and its inch set 7 collets from 1/16 to 1/4 in.[1] Command Tool's largest inch ER11 collet clamps 0.231-0.250 in,[2] its largest inch ER16 collet 0.336-0.375 in,[3] and its ER20-F500 0.461-0.500 in.[4]
- Precision claims say how they were measured, or we leave them out. PreciseBits grades its collets by TIR at the collet face and 1 in down a calibration blank, a maker claim.[5] CMT offers ER20 collets in standard and high-precision versions without stating how the tiers are measured,[6] so we publish no runout figure for them. The approved sets give no measuring point either.
- It is in our approved catalog with a store listing.
Two sets met this bar on 2026-10-11. We do not add others to fill the list.
ER11 set with metric and inch sizes
Genmitsu ER11 precision spring collet set, 7 or 15 pieces (1‑7 mm; 15‑piece adds 1/8 in and 1/4 in)
Pick it if: ER11 spindles and ER-11 routers running 1/8 and 1/4 in bits, plus metric bits
- Why it's here
- SainSmart sells this Genmitsu ER11 set in a 15-piece version (1-7 mm in 0.5 mm steps plus 1/8 and 1/4 in) and a 7-piece metric version, covering the ER11 range collet makers publish, which stops near 1/4 in.
- Watch out
- ER11 only: no size above 7 mm or 1/4 in. The 7-piece set has no inch collets, and 6 mm is not 1/4 in. SainSmart's accuracy figure gives no measuring point, so we do not repeat it. On Amazon, check that 'Ships from / Sold by' shows Amazon.com or the brand.
- Mount (body) diameter
- Not stated
- Collet system (ER11, ER16, ER20, router collet)
- ER11
- Shank sizes held
- 15-piece: 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7 mm, 1/8 in, 1/4 in · 7-piece: 1, 2, 3, 4, 5, 6, 7 mm
- Spindle power and supply voltage (maker claim)
- Not stated
Values are the manufacturer's specs unless marked.
ER20 set up to 1/2 in
Genmitsu ER20 router collet set, 14 pieces (1/16 in to 1/2 in)
Pick it if: 80 mm ER20 spindle owners running 1/4, 3/8 and 1/2 in bits
- Why it's here
- SainSmart lists 14 Genmitsu ER20 collets from 1/16 to 1/2 in in 1/32 in steps. ER20 is the system that reaches 1/2 in where ER16 does not.
- Watch out
- Inch sizes only. SainSmart's listing misprints one size and gives collet dimensions that match ER11, so confirm the contents on arrival. No runout figure is published. On Amazon, check that 'Ships from / Sold by' shows Amazon.com or the brand.
- Mount (body) diameter
- Not stated
- Collet system (ER11, ER16, ER20, router collet)
- ER20
- Shank sizes held
- 14 inch sizes from 1/16 in to 1/2 in, including 1/8, 1/4, 3/8 and 1/2 in
- Spindle power and supply voltage (maker claim)
- Not stated
Values are the manufacturer's specs unless marked.
Fit at a glance
| Set | System | Sizes | Largest |
|---|---|---|---|
| Genmitsu 101-63-ER11 (15 pieces) | ER11 | 1-7 mm in 0.5 mm steps, plus 1/8 and 1/4 in | 7 mm, 1/4 in |
| Genmitsu 101-60-70ER11 (7 pieces) | ER11 | 1-7 mm in 1 mm steps | 7 mm |
| Genmitsu 101-63-ER20 (14 pieces) | ER20 | 1/16-1/2 in in 1/32 in steps | 1/2 in |
A single collet can be the better buy. Haas lists part 04-1180 as an ER20 1/2 in collet clamping 0.500-0.461 in.[7]
See ER11 vs ER16 vs ER20 and the collets hub.
Questions
Do I need a full set or single collets?
Buy the sizes you run. A set suits a shop with mixed bits; a single collet suits one shank size. Haas, for example, sells a single ER20 1/2 in collet (04-1180) with a 0.500-0.461 in range.[7]
Can I clamp a 1/4 in bit in a 6 mm collet?
No. A 1/4 in shank is 6.35 mm, larger than 6 mm, and REGO-FIX advises against clamping a shank larger than the collet's nominal size.[9][8]
Why is there no ER16 set here?
None is in our approved catalog yet. If your spindle is ER16, buy ER16 collets: an ER11 or ER20 collet will not fit its nose.