Collet system
ER20 collets: 1/2 in range, nut threads and 80 mm spindles
ER20 ranges by maker (to 13 mm and 1/2 in), standard vs mini nut threads, the 80 mm spindles that use ER20, kit sizes and makers' runout claims.
Also listed as ER-20, ER 20 collet
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Short answer
ER20 is the smallest ER series in these catalogs that reaches 1/2 in: Command Tool's ER20-F500 clamps 0.461-0.500 in, and Galaxy and Command Tool list metric sizes to 12-13 mm. Most 80 mm spindle kits use ER20. A nut labeled only ER20 does not tell you the thread: standard nuts are M25 x 1.5 and mini nuts M24 x 1.0, per PreciseBits.
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 (Form A and Form B collets). Haas labels its 04-1180 Class 1 per DIN ISO 15488; CMT sells DIN6499 precision collets.[1][3][4]Scope from the Standards Norway listing; we state no edition status.
- Collet dimensions
- D 21.0 mm, length 31.0 mm per Galaxy's drawing fields[5]Galaxy does not label D as the outside diameter.
- Shank range makers list
- Galaxy: 1.0-2.0 mm (ER20-020) to 12.0-13.0 mm (ER20-130). Command Tool: largest metric ER20-1300 at 12.0-13.0 mm. Somma: 1-13 mm and 1/16-1/2 in.[5][6][7]
- Largest inch size listed
- 1/2 in (12.7 mm, calculated from 25.4 mm per inch): Command Tool ER20-F500 clamps 0.461-0.500 in; Haas 04-1180 is a 1/2 in straight-bore collet rated 0.500-0.461 in; CMT lists 1/2 in (184.127.20)[6][3][4][8]
- Range per collet
- Somma: 1/32 in per collet for its non-sealed ER collets, except ER8, ER11 and ER12[7]This is the range of one collet, not the range of the whole series.
- Nut thread
- Hex, standard and UM nuts M25 x 1.5; mini nuts M24 x 1.0 (PreciseBits)[9]A nut labeled only ER20 does not identify which spindle thread it fits.
- Spindles and routers that use it
- PwnCNC 80 mm motors (1.5 kW 110 V and 2.2 kW 220 V); Onefinity Redline 80 mm 1.5 kW and 2.2 kW; Carbide 3D 80 mm spindle kit; Genmitsu V2 2.2 kW water-cooled spindle; SainSmart's earlier 2.2 kW water kit; VEVOR 2.2 kW spindles (listing claims)[10][11][12][13][14][15][16][17]Genmitsu's V2 kit page conflicts with itself on ratings; only the collet assignment is used here.
- Sizes supplied in kits
- Carbide 3D 80 mm kit: 1/8, 1/4 and 1/2 in. PwnCNC ER20 kits: 1/8, 1/4 and 1/2 in. Onefinity Redline 80 mm kits: 1/2, 3/8, 1/4 and 1/8 in. VEVOR 010298669207: 14 ER20 collets (listing claim).[13][18][11][12][16]
- Runout claims (maker's)
- Haas rates its 04-1180 1/2 in collet at 0.0006 in TIR, with no measuring point stated. CMT offers standard-precision and high-precision tiers. PreciseBits grades its ER collets by TIR at the face and 1 in down a calibration blank. REGO-FIX lists 10 um TIR for its ER standard line without a measuring point.[3][4][19][20]Maker claims, not measurements of ours. CMT's tier values are not published here because the page gives no units or method.
- 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.[20][2]
- Not confirmed
- Not confirmed
Watch out for
- ER20 standard and mini nuts use different threads (M25 x 1.5 and M24 x 1.0 per PreciseBits); a nut sold as just ER20 may not fit your spindle.
- Galaxy's table lists a 1/2 in part (ER20-12) without a range; use a maker that states the 0.461-0.500 in range.
- Not every 80 mm spindle uses ER20: SainSmart's earlier 1.5 kW water kit used ER11.
- Never run a collet or bit above its maker's stated speed or past its maker's shank range.
What fits
Product details below are the seller's own description unless a source is shown. Pick the variant named for each item.
Collet set
Genmitsu ER20 router collet set, 14 pieces (1/16 in to 1/2 in)Choose the 14-piece inch set (1/16 to 1/2 in).
SainSmart sells it for ER20 routers and spindles; it does not fit ER11 or ER16.
ER20 spindles are mostly 80 mm bodies: see 80 mm mounts. For smaller shanks, see ER11 and ER16.
Questions
Which ER collet holds a 1/2 in router bit?
In the catalogs checked, ER20 is the first: Command Tool's ER20-F500 clamps 0.461-0.500 in and Somma lists ER20 to 1/2 in. ER16 stops at 3/8 in or 13/32 in.[6][7][21]
Do all ER20 nuts fit all ER20 spindles?
No. PreciseBits lists ER20 standard nuts at M25 x 1.5 and mini nuts at M24 x 1.0, so a nut labeled only ER20 does not identify the spindle thread it fits.[9]