ER Collet Ultra High Precision 0.005mm / 5u run-out. These are not your blue/yellow boxed collets that are the cheapest of cheapest of collets that do not specify a precision value. A high precision collet allows for quieter machining, longer tool life and greater cut accuracy.
Available in ER11, ER16, ER20 and ER25 in common sizes 3.175mm (1/8"), 4mm, 6mm, 6.35mm (1/4"), 8mm, 10mm and 12.7mm (appropriate to ER size). Clamping range is that of nominal inner diameter size -1mm (eg. 6mm would accept 5mm to 6mm).
How to check what diameter you have
| ER Collet | Length | Diameter | Range |
|---|---|---|---|
| ER-11 | 18 mm | 11.5 mm | 0.5—7 mm |
| ER-16 | 27.5 mm | 17 mm | 0.5—9 mm |
| ER-20 | 31.5 mm | 21 mm | 1—13 mm |
| ER-25 | 34 mm | 26 mm | 1—16 mm |
| ER-32 | 40 mm | 33 mm | 1—21 mm |
| ER-40 | 46 mm | 41 mm | 3—26 mm |
Best for
- Replacing a worn ER20 collet in a CNC spindle or ER20 tool holder
- Upgrading cheap unrated collets to 0.005mm runout for longer tool life and a better finish
- Shank sizes from 3.175mm (1/8") to 12.7mm (1/2")
Not for
- Makita trim routers and Perske RDO spindles: they use their own collets
- Sharing one collet across shank sizes: each clamps only down to 1mm under its size
Adam's Tip
Order the collet that matches your bit's shank exactly, and buy the ER20 nut if yours is worn. Clean the collet, nut and spindle taper every bit change, and never tighten the nut on an empty collet.
Buying guide: ER Collet Size Guide
11 Reviews Hide Reviews Show Reviews
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Collet
Recommend shop
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8mm Collet
Ordered express post and was delivered the following day. Good stuff. Collet is good.
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Collet run-out
I have purchased 4 ER20 collets. 2 have half of the claimed run-out (0.0025mm) and that includes the spindle run-out. For woodworking purposes it can be deemed perfection. The other 2 measured 0.010mm run-out and that includes the spindle run-out.
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ER20 collet
As always Adam’s bits have never let me down and the price a very competitive.
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ER20 Collets
I have bought a number of end mills from Adam’s Bits and every time I was impressed with the quality as well as how fast the delivery was. I use these on my YouTube channel (https://youtube.com/@TwinSummitDesigns) and I would highly recommend them.
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ER20 Collet
Item as described, fast post - recommended
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Adams Bits are the best
Once again, a great product without a heavy price.
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ER 20 Collet Ultra High Precision
I bought the 6mm set and they seem to be working fine, no issues found so far.
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ER20 Collets
Excellent quality, run much smoother and quieter than the ones we had. Has a smoother and better clamping power.
