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ER Collet Sizes

ER collets have a wide clamping range and high accuracy. While they are designed for tool holding, they work great for work holding in small lathes. With a full set of ER collets you can hold any diameter that is in the clamping range of the set.

ER Collet Outline

ER Collet Length Diameter Clamping Range
ER-11 18 mm (0.71") 11.5 mm (0.45") 0.5—7 mm (0.020—0.276")
ER-16 27.5 mm (1.08") 17 mm (0.67") 0.5—9 mm (0.020—0.354")
ER-20 31.5 mm (1.24") 21 mm (0.83") 1—13 mm (0.039—0.512")
ER-25 34 mm (1.34") 26 mm (1.02") 1—16 mm (0.039—0.630")
ER-32 40 mm (1.57" 33 mm (1.30") 1—21 mm (0.039—0.827")
ER-40 46 mm (1.81") 41 mm (1.61") 3—26 mm (0.118—1.024")

There are several types of collets that look like ER collets. If your collet looks like an ER collet, but does not match one of the sizes shown above, it is a different type of collet and not an ER collet.

Chris Chris' Tips
With all ER collet chucks, the collet must be snapped into the nut before placing it into the chuck. There is an eccentric ring inside the nut that engages the groove in the collet. That is what makes them self-ejecting. Tilt the collet again to remove it from the nut.


The table below shows the available sizes of ER collets. Click the collet size at the top of the column (ER-32, for example) to go to the page that lists all the collets in that size range. This makes ordering several collets in the same size range simple.


Size Range (in) Range (mm) ER-11 ER-16 ER-20 ER-25 Metric
ER-25
ER-32 Metric
ER-32
ER-40
1/32" 0.020—0.039" 0.5—1.0 mm 4797 4613            
1/16" 0.039—0.079" 1.0—2.0 mm 4601 4614 4620 5053   4558    
3/32" 0.079—0.118" 2.0—3.0 mm 4398 4615 4621 5054 4332 4559 4333  
1/8" 0.118—0.157" 3.0—4.0 mm 4454 4434 2443 5055 4332 4560 4333 5885
3/16" 0.157—0.197" 4.0—5.0 mm 4455 4435 4622 5056 4332 4561 4333 5886
7/32" 0.197—0.236" 5.0—6.0 mm 4399 4616 4623 5057 4332 4562 4333 5887
1/4" 0.236—0.276" 6.0—7.0 mm 4456 4436 2444 5058   4563   5888
5/16" 0.276—0.315" 7.0—8.0 mm   4617 4624 5059 4332 4564 4333 5889
11/32" 0.315—0.354" 8.0—9.0 mm   4619 4625 5060   4565   5890
3/8" 0.354—0.394" 9.0—10 mm   4618 2445 5061 4332 4566 4333 5891
13/32" 0.394—0.433" 10—11 mm     4626 5062   4567   5892
7/16" 0.433—0.472" 11—12 mm     4627 5063 4332 4568 4333 5893
1/2" 0.472—0.512" 12—13 mm     4628 5064   4569   5894
17/32" 0.512—0.551" 13—14 mm       5065 4332 4570 4333 5895
9/16" 0.551—0.591" 14—15 mm       5066 4332 4571 4333 5896
5/8" 0.591—0.630" 15—16 mm       5067 4332 4572 4333 5897
21/32" 0.63—0.669" 16—17 mm           4573   5898
11/16" 0.669—0.709" 17—18 mm           4574 4333 5899
23/32" 0.709—0.748" 18-19 mm           4575   5900
3/4" 0.748—0.787" 19—20 mm           4576 4333 5901
13/16" 0.787—0.827" 20—21 mm           4578   5903
27/32" 0.827—0.866" 21—22 mm               5904
7/8" 0.866—0.906" 22—23 mm               5905
15/16" 0.906—0.945" 23—24 mm               5906
31/32" 0.945—0.984" 24—25 mm               5907
1" 0.984—1.024" 25—26 mm               2908