ER Collet Sizes - LittleMachineShop
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' Tips.
