ER-style and R8 collet holders are now offered for use on knee mills. Holders are stocked in three sizes to hold ER-style toolholder collets to grip drills, taps, reamers, end mills, boring bars and special round shank endworking tools. One holder will accommodate a range of collets, the company says. The maximum round tool capacities are 3/8" (ER16), 25/32" (ER32), and 1" (ER40).
The collets are of a multi-slot design, which are said to provide maximum gripping force for efficient "push-back" control. This control helps prolong tool life, which in turn, reduces machine downtime to produce more parts per hour. The manufacturing process ensures each collet will have a total indicator reading of 0.0005" or less, the company says.
The standard R8 collets’ "one-piece" construction is said to eliminate breakage associated with other brands that have a two-piece design with a separate bushing. In the two-piece design, the bushing often breaks off in the spindle and results in the costly replacement of the spindle drawbar as well as the collet, according to the company.