What are the differences between SK and ER Collet Systems?

• ER collets have an included angle of 16 degrees and most collets have a range of 1mm. Grip is strong and in most applications sufficient. Grip is stronger than SK due to its double angle design.
• SK collets have an included angle of 8 degrees and most collets have a range of .5mm. SK collet system is recommended for medium roughing to fine finishing due to slightly better concentricity than ER collets. More of the collet sits in the taper pocket so concentricity is equal or better than ER collets.

Differences between standard SK Collet Chucks and SK Collet Chucks with the HT Nut

• The tool holder itself is the same and both nuts will be interchangeable
• The HT nut will handle higher torque and will clamp the collet much tighter
• The HT nut is made from a higher tensile steel, is coated with an anti-friction coating, and has a proprietary nut design allowing higher torquing without stripping or distortion
• Wrenches for the SK-HT nuts are available here