Ultra-Precision ER Collet Nuts and Wrenches

  • used in applications where speeds exceed 10,000 PRM
  • balanced to G2.5 for 20,000 RPM's
  • used on collet holders and multi-spindle heads where center or shoulder distances are critical.
ER20A Nut

ER20A Hex Nut

ER20M Nut

ER20M Mini Nut

ER-20 wrench

ER20M Castle Wrench

  • Steel : SCM430
  • H.R.C. 38-42
  • Surface Roughness: Ra 1.6um
  • Deburred & free of sharp edges & corners
  • purely tangential tightening torque
  • no radial nut distortion
  • castle design for high-torque tightening
  • secure, no-slip design
Type OD Length Thread Max. Torque
ER 11 Mini Nut 16mm 12mm M13 x 0.75 14 ft/lbs. (19 N-m)
ER 16 Mini Nut 22mm 18mm M19 x 1.0 22 ft/lbs. (30 N-m)
ER 20 Hex Nut 34mm 19mm M25 x 1.5 25 ft/lbs. (34 N-m)
ER 20 Mini Nut 28mm 19.5mm M24 x 1.0 25 ft/lbs. (34 N-m)
ER 25 Mini Nut 35mm 21mm M30 x 1.0 29 ft/lbs. (39 N-m)
CAUTION: If your spindle currently has a HEX nut, it is probably has an ER-A thread. You must use an ER-A spanner!

Part Number Description Reviews Price


ER-11 High Speed Collet mini-nut, M13 x 0.75 ER-11..



ER-11M Castle wrench (for ER-11M Collet mini-nut, and tool-holder)..



ER-16 High Speed Collet mini-nut, M19 x 1.0..



ER-16M Castle wrench (for ER-16M Collet mini-nut, tool-holder and collet adapter)..



ER-20A High Speed Collet hex nut, M25 X 1.5..



ER-20A Hex wrench (for ER-20A Collet nut)..



ER-20 High Speed Collet mini-nut, M24 X 1.0..



ER-20M Castle wrench (for ER-20M Collet mini-nut)..



ER-25 High Speed Collet mini-nut, M30 X 1.0..



ER-25M Castle wrench (for ER-25 Collet mini-nut)..