Value Collection 231-4740 R8 Round Collet 5/8 Inch

Product Description

The VALUE COLLECTION 231-4740 is a 5/8 inch R8 round collet machined from steel for use in milling machines equipped with an R8 spindle taper. It accepts 5/8 inch round shank tooling and secures it via a 7/16-20 drawbar thread. The collet is manufactured to a total indicator runout (TIR) of 0.0007 inches, providing the concentricity required for accurate milling, drilling, and boring operations. This type of collet is a standard consumable in manual and CNC knee mills and is installed and serviced by machinists and toolroom technicians.

R8 collets are the standard toolholding format for Bridgeport-style knee mills and many similar vertical milling machines found in job shops, maintenance departments, and machine shops. The 231-4740 accepts 5/8 inch round shank end mills, drills, and boring tools. It is suited for both production and general-purpose machining environments where consistent tool runout directly affects surface finish and dimensional accuracy.

Key Features

• 5/8 inch bore diameter for standard round shank tooling
• R8 taper profile compatible with R8 spindle milling machines
• 7/16-20 drawbar thread for secure spindle engagement
• 0.0007 inch TIR for precise concentricity and reduced tool runout
• Steel construction for durability under repeated clamping cycles

Compatibility

Designed as an OEM-style replacement collet for vertical milling machines with an R8 spindle taper and 7/16-20 drawbar thread.

Installation Notes

R8 collets are installed and removed by machinists using the machine drawbar and a spindle wrench. Always power down and lock out the milling machine before changing collets. Inspect the spindle bore and collet taper for chips or debris before seating the collet, as contamination will directly affect runout. Do not overtighten the drawbar, as this can distort the collet and reduce clamping accuracy over time.