Value Collection 231-4756 R8 Round Collet 7/8 Inch

Product Description

The VALUE COLLECTION 231-4756 is a 7/8 inch R8 round collet machined from steel for use in R8-spindle milling machines. It accepts round workpieces and tooling shanks at the 7/8 inch bore size and secures them via a 7/16-20 drawbar thread. Total Indicator Runout (TIR) is rated at 0.0007 inches, delivering the concentricity required for precise milling, drilling, and boring operations. At 0.4 pounds, the collet is a direct-fit tool-holding component installed by machinists and tool-room technicians in manual and CNC knee mills.

This collet is suited for manual knee mills and vertical milling machines equipped with an R8 spindle taper — a standard found widely in Bridgeport-style and similar knee-mill platforms. It is appropriate for production shops, tool rooms, and maintenance machining environments where consistent tool runout and repeatable clamping force are required. The 7/8 inch bore accommodates end mills, drill chucks, arbors, and other tooling shanks ground to that diameter.

Key Features

• 7/8 inch bore diameter for standard R8-spindle tool holding
• 0.0007 inch TIR for high concentricity and reduced tool runout
• 7/16-20 drawbar thread compatible with standard R8 drawbar assemblies
• Steel construction for durability under repeated clamping cycles
• Lightweight at 0.4 pounds for easy single-hand handling during tool changes

Compatibility

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

Installation Notes

Installation is performed by a machinist or mill operator. Power down and lock out the machine spindle before inserting or removing the collet. Thread the collet into the R8 spindle nose and secure it using the machine drawbar torqued to the mill manufacturer's specification. Inspect the collet bore and spindle taper for chips or debris before seating to protect TIR performance.