Sandvik Coromant 6138403 Threading Toolholder 3/4 Inch

Product Description

The SANDVIK COROMANT 6138403 is an external, right-hand indexable threading toolholder designed for precision thread-turning operations on CNC lathes and turning centers. Part of the CoroThread 266 series, it accepts 266.RG to 16.. inserts secured by a screw-clamping method, ensuring repeatable positioning and rigid insert lockdown during cut. The steel shank measures 0.75 inches wide by 0.75 inches tall with an overall length of 4.5 inches, making it a compact but robust choice for threading passes on external workpiece diameters. Machinists and toolroom professionals handling production threading work will find this holder well-suited to both interrupted and continuous thread profiles.

This toolholder is intended for external threading applications on turning equipment where a right-hand cutting orientation is required. The CoroThread 266 series is engineered for consistent thread form accuracy across high-volume production runs as well as job-shop single-part work. It is compatible with standard CNC lathe turrets that accept 0.75 x 0.75 inch shank tooling. Coolant-through capability is not included on this holder, so external coolant delivery should be directed at the cutting zone as needed for the workpiece material.

Key Features

• External, right-hand threading orientation for standard CNC lathe setups
• CoroThread 266 series toolholder style 266R/LFA with screw-clamping insert retention
• Accepts 266.RG to 16.. indexable threading inserts
• Steel construction for rigidity and long-term dimensional stability
• Compact 4.5 inch overall length with 0.921 inch head length for close-clearance applications
• Back-of-bar to cutting edge distance of 0.77 inches for precise tool offset setup

Compatibility

Compatible with indexable inserts in the 266.RG to 16.. designation range within the CoroThread 266 series. Fits CNC lathe turrets and toolblocks that accept 0.75 x 0.75 inch square shank external threading toolholders.

Installation Notes

Installation should be performed by a qualified machinist or toolroom technician. Power down and lock out the machine spindle before mounting or removing the toolholder from the turret. Ensure the turret pocket and shank seating surfaces are clean and free of chips before tightening clamp screws to the machine manufacturer's specified torque. Verify tool offset and cutting edge height against centerline before initiating a threading pass.