The Carmex Single Threading Insert Holder SR0018H21 is a precision tool holder engineered for CNC milling threading applications. It supports carbide external and internal threading inserts, helping engineers, machinists, and hobbyists produce accurate, repeatable threads with minimal setup.

As part of the Mill-Thread family, this holder is designed to enable high-speed threading through helix interpolation and multi-tooth carbide inserts. It delivers productive results with lower tooling costs compared with traditional taps and dies. Important compatibility notes: SR0018H21 is incompatible with inserts 21 I 3.5 ISO, 21 I 8 UN, 21 I 7 UN, 21-11 BSPT, 21-11.5 NPT, and 21-11.5 NPTF.

• Internal coolant bore for clean, controlled cutting: Delivers coolant directly to the cutting edge to improve chip evacuation, reduce heat buildup, and extend insert life during threading on CNC mills.
• Optimized for Mill-Thread carbide inserts: Works with multi-tooth carbide inserts to enable fast, reliable threading through helix interpolation, delivering consistent thread quality across a range of materials.
• Cost-efficient threading solution: A modular holder with replaceable inserts that lowers tooling costs compared with taps and dies, while simplifying maintenance and reducing downtime.

Pairing this holder with compatible carbide inserts gives you a dependable, repeatable threading process that helps you tighten production schedules, improve finish quality, and lower overall production costs. The design supports quick insert changes to keep your workflow moving and your results consistent.