Meet the Carmex SR0021K21C Single Long Carbide Shank Threading Insert Holder — a precise, long-reach solution for external and internal threading on CNC mills. Built for shops tackling deep or extended overhang threading, this holder combines rigid support with efficient coolant delivery to boost productivity.

• Internal coolant bore: Directs coolant to the cutting edge for improved chip control and insert life.
• Long reach up to 270 mm / 10.5 in: Supports deep or extended overhang threading jobs with stability.
• Carbide shank tool holders: Part of Carmex’s line designed for efficient, cost-effective long-overhang applications.
• Compatibility with carbide external/internal threading inserts: Flexible use for both threading tasks on a single holder system.
• Optimized for CNC milling with helical interpolation: Enables higher cutting speeds and effective multi-tooth inserts for smoother thread profiles.
• Guidelines for long overhangs: When machining with long overhangs, reduce cutting speed and feed by 20–40% depending on workpiece material, thread pitch, and overhang.
• Important compatibility note: SR0390K12C can’t be used with conical inserts: 12-18 NPT / 12-18 NPTF / 12-19 BSPT.

Benefits: This holder setup offers tangible efficiency and cost advantages. You gain faster threading cycles and lower tooling costs, thanks to multi-tooth carbide inserts that outperform traditional taps and dies in many applications. The long, rigid carbide shank provides dependable guidance for deep threads, while the integrated coolant bore helps maintain tool life and consistent thread quality. Ideal for shops performing long overhang threading on CNC mills, this holder supports precise, repeatable results across external and internal threading tasks.