Emuge CU203010.5621 Spiral Point Sti Tap 1/2-13 Unc

Product Description

The EMUGE CU203010.5621 is a spiral point STI tap designed for cutting STI (Screw Thread Insert) threads in through-hole applications. Built from cobalt high-speed steel with a nitride finish, this plug chamfer tap handles tough materials and high-heat cutting environments without losing edge integrity. It produces a 1/2-13 UNC thread form to a 3B class of fit, meeting standard tolerance requirements for threaded insert installations. With an overall length of 4.331 inches and a thread length of 1.969 inches, it fits standard tap holders and is part of the EMUGE Rekord B-VA series. Licensed machinists and maintenance professionals install this tap in production and repair settings.

This tap is suited for through-hole threading operations where a spiral point geometry pushes chips forward ahead of the cutting edge, reducing chip packing and breakage risk. It is commonly used when tapping steel, stainless, cast iron, and similar materials in industrial machining, MRO repair, and insert-thread restoration work. The STI thread form is specifically required when installing Heli-Coil or equivalent threaded inserts to restore or upgrade a damaged or undersized tapped hole.

Key Features

• Spiral point geometry pushes chips forward, suited for through-hole tapping
• STI UNC thread form produces the correct oversized profile for threaded insert installation
• Cobalt construction provides heat and wear resistance in tough ferrous and stainless materials
• Nitride finish reduces friction and improves surface hardness at the cutting edge
• Plug chamfer with 3-flute design balances cutting load and thread quality
• 3B class of fit meets standard tolerance requirements for precision threaded insert applications

Compatibility

Designed for use in through-hole STI tapping operations requiring a 1/2-13 UNC thread form to 3B class of fit, compatible with standard tap holders accepting a 0.480-inch shank diameter. Part of the EMUGE Rekord B-VA series.

Installation Notes

This tap should be installed and operated by a qualified machinist or maintenance technician familiar with tapping feeds, speeds, and cutting fluid requirements for the workpiece material. Always secure the workpiece and ensure proper alignment before engaging the tap to avoid thread misalignment or tap breakage. Shut down and de-energize any CNC or powered tapping equipment before changing tooling. Follow the machine manufacturer guidelines and applicable shop safety standards when selecting RPM and feed rate for cobalt taps.