Hertel K007063AS Hand Sti Tap 5/16-18 Unc H4 Plug Chamfer

Product Description

The HERTEL K007063AS is a hand STI (Screw Thread Insert) tap designed for cutting internal threads that accept Helicoil-style wire thread inserts. Ground to an H4 thread limit with a 5/16-18 UNC thread form, this tap produces oversized threads sized to accept standard helical coil inserts, restoring or creating strong threaded holes in worn or soft parent materials. The 4-flute, plug chamfer geometry makes it well suited for through-hole tapping in a range of metals. Manufactured from high-speed steel with a bright uncoated finish, it delivers consistent thread form across production and repair work. Overall length is 2-15/16 inches with a 1-1/4 inch thread length.

This tap is used in maintenance, repair, and manufacturing applications where threaded inserts are required to reinforce threads in aluminum, cast iron, steel, and similar materials. The plug chamfer provides a gradual lead-in, making it practical for both through holes and deeper blind holes where some lead room is available. It is a hand tap intended for use with a standard tap wrench or similar manual driver and is not designed for machine tapping under power.

Key Features

• 5/16-18 UNC thread form ground to H4 thread limit for STI insert applications
• 4-flute design provides good chip clearance and thread surface finish
• Plug chamfer with gradual lead-in suits through-hole and accessible blind-hole tapping
• High-speed steel construction handles a broad range of workpiece materials
• Bright uncoated finish — no coating buildup to affect tolerance in precision thread repair work
• Helicoil reference number 5CPA for cross-referencing insert system compatibility

Compatibility

Designed for use with Helicoil-style screw thread inserts; Helicoil reference number 5CPA. Produces oversized 5/16-18 UNC internal threads sized to accept standard helical coil wire thread inserts.

Installation Notes

This is a hand tap and should be driven with a tap wrench — do not use in a power tapping head or drill press chuck without appropriate torque control. Before tapping, drill the correct STI tap drill size for the 5/16-18 insert being installed; the required drill diameter differs from a standard 5/16-18 tap drill. Apply cutting fluid appropriate to the workpiece material and back the tap off periodically to break chips. Ensure the workpiece is securely fixtured before starting the thread.