Osg 3370716143 Spiral Point Tap 7/16-14 Unc Hr Coated

Product Description

The OSG 3370716143 is a spiral point plug tap designed for threading through-holes in demanding materials. Built from powdered metal high-speed steel and finished with an HR (heat-resistant) coating, this tap handles hardened steel, stainless steel, and high-nickel alloys where standard HSS taps wear prematurely. It cuts a 7/16-14 UNC right-hand thread to a 3B class of fit with an H3 thread limit, producing consistent tolerance in production and repair work. The three-flute spiral point geometry pushes chips forward ahead of the cutting zone, making it well suited for through-hole tapping on CNC machining centers and manual machines alike.

This tap is used in metalworking and maintenance applications where tight thread tolerances are required in tough base materials. Typical scenarios include tapping threaded fastener holes in stainless steel weldments, high-nickel alloy components, and hardened steel fixtures. The plug chamfer provides a gradual lead-in, making it appropriate for through-holes where full thread engagement is needed before breakthrough. It does not require coolant-through tooling, so it fits standard tool holders without modification.

Key Features

• Spiral point geometry pushes chips forward, clearing the cutting zone in through-hole applications
• HR coating improves wear resistance and heat tolerance in stainless steel and high-nickel alloys
• Powdered metal HSS substrate offers finer grain structure and greater toughness than conventional HSS
• H3 thread limit and 3B class of fit ensure consistent, inspectable thread tolerance
• Plug chamfer provides gradual engagement suited to through-hole tapping
• Right-hand cut, no coolant-through requirement - compatible with standard holders

Compatibility

Rated for use in hardened steel, stainless steel, and high-nickel alloy workpieces. Cuts 7/16-14 UNC threads per the Series 337NI specification. Intended for through-hole applications; not designed for blind-hole use where chip evacuation forward is not possible.

Installation Notes

Threading operations should be performed by a qualified machinist following applicable shop safety procedures. Secure the workpiece and ensure the tap is properly aligned to the drilled hole before engaging to avoid tap breakage. Use a recommended cutting fluid for the workpiece material to extend tap life, even though this tap does not require coolant-through delivery. Inspect thread form with a 3B go/no-go gauge after tapping to verify tolerance compliance.