Osg 1707301 Spiral Point Tap 1/4-28 Unf Plug 3 Flute

Product Description

The OSG 1707301 is a spiral point tap designed for threading 1/4-28 UNF internal threads in demanding materials. Also called a gun tap, the spiral point pushes chips forward ahead of the cutting zone, making it well suited for through-hole applications where chip evacuation is a priority. The tap is manufactured from powdered metal and finished with a steam oxide coating, which reduces friction and improves lubrication retention during the cut. With a 3B class of fit and an H3 thread limit, it produces threads to tight tolerance standards. Licensed machinists, tool-and-die technicians, and maintenance mechanics working in aerospace, oil and gas, and general manufacturing are the primary users of this tool.

This tap is rated for use in hardened steel, stainless steel, high-nickel alloy, and titanium — materials that are abrasive and work-hardening. The plug chamfer, which features a standard entry taper, starts the thread slightly below the surface and provides good alignment in both CNC and hand-tapping setups. It is part of the OSG 312NI series, a line developed specifically for nickel-based and high-hardness alloy applications. The 1/4-28 UNF thread form is common in aerospace fastener assemblies and precision instrumentation where fine thread pitch provides higher clamping force and finer adjustment than UNC equivalents.

Key Features

• Spiral point (gun tap) geometry pushes chips forward for clean through-hole threading
• Powdered metal construction provides higher wear resistance than standard HSS in abrasive alloys
• Steam oxide coating reduces friction and improves cutting fluid retention
• H3 thread limit and 3B class of fit ensure consistent tolerance control in precision assemblies
• Plug chamfer allows use in both CNC tapping cycles and hand-tapping operations
• Right-hand thread direction; no coolant-through requirement simplifies setup

Compatibility

Designed for threading 1/4-28 UNF through-holes in hardened steel, stainless steel, high-nickel alloy, and titanium workpieces. Part of the OSG 312NI series.

Installation Notes

Tapping operations should be performed by qualified machinists or maintenance mechanics following shop safety protocols. Secure the workpiece fully before tapping and confirm spindle alignment to prevent tap breakage, particularly in hard alloys. Use a cutting fluid or tapping compound appropriate for the workpiece material — dry tapping in stainless or nickel alloy is not recommended. When replacing a tap, inspect the tapped hole for any remaining chip debris before running the new tap through.