Osg 1707901 Spiral Point Tap 3/8-16 Unc Plug H3

Product Description

The OSG 1707901 is a spiral point tap designed for threading through-holes in demanding materials. It cuts a 3/8-16 UNC right-hand thread to a 3B class of fit using a plug chamfer, which allows the tap to start easily and cut progressively into the workpiece. The powdered metal construction delivers superior wear resistance and toughness compared to standard high-speed steel, and the steam oxide coating reduces friction and helps resist corrosion during cutting. With three flutes and a spiral point geometry, the tap pushes chips ahead of the cutting edge rather than packing them into the flute, making it well suited for blind-hole adjacent and through-hole applications in tough materials. Licensed machinists and toolroom professionals install this tap in CNC machining centers, drill presses, and tapping heads.

The OSG 1707901 is built for use in hardened steel, stainless steel, high-nickel alloys, and titanium — materials that demand a tap with high edge retention and consistent thread geometry. Its H3 thread limit provides the tight tolerance oversize control needed when tapping materials prone to springback, such as stainless and nickel alloys. The Series 312NI designation indicates it is purpose-built for nickel-based and difficult-to-machine alloys. It is appropriate for both production environments and precision repair work where thread accuracy and surface finish in the tapped hole are critical.

Key Features

• 3/8-16 UNC thread form, right-hand cut, 3B class of fit for standard tolerance threading
• Plug chamfer for progressive cutting and easy starting in through-hole applications
• Powdered metal construction for increased wear resistance in hardened and abrasive materials
• Steam oxide coating reduces friction and provides light corrosion resistance during use
• H3 thread limit controls oversize for tight tolerance fits, particularly important in stainless and high-nickel alloys
• Spiral point geometry pushes chips forward, reducing chip packing in through-hole threading

Compatibility

Designed for through-hole tapping in hardened steel, stainless steel, high-nickel alloys, and titanium. Part of the OSG Series 312NI line, purpose-engineered for nickel-based and difficult-to-machine alloy applications. Fits standard 3/8-inch tap holders and collets compatible with straight-shank taps.

Installation Notes

This tap should be installed by a qualified machinist following standard tapping procedures. Ensure the workpiece is securely fixtured and that the spindle or tapping head is properly aligned before engagement. Use a cutting fluid or tapping compound appropriate for the workpiece material — this is especially important when tapping stainless steel or high-nickel alloys to prevent galling and premature tap wear. Never reverse the tap under power until chips are clear of the flutes, and inspect the tap for wear or chipping regularly when working in abrasive or hardened materials.