Osg 1703601 Spiral Flute Tap 1/4-28 Unf Modified Bottoming

Product Description

The OSG 1703601 is a spiral flute tap designed for cutting internal 1/4-28 UNF right-hand threads in a range of demanding materials. Built from powdered metal with a steam oxide coating, it offers improved lubricity and corrosion resistance compared to standard HSS taps. The modified bottoming chamfer allows threading close to the bottom of blind holes. With a 15-degree helix angle and 3 right-hand spiral flutes, the tool efficiently evacuates chips upward out of the hole during tapping operations. Machinists, toolroom technicians, and maintenance professionals working on precision assemblies install this tap in CNC machining centers, drill presses, and tapping arms.

This tap is suited for threading alloy steel, stainless steel, hardened steel, titanium, and high-nickel alloys where standard carbon steel or HSS tooling falls short. The spiral flute design makes it particularly effective in blind-hole applications where chip buildup can cause tap breakage or thread damage. Thread limit H4 and Class of Fit 2B ensure threads produced meet standard tolerance requirements for general fastener applications in manufacturing and repair environments.

Key Features

• 1/4-28 UNF thread form with right-hand thread direction
• Modified bottoming chamfer for threading close to blind hole floors
• 3 right-hand spiral flutes with 15-degree helix angle for upward chip evacuation
• Powdered metal construction for extended tool life in tough materials
• Steam oxide coating reduces friction and provides mild corrosion resistance
• H4 thread limit, Class of Fit 2B for standard fastener tolerance applications
• No coolant-through requirement — compatible with standard flood or manual lubrication

Compatibility

Rated for use in alloy steel, stainless steel, hardened steel, titanium, and high-nickel alloys. Part of OSG Series 313.

Installation Notes

Install in a tap holder, tapping chuck, or rigid tapping setup appropriate for 1/4-28 UNF tooling. Always apply a suitable cutting fluid or tapping compound for the workpiece material — this is especially important with stainless steel, titanium, and high-nickel alloys. Ensure the tap is properly aligned with the pilot hole before engagement to avoid cross-threading or tool breakage. Follow shop-standard speeds and feeds for the workpiece material and consult OSG Series 313 documentation for recommended parameters.