Osg 1719101 Spiral Flute Tap 4-40 Unc Modified Bottoming

Product Description

The OSG 1719101 is a spiral flute tap designed for threading 4-40 UNC holes in difficult-to-machine materials. It features a modified bottoming chamfer, powdered metal construction, and a steam oxide coating that reduces friction and helps resist built-up edge. With 3 right-hand flutes at a 10-degree helix angle, this tap is engineered to lift chips up and out of blind holes, making it a reliable choice for production tapping in tight thread sizes. Overall length is 1.875 inches with a shank diameter of 0.141 inches. Thread limit is H3, suitable for Class 2B or 3B fit depending on application requirements.

This tap is suited for threading stainless steel, hardened steel, titanium, and high-nickel alloys where chip evacuation and tool life are critical concerns. The spiral flute geometry and steam oxide finish work together to manage the work-hardening tendencies common in these materials. It is used in precision machining environments including aerospace, medical device, and industrial fabrication where 4-40 UNC fastener threads are required in challenging base materials. The 313NI series designation indicates a formulation optimized for nickel-containing alloys.

Key Features

• Modified bottoming chamfer allows threading close to the bottom of blind holes
• Spiral flute design evacuates chips upward, reducing clogging in tough alloys
• Powdered metal construction provides consistent grain structure and wear resistance
• Steam oxide coating reduces friction and extends tool life in hard-to-machine materials
• H3 thread limit for controlled thread tolerance in Class 2B and 3B applications
• 10-degree right-hand helix angle suited for short-chipping and work-hardening materials

Compatibility

Designed for tapping 4-40 UNC threads in stainless steel, hardened steel, titanium, and high-nickel alloys. Part of the OSG 313NI series.

Installation Notes

Installation should be performed by a qualified machinist using a tap handle, tapping head, or CNC machine set to the correct feed rate for 4-40 UNC at 40 threads per inch. Ensure the workpiece is securely fixtured and the tap is aligned perpendicular to the hole to prevent breakage in small-diameter taps. Use a cutting fluid or tapping compound appropriate for the base material, particularly when working in stainless steel or high-nickel alloys. Coolant-through is not available on this tap; external lubrication is required.