Osg 1776301 Spiral Point Tap 4-40 Unc Plug 3 Flute

Product Description

The OSG 1776301 is a spiral point plug tap designed for threading 4-40 UNC holes in demanding materials. Built from powdered metal and finished with a steam oxide coating, it handles hardened steel, stainless steel, high-nickel alloys, and titanium — materials that wear out standard taps quickly. The 3-flute spiral point geometry pushes chips forward ahead of the cut, making it well suited for through-hole applications. Overall length is 1.874 inches with a thread length of 0.66 inches (9/16 inches nominal) and a shank diameter of 0.141 inches. The H3 thread limit provides the tolerance class commonly required for standard UNC fits in harder workpieces. Right-hand thread direction only.

This tap is intended for production and maintenance machining environments where fine 4-40 UNC threads must be cut in tough alloys. Typical applications include aerospace fastener holes, medical device housings, electronic enclosures, and instrumentation components made from stainless steel or high-nickel materials. The plug chamfer style makes it appropriate for through-holes or holes with adequate clearance past the thread depth. It is not designed for coolant-through use and does not produce an interrupted thread form.

Key Features

• Spiral point geometry pushes chips forward — optimized for through-hole tapping
• Powdered metal construction provides improved wear resistance in abrasive and hard materials
• Steam oxide coating reduces friction and helps resist galling in stainless and nickel alloys
• H3 thread limit suits standard tolerance fits in UNC 4-40 applications
• Plug chamfer for general-purpose through-hole starting and full thread engagement
• Right-hand cut, no coolant-through requirement, no oversize thread form

Compatibility

Designed for cutting 4-40 UNC right-hand threads in hardened steel, stainless steel, high-nickel alloy, and titanium workpieces. Series 312NI designation indicates suitability for nickel-alloy and stainless applications specifically.

Installation Notes

Machining professionals should ensure the correct tap drill size for 4-40 UNC is used prior to tapping and that the workpiece is securely fixtured. Power down or disengage the spindle before loading or removing the tap from the holder. Use an appropriate cutting fluid or tapping compound rated for stainless or high-nickel alloys to extend tool life and reduce galling risk. Follow shop-standard feeds and speeds for small-diameter taps in hard materials to avoid tap breakage.