{"product_id":"osg-1298300-spiral-flute-extension-tap-1-4-28-unf","title":"Osg 1298300 Spiral Flute Extension Tap 1\/4-28 Unf","description":"\u003ch3\u003eProduct Description\u003c\/h3\u003e\n\u003cp\u003eThe OSG 1298300 is a spiral flute extension tap designed for threading 1\/4-28 UNF holes in a wide range of metal workpieces. Built from high-speed steel with a bright, uncoated finish, this tap features a bottoming chamfer for threading close to the bottom of blind holes. The 50-degree helix angle drives chips up and out of the flute during the cut. At 6 inches overall length, the extended reach makes it suited for applications where a standard-length tap cannot access the work area. Three flutes and an H3 thread limit provide consistent thread tolerance control on production and repair work alike.\u003c\/p\u003e\n\u003cp\u003eThis tap is intended for use in aluminum, carbon steel, and cast iron. The bottoming chamfer allows full thread engagement near the base of a blind hole, making it appropriate for fastener bores with limited depth clearance. The reduced shank and 1-inch thread length support use in both CNC tapping cycles and hand-tapping setups where tool clearance is a factor. The 3B class of fit targets standard tolerance internal threads used across general mechanical assembly.\u003c\/p\u003e\n\u003ch4\u003eKey Features\u003c\/h4\u003e\n\u003cul\u003e\n  \u003cli\u003e1\/4-28 UNF thread form with H3 thread limit for controlled tolerance\u003c\/li\u003e\n  \u003cli\u003eBottoming chamfer for threading to the bottom of blind holes\u003c\/li\u003e\n  \u003cli\u003e50-degree helix angle for efficient chip evacuation in spiral flute design\u003c\/li\u003e\n  \u003cli\u003e6 inches overall length provides extended reach into recessed bores\u003c\/li\u003e\n  \u003cli\u003eHigh-speed steel construction suitable for aluminum, carbon steel, and cast iron\u003c\/li\u003e\n  \u003cli\u003eReduced shank with 0.255-inch shank diameter for compatibility with standard tap holders\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4\u003eCompatibility\u003c\/h4\u003e\n\u003cp\u003eDesigned for use in standard tap holders and CNC tapping chucks that accept a 0.255-inch reduced shank. Suitable for threading 1\/4-28 UNF internal threads in aluminum, carbon steel, and cast iron workpieces.\u003c\/p\u003e\n\u003ch4\u003eInstallation Notes\u003c\/h4\u003e\n\u003cp\u003eInstallation and use should be performed by a machinist or qualified tradesperson familiar with tapping operations. Always secure the workpiece and use the appropriate cutting fluid for the material being tapped. Ensure the tap driver or chuck is properly aligned to avoid tap breakage, especially near the bottom of blind holes. Follow applicable shop safety practices and machine manufacturer guidelines when operating tapping equipment.\u003c\/p\u003e\n\u003ch4\u003eTechnical Specifications\u003c\/h4\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eThread Size\u003c\/strong\u003e: 1\/4-28\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eThread Standard\u003c\/strong\u003e: UNF\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eThread Limit\u003c\/strong\u003e: H3\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eClass of Fit\u003c\/strong\u003e: 3B\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eNumber of Flutes\u003c\/strong\u003e: 3\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eTap Type\u003c\/strong\u003e: Spiral Flute\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eChamfer\u003c\/strong\u003e: Bottoming\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eThread Direction\u003c\/strong\u003e: Right Hand\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFlute Direction\u003c\/strong\u003e: Right Hand\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHelix Angle\u003c\/strong\u003e: 50 degrees\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eOverall Length\u003c\/strong\u003e: 6 inches\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eThread Length\u003c\/strong\u003e: 1 inch (0.645 inches decimal)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eNeck Length\u003c\/strong\u003e: 1.007 inches\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eShank Diameter\u003c\/strong\u003e: 0.255 inches\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSquare Size\u003c\/strong\u003e: 0.191 inches\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSquare Length\u003c\/strong\u003e: 0.3125 inches\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eReduced Shank\u003c\/strong\u003e: Yes\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMaterial\u003c\/strong\u003e: High-Speed Steel\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCoating\/Finish\u003c\/strong\u003e: Bright\/Uncoated\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMaterial Application\u003c\/strong\u003e: Aluminum, Carbon Steel, Cast Iron\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSeries\u003c\/strong\u003e: 918\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eWeight\u003c\/strong\u003e: 0.09 pounds\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4\u003eStandard Information\u003c\/h4\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBrand\u003c\/strong\u003e: OSG\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number\u003c\/strong\u003e: 1298300\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"OSG","offers":[{"title":"Default Title","offer_id":51743427068210,"sku":"1298300","price":99.36,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0270\/4519\/9983\/files\/e6dd4842d49c9167407aca18df7399a3.jpg?v=1788846922","url":"https:\/\/voomisupply.com\/products\/osg-1298300-spiral-flute-extension-tap-1-4-28-unf","provider":"Voomi Supply","version":"1.0","type":"link"}