{"product_id":"osg-1660200-straight-flute-tap-1-4-20-unc-bottoming-hss","title":"Osg 1660200 Straight Flute Tap 1\/4-20 Unc Bottoming Hss","description":"\u003ch3\u003eProduct Description\u003c\/h3\u003e\u003cp\u003eThe OSG 1660200 is a straight flute bottoming tap designed for cutting internal left-hand threads to a 1\/4-20 UNC specification in a range of ferrous and non-ferrous materials. Built from high-speed steel with an oxide coating, this tap operates in the 3B class of fit with an H3 thread limit, delivering tight dimensional control suited to production and maintenance threading applications. The bottoming chamfer allows threading to the bottom of blind holes where standard or plug chamfer taps cannot reach. Overall length is 2.5 inches with a thread length of 0.854 inches. It is installed by machinists and maintenance technicians using a tap wrench or machine holder.\u003c\/p\u003e\u003cp\u003eThis tap is appropriate for use in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. The left-hand thread direction makes it suitable for applications where standard right-hand threads would loosen under torque, such as certain rotating assemblies or where reverse-thread fasteners are required by design. It fits the OSG 101L series and is suited to both manual and machine tapping operations in job shop, production, and field maintenance settings.\u003c\/p\u003e\u003ch4\u003eKey Features\u003c\/h4\u003e\u003cul\u003e\n\u003cli\u003eBottoming chamfer for threading to the bottom of blind holes\u003c\/li\u003e\n\u003cli\u003eLeft-hand thread direction for reverse-thread applications\u003c\/li\u003e\n\u003cli\u003eHigh-speed steel construction with oxide coating for wear and chip resistance\u003c\/li\u003e\n\u003cli\u003e3B class of fit with H3 thread limit for consistent, inspectable thread geometry\u003c\/li\u003e\n\u003cli\u003e4 straight flutes suited to through-hole and short blind-hole threading\u003c\/li\u003e\n\u003cli\u003eCompatible with multiple ferrous and non-ferrous base materials\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch4\u003eCompatibility\u003c\/h4\u003e\u003cp\u003eDesigned as an OEM-style replacement or direct substitute tap for 1\/4-20 UNC left-hand bottoming applications across standard machine and hand tapping setups. Material suitability includes aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel per manufacturer specification.\u003c\/p\u003e\u003ch4\u003eInstallation Notes\u003c\/h4\u003e\u003cp\u003eA licensed machinist or qualified maintenance technician should install this tap using a properly sized tap wrench or machine holder that matches the square drive dimensions. Before tapping, verify the drilled hole diameter matches the recommended tap drill size for 1\/4-20 UNC threads and that hole depth allows for the bottoming chamfer engagement. Use appropriate cutting fluid for the material being tapped to reduce heat and extend tap life. Left-hand taps require counterclockwise rotation to advance  -  confirm thread direction before beginning the operation to avoid tap breakage.\u003c\/p\u003e\u003ch4\u003eTechnical Specifications\u003c\/h4\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eThread Size\u003c\/strong\u003e: 1\/4-20 UNC\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThread Standard\u003c\/strong\u003e: UNC\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThreads per Inch\u003c\/strong\u003e: 20\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThread Direction\u003c\/strong\u003e: Left Hand\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eChamfer\u003c\/strong\u003e: Bottoming\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eClass of Fit\u003c\/strong\u003e: 3B\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThread Limit\u003c\/strong\u003e: H3\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNumber of Flutes\u003c\/strong\u003e: 4\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOverall Length\u003c\/strong\u003e: 2.5 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThread Length\u003c\/strong\u003e: 0.854 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNeck Length\u003c\/strong\u003e: 1.287 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 Length\u003c\/strong\u003e: 0.3125 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\u003eMaterial\u003c\/strong\u003e: High-Speed Steel\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCoating\u003c\/strong\u003e: Oxide\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCoolant Through\u003c\/strong\u003e: No\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSeries\u003c\/strong\u003e: 101L\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight\u003c\/strong\u003e: 0.029 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial Application\u003c\/strong\u003e: Aluminum, Cast Aluminum, Cast Iron, Low-Carbon Steel, Medium-Carbon Steel, High-Carbon Steel\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch4\u003eStandard Information\u003c\/h4\u003e\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: 1660200\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"OSG","offers":[{"title":"Default Title","offer_id":51739953234226,"sku":"1660200","price":23.68,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0270\/4519\/9983\/files\/21152679f93c495df9639436855b27fe.jpg?v=1788820694","url":"https:\/\/voomisupply.com\/products\/osg-1660200-straight-flute-tap-1-4-20-unc-bottoming-hss","provider":"Voomi Supply","version":"1.0","type":"link"}