Osg 1726408 Spiral Flute Tap 1-8 Unc 4 Flutes Modified Bottoming

Product Description

The OSG 1726408 is a spiral flute tap designed for cutting 1-8 UNC right-hand internal threads in a range of ferrous materials. Built from vanadium high-speed steel and finished with a TICN (titanium carbonitride) coating, it delivers improved wear resistance and surface hardness over standard HSS taps. The 45-degree helix angle evacuates chips upward out of the hole, reducing the risk of chip packing in blind and through-hole applications. The modified bottoming chamfer allows threading closer to the bottom of a blind hole than a standard taper or plug chamfer. Overall length is 5.125 inches with a 2.5-inch overall decimal length. This tap is used by machinists and maintenance technicians on manual and CNC equipment.

Rated for use in stainless steel, high-carbon steel, low-carbon steel, and medium-carbon steel, the 1726408 fits production and job-shop threading operations where thread quality and tool life in tough materials are the primary concerns. The H4 thread limit and 3B class of fit target standard tolerance threaded assemblies where controlled clearance is required. With a shank diameter of 0.255 inches and a square size of 0.6 inches, it seats in standard tap holders and drive adapters sized for 1-inch nominal taps. Coolant-through capability is not included in this configuration.

Key Features

• 45-degree right-hand spiral flute for upward chip evacuation in blind and through holes
• TICN coating increases surface hardness and reduces built-up edge in ferrous materials
• Modified bottoming chamfer for threading close to the bottom of blind holes
• H4 thread limit with 3B class of fit for controlled tolerance threading
• Vanadium high-speed steel substrate for elevated hot hardness and wear resistance
• 4-flute design balances chip clearance with thread form support

Compatibility

Designed for cutting 1-8 UNC right-hand threads in stainless steel, high-carbon steel, low-carbon steel, and medium-carbon steel. Part of the OSG EXOTAP VA3 series (Series 303).

Installation Notes

This tap is installed and driven by a qualified machinist using a standard tap wrench, tapping head, or CNC rigid tapping cycle with a matching tap holder. Power down or disengage the spindle and secure the workpiece before tool changes. Apply appropriate cutting fluid for the workpiece material — sulfo-chlorinated oil is commonly used for carbon and stainless steel tapping. Do not force a worn or chipped tap; inspect the cutting edge before each use and replace when thread quality degrades.