Osg 10900900 Spiral Flute Sti Tap M12x1.75 Hss

Product Description

The OSG 10900900 is a spiral flute STI (Screw Thread Insert) tap designed to cut M12x1.75 metric coarse threads in a wide range of materials. Built from high-speed steel with a bright finish, this tap features a 50-degree helix angle and three flutes that evacuate chips efficiently in through-hole and semi-blind applications. The semi-bottoming chamfer allows the tap to start cleanly and thread closer to the bottom of a blind hole than a standard taper chamfer. With an overall length of 3-13/16 inches and a shank diameter of 0.48 inches, it fits standard tap holders used in CNC machining centers and manual tapping operations. Machinists and tool-and-die technicians working with insert-threaded fastener systems are the primary users of this tap.

This tap is used to produce 6H class-of-fit threads intended to accept Heli-Coil or similar STI inserts in both production and repair applications. It is appropriate for use in ferrous and non-ferrous base materials where thread repair or reinforced thread inserts are required. The 1-13/16 inch thread length accommodates standard insert depths for M12 insert applications. The right-hand flute direction suits conventional right-hand tapping operations on manual machines and CNC equipment with synchronized tapping cycles.

Key Features

• M12x1.75 metric coarse thread form for STI insert applications
• 50-degree helix angle promotes chip evacuation in deeper holes
• Semi-bottoming chamfer allows threading closer to hole bottom in blind-hole setups
• 6H class of fit for proper engagement with standard STI inserts
• High-speed steel construction suitable for a broad range of workpiece materials
• Bright finish with no coating — allows direct visual inspection of cutting edges

Compatibility

Designed as an OEM-style STI tap for use in standard tap holders accepting a 0.48-inch shank diameter, compatible with M12x1.75 Heli-Coil and equivalent screw thread insert systems requiring a 6H class-of-fit tapped hole.

Installation Notes

This tap should be installed by a qualified machinist using a synchronized tapping head or rigid tapping cycle to prevent thread damage and tap breakage. Ensure the workpiece is securely fixtured and the correct tap drill size for the M12x1.75 STI application is used before tapping — the STI drill size is larger than the standard M12 clearance drill. Apply appropriate cutting fluid for the workpiece material. Never reverse a spiral flute tap mid-cycle without confirming the machine supports it; back the tap out only after the full tapping cycle is complete.