Osg 1729901 Spiral Point Tap 1-12 Unc 3 Flute Hss

Product Description

The OSG 1729901 is a spiral point plug tap designed for cutting 1-12 UNC internal threads in a range of ferrous materials. Built from Vanadium High Speed Steel (HSS-E) with a steam oxide finish, it provides improved lubricity and corrosion resistance during tapping operations. The plug chamfer distributes cutting load across the lead threads, making it well suited for through-hole applications. With 3 flutes and an H4 thread limit, it maintains tight dimensional control for 3B class of fit threads. Overall length is 5.126 inches, with a thread length of 1.543 inches and a shank diameter of 0.8 inches. This tap is intended for installation by machinists and toolroom technicians in production or maintenance environments.

The 1729901 is designed for tapping through-holes in hardened steel, low-carbon steel, medium-carbon steel, and stainless steel. The spiral point geometry pushes chips ahead of the tap into the hole, keeping the flutes clear and reducing the risk of chip packing. It is appropriate for use in manual tapping handles, CNC machining centers, and drill press setups where right-hand threading is required. The Series 300 designation places it within OSG standard tap product lines. Coolant-through capability is not included on this tap.

Key Features

• 1-12 UNC thread form, right-hand direction, 3B class of fit
• Vanadium High Speed Steel (HSS-E) construction for increased wear resistance
• Steam oxide coating improves lubricity and reduces galling in ferrous materials
• Plug chamfer distributes cutting load — optimized for through-hole applications
• H4 thread limit for consistent dimensional control on close-tolerance threads
• 3-flute spiral point design pushes chips forward, preventing packing in blind or through holes

Compatibility

Suitable for tapping 1-12 UNC through-holes in hardened steel, low-carbon steel, medium-carbon steel, and stainless steel workpieces. Verify machine spindle and tap holder compatibility with the 0.8-inch shank diameter before use.

Installation Notes

This tap should be installed by a qualified machinist or toolroom technician using a tap holder appropriate for the shank diameter. Always secure the workpiece and ensure the spindle is properly aligned before beginning the tapping cycle. Apply cutting fluid suitable for the workpiece material, particularly when tapping stainless or hardened steel, to extend tool life and maintain thread quality. Never reverse a spiral point tap under power without confirming the machine has a synchronized reversal cycle.