Osg 1122205 Straight Flute Tap 7/16-20 Unf Hss Tin

Product Description

The OSG 1122205 is a straight flute hand tap designed for cutting right-hand internal threads to the 7/16-20 UNF specification. Built from high-speed steel (HSS) with a titanium nitride (TiN) coating, it delivers improved wear resistance and longer tool life compared to uncoated HSS. The plug chamfer — 3 to 5 threads of lead — makes it suitable for through-hole applications and easier starting in blind holes with sufficient depth. With a thread limit of H3, the 1122205 produces a Class 3B fit, providing a tighter thread tolerance appropriate for precision fastener applications. Machinists, toolmakers, and maintenance technicians use this tap in both manual and low-speed machine tapping operations.

This tap is suited for use in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel workpieces. The straight flute design is most effective in through-hole threading and in materials that produce short, brittle chips. It is a standard production tap from OSG Series 101, appropriate for job shop, production floor, and MRO applications where a UNF thread form is required at 7/16 inch diameter.

Key Features

• 7/16-20 UNF right-hand thread form with H3 thread limit for Class 3B fit
• Plug chamfer with 3 to 5 lead threads for easy starting in through holes
• 4-flute straight flute geometry suited for short-chipping materials
• High-speed steel (HSS) construction provides toughness across a broad material range
• TiN coating increases surface hardness and reduces friction for extended tool life
• No coolant-through design — standard external coolant or cutting fluid application

Compatibility

Designed for threading 7/16-20 UNF holes in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. Compatible with standard tap handles and tapping heads sized for a 0.323-inch shank diameter.

Installation Notes

This tap should be used by a machinist or toolroom technician familiar with tap drill sizing for UNF threads. Ensure the workpiece is securely fixtured and the tap is properly aligned before starting — misalignment is the leading cause of tap breakage. Apply an appropriate cutting fluid for the workpiece material before and during tapping. When using in a tapping machine or drill press, set spindle speed appropriate for the tap diameter and material to avoid overloading the tap.