Osg 1121001 Straight Flute Tap 5/16-24 Unf Plug Hss

Product Description

The OSG 1121001 is a straight flute hand tap designed to cut internal 5/16-24 UNF right-hand threads in a range of ferrous and non-ferrous workpiece materials. Built from high-speed steel with an oxide coating, this plug-chamfer tap is suited for general-purpose threading operations in machine shops and maintenance environments. It carries a 3B class of fit and an H3 thread limit, delivering threads within the tolerance band required for standard fastener assembly. The 4-flute straight flute geometry channels chips back through the flute rather than forward, making it best suited for through-hole applications or short blind holes where chip clearance is manageable.

This tap is used in production and maintenance machining where 5/16-24 UNF threads are required. Compatible material applications include aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel. The plug chamfer, with its moderate lead-in, is the standard choice for starting threads in pre-drilled through holes and is the most commonly stocked chamfer style for general shop use. It is appropriate for both hand tapping and low-speed machine tapping setups.

Key Features

• 5/16-24 UNF thread form with right-hand direction for standard fastener compatibility
• Plug chamfer provides a balanced lead-in suitable for through-hole threading
• High-speed steel construction handles a broad range of ferrous and non-ferrous materials
• Oxide coating provides mild lubricity and corrosion resistance during storage and use
• H3 thread limit and 3B class of fit meet standard tolerance requirements for fastener assembly
• 4 straight flutes allow effective chip evacuation in through-hole applications

Compatibility

Designed for threading aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel workpieces requiring 5/16-24 UNF internal threads to a 3B class of fit.

Installation Notes

Always use the correct tap drill size for a 5/16-24 UNF thread before tapping to ensure proper thread engagement and avoid tap breakage. Secure the workpiece firmly and use a tapping fluid or cutting oil appropriate for the workpiece material to extend tap life and improve thread quality. For machine tapping, set spindle speed conservatively and ensure the tap is properly aligned with the drilled hole to prevent cross-threading or breakage. When hand tapping, use a quality tap wrench and back off periodically to break chips.