Osg 1130502 Straight Flute Tap 1/4-28 Unf Bottoming Hss

Product Description

The OSG 1130502 is a straight flute bottoming tap designed for cutting 1/4-28 UNF internal threads in a wide range of ferrous and non-ferrous materials. Built from high-speed steel, it delivers consistent thread quality in production and maintenance applications. With 4 flutes, a 2B class of fit, and an H4 thread limit, this tap produces threads that meet standard tolerance requirements for general mechanical assemblies. The 1-inch thread length and 2.5-inch overall length make it well-suited for threading shallow or blind holes where a bottoming chamfer is required to thread as close to the bottom of the hole as possible.

This tap is appropriate for use in machine shops, maintenance facilities, and light manufacturing environments. It is rated for use in aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel. The right-hand thread direction and straight flute design make it compatible with standard tapping machines, drill presses, and tapping attachments. It is best applied in through-hole and blind-hole applications where chips can be managed manually or with coolant flushing.

Key Features

• Bottoming chamfer for threading to the bottom of blind holes
• 4 straight flutes for chip clearance in short-chipping materials
• High-speed steel construction for durability across ferrous and non-ferrous workpieces
• 2B class of fit and H4 thread limit for standard tolerance internal threads
• 1/4-28 UNF thread form for fine-pitch fastener applications
• Right-hand thread direction compatible with standard tapping equipment

Compatibility

Designed for tapping 1/4-28 UNF right-hand threads in aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel. Part of OSG Series 101.

Installation Notes

This tap is installed by machinists and toolroom technicians using tapping machines, drill presses, or hand tap wrenches. Ensure the workpiece is securely fixtured and the pilot hole is drilled to the correct tap drill diameter for a 1/4-28 UNF thread before tapping. Apply appropriate cutting fluid for the workpiece material to extend tool life and improve thread finish. Do not force the tap if resistance increases - back off to clear chips and prevent tap breakage.