Osg 1120202 Straight Flute Tap 1/4-20 Unc Bottoming Hss

Product Description

The OSG 1120202 is a straight flute tap designed for cutting internal threads in a range of ferrous and non-ferrous metals. Built from high-speed steel, this bottoming-style tap features a 1/4-20 UNC thread form with a 3B class of fit and H3 thread limit, making it suitable for close-tolerance threading work. It has 4 flutes and a 1-inch thread length, with an overall length of 2.5 inches. Right-hand thread direction and straight flute geometry make it a reliable choice for through-hole and blind-hole applications where chip control is manageable and full thread depth near the bottom of the hole is required. Machinists and maintenance trades install this tap in manual tap handles, tapping fixtures, or CNC machines.

This tap is suited for production and maintenance threading in aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel. The bottoming chamfer - typically 1 to 2 thread leads - allows the tap to cut threads close to the bottom of a blind hole, making it the final step in a two- or three-tap sequence following a taper or plug tap. It fits standard 1/4-20 tooling setups and is appropriate for both job shop and production floor environments.

Key Features

• Bottoming chamfer for threading close to the bottom of blind holes
• High-speed steel construction for durability across steel, cast iron, and aluminum workpieces
• 3B class of fit with H3 thread limit for consistent, close-tolerance thread production
• 4-flute straight flute design for use in short-chipping materials
• Right-hand thread direction, 1/4-20 UNC form
• Compact 2.5-inch overall length fits standard tap holders and manual wrenches

Compatibility

Designed for use in materials including aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel. Compatible with standard 1/4-20 UNC tooling and tap holders sized for this shank profile.

Installation Notes

This tap is installed by machinists and maintenance technicians using a manual tap wrench, tap handle, or appropriate machine tapping attachment. Ensure the pilot hole is drilled to the correct tap drill size for 1/4-20 UNC threads before tapping. Apply a suitable cutting fluid for the workpiece material to extend tap life and improve thread quality. When used in a blind hole, use a taper or plug tap first and follow with this bottoming tap to achieve full thread depth.