Osg 1136202 Straight Flute Tap 1-8 Unc Bottoming Hss

Product Description

The OSG 1136202 is a straight flute bottoming tap designed for cutting internal threads in a wide range of ferrous and non-ferrous materials. Built from high-speed steel, it produces 1-8 UNC right-hand threads with a 3B class of fit and an H4 thread limit. The bottoming chamfer allows threading close to the bottom of blind holes. With 4 flutes and a 2.5-inch thread length, this tap is suited for production and maintenance applications where accurate thread form and consistent fit are required. It is part of OSG Series 101 and carries an overall length of 5.125 inches.

This tap is designed for use in machine-tapping operations across a broad range of materials including aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. The 1-8 UNC thread form is common in structural fastening applications, heavy equipment, and general industrial manufacturing. The bottoming chamfer makes it particularly useful when threads must extend to the full depth of a blind hole with minimal runout space.

Key Features

• Bottoming chamfer for threading to the bottom of blind holes
• 1-8 UNC thread form with 3B class of fit and H4 thread limit
• High-speed steel construction for durability across ferrous and non-ferrous materials
• 4-flute geometry for chip management during machine tapping
• Right-hand thread direction, 2.5-inch thread length, 5.125-inch overall length
• No coolant-through requirement - compatible with standard tapping fluid application

Compatibility

Designed for use in standard machine tapping applications requiring 1-8 UNC internal threads in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel workpieces.

Installation Notes

Installation should be performed by a qualified machinist or tooling technician using a tapping head, CNC machine, or drill press with a tapping attachment. Ensure the workpiece is securely fixtured and the pilot hole diameter is correctly sized for 1-8 UNC threading before starting. Apply appropriate tapping fluid or cutting oil to extend tool life and improve thread quality. Inspect the tap for wear or chipping before each use and replace if thread form is degraded.