Osg 1136200 Straight Flute Tap 1-8 Unc Bottoming Hss

Product Description

The OSG 1136200 is a straight flute bottoming tap designed to cut 1-8 UNC internal threads in through-holes and blind holes where full thread depth is required close to the bottom. Built from high-speed steel with a bright uncoated finish, it carries a 3B class of fit and an H4 thread limit for consistent tolerance control. The 4-flute straight flute geometry provides chip support and stability during the tapping operation. Overall length is 5-1/8 inches, thread length is 2-1/2 inches, and the tool weighs 0.631 pounds. This tap is part of the OSG Series 101 product line and is intended for use by machinists and toolroom professionals.

This tap is suited for production and maintenance machining applications where 1-8 UNC bottoming threads are required. It performs in a range of ferrous and non-ferrous workpiece materials including aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. The bottoming chamfer makes it the correct choice when threading to the bottom of a blind hole after a taper or plug tap has started the thread. Right-hand thread direction matches standard UNC fastener convention.

Key Features

• Bottoming chamfer for threading close to the bottom of blind holes
• 4 straight flutes for chip support and rigidity in short-chipping materials
• H4 thread limit for consistent 3B class of fit tolerance
• High-speed steel construction handles a broad range of workpiece materials
• Bright uncoated finish suitable for use with cutting oil or tapping fluid
• Right-hand thread direction, no coolant-through requirement

Compatibility

Designed for use in standard CNC machining centers, drill presses, and tapping machines configured for 1-8 UNC right-hand thread cutting in aluminum, cast iron, and carbon steel workpieces.

Installation Notes

This tool is installed by machinists and toolroom technicians in compatible tap holders or tapping heads. Ensure the spindle is stopped and the machine is in a safe state before changing tooling. Use appropriate cutting fluid or tapping compound for the workpiece material to extend tool life and improve thread quality. Verify correct drill hole diameter for 1-8 UNC before tapping to maintain the specified class of fit.