Osg 1007900 Straight Flute Tap 4-40 Unc Bottoming Hss

Product Description

The OSG 1007900 is a straight flute bottoming tap designed for cutting internal threads in a wide range of ferrous and non-ferrous materials. It produces 4-40 UNC right-hand threads and is manufactured from high-speed steel with a bright, uncoated finish. With 2 flutes and an H1 thread limit, this tap delivers close tolerance control in shallow blind-hole applications where a bottoming chamfer is required to thread as close to the bottom of a hole as possible. Overall length is 1.875 inches with a thread length of 0.5625 inches. Licensed machinists, toolroom technicians, and precision fabricators are the primary users of this tap.

This tap is suited for tapping 4-40 UNC threads in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. Its straight flute geometry makes it appropriate for through-hole and short blind-hole applications where chip flow is manageable. The bottoming chamfer allows threading to the full depth of a blind hole after pre-chamfering with a taper or plug tap. It is commonly used in precision machining, light manufacturing, and toolroom work where small-diameter threads are required.

Key Features

• Bottoming chamfer for threading to the base of blind holes
• 2-flute straight design supports chip clearance in short blind and through-hole applications
• H1 thread limit for close tolerance fits in 4-40 UNC threads
• High-speed steel construction provides durability across multiple material types
• Bright, uncoated finish suitable for use with cutting fluids on a broad range of workpiece materials
• Right-hand thread direction, no coolant-through requirement

Compatibility

Compatible with aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel workpieces requiring 4-40 UNC internal threads. Part of OSG Series 104.

Installation Notes

This tap is installed using a standard tap wrench or machine tap holder appropriate for the shank diameter of 0.141 inches. Always secure the workpiece and ensure the tap is properly aligned to avoid thread damage or tap breakage. For blind holes, use a taper or plug tap first before following with this bottoming tap. Apply an appropriate cutting fluid for the workpiece material to extend tool life and improve thread finish.