Osg 1100200 Straight Flute Tap 1/4-20 Unc Bottoming Hss

Product Description

The OSG 1100200 is a straight flute bottoming tap designed to cut internal threads in blind and through holes where full thread engagement close to the bottom of the hole is required. Manufactured from high-speed steel with a bright, uncoated finish, this tap produces right-hand 1/4-20 UNC threads and features four flutes for efficient chip evacuation in shorter-chipping materials. The bottoming chamfer allows threading to within a few pitches of the hole bottom, making it the final step in a three-tap sequence or the go-to choice when depth is critical. It carries an H1 thread limit for close-tolerance work and is built to the OSG Series 101 specification.

This tap is suited for production and maintenance tapping operations in machine shops, manufacturing facilities, and field service environments. It performs in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. The 2.5-inch overall length accommodates standard tap handles, tapping heads, and CNC spindle tap holders. It is a practical choice for HVAC equipment fabrication, electrical panel and enclosure work, plumbing fixture assembly, and general trade applications where 1/4-20 UNC fasteners are common.

Key Features

• Bottoming chamfer threads to within 1-2 pitches of blind hole bottom
• Four-flute design provides stable cutting and chip clearance in short-chipping materials
• High-speed steel construction handles a broad range of ferrous and non-ferrous workpieces
• H1 thread limit delivers close-tolerance threads suitable for standard 1/4-20 UNC fasteners
• Bright uncoated finish - no coating buildup risk; easy to inspect for wear
• No coolant-through requirement; compatible with flood coolant or cutting fluid applied externally

Compatibility

Designed for use in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel workpieces. Cuts standard 1/4-20 UNC right-hand internal threads and fits tap handles and machine holders accepting a 0.255-inch shank diameter.

Installation Notes

Tapping should be performed by a machinist or qualified tradesperson familiar with thread-cutting procedures. Ensure the workpiece is securely clamped and the tap is started square to the drilled hole before applying cutting pressure. Apply an appropriate cutting fluid or tapping compound for the workpiece material to extend tool life and improve thread finish. When used in a tapping sequence, the bottoming tap should follow a taper tap and a plug tap to minimize stress on the tool.