Osg 1009102 Straight Flute Tap 1/4-20 Unc Bottoming Hss

Product Description

The OSG 1009102 is a straight flute bottoming tap designed for cutting right-hand internal threads in a wide range of ferrous and non-ferrous materials. Ground from high-speed steel (HSS), it cuts a 1/4-20 UNC thread with a 1-inch thread length and a 2.5-inch overall length. The bottoming chamfer allows threading to within one or two threads of a blind hole bottom, making this tap the go-to choice when full thread depth is required close to the base of a drilled hole. With four flutes and an H11 thread limit, it holds tight tolerances and suits production and maintenance applications alike.

This tap is suited for threading operations in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. It is commonly used in machine shops, maintenance and repair operations, and fabrication environments where consistent thread quality in blind holes is required. The 1/4-20 UNC size is one of the most common fastener thread profiles in North American manufacturing, making this tap a practical addition to any thread tooling set.

Key Features

• Bottoming chamfer allows threading to the bottom of blind holes
• High-speed steel construction for durability across ferrous and non-ferrous materials
• H11 thread limit provides controlled oversize tolerance for accurate thread fitment
• Four-flute design supports chip control and stable cutting action
• Right-hand thread direction, 1/4-20 UNC standard
• No coolant-through requirement — compatible with standard hand or machine tapping

Compatibility

Designed for use on aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel workpieces. Part of OSG Series 101H straight flute tap line.

Installation Notes

Tapping operations should be performed by a machinist or qualified tradesperson using a properly aligned tap wrench, tapping head, or CNC spindle. Always drill to the correct tap drill diameter for 1/4-20 UNC threads before tapping, and ensure the workpiece is securely fixtured. Apply an appropriate cutting fluid for the material being tapped to reduce friction and extend tap life. For blind holes, use a plug tap first if thread depth allows, then follow with this bottoming tap to achieve full thread depth.