Osg 1430501 Spiral Flute Tap 5/16-18 Unc Bottoming Hss

Product Description

The OSG 1430501 is a spiral flute bottoming tap designed to cut internal threads in a wide range of ferrous and non-ferrous materials. It produces a 5/16-18 UNC right-hand thread to a 3B class of fit, with an H3 thread limit for consistent dimensional accuracy. The 50-degree helix angle on the three flutes efficiently evacuates chips up and out of the hole, making this tap well suited for blind-hole applications where chip packing is a common concern. Manufactured from high-speed steel and finished with a steam oxide coating, it offers improved lubricity and corrosion resistance during cutting operations. Machinists, tool-and-die tradespeople, and maintenance mechanics rely on this style of tap for production threading and repair work.

The OSG 1430501 is appropriate for threading blind holes in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. The bottoming chamfer allows threads to be cut close to the bottom of a hole, making it the preferred choice when thread engagement depth is limited by workpiece geometry. It is used in both manual tapping operations and CNC tapping with synchronous feed control. The Series 107 designation places this tap within a well-established OSG product family used across general machining, maintenance, and fabrication environments.

Key Features

• 5/16-18 UNC thread form with 3B class of fit and H3 thread limit for controlled tolerance
• Bottoming chamfer allows threading to near the bottom of blind holes
• 50-degree helix angle promotes upward chip evacuation in blind-hole applications
• High-speed steel construction provides toughness across a broad range of workpiece materials
• Steam oxide coating improves lubricity and reduces galling during cutting
• Right-hand flute direction matches right-hand thread for standard tap wrench and machine spindle use

Compatibility

Designed for use in materials including aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. Coolant-through is not supported on this tap.

Installation Notes

This tap is installed and operated by a licensed machinist or qualified maintenance mechanic using a tap wrench, tapping stand, or CNC machine with rigid or synchronous tapping capability. Before tapping, ensure the pilot hole is drilled to the correct tap drill diameter for a 5/16-18 UNC thread and that the workpiece is securely fixtured. Apply cutting fluid appropriate for the workpiece material to extend tool life and improve thread quality. Do not reverse a bottoming tap into a hole that still has uncut material, as this risks tap breakage.