Osg 3147803 Straight Flute Tap 1/4-20 Unc Cobalt Nitride

Product Description

The OSG 3147803 is a straight flute tap designed for cutting internal 1/4-20 UNC threads in plastic and similarly machinable materials. Built from cobalt high-speed steel and finished with a nitride coating, it delivers solid wear resistance and heat tolerance across production and maintenance threading applications. The plug chamfer style provides a gradual thread lead-in, making it well suited for through-hole tapping. With 4 flutes and a 2B class of fit, this tap produces threads that meet standard fastener engagement requirements. Overall length is 2.5 inches, and the shank diameter measures 0.255 inches. Installation is performed by machinists and maintenance technicians using standard tapping equipment.

The OSG 3147803 is intended for through-hole threading operations in plastic workpieces, though the cobalt construction and nitride coating extend its service life in moderately abrasive materials as well. The plug chamfer entry distributes cutting load across several lead threads, reducing tap breakage risk in hand-tapping and machine-tapping setups alike. It belongs to OSG Series 114 and carries a right-hand thread direction. This tap is a practical stock item for shops that regularly thread 1/4-20 UNC holes in light-duty assemblies, fixtures, and enclosures.

Key Features

• Cobalt high-speed steel construction for improved heat and wear resistance over standard HSS
• Nitride coating reduces friction and extends cutting tool life
• Plug chamfer distributes cutting forces across multiple lead threads for smoother entry
• 4-flute design provides good chip clearance and thread form stability
• 2B class of fit meets standard tolerance requirements for general-purpose 1/4-20 UNC threaded assemblies
• Right-hand thread direction for conventional tapping setups

Compatibility

Designed for cutting 1/4-20 UNC internal threads in plastic; cobalt construction and nitride coating also support use in other machinable materials where heat generation is a factor. Straight flute geometry is best suited to through-hole applications.

Installation Notes

This tap should be installed and operated by machinists or maintenance technicians familiar with threading tool setup. Ensure the workpiece is securely fixtured and the tap is properly aligned to the hole axis before beginning the threading operation. Use an appropriate tapping fluid or cutting compound recommended for the workpiece material to reduce heat and improve thread finish. Always back the tap out periodically to clear chips and prevent tap breakage.