Milwaukee Tool 49-57-5138 Straight Flute Plug Tap 1/4-28 Unf

Product Description

The MILWAUKEE TOOL 49-57-5138 is a straight flute plug tap designed for cutting right-hand internal threads in through-holes and blind-hole applications. Built from high-carbon steel with a black oxide finish, this tap produces 1/4-28 UNF threads and carries a Class 2B fit tolerance, making it suitable for standard fastener applications across a range of materials. It features 3 flutes and a plug chamfer, which provides a balance between ease of starting and thread-cutting depth. Machinists, maintenance technicians, and trade professionals use this tap for repair threading, new thread creation, and production work in metal fabrication and field service environments.

This tap is suited for use in light-to-medium duty threading operations on steel, cast iron, aluminum, and similar machinable materials. The 1/4-28 UNF thread size is common in precision assemblies, hydraulic fittings, and instrument enclosures where a fine thread pitch improves holding strength. The black oxide coating reduces friction during cutting and provides mild corrosion resistance during storage and use. It is appropriate for hand tapping and compatible with standard tap handles and low-speed machine tapping setups where coolant-through is not required.

Key Features

• 1/4-28 UNF right-hand thread form with Class 2B fit tolerance
• Plug chamfer for balanced starting and cutting performance in through-hole and shallow blind-hole work
• 3-flute straight flute geometry suitable for shorter chips in less ductile materials
• High-carbon steel construction provides hardness for threading common metals
• Black oxide finish reduces friction and provides mild corrosion resistance
• No coolant-through required - compatible with standard hand and machine tapping setups

Compatibility

Designed as a standard 1/4-28 UNF straight flute plug tap compatible with conventional tap handles, T-handle wrenches, and low-speed tapping heads sized for the corresponding shank diameter.

Installation Notes

This tap is installed by machinists and maintenance technicians using a tap handle or low-speed tapping machine. Always drill the correct tap drill size for 1/4-28 UNF threads before tapping and ensure the workpiece is securely clamped. Apply cutting oil to reduce heat and tool wear, and back off the tap periodically to break chips when working in deeper holes. Never force a tap - if resistance increases unexpectedly, back out and clear chips before continuing.