Milwaukee Tool 49-57-5151 Straight Flute Tap 3/8-24

Product Description

The MILWAUKEE TOOL 49-57-5151 is a straight flute tap designed to cut 3/8-24 UNF internal threads in through-holes and shallow blind holes. Built from high-carbon steel with a black oxide finish, this 4-flute tap features a plug chamfer that starts the thread gradually and maintains cutting stability. It is sized at 2.75 inches overall length with a thread length of 1.25 inches, making it a practical choice for maintenance, fabrication, and field repair work. Machinists, pipefitters, and mechanical contractors reach for this style of tap when threading ferrous metals and similar materials in right-hand thread applications.

Straight flute taps like the 49-57-5151 are well suited for through-hole threading on the bench, in a drill press, or with a tapping arm. The plug chamfer - typically 3 to 5 threads of lead - makes this tap versatile across production and repair scenarios where a starting taper is not required. It carries a Class of Fit 2B, the standard tolerance class for general-purpose inch-series internal threads found in most mechanical assemblies and structural fastening applications. No coolant-through capability is present, so conventional flood or brush-applied cutting fluid is standard practice.

Key Features

• 3/8-24 UNF thread size for fine-pitch internal threading
• Plug chamfer with gradual lead-in for versatile through-hole and shallow blind-hole use
• 4-flute straight flute geometry for stable cutting in ferrous and similar materials
• High-carbon steel construction for durability in hand and machine tapping
• Black oxide finish provides mild corrosion resistance and reduces galling
• Class of Fit 2B - standard general-purpose tolerance for inch-series internal threads
• Right-hand thread direction, compatible with standard fastener conventions

Compatibility

Designed as a standard-tolerance replacement or addition for 3/8-24 UNF tapping applications in general mechanical assembly, maintenance, and repair work. Fits standard tap handles, T-handle wrenches, and machine tool holders sized for the corresponding shank diameter.

Installation Notes

Tapping operations should be performed by a qualified machinist or tradesperson familiar with proper speeds, feeds, and cutting fluid selection for the workpiece material. Always secure the workpiece before tapping and use a properly sized tap wrench or machine holder to maintain alignment and prevent tap breakage. Apply appropriate cutting fluid continuously during the tapping process to extend tap life and improve thread quality. For machine tapping, follow the tool manufacturer and machine tool guidelines for spindle speed and feed rate.