Cleveland
Cleveland C55031 Straight Flute Hand Tap 1-3/8"-12 UNF Plug 6 Flutes
Straight flute hand tap cuts 1-3/8"-12 UNF threads in through-holes with six flutes for chip clearance
- TypeTaps
- Straight flute design clears chips efficiently in through holes
- 1-3/8"-12 UNF thread size matches precise fastening requirements
- Plug chamfer starts threads smoothly for accurate alignment
- Six flutes distribute cutting load for longer tool life
- High-speed steel construction resists wear during repeated threading operations
Cleveland C55031 Straight Flute Tap
The Cleveland C55031 is a straight flute hand tap designed for cutting 1-3/8"-12 UNF threads in a variety of materials. It suits machinists and maintenance technicians who need to create internal threads for fine-pitch fasteners. The H4 thread limit targets a Class 2B fit for standard assemblies. This tool is not for automated high-volume tapping operations or for users requiring coated cutting geometry.
High-Speed Steel Construction and Plug Chamfer
The tap is manufactured from high-speed steel with a bright, uncoated finish for general-purpose cutting performance. Its straight flute design with six flutes provides chip clearance in through-hole and blind-hole applications. The plug chamfer offers a moderate lead-in for easier starting alignment by hand. The 3-inch thread length and 6 1/16-inch overall length give adequate reach for common workpieces. The right-hand cut orientation matches standard fastener threads.
UNF Thread Standard and Drill Size Requirement
This tap produces Unified National Fine threads with a 12 threads-per-inch pitch diameter. The fine pitch limits material removal rate compared to coarse series taps, requiring more torque per revolution. A precise 75 percent thread drill size of 1.2938 inches must be used to achieve the correct Class 2B fit. The fixed H4 limit means the tap cannot compensate for hole size variation or provide oversize threads for plating allowances.
Highlights
- Straight flute design clears chips efficiently in through holes
- 1-3/8"-12 UNF thread size matches precise fastening requirements
- Plug chamfer starts threads smoothly for accurate alignment
- Six flutes distribute cutting load for longer tool life
- High-speed steel construction resists wear during repeated threading operations
Specifications
| Brand | CLEVELAND |
|---|---|
| Type | Taps |
Questions about this item
What thread standard does the 1-3/8"-12 UNF tap follow, and what class of fit does it produce?
It follows the UNF standard and cuts a 2B class of fit with an H4 thread limit.
What drill size is required for the 75 percent thread engagement this tap is designed for?
Use a 1.2938 in drill to achieve the recommended 75 percent thread depth.
How do you start the plug tap correctly in a through hole, and what common error should be avoided?
Apply cutting fluid, keep the tap perpendicular, and turn the wrench steadily; do not force it or skip the starter hole.
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