Cleveland
Cleveland C57153 Spiral Point Tap 5/16-18 UNC 3 Flutes
A spiral-point tap cuts 5/16-18 UNC threads in through-holes using three flutes and high-speed steel
- Spiral-point design drives chips ahead for cleaner through-holes
- High-speed steel construction resists wear during repeated threading operations
- Bright uncoated finish suits general-purpose cutting in steel and iron
- Three-flute geometry balances chip clearance with thread strength
- 5/16-18 UNC size matches standard coarse-thread fastener requirements
Cleveland 5/16-18 UNC Spiral Point Tap
This Cleveland C57153 spiral point tap cuts 5/16-18 UNC threads in through-holes using three flutes. It is made from high-speed steel with a bright uncoated finish for general-purpose threading in steel and non-ferrous metals. The H3 thread limit produces a class 2B fit. Machinists and maintenance technicians use it for production tapping where chip evacuation ahead of the tool is preferred.
Practical limits of UNC thread cutting
The tap has an overall length of 2 23/32 inches and a thread length of 1 1/8 inches, so the workpiece must accommodate that reach. A 75 percent thread depth requires a drill size F hole before tapping. The UNC coarse pitch suits standard fastening but is not intended for fine-pitch or high-vibration applications where a UNF thread would be specified. Right-hand cutting direction only.
Installation notes and common issues
Secure the tap in a properly aligned holder and apply cutting fluid to reduce torque and improve thread finish. The spiral point pushes chips forward, so ensure the through-hole allows chips to exit cleanly. Misalignment or a dull drill often causes oversize threads or tap breakage. Reverse the tap frequently to break chips in deeper holes.
Highlights
- Spiral-point design drives chips ahead for cleaner through-holes
- High-speed steel construction resists wear during repeated threading operations
- Bright uncoated finish suits general-purpose cutting in steel and iron
- Three-flute geometry balances chip clearance with thread strength
- 5/16-18 UNC size matches standard coarse-thread fastener requirements
Specifications
| Brand | CLEVELAND |
|---|
Questions about this item
Which thread size should I select for a 5/16-18 UNC hole?
The tap is made for a 5/16 in. -18 UNC thread, so choose this exact size to match the hole.
What does the 75 percent thread drill size F mean when I use the tap?
It tells you to drill the hole with an F-size drill bit so the tap cuts about 75 percent of the full thread depth.
How does the H3 thread limit affect the fit of the finished thread?
H3 sets the pitch-diameter tolerance for a class 2B fit, giving a standard medium allowance for nuts or tapped holes.
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