Cleveland
Cleveland C55148 Straight Flute Hand Tap 7/8"-9 Plug H4
Straight-flute hand tap cuts 7/8"-9 UNC threads with a 4.69 in overall length, 2.22 in thread length, H4 limit and TiN-coated high-speed steel
- TypeTaps
- Cuts UNC threads cleanly with straight-flute design
- Plug chamfer starts threads easily in through-holes
- H4 limit matches Class 2B fit requirements
- TiN-coated high-speed steel resists wear longer
- 22 in thread length handles standard depths
Cleveland C55148 Straight Flute Hand Tap
The Cleveland C55148 is a straight flute hand tap designed for creating internal UNC threads in a variety of materials. It targets machinists and maintenance technicians who need to cut 7/8"-9 threads by hand or with a tapping head. The H4 thread limit produces a class 2B fit for general-purpose fastening applications. High-speed steel construction with a TiN coating offers improved wear resistance during repeated use.
Installation and common issues
Starting the tap square to the workpiece is critical because the straight flute design does not pull itself into the hole like a spiral point. Use the recommended 19.50 mm drill size to achieve approximately 75 percent thread engagement before tapping. Apply steady pressure and reverse frequently to break chips, especially in deeper holes. Misalignment or dull cutting edges quickly produce oversized or bell-mouthed threads that will not gauge correctly.
Practical limits of UNC hand tapping
The 4.69 inch overall length and 2.22 inch thread length restrict reach in deep or blind holes where chip evacuation becomes difficult. Straight flutes are less efficient at clearing chips upward than spiral flute designs, increasing the risk of tap breakage in materials that produce long, stringy swarf. The TiN coating extends tool life but does not eliminate the need for proper lubrication and speed control when cutting tough alloys.
Highlights
- Cuts UNC threads cleanly with straight-flute design
- Plug chamfer starts threads easily in through-holes
- H4 limit matches Class 2B fit requirements
- TiN-coated high-speed steel resists wear longer
- 22 in thread length handles standard depths
Specifications
| Brand | CLEVELAND |
|---|---|
| Type | Taps |
Questions about this item
How can I confirm the tap is cutting a proper 7/8"-9 UNC 2B thread after setup?
Check the thread gauge for a 2B class of fit and verify the thread length reaches 2.22 in; the TiN coating on the high-speed steel should show even wear without chipping.
What comes with the Cleveland C55148 tap and what must I source separately?
The box contains the straight-flute plug tap only; you will need a 19.50 mm drill bit for the 75 percent thread depth and a suitable tap wrench or holder.
When should I choose this H4 plug tap over other thread limits or chamfer styles?
Select the H4 limit when a standard 2B fit is required for 7/8"-9 UNC; the plug chamfer suits through-holes or blind holes with clearance beyond the 2.22 in thread length.
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