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Cleveland C86218 spiral point tap plug 3/8-16 UNC cobalt 3 flutes black oxide finish

Cleveland

Cleveland C86218 Spiral Point Tap Plug 3/8-16 UNC Cobalt 3 Flutes

SKU CH-3HTH-YPKMJ

Cuts 3/8-16 UNC threads in through-holes using a cobalt spiral-point plug tap with three flutes

  • Spiral-point design pushes chips forward for smoother tapping in through-holes
  • Cobalt construction with black-oxide finish resists wear and extends tool life
  • Three flutes provide balanced cutting action and efficient chip evacuation
  • 3/8-16 UNC thread size with 2B class of fit ensures accurate internal threads
  • 75 % thread drill size .3125 in simplifies hole preparation for consistent results

Cleveland C86218 Spiral Point Tap

The Cleveland C86218 is a spiral point tap designed for creating 3/8 inch UNC threads in through-hole applications. Its cobalt construction and black oxide finish provide durability for general-purpose threading tasks. This plug-style tap suits machinists and maintenance technicians who need reliable thread cutting in ferrous materials.

UNC thread standard limits

The tap produces a unified coarse thread with a 2B class of fit, which defines the allowable tolerance for assembly with mating parts. A 75 percent thread drill size of 0.3125 inch is required to prepare the hole before tapping. These parameters determine the functional limits of the finished thread and the preparation needed.

Cobalt material for ferrous metals

Cobalt high-speed steel offers higher heat resistance than standard high-speed steel, extending tool life when cutting steel and other ferrous alloys. The spiral point design pushes chips ahead of the tap, making it unsuitable for blind holes where chips cannot escape. Buyers needing to thread blind holes should select a spiral flute or bottoming tap instead.

How it compares

Measured against everything we stock in Bits, Hole Saws & Accessory Kits, at today’s prices. Recalculated every night.

Price $17.99
Cheaper than about 68% of the 5,493 comparable items (median $27.99).

Specifications

Product
Brand nameCLEVELAND

Questions about this item

Should I pick the 3/8-16 UNC tap or a different thread size for my job?

Choose the 3/8-16 UNC tap when you need to cut 3/8 inch coarse threads with a 16 threads-per-inch pitch; other sizes cut different diameters or pitches.

What does the 75 percent thread drill size of 0.3125 in mean when I am tapping?

Drill the hole to 0.3125 inch diameter before tapping; this produces roughly 75 percent thread engagement for the 3/8-16 UNC thread.

How does the cobalt material and black oxide finish affect tap life in steel?

Cobalt resists heat better than high-speed steel, and the black oxide finish helps retain cutting fluid, so the tap lasts longer in tough materials.

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