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Cleveland straight flute hand tap 9/16-18 plug HSS TiN coated

Cleveland

Cleveland C55138 Straight Flute Hand Tap 9/16"-18 Plug

SKU CH-6QN8-0N4PE

Cuts UNF 9/16"-18 threads in through-holes with a 1.66 in thread length and 3.59 in overall length

  • Product typeTaps
  • Straight flute design clears chips in through-holes
  • 9/16"-18 UNF thread cuts fine-pitch fasteners
  • Plug chamfer starts threads easily in existing holes
  • High-speed steel with TiN coating resists wear
  • 59 in overall length reaches deep workpieces

Cleveland C55138 Straight Flute Tap

This Cleveland C55138 is a straight flute hand tap designed for creating internal UNF threads. It suits machinists and maintenance technicians who need to cut 9/16"-18 threads in through-holes or blind holes with adequate clearance.

High-speed steel with TiN coating

The tap is made from high-speed steel with a titanium nitride coating to resist wear during threading operations. A 12.90 mm drill size prepares the hole for 75 percent thread engagement, while the H3 thread limit and 2B class of fit ensure standard tolerance. The plug chamfer starts threads easily in a range of ferrous and non-ferrous materials.

Sustained threading performance

Under continuous hand or machine tapping, the TiN surface reduces friction and heat buildup compared with uncoated tools. The 1.66 inch thread length and 3.59 inch overall length provide reach for deeper holes without excessive deflection. Right-hand cutting geometry matches standard thread direction for consistent chip formation.

How it compares

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

Price $33.99
Pricier than about 56% of the 5,493 comparable items (median $27.99).

Specifications

Product
Brand nameCLEVELAND
Product typeTaps

Questions about this item

Will the H3 thread limit still produce a 2B class of fit after the tap wears?

The H3 limit is manufactured to a 2B class of fit; normal wear will gradually reduce thread height but the starting tolerance meets the 2B specification.

Does the TiN coating reduce cutting heat during extended hand tapping?

TiN coating lowers friction and heat buildup, helping the high-speed steel stay sharper during repetitive 1.66 in thread cuts.

What size drill bit do I need before using this 9/16"-18 tap?

A 12.90 mm drill provides the 75 percent thread engagement recommended for this tap.

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