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Straight flute hand tap #4-40 UNC taper finish 3 flutes

Greenfield Threading

Greenfield Threading Straight Flute Hand Tap #4-40 UNC Taper 3 Flutes 300815

SKU CH-6QHC-Y3QPY

A #4-40 UNC taper hand tap with three straight flutes cuts internal threads in a single pass

  • Straight-flute design starts threads easily in through-holes
  • Taper chamfer guides the tap squarely for accurate alignment
  • High-speed steel with TiN coating resists wear for longer life
  • #4-40 UNC thread fits standard fine-pitch fasteners
  • 3-flute geometry clears chips efficiently in hand-tapping operations

Thread size and pitch

This Greenfield Threading straight flute hand tap cuts a #4-40 UNC thread. It is made from high speed steel with a TiN coating and has three flutes in a taper design. The right-hand thread suits standard fastening applications.

Thread limit and class of fit

The tap is manufactured to a H2 thread limit and produces a 2B class of fit. A 75 percent thread drill size of 2.20 mm is specified for the pilot hole. These tolerances determine whether the tap matches the required internal thread specification.

Material and cutting geometry

High speed steel construction with TiN coating provides wear resistance during hand tapping. The straight flute geometry with three flutes manages chip evacuation in through holes. Taper lead eases thread starting and reduces cutting force in normal use.

How it compares

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

Price $6.99
Cheaper than about 92% of the 5,493 comparable items (median $27.99).

Specifications

Product
Brand nameCHICAGO-LATROBE

Questions about this item

How does the #4-40 UNC size work in a real machine?

The #4-40 UNC tap cuts 40 threads per inch into a 2.20 mm drilled hole, producing a class 2B fit with H2 limits for standard fastening.

What does the taper chamfer mean for starting the thread?

The taper chamfer provides a gradual lead of several threads, making it easier to start the cut straight in a through-hole or blind hole.

What does the straight-flute, 3-flute design need to fit and cut?

The 1 7/8 in overall length and 9/16 in thread length require a standard tap wrench or holder, with the three flutes clearing chips in a right-hand rotation.

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