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4-40 Tap, UNC STI thread, H2/H3, 3 flutes, HSS-E, TiN Coated, 40° Spiral Flute

  • Item Code: 3988-2.845
  • Brand: Guhring
  • Unit Size: 1

Description

An STI tap thread tap is designed to create an oversized thread to accommodate the required Heli-Coil insert. Screw Thread Inserts (STI) are helically formed diamond shaped stainless steel or phosphorous bronze wire that screw into a threaded hole to form a mating internal thread. Screw thread inserts are a convenient way of repairing stripped out threads and are also used to provide stronger threads in softer materials than can be obtained by directly tapping the base metal.

Tech Specs

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Brand Guhring
Diameter 4-40
Diameter (mm) 2.8448
Overall Length (decimal) 2.0000
threadtype UNC STI
H Limit H2/H3
Square Size (decimal) 0.1098
Reach (decimal) 0.7480
Coating TiN
Helix Angle 40°
Material HSS-E
Coolant without
Series 3988
Shank Diameter (mm) 3.5814
Number of flutes 3
Overall Length (mm) 50.8