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    Indianapolis, IN 46203
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1/2-20 Tap, UNF STI thread, H5/H6, 4 flutes, HSS-E, TiN Coated, 40° Spiral Flute

  • Item Code: 3989-12.70
  • 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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Overall Length (decimal) 3.5945
Overall Length (mm) 91.3003
Series 3989
Material HSS-E
Number of flutes 4
Coating TiN
Coolant without
Diameter (mm) 12.7
Helix Angle 40°
H Limit H5/H6
Shank Diameter (mm) 10.8966
Square Size (decimal) 0.2752
Diameter 1/2-20
threadtype UNF STI
Brand Guhring