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5/16-18 Tap, Spiral Point Plug, UNC STI thread, H4/H5, 3 flutes, HSS-E, TiN Coated

  • Item Code: 3990-7.938
  • 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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Series 3990
chamfer (decimal) Spiral Point Plug
H Limit H4/H5
Shank Diameter (mm) 9.6774
Coating TiN
Diameter (mm) 7.938
Material HSS-E
Overall Length (decimal) 2.9370
Square Size (decimal) 0.2382
threadtype UNC STI
Number of flutes 3
Brand Guhring
Diameter 5/16-18
Reach (decimal) 1.4560
Overall Length (mm) 74.5998