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Bright uncoated high speed steel STI tap with four flutes

Helicoil

Helicoil 8187-16 STI Tap 1 in-8 UNC HSS Bright

SKU CH-ZJNY-XV57P

A high-speed steel STI tap for repairing 1 in-8 UNC threads with a plug chamfer and four flutes

  • HSS construction resists wear during thread cutting
  • Plug chamfer starts threads easily in through holes
  • Four flutes clear chips for smoother tapping
  • Bright finish suits general-purpose steel applications
  • Designed for 1 in-8 UNC STI thread repair

Thread Repair Kit for 1 Inch UNC Threads

This Helicoil 8187-16 STI tap is designed to prepare holes for screw thread inserts in 1 in-8 UNC applications. It is suited for mechanics and engineers repairing damaged threads in heavy machinery, structural steel or automotive components where a secure internal thread is required.

High Speed Steel Construction With Bright Finish

The tap is manufactured from high speed steel with an uncoated bright finish, providing hardness and wear resistance during cutting. Its four-flute design and plug chamfer support efficient chip evacuation and a smooth start in through-hole or blind-hole work, delivering consistent thread geometry under normal shop conditions.

Replaces Worn or Damaged Taps for Larger UNC Sizes

This tool upgrades from smaller or worn taps when restoring 1 in-8 UNC threads to accept HELI-COIL inserts. The jump is justified when existing threads are stripped, galled or out of tolerance and a standard tap cannot produce the oversize pitch diameter needed for insert installation.

Highlights

  • HSS construction resists wear during thread cutting
  • Plug chamfer starts threads easily in through holes
  • Four flutes clear chips for smoother tapping
  • Bright finish suits general-purpose steel applications
  • Designed for 1 in-8 UNC STI thread repair

Specifications

BrandHELI-COIL

Questions about this item

How do I install the Helicoil 8187-16 STI tap and what step is commonly missed?

Drill the damaged hole to the correct STI size, then run the H4 limit plug tap straight through with cutting fluid; the step often skipped is verifying the 2 9/16 inch thread depth before inserting the coil.

What maintenance or replacement will the Helicoil 8187-16 tap need over time?

The bright uncoated high-speed steel flutes dull with use; replace the tap when it no longer cuts clean 1 in-8 UNC threads or when the four flutes show visible wear.

What limit appears first when using the Helicoil 8187-16 tap continuously in hard material?

Heat buildup in the uncoated HSS body reduces cutting efficiency after several holes, so pause to cool the tap and replenish lubricant to maintain the H4 thread limit accuracy.

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