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Silver metal straight-flute tap with four cutting grooves and square shank

Helicoil

Helicoil 8187-10 Straight Flute Hand Tap 5/8"-11 Plug Uncoated 4 Flutes

SKU CH-2HTB-NFGM0

Cuts 5/8"-11 UNC threads in through-holes using four-flute high-speed steel

  • Product typeHole, Drill, Bore & Wire Gauges
  • Thread repair ready with 5/8"-11 UNC sizing
  • Clean starts from plug chamfer design
  • Durable high-speed steel construction
  • Four flutes clear chips efficiently
  • Uncoated finish suits general-purpose tapping

Purpose and User

The Helicoil 8187-10 is a straight flute hand tap designed to cut internal threads for screw thread inserts in a 5/8"-11 UNC size. It suits maintenance technicians and machinists who repair or create threaded holes in metal components using hand tools.

Thread Standard Limits

The tap follows a 5/8"-11 UNC thread form with an H3 thread limit and a plug chamfer. Its four-flute high-speed steel construction cuts right-hand threads to a depth of 2 inches, but the uncoated surface offers no wear resistance for abrasive or high-volume production work.

Setup Verification

Confirm the workpiece material suits uncoated high-speed steel and that the drilled hole matches the required minor diameter for a 5/8"-11 STI tap. Ensure you have a tap wrench for the 4 1/4 inch overall length and that the application tolerates a plug chamfer rather than a bottoming or taper lead.

How it compares

Measured against everything we stock in Utility & Specialty Hand Tools, at today’s prices. Recalculated every night.

Price $51.99
Pricier than about 73% of the 2,474 comparable items (median $23.99).

Specifications

Product
Brand nameHelicoil
Product typeHole, Drill, Bore & Wire Gauges

Questions about this item

Should I choose the H3 thread limit or a different limit for my 5/8"-11 UNC application?

The H3 limit is the standard class of fit for general-purpose 5/8"-11 UNC threading and matches the specification of this tap.

What does the 4-flute design mean for chip evacuation in a through-hole?

Four straight flutes provide adequate chip clearance for through-holes but can pack chips in blind holes where a spiral-flute tap would perform better.

How does the plug chamfer affect thread engagement on a 5/8"-11 UNC hole?

The plug chamfer offers a moderate lead of 3-5 threads, making it easier to start the tap straight than a bottoming chamfer while cutting full threads deeper than a taper chamfer.

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