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Silver metal tap with four straight flutes and plug chamfer

Helicoil

Helicoil 5CPB Straight Flute Hand Tap 5/16"-18 Plug Uncoated 4 Flutes

SKU CH-Y8YG-4KM9Y

Cuts UNC 5/16"-18 threads for helical coil inserts using a four-flute H3 plug tap

  • Product typeHole, Drill, Bore & Wire Gauges
  • Thread insert tap cuts 5/16"-18 UNC threads
  • Plug chamfer starts threads in through-holes easily
  • Four-flute design clears chips for smooth cutting
  • High-speed steel body resists wear during use
  • Bright uncoated finish suits general-purpose tapping

Thread repair tap for UNC 5/16"-18 holes

The Helicoil 5CPB is a straight-flute STI hand tap designed to cut threads for 5/16"-18 UNC screw-thread inserts. It suits mechanics and technicians who repair stripped or damaged threads in softer metals. The H3 thread limit and plug chamfer make it a standard choice for through-hole and blind-hole work in general maintenance.

High-speed steel construction cuts cleanly

Bright uncoated high-speed steel resists wear during manual tapping operations. Four flutes provide balanced chip evacuation so the tap runs true without excessive torque. The 2 15/16 in overall length and 1 1/4 in thread length give enough reach for typical repair depths while keeping the tool manageable in tight spaces.

Requires matching drill size

This tap prepares the hole only; a correctly sized STI drill bit and Helicoil insert set are needed to finish the job. It does not replace a standard 5/16"-18 tap for cutting bolt threads directly. Buyers who need to cut standard fastener threads or work with metric inserts should select a different tool.

How it compares

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

Price $16.99
Cheaper than about 64% of the 2,474 comparable items (median $23.99).

Specifications

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

Questions about this item

How do I install the 5/16"-18 plug tap and what step causes broken threads?

Use a matching drill size, apply cutting oil, and start the tap square to the hole; the step most often missed is keeping the tap perfectly perpendicular during the first few turns.

What maintenance or replacement will the H3 limit uncoated tap need?

The high-speed steel flutes dull with use; resharpen or replace the tap when thread quality drops or cutting torque rises noticeably.

What limit appears first during sustained tapping of 5/16"-18 UNC holes?

Chip packing in the four straight flutes becomes the bottleneck, especially in deeper holes, and forces frequent back-out to clear swarf.

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