Taps and gauges

for HELICOIL® threaded inserts

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Hole preparation

A range of taps are available to suit the precise tolerance and dimensions required by the HELICOIL® insert to ensure the correct interferance fit. To ensure holes have been correctly drilled and tapped we recommend the use of a hole gauge.

  • Roughing tap for HELICOIL® wire thread inserts

    Roughing tap

    Straight fluted taps made undersize to reduce the load on the finishing tap and particularly for difficult tapping operations.
    Recommended for use when tapping steels o close tolerance fits as required, reducing wear on the finishing tap.

  • Finishing tap for HELICOIL® wire thread inserts

    Finishing tap

    Hand or machine tapping for through holes and blind holes where ample chip clearance is available.
    The lead chamfer permits easier starting and requires less tapping torque than bottoming taps.

  • Bottoming tap for HELICOIL® wire thread inserts

    Bottoming tap

    Used for tapping blind holes when maximum full form threads are required in minimum depth holes.

  • Spiral flute tap for HELICOIL® wire thread inserts

    Spiral flute tap

    Tap designed with spiral flutes in the same “hand” as the thread. This directs the swarf backwards out of the hole. Recommended for blind or deep hole applications in soft (eg. Aluminium) materials.
    Due to the suitability blind hole tapping the lead chamfer is normally that of a bottoming tap.

  • Spiral point tap for HELICOIL® wire thread inserts

    Spiral point tap

    Designed primarily as a machine tap for tapping through holes.
    The Spiral Point is formed in the lead teeth at an angle to the tap axis. The swarf, due to the cutting action, is pushed forwards ahead of the tap.
    The flutes of the spiral point tap serve only to deliver coolant to the cutting edges, therefore much shallower flutes are used. Subsequently the tap has greater strength and makes precise tapping possible.
    Not recommended on abrasive materials.

  • Gauges for HELICOIL® wire thread inserts


    Gauges are available in both 5H or 6H class of fits for Metric Threads, 2B or 3B for Unified Threads and close medium for Whitworth Threads.
    Class of Fit of the finished assembly is dependant on the accuracy of the tapped hole. If the tapped hole gauges correctly it is not necessary to gauge the installed inserts.
    After the HELICOIL® is installed, the Go Gauge occasionally does not enter freely. However the insert will always seat itself when the bolt or screw is installed and tightened.

HELICOIL® repair step 1: Drilling open a defective thread

HELICOIL® repair step 2: Cutting the new HELICOIL® thread


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