Processes for Fitting Helicoils

Updated February 21, 2017

A helicoil refers to a thread insert or coiled wire fastener that inserts into an object in order to add a new hole or repair a stripped threaded hole. Helicoil fitting entails careful procedures that ensure a proper insert.

Bolt Removal

Fitting helicoils often entails removing the broken stud or bolt. The drill should be centred as precisely as possible to the hole before drilling out the bolt. Grinding the end of the broken bolt square facilitates the most precise centring. The bolt can then be drilled out until only the thread remains.

Drilling the Hole

In order to insert a helicoil, the operator should select a drill sized appropriately to the outer thread area of the helicoil. A parallel drilling jig, or tool used to control the motion of a drill, may be used to guide the drilling through the hole. If the component permits the drill to travel completely through, the hole should penetrate the outer side.


Once the hole attains the necessary size and depth, the operator uses a handheld tool called a screw thread insert tap to tap the hole, or cut threads inside the hole to form a surface that functions as a nut. Using a lubricant facilitates helicoil insertion after the hole is tapped.

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