How To Repair A Damaged Thread

If you come across a damaged thread during a project, don’t despair – it can often be repaired. It’s a case of using the correct tool in the right way. Here are our tips;

To repair a female thread with a tap

Although taps are tools that primarily used by engineers for creating a new female thread inside a hole, they can also be used to repair a damaged thread. The tap is inserted into a special wrench and turned whilst cutting oil is used to lubricate the tap.

USING A TAP

There are three different stages to tapping a new hole, but for repairs we suggest the following. You can use any of the taper, second or plug tap versions but it is advised by most engineers to use a second tap if you can get right through the hole. If the hole bottoms out then you should use a plug tap.

Confusingly, second taps are called plug taps in the USA! Whichever tap you choose, remember to always use a lubricant such as our cutting and tapping fluid spray, or tapcut cutting compound. Never attempt to tap a thread without any lubrication.

To repair a female thread with a Helicoil

If the thread is irreparably damaged you should consider using a helicoil. Helicoils, sometimes called recoils or thread repair inserts, are precision inserts that are most commonly used to repair damaged or worn threads.

A Helicoil is essentially a free-running, stainless steel wire coil that is inserted into a hole with a thread that has been specially tapped to accept it. It is used to create a standard-sized, internal screw thread within the existing hole. Helicoils come in a range of different metric thread sizes.

USING A HELICOIL

Our helicoils are available as individual coil inserts or as a kit. The kits contain everything needed to install a Helicoil, including the inserts themselves, a drill bit and a tap, an inserting tool and a tang break off tool.

To repair a male thread with a Hexagon Die Nut

Hexagon die nuts are generally the fitting to use when repairing a damaged male thread. Unlike split dies, they are not adjustable.

Hexagon die nuts can be turned using a standard spanner, wrench or socket. They are occasionally used to cut new threads in difficult to reach locations where there is no room to use the standard split die method.

As with tapping, be sure to always lubricate whilst cutting the thread.

USING A HEXAGON DIE NUT