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How to Use Thread Repair Kits and Fix

May. 18, 2022

In the past, damaged or broken threads would have been a major production setback and could have meant scrapping a job or component. However, this is no longer the case; thread repair kits can now be used to save those oversized, spalled and damaged threads.

You can also use thread repair kits to strengthen threads, especially in soft or brittle materials such as aluminum, plastic and cast iron. This will allow you to further tighten bolts and screws without risking thread stripping.

How to Use Thread Repair Kits and Fix

How do they work?

When you determine that the threaded hole is no longer suitable for reasonable use, you will need to use a thread repair kit to drill the threaded hole to a larger size (yes, you read that right!) . The size of the hole and the repair tap are predetermined and both relate to the thread size you want to finish (for example, to get a M6 X 1 finished repair thread, you would drill to 6.2mm diameter and use the size tap provided in the kit).

The main reasons for doing this are

You can clean up the existing hole.

Any signs of the previous thread will be removed.

We can start the thread process from scratch.

This new larger hole can now be threaded using a special thread repair tap. The hole will still be larger than the actual finished size required, even when tapping, but don't worry: it's an integral part of the process!

To match the expected threaded hole size to our larger holes, a robust stainless steel insert is used. This is inserted by hand into the newly threaded hole using a special insertion tool that screws into the depth through the shank foot on the stainless steel threaded insert, but is then removed. Once the insert is flush with or just below the surface of the hole, another special tool called a break tool/stamp is used to remove the drive shank foot used to screw the insert into the depth. (The damaged drive shank needs to be removed from the bottom of the hole.

With the thread repair insert in place, you are now ready to use the newly restored and reinforced threads.

How to Use Thread Repair Kits and Fix

ISO529 Screw Thread Insert Taps M3-24

To summarize

1. Drill out the damaged hole/thread using the specific drill bit for the thread you are repairing.

2. Clean the hole with a cloth or cleaning spray to make sure there is no debris in the hole.

3. Drive the tap into the correct depth by hand or on the machine.

4. Clean the thread with a cloth or cleaning spray to make sure there is no debris in the hole.

5. Use the insertion tool to screw in the thread repair insert.

6. Use the break-off tool to break the shank foot you used to drive the wire to depth.

7. Clean the wire and remove all dust/debris. 

8. You are now ready to use the repaired threads.

GSR now offers a complete range of inserts for metric threads, as well as tools for professional assembly. To store the kit we developed shapely plastic boxes for the individual sizes as well as two big boxes for the repair assortments.

How to Use Thread Repair Kits and Fix