Repair internal thread - All you need to know

Threads play a pivotal role in ensuring the structural integrity of various components. Given the immense responsibility they bear, it's unsurprising that they occasionally require support. Fortunately, damaged threads don't necessarily warrant the disposal or replacement of an entire component. Repairing internal threads is straightforward, especially when you have the right tools. In this blog post, we introduce BaerCoil® and BaerFix®: two professional solutions for repairing internal threads.

DIY Solutions for Internal Thread Repairs

Can you repair internal threads using household methods? When it comes to threads, precision and durability are crucial. Consequently, we advise against using materials or tools not specifically designed for repairing internal threads. The good news is that with BaerCoil® and BaerFix®, repairing internal threads becomes quick, cost-effective, and so simple that even novices can handle it.

Repair Internal Threads with BaerCoil® Wire Thread Inserts

BaerCoil® thread inserts are made of wire that's cold-formed into a diamond-shaped cross-section during production. This ensures maximum stability while occupying minimal space, making it perfect for safely and easily repairing internal threads.

What types of BaerCoil® Wire Thread Inserts are available?

These thread inserts come in three distinct variations, each with its unique features: free-running, screw grip (screw-locking), and NoTang (without tang).

The standard “free-running” type is available in various materials, such as:

• Stainless Steel V2A for general applications.
• Stainless Steel V4A with enhanced corrosion resistance.
• Inconel X750 for high thermal resistance.
• Bronze, which is non-magnetic and offers excellent electrical conductivity.

BaerCoil® thread inserts of the “screw grip” type feature one or more polygon-shaped turns that exert a clamping force on the flanks of the screw when repairing an internal thread. This ensures exceptional strength, especially in the presence of shocks and vibrations. However, this design demands the use of high-strength screws.

The “NoTang” type operates without a tang, eliminating one step in the installation process.

What tools are required for internal thread repairs with BaerCoil®?

BaerCoil® wire thread inserts can be installed manually or using machinery. To prepare the thread for repair, you'll need a twist drill bit and the appropriate STI tap for screw thread inserts. If you intend to countersink the core hole of the receiving thread, a countersink tool will be necessary. Next, you'll use the installation tool. Note: If you're using a stationary drill machine, make sure to use the specific machine installation tool. Finally, a tang breaker completes the internal thread repair process.

By the way, all the tools and inserts required for internal thread repairs are available in convenient sets and assortments, saving you the hassle of sourcing individual items.

Here's how it's done:

• 1. Drill out the damaged thread or pre-drill the core hole.
• 2. Cut the receiving thread into the drilled hole.
• 3. Place the BaerCoil® thread insert on the installation tool or machine installation tool and screw it into the receiving thread.
• 4. Unscrew the tool, leaving the wire insert inside the thread.
• 5. Break the tang using a tang breaking tool.

Repairing internal threads with BaerFix® self-tapping threaded bushings

The special feature of BaerFix® thread inserts for internal thread repair is the self-tapping mechanism. This means that no thread needs to be pre-cut for this type of internal thread repair. This is done by the threaded bush itself when it is inserted into the material.

Which BaerFix® thread inserts are available?

The self-tapping thread inserts are available in different versions.

• Made from case-hardened steel, stainless steel or brass with cutting slots for easy to medium machinable materials
• Made of case-hardened steel or stainless steel with cutting holes for materials that are easy to difficult to machine
• Made from case-hardened steel with cutting holes for spark plug threads

Which tool do you need to repair internal threads with BaerFix®?

You only need a few assembly tools to use the self-tapping thread inserts. A suitable twist drill and a countersink are suitable for preparing the locating hole. The actual installation of the thread insert is then carried out by hand using a special installation tool or with a machine installation tool if you decide to use a stationary drilling machine.

For the BaerFix® product series, you will also find practical sets and assortments with all the individual parts you need to repair internal threads in our online shop.

And this is how it works

• 1. drill out the damaged thread or pre-drill the core hole
• 2. turn the BaerFix® thread insert onto the installation tool or the machine installation tool
• 3. screw in the BaerFix® thread insert with the installation tool
• 4. unscrew the installation tool again

The right product for every purpose: BaerCoil® and BaerFix® in comparison

What are the differences between the two types of internal thread repair and which variant should you choose? That depends on your intended use.

In most cases, BaerCoil® wire thread inserts are a good choice for internal thread repair. The wire springs are very flexible and can align themselves in the coils of a thread according to the load. This distributes the forces acting on the thread evenly across all threads and significantly increases the load-bearing capacity. Installing the wire thread inserts requires a little more effort, as you have to pre-cut the thread. However, you can also use them in materials up to approx. 750 N/mm².

The strengths of BaerFix® thread inserts are particularly evident in very soft materials and materials with low shear strength. The threaded inserts are thick-walled and have a lot of contact with the receiving material due to the large external thread. As the insert cuts its own thread, the tolerance is almost zero. This means that very strong threaded connections are possible even in soft materials, which would not be possible without a threaded insert. The self-cutting process also means that the thread insert is literally pressed into the host material, which further anchors the insert in the material. However, the BaerFix® thread insert already reaches its limits with materials from approx. 400 N/mm², as it can no longer cut anything above this. In addition, the insert requires more space due to its thick walls and may fail in some applications for this reason alone.

BaerCoil® and BaerFix® are both systems with which you can easily repair internal threads at home without much prior knowledge. While BaerCoil® is the flexible all-round version that is suitable for the majority of applications, BaerFix® is particularly suitable for soft materials. You can find both systems for repairing internal threads in the BAER online shop!