Thread Chasers Are A Shop Essential

Thread chasers are tools used for cleaning and restorating threads on nuts, bolts, studs and threaded “or tapped” holes and more.

Threads on fasteners get bent, nicked or clogged up with gunk and corrosion from use. When they do, the female and male threaded parts (think nuts and bolts respectively) can become misaligned. And when that happens, their ability to hold together parts, equipment, machinery – and even structures – gets compromised and performance suffers.

In the shop, there are many occasions where thread restoration and cleaning are important. The remedies range using mild thread chasers to employing more invasive tools for rethreading or replacing the threads on a workpiece or part.

The most common go-tos for thread restoration are taps and dies. But using them is often overkill because it sheers away material, leaving threads in a diminished state. Taps and dies are designed for cutting new threads, after all.

Thread chasers are the gentle, effective alternative because they are not as sharp, hard or severe as taps and dies. Designed to clean and straighten threads, thread chasers play an important role in improving performance while preserving parts integrity.

On vehicles, there are threaded parts in the engine and brakes for example, that have to be in good shape to handle high torque loads. That makes thread maintenance and repair a high priority. Thread chasers are the smart tool for the job. 

Many Uses in Multiple Industries

Threaded fasteners are used in a wide range of industries from construction and oil refining to aerospace engineering and automotive manufacturing and maintenance. Thread integrity is critical in every one of these settings – a testament to the importance of thread chasers in maintaining systems and enhancing performance everywhere. 

Thread chasers can be an important part of the preventative maintenance performed on trucks and automobiles – one that is compounded at the fleet level. Worn threads on engine parts can lead to fluid seepage, loss of torque, exhaust leaks, compromised structural strength, and the increased risk of component failure.

These risks can be mitigated through thread restoration and cleaning performed with thread chasers. 

10 Common Uses for Thread Chasers in Fleets

1.        Hub and wheel studs  

2.        Cylinder heads  

3.        Engine blocks

4.        Transmission housings

5.        Suspension components

6.        Exhaust systems  

7.        Brakes

8.        Fuel system parts  

9.        Cooling systems

10.      Body and trailer parts

How Thread Chasers Work

ID and OD thread chasers function the same way. The basic premise is that flutes running perpendicular to the threads are cut into the threads of an ID or OD tool. When these tools are spun onto the threads being cleaned, the imperfections are corrected and dirt and corrosion are removed and collected in the flute channels.  

Once you’ve selected the right tool for the threaded piece – something we’ll go into in a later section – it’s about gently and firmly working the tool over the length of the threads being chased.

This gentle motion of working through burrs, bent threads, corrosion and dirt helps ensure you don’t do more harm than good. This is about cleaning, reforming and restoring existing threads. It shouldn’t take more torque than a ratchet set can provide in the hardest sections – but be careful not to exert force that will cause cross-threading.  

Tools for thread chasing are readily available. Thread restorer kits resemble a collection of nuts and bolts. They contain ID and OD thread chasers in a multitude of sizes that conform to metric and SAE conventions. OD tools have a hex bolt on the end that a wrench or ratchet can be attached to. ID tools are shaped like nuts that can be gripped with a wrench, pliers or a vice 

Cost and Performance Benefits

The simple, often-overlooked act of thread chasing brings a host of important benefits to shops, starting with providing the opportunity to restore rather than replace expensive parts. Even chasing the threads of inexpensive nuts and bolts can add up in a busy shop.

Savings aside, the importance of having a good, clean thread can make a critical difference. A prime example is locking a head down to an engine block. The condition of the threads affects torque value. Head bolts, caliper bolts and other parts of trucks and automobiles that take torque, benefit from thread chasing that can help maintain a tightening torque spec.

When threaded fasteners maintain proper clamping strength, they maximize component performance. Chasing threads helps threads mate precisely for strong clamping and less play in the parts. This helps prolong the life of machinery and components.

Making thread chasing part of regular inspection and maintenance helps identify worn threads early to mitigate potential failures before they happen. An example is using thread chasers to maintain the threads in cylinder heads for spark plugs. Having well-mated threads will prevent oil from leaking into the engine.

Choosing the Right Tool

Thread chasing jobs start with determining the system (metric or SAE), size and density (space between threads) of the part you’re cleaning.

Threaded fasteners conform to either metric or SAE (Society of Automobile Engineers) standards. SAE – also referred to as standard – is predominant in the U.S. and Canada.

Metric bolts tend to have numbers on the head while standard bolts usually display three hash marks. Use thread measuring gauges to determine the diameter of the bolt once you know whether it is SAE or metric.

When choosing the right thread chaser it is important to determine the thread pitch with the help of a thread gauge. Use an SAE thread gauge to measure standard threads and a metric gauge to measure metric threads. Make sure you match the pitch and angle of the chaser to the thread you’re cleaning. SAE and metric threads are far from the same. Forcing an SAE thread chaser onto a metric thread will strip threads and or cause cross-threading.

Also be sure to identify the direction of the thread and whether it is right or left. The vast majority are right-hand, but some out there are left.

Tips for Protecting Workers and Workpieces

Prior to using a thread chaser, always set the stage for safety by working in a clutter-free, clean workspace, making sure there’s enough light, and securing the workpiece with a vice or clamps. Wear approved eye protection and secure any loose clothing, ponytails or jewelry that could get caught on threads. 

Start by cleaning any corrosion, dirt and grease from the threads that you can with a brush, solvent or air blower. Then be sure you choose a thread chaser that is the right size, pitch and standard (metric or SAE).

When using thread chasers, gentle is the overarching theme and precision is the goal. Take the time to secure the workpiece and align the chaser with it perfectly. Turning too hastily and not observing the back-and-forth motion mentioned earlier can break threads. Be careful not to over-torque, and use cutting fluid to smooth out the chasing.

Make sure you clean the flutes of the thread chaser periodically so you aren’t grinding over swarf you’ve removed. Not doing so can mess up thread alignment and leave dings.

Thread chasers used repeatedly can themselves become worn and imprecise. Always inspect a chaser before using it for bent threads, nicks and dirt that may damage the threads you’re trying to fix. Also do an inspection of the threaded piece itself. Is it even salvageable? If there are no threads to clean and restore, you’ll have to replace it or switch to one of many thread repair options.

When you’re finished, put your tools away and cover them so that they are preserved and protected for the next project. Clean them to remove chips and dirt, make sure they are completely dry so they don’t corrode. Store them in their own compartments or in separate slots so they don’t hit each other. Contact chips and dulls tools. Coat with a wipe of oil to protect against corrosion and rust especially in humid environments.

Pro Thread-Chasing Tips

When threads are corroded and damaged, pre-work can help clear the path to success. For fasteners that thread with difficulty, try using a wire wheel or wire brush, applying a solvent and lubricating.

Another option is using a thread restoring file before or instead of using a thread chaser. These are often included in thread restorer kits. By selecting a thread restoring file with the right thread pitch and angle, you can zero-in on specific damage areas.

What about dirty and damaged threads that are hard to reach? Engines have hard to reach threads that sometimes need restoration, and ratcheting tap wrenches can help. They can be fitted with thread chasers and used in spaces that don’t allow for rotation or long handles.

Making Thread Integrity a Priority

1.    Inspect threads regularly. Repairing and restoring threads early prevents bigger problems from developing.

2.    Follow manufacturer’s specifications for tightening torque to avoid undertightening that can lead to loose connections and overtightening which can lead to stripping.

3.    Protect threaded parts to prevent chips and bends in threads – especially when dealing with soft metals like brass or aluminum.

4.    Lubricate to reduce friction when tightening threaded connections to prevent galling (joining of metals under pressure) and thread damage.

5.    Align threads from the onset to avoid cross threading damage that can’t be repaired.

6.    Cover threads from dust and moisture to prevent corrosion – especially when they are being stored.

7.    Don’t mix SAE and metric threads. Damage to threads and misalignment will result.

8.    Use thread protectors to cap and shield threaded parts – especially expensive ones

9.    Control vibration that can loosen threaded connections. Washers, threadlockers and lock nuts can help reinforce connections.

10.  Choose suitable metals for where threaded parts will be used. Account for environments where there is excessive wear or the risk of corrosion.  

The options for fasteners are limitless today, but amidst all the alternatives and technological advances, threaded connectors remain widespread because of their superior properties.

But those properties of secure fastening, sealing capability, adjustability and ease of assembly are compromised when threads get damaged and dirty.

Thread chasers help preserve the prized properties of threaded fasteners by offering an easy procedure to restore or perform preventative maintenance on threads.

With about the same amount of effort that it takes to tightening a bolt, shops can boost mechanical performance, save the cost of replacing parts and preserve the integrity of the threaded fasteners they rely on.

Talk to your Imperial partners about the thread chaser set-up that is right for your team and all the threaded connections in your shop.