# The Ultimate Guide to Removing Broken Bolts
Dealing with a broken bolt can be a frustrating experience, turning a simple repair job into a time-consuming headache. Whether it’s a stubborn fastener in an engine, a piece of machinery, or even furniture, a bolt that snaps off can leave you wondering how to proceed. Fortunately, with the right tools and techniques, removing a broken bolt is a manageable task. This guide will walk you through various methods, from simple approaches for accessible bolts to more advanced techniques for those deeply embedded or rusted in place.
Understanding the type of metal the bolt is made from and the surrounding material can help you choose the most effective removal strategy. For instance, steel bolts in aluminum can lead to galvanic corrosion, making them harder to remove. Success often lies in patience and applying the correct force and lubricants.
| Category | Information |
| :—————— | :—————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————– |
| **Bolt Removal** | **Objective:** To extract a fastener shaft that has broken off, leaving a portion still engaged within its threaded hole. |
| **Common Scenarios** | – **Automotive repair:** Engine components, exhaust systems, suspension parts.
– **Machinery maintenance:** Industrial equipment, tools, appliances.
– **DIY projects:** Furniture assembly, home repairs. |
| **Key Challenges** | – **Rusted or Corroded Bolts:** Oxidation can seize the bolt, making extraction difficult.
– **Sheared Flush:** When the bolt breaks at or below the surface of the material.
– **Damaged Threads:** The surrounding threads may be compromised, requiring careful work.
– **Soft Materials:** In some cases, the surrounding material might be softer than the bolt, risking damage during removal. |
| **Essential Tools** | – Penetrating oil (e.g., WD-40, PB Blaster)
– Safety glasses and gloves
– Hammer
– Center punch
– Drill and drill bits (various sizes)
– Screw extractors (easy-outs)
– Pliers (locking pliers, needle-nose)
– Wrenches or socket set
– Dremel or rotary tool with cutting discs
– Welding equipment (optional, for advanced techniques) |
| **Reference** | [How to Remove a Broken Bolt – This Old House](https://www.thisoldhouse.com/tools/21107116/how-to-remove-a-broken-bolt) |
## Common Causes of Bolt Breakage
Before diving into removal techniques, it’s helpful to understand why bolts break in the first place. Over-tightening is a primary culprit, exceeding the bolt’s tensile strength. Rust and corrosion also weaken the metal over time, making it more susceptible to snapping under stress. Using the wrong type of bolt for an application, such as one not rated for the load or environment, can lead to premature failure. Finally, old or fatigued metal can simply give way, especially in applications subject to vibration or repeated stress.
## Methods for Removing Broken Bolts
The best approach depends on how much of the bolt is left protruding and how tightly it’s seized.
### The “Easy-Out” Method (Screw Extractors)
This is one of the most common and effective methods for bolts that have broken off, leaving a small portion exposed or flush with the surface.
1. **Center Punch:** Use a center punch to create a small indentation precisely in the center of the broken bolt. This provides a starting point for your drill bit and prevents it from wandering.
2. **Drill a Pilot Hole:** Select a drill bit slightly smaller than the diameter of the bolt. Carefully drill a hole straight down into the center of the broken bolt. The depth of the hole will depend on the size of the screw extractor you plan to use.
3. **Insert the Extractor:** Tap the appropriate-sized screw extractor into the drilled hole. These extractors have a reverse thread.
4. **Turn Counter-Clockwise:** Using a wrench or tap handle, slowly turn the screw extractor counter-clockwise. As you turn, the extractor’s threads will bite into the bolt, hopefully unscrewing it.
#### Tips for Screw Extractor Success
* **Lubrication is Key:** Apply a generous amount of penetrating oil to the broken bolt and let it soak for at least 15-30 minutes (or even overnight for severely seized bolts).
* **Gentle but Firm:** Apply steady, even pressure. Forcing it too quickly can break the extractor, which is a much harder problem to solve.
* **Heat Application:** For stubborn bolts, gently heating the area around the bolt with a heat gun or propane torch can help expand the surrounding material, breaking the bond. Be cautious not to overheat or damage surrounding components.
**Factoid:** The tensile strength of a bolt is its maximum resistance to breaking under tension. This is a critical factor in determining how much force can be applied before it snaps. Different grades of bolts have significantly different tensile strengths.
### Pliers and Vice Grips for Protruding Bolts
If a significant portion of the bolt is still sticking out, you might be able to grip it firmly and twist it out.
* **Locking Pliers (Vice Grips):** Clamp a pair of locking pliers tightly onto the exposed portion of the bolt. Ensure a very secure grip.
* **Wrench or Socket:** If there’s enough of the bolt head or shaft remaining, you might be able to get a wrench or socket onto it and carefully turn it counter-clockwise.
### Drilling Out the Bolt
If other methods fail, or if the bolt is completely broken off flush or below the surface, drilling out the bolt entirely may be necessary. This is a more aggressive approach and requires precision.
1. **Center Punch and Pilot Hole:** As with the screw extractor method, accurately center punch and drill a small pilot hole.
2. **Enlarge the Hole:** Gradually increase the size of your drill bit, drilling out more of the bolt material. Your goal is to drill close to the size of the bolt’s threads without damaging the threads in the hole.
3. **Remove Remaining Material:** Once most of the bolt material is removed, you may be able to pick out the remaining pieces with a pick or small screwdriver. If the hole was drilled perfectly, the remaining threads might fall out.
4. **Re-tap the Threads:** After removing the broken bolt, you will likely need to clean up the threads using a tap of the correct size. This will restore the integrity of the threaded hole.
### The Welding Method (Advanced)
For heavily seized or rusted bolts, welding a nut onto the broken bolt can be an extremely effective method. The intense heat from welding helps break the rust bond, and the nut provides a solid surface to grip.
* **Weld a Nut:** Place a nut (one that fits loosely over the broken bolt shank) onto the broken bolt. Arc weld the inside of the nut to the top of the broken bolt.
* **Cool and Turn:** Allow the assembly to cool slightly. Then, use a wrench on the welded nut to turn the broken bolt counter-clockwise. The heat and the solid grip often make this method very successful.
**Factoid:** Extreme temperatures can significantly affect a bolt’s integrity. Rapid cooling (quenching) of hot steel can make it brittle, while prolonged heating can anneal it, making it softer and easier to work with.
## Preventive Measures
* **Use Anti-Seize Compound:** Apply a small amount of anti-seize compound to threads, especially on fasteners exposed to moisture or high heat. This prevents corrosion and makes future removal easier.
* **Use Correct Torque:** Tighten bolts to the manufacturer’s specified torque settings. Over-tightening is a leading cause of breakage.
* **Regular Maintenance:** Inspect fasteners regularly, especially in critical applications, and address any signs of rust or wear promptly.
## Frequently Asked Questions (FAQ)
**Q1: What is the first thing I should try when a bolt breaks?**
A1: Start with penetrating oil. Apply it liberally to the broken bolt and let it soak in for at least 15-30 minutes. This can help loosen rust and corrosion.
**Q2: Can I use heat to remove a broken bolt?**
A2: Yes, heat can be very effective, especially for stubborn bolts. Applying heat to the surrounding material (not directly to the bolt for too long) can cause it to expand, breaking the seized bond. A propane torch or heat gun can be used. Be cautious of surrounding materials that could be damaged by heat.
**Q3: What happens if I break a screw extractor inside the bolt?**
A3: This is a difficult situation. If the extractor is hardened steel, drilling it out is extremely challenging. Sometimes, specialized carbide drill bits can work, or you might need to resort to grinding or using a EDM (Electrical Discharge Machining) service if the part is valuable
