Using a screw extractor is an effective method to remove stripped, broken, or seized screws that cannot be removed with a standard screwdriver. It typically involves drilling a pilot hole into the damaged fastener, then inserting a specialized bit that grips and extracts the screw.
Understanding Screw Extractors
Screw extractors are essential tools for anyone working with fasteners, from DIY enthusiasts to professional tradespeople. They work by creating a strong grip within the damaged screw, allowing it to be twisted out.
When to Use a Screw Extractor
- Stripped Screw Heads: When the screw head's drive (Phillips, flat, Torx, etc.) is worn down, preventing a screwdriver from gripping.
- Broken Screw Heads: If the head of the screw snaps off, leaving the shank embedded in the material.
- Seized or Rusted Screws: When screws are stuck due to corrosion or over-tightening.
Step-by-Step Guide to Using a Screw Extractor
Successfully removing a damaged screw requires careful execution. Follow these steps for the best results:
1. Preparation and Safety
Before you begin, ensure you have all necessary tools and take appropriate safety precautions.
- Safety Gear: Always wear safety glasses to protect your eyes from debris. Gloves can also provide better grip and protection.
- Gather Tools: You'll need a power drill, a set of screw extractors (which often include compatible drill bits), a hammer (optional, for tapping), and potentially penetrating oil for stubborn screws.
2. Drilling the Pilot Hole
The first crucial step is to create a clean, centered pilot hole in the damaged screw.
- Select the Right Drill Bit: Choose a drill bit that is slightly smaller than the core of the screw you're trying to extract. Most screw extractor sets come with corresponding drill bits.
- Center the Hole: Use a center punch if available, to create a small dimple in the exact center of the screw head. This helps prevent the drill bit from "walking."
- Drill Slowly and Straight: With your drill set to a slow speed, carefully drill straight into the center of the damaged screw. Apply steady, moderate pressure. The goal is to create a clean, concentric hole deep enough for the extractor to get a good bite.
- Tip: For harder screws, use a metal-specific drill bit.
3. Inserting the Extractor
Once the pilot hole is drilled, it's time to insert the extractor bit.
- Choose the Correct Extractor Size: Select an extractor bit that fits snugly into the pilot hole you've just drilled.
- Insert the Extractor: Most extractors have a tapered, reverse-threaded design. Insert the extractor directly into the pilot hole. Many sets are two-sided, where one side is for drilling and the other is the extractor. Once the hole is smooth, you'll use side two of the extractor and insert side two into the screw head.
- Tap (Optional): Gently tap the extractor with a hammer to ensure it seats firmly into the hole, allowing its reverse threads to bite into the screw material.
4. Extracting the Screw
With the extractor firmly in place, you can now attempt to remove the screw.
- Attach to Drill or Tap Wrench: Secure the extractor into your drill chuck (set to reverse/counter-clockwise) or a tap wrench.
- Apply Counter-Clockwise Pressure: Begin turning the extractor slowly in a counter-clockwise direction. The reverse threads of the extractor will bite deeper into the screw as you turn, eventually gripping it tightly.
- Steady and Smooth Removal: Continue turning with steady, even pressure. As the extractor grips, it will begin to unthread the damaged screw. If done correctly, it should come out pretty easily.
- Important: Do not apply excessive force, as this can break the extractor itself, making the problem significantly worse.
Troubleshooting Tips
- Stubborn Screws: For very stubborn screws, apply penetrating oil and let it soak for several minutes or even hours before attempting extraction.
- Extractor Breaks: If an extractor breaks inside the screw, it creates a much harder problem to solve. These bits are made of hardened steel. Consider seeking professional help if this occurs.
- Preventing Future Strips:
- Always use the correct size and type of screwdriver or bit for the fastener.
- Apply consistent, firm pressure while driving screws.
- Avoid using impact drivers on delicate or soft screws.
- Consider pre-drilling pilot holes for screws in hard materials.
Types of Screw Extractors
| Type of Extractor | Description | Best For |
|---|---|---|
| Spiral/Fluted | Features a tapered, reverse-threaded design. Most common type. | General stripped screws, slightly deeper extraction |
| Square/Straight | Has straight flutes that wedge into a drilled hole. Often requires a tap wrench. | Smaller, more delicate screws, shallow stripped heads |
| Two-in-One Sets | Combines a drill bit and extractor on opposite ends of a single tool or in a sequential set. | Quick, convenient removal of various screw sizes |
By following these steps, you can effectively use a screw extractor to salvage your project and remove those challenging damaged fasteners.
