Can’t remove an din931 hex bolt because the head is stripped? 5 Practical Methods + A Guide to Avoiding Pitfalls—Even Beginners Can Handle It!

Rubber Shim Method (Preferred Emergency Solution — Zero Cost)

This method boasts a success rate of approximately 60% and is ideal for cases involving minor stripping; furthermore, the cost is virtually zero.

Procedure:
1. Find a piece of firm rubber (e.g., a bicycle inner tube or a wide rubber band; a thickness of 0.5–1 mm is recommended) and cut it into a small patch roughly the size of the screw head.
2. Lay the rubber patch flat over the rounded screw head, ensuring it completely covers the worn-down hexagonal facets.
3. Select a wrench or socket that matches the screw’s specifications. Press down firmly onto the rubber patch, ensuring the tool makes tight contact with both the rubber and the screw head to prevent slippage.
4. While maintaining constant downward pressure, slowly turn the wrench counter-clockwise. The friction generated by the rubber fills the worn gaps in the screw head, allowing the tool to grip and rotate the screw, thereby enabling you to gradually extract it.

Tips: The thicker and firmer the rubber patch, the greater the friction and the higher the success rate. If rubber is unavailable, steel wool can be used as a substitute with similar results.

File Repair Method (Simple and Easy to Execute; Suitable for Moderate Rounding)

Suitable Scenario: The screw head is significantly rounded off, preventing a standard wrench from gripping it; however, the screw head protrudes above the workpiece surface, providing sufficient clearance for manipulation.
Procedure:
1. Prepare a triangular file (or a flat file), ensuring it is sharp to facilitate rapid filing.
2. Position the file against the side of the screw head and slowly file two parallel flat surfaces. The spacing between these two surfaces should match the jaw width of an adjustable wrench, thereby creating a gripping surface similar to a “slotted” screw head.
3. Select an adjustable wrench of appropriate size and firmly clamp it onto the two newly filed parallel surfaces, ensuring a tight, secure grip.
4. Slowly turn the wrench counter-clockwise, applying steady, even pressure to prevent slippage, and gradually extract the screw.
**Precautions:** When filing, ensure that the two flat surfaces remain parallel; avoid filing them at an angle, as this will still cause the wrench to slip. Additionally, control your filing pressure carefully to avoid damaging the surface of the workpiece; it is recommended to place a soft cloth over the workpiece surface to provide protection.

 

Screw Extractor Method (Professional and Efficient; Suitable for Severely Rounded Screws)

Suitable Scenarios: This method serves as one of the most reliable professional solutions when a screw head has become completely rounded (stripped)—preventing wrenches or sockets from gripping it—or when a screw has broken off and remains embedded within a workpiece.
Operating Steps:
1. Preparation:Gather a set of screw extractors (typically featuring a reverse-thread design and constructed from high-strength Chrome-Vanadium steel or High-Speed ​​Steel to withstand high torque) and a power drill.
2. Drilling the Pilot Hole: Using the power drill fitted with a small-diameter drill bit (1–2 mm smaller in diameter than the screw extractor), drill a vertical pilot hole directly into the center of the screw head. It is recommended that the hole depth reach 1/3 to 1/2 of the screw’s total length; ensure the hole is drilled straight and does not veer off-center.
3. Inserting the Extractor: Insert one end of the screw extractor into the pilot hole you just drilled. Use a wrench to grip the other end of the extractor and slowly turn it counter-clockwise.
4. Extraction: The extractor’s reverse threads will gradually bite into the interior of the screw, generating sufficient friction and torque to drive the screw to rotate counter-clockwise until it is completely removed.
Tips: Screw extractors come in various specifications; be sure to select a model that is appropriately sized for the screw you are attempting to remove. When drilling, applying a small amount of lubricant to the drill bit can help reduce friction and prevent the bit from overheating and sustaining damage. If a dedicated screw extractor is unavailable, a reverse tap can be used as a substitute, employing a similar operating procedure.

Locking Pliers Method (Suitable for screws with protruding heads)

Suitable Scenario: The screw head protrudes from the workpiece surface, is severely rounded (stripped), cannot be gripped by a wrench, and there is ample operating space available.
Operating Steps:
1. Prepare a pair of locking pliers (also known as vise grips); adjust the jaw opening so that it can firmly clamp the screw head.
2. Position the jaws of the locking pliers over the screw head and clamp down forcefully, ensuring a tight, secure fit with no slippage.
3. Grasp the handles of the locking pliers and slowly turn them counter-clockwise, applying steady, even pressure to avoid snapping the screw by applying excessive force.
4. If the screw is rusted or encounters significant resistance, apply a small amount of rust penetrant to the threads; allow 5–10 minutes for it to penetrate before attempting to turn the screw.
Precautions: When clamping, take care to prevent the jaws from slipping and damaging the surface of the workpiece. If the screw head is relatively small, you may place a soft cloth between the jaws and the screw head to increase friction while simultaneously protecting the screw head.

Destructive Removal Method (The Ultimate Resort—To be used only as a last resort)

Suitable Scenarios: The methods described above have all failed, the screw is severely seized, and the workpiece can tolerate minor damage.
Procedure (Two Options):
1. Drilling Method: Select a drill bit that is 1–2 mm smaller in diameter than the screw. Drill vertically into the center of the screw until the drill bit penetrates the screw head. Then, use needle-nose pliers to grip the remaining portion of the screw head and twist it out counter-clockwise. If the screw still cannot be removed, continue drilling to break the screw into pieces, then use tweezers to extract the remaining fragments.
2. Torch Cutting / Welding Method: Suitable for large external-hex screws or situations where drilling is not feasible. Use a cutting torch or welding equipment to sever the screw head, then use a wrench or pliers to grip the remaining portion and extract it. This method requires professional expertise to prevent high heat from damaging surrounding workpieces and equipment; appropriate protective gear must be worn during operation.
Precautions: Destructive removal methods will ruin the screw and may damage the threads within the workpiece. Consequently, the workpiece threads must be repaired (e.g., by re-tapping with a tap), and a new screw must be installed.