I. Mild Stripping: Attempt to Restore Engagement (No Special Tools Required)
When the screw groove is slightly worn but not completely smooth, try the following methods:
Rubber Pad Friction Enhancement Method: Cut a small piece of bicycle inner tube or elastic rubber and cover the stripped screw head. Then, use an original-sized Allen wrench to turn it counterclockwise. The elasticity of the rubber can fill the wear gap and enhance torque transmission.
Tape Assistance Method: If rubber is unavailable, use electrical tape or multiple layers of paper to wrap around the screw head to increase the roughness of the contact surface and help with engagement.
Tap Positioning Method: Align the Allen wrench with the groove and gently tap it with a hammer to make it embed deeper. Then, slowly rotate it. This method is suitable when the tool is not fully engaged.
II. Moderate Stripping: Removal with Specialized Tools
If the above methods are ineffective, specialized tools are required:
1. Screw Extractor (Broken Thread Extractor)
Suitable for: Screw heads still intact, but severely worn grooves.
Operation:
① Use a center punch to mark a positioning point in the center of the screw to prevent drilling deviation;
② Use a drill bit 1-2mm smaller than the screw diameter to pre-drill a hole;
③ Insert the reverse thread extractor and rotate it in the opposite direction at low speed to unscrew it.
Advantages: Precise operation, minimal damage to surrounding areas.
2. Saw a Slotted Groove Modification
Use a saw blade or angle grinder to saw a slotted groove on the top of the screw head, then use a flathead screwdriver and a hammer to gently tap it out.
Caution: Wear safety goggles during operation to prevent metal shavings from flying.
3. Weld a Nut Assistance
Place a hexagonal nut over the stripped screw and weld it to the screw remnant using electric welding or argon arc welding. After cooling, use a wrench to rotate and remove the nut. Suitable for larger screws or broken screws, but care must be taken to avoid high temperatures damaging surrounding components.
III. Severe Stripping or Breakage: Advanced Solutions
Reverse Drilling: Use a high-cobalt carbide drill bit to drill a hole in the center of the screw, then use a reverse thread remover to remove the remaining part. This method requires careful operation to avoid damaging the base material threads.
Chemical Dissolution Assistance: If the screw is stuck due to rust, spray WD-40 or rust remover first, wait 10–15 minutes for penetration, and then attempt disassembly.
Component Replacement: If all methods fail and the overall structure is not affected, consider replacing the entire component.
IV. Prevention Recommendations: Reduce Stripping
Use a high-quality S2 alloy steel Allen wrench to avoid tool deformation leading to uneven force.
Use a torque wrench when tightening, following standard torque values (e.g., 10–12 N·m for M6 8.8 grade screws).
Regularly inspect and replace aged or slightly worn screws to prevent future problems.
