1. Prioritize Low-Damage Removal Methods
If the broken edge is exposed: Use needle-nose pliers or diagonal pliers to hold the edge of the broken edge and slowly unscrew it. Avoid drilling a second hole in the screw and protect the original screw hole from damage.
If the broken edge is flush: Prioritize using the slotting method (cut a slot with an angle grinder), then use a screwdriver to unscrew it in the opposite direction. This is more precise than drilling and reduces interference with surrounding threads.
2. Use Drilling Tools with Caution
If a screw extractor must be used:
Precisely locate the center of the broken edge and use a small-diameter drill bit to drill a guide hole to prevent eccentric enlargement;
Control the drilling speed to avoid high temperatures causing metal deformation or thread annealing;
Drill to a moderate depth, only penetrating the broken screw, avoiding drilling to the bottom of the screw hole and causing irreversible damage.
3. Utilize Auxiliary Methods to Improve Success Rate
Lubricant Application: Apply WD-40 or machine oil around the break, let it sit for 10 minutes to help loosen rust and reduce removal resistance.
Heating Method: Locally heat the metal part (e.g., with a heat gun) to loosen the broken screw using thermal expansion and contraction, reducing damage from forced operation.
4. Remedial Measures in Extreme Cases
If the broken screw cannot be removed and does not affect the overall structure:
Consider sealing the broken screw in situ (e.g., injecting metal glue and then grinding it flat) to avoid enlarging the hole;
Or re-drill a hole nearby and install it, retaining the original screw hole as a backup.
✅ Core Principles: During operation, keep the tool perpendicular to the screw hole to avoid lateral force that amplifies damage; prioritize non-drilling solutions to preserve the integrity of the original thread to the greatest extent possible.
