Got a problem with a rusted or rounded nut? A nut splitter will help you to dislodge the damaged nut so you can replace it with a new one. When a screw or bolt has broken and can't be unscrewed, you might find a set of screw extractors useful. Drill a hole in the broken screw, knock and screw in the screw extractor and keep screwing until the remains of the broken screw are extracted. Then if you need to know what thread the broken screw had, you can check with a thread gauge.