Screw extractors are available in two common types: one has reverse threads and the other has straight flutes. The objective of this procedure is to show you how to use a screw extractor to remove a broken stud or screw.
Part 1. Preparation and safety
- Use a screw extractor to remove a broken stud or screw.
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection - such as rubber gloves and barrier cream
- Respiratory equipment - such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
- Always wear eye protection when drilling and removing a broken stud or bolt.
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- Fasteners can fail for many reasons: over-tightening, over-stressing, fatigue and old age are all possible causes.
- If the fastener is broken near the surface, a screw extractor will be needed to remove it.
- Screw extractors are available in two common types: One has reverse threads and the other has straight flutes.
- The fastener needs to be drilled before the screw extractor can be inserted.
- Always drill to the size recommended by the screw extractor instructions. If you are unsure of the correct size, ask your supervisor.
- If a fastener is rusted into place, use a penetrating fluid on the threads and allow it time to work before attempting to loosen it.
- Sometimes the fastener can be made easier to remove by the application of heat to the surrounding area. Ask your supervisor to demonstrate this to you.
- When fitting a replacement stud, apply the recommended coating to the thread. It may be thread locking or anti-seize compound. Follow the manufacturer's instructions on the application and use of the compound.
- Use a jam and drive nut to fit the replacement stud.
Part 2: Step-by-step instruction
- Select the correct tools for the job
Open your screw extractor set and study the instructions, which should be enclosed. Identify and select the correct size drill and screw extractor for the job.
- Mark the exact center
With a center punch, mark the exact center of the broken screw to get the power drill started.
- Drill a hole
Drill a hole through the center of the bolt. Drill only to the depth specified in your screw extractor instructions.
- Select the correct size
Make sure you use the correct screw extractor – that is, the one that matches the drill bit you used.
- Turn extractor counterclockwise
Because the screw extractor has reverse threads, you will need to remember to turn it counter-clockwise.
- Use a tap wrench
Use a tap wrench and turn the screw extractor into the hole. The reverse threads will force the extractor into the hole until the broken bolt or stud is forced to turn. Continue turning until the stud is removed.