Removing a screw or bolt can be exasperating if the slots on the screw or the head of the bolt have been damaged from efforts to remove the fastener. This predicament can easily happen if the fastener is rusted in place or if you've used the wrong-sized tool. A few slips of the screwdriver or wrench and the head of the screw or bolt can be so damaged or stripped that it's almost impossible to get a good grip on it.
To your rescue comes this clever little accessory—the screw extractor. Screw extractors come in a range of sizes for screws of diameters ranging from 3/32 inch to upwards of 1/2 inch. You can use them on all manner of screws and bolts.
Before You Begin
A screw extractor is a high-strength steel shaft with a square head on one end and reverse tapered cutting screw threads on the other. The square head fits into a T-handle used to turn the extractor. You can also grip and turn the head of the tool with locking pliers.
The tapered threads are at the business end of the tool. These are designed to screw backward (counterclockwise) into the head of the screw or bolt after a pilot hole has first been drilled. The end is sharply tapered so that the extractor digs into the damaged screw deeper and tighter as the extractor is turned. So while turning the extractor counterclockwise, it's digging into the damaged screw more and more as the damaged screw is backing out.
A T-handle is a useful accessory when using a screw extractor. Named for its shape, the handle fits over the end of an extractor bit. T-handles are made to fit various extractor sizes, and many types also work with taps for threading holes. You can turn a screw extractor with locking pliers if you don't have a T-handle.
Equipment / Tools
- Screw extractor with T-handle
- Locking pliers (optional)
- Power drill with twist bits
- Cutting oil
Watch Now: 4 Ways to Remove a Broken Screw or Bolt
Drill a Pilot Hole
To use a screw extractor to remove a screw, drill a pilot hole into the center of the damaged screw, using a power drill and a twist bit of appropriate size. If the head of the damaged screw is rough or uneven, it can help to start with a very small pilot hole, such as a 1/16-inch bit. Make sure to place a drop or two of motor or cutting oil on the damaged screw before drilling; it will help keep the drill bit from overheating. Oil is also a key ingredient for unscrewing a screw that won't budge.
Then drill a larger hole with the bit sized for the extractor. The pilot hole diameter varies according to the extractor size you are using. Follow the recommendations on the package that came with the extractor.
Extract the Screw
Attach the extractor bit firmly to a T-handle or grip it with locking pliers. Place the extractor bit into the pilot hole in the damaged screw.
Using a hammer, tap the extractor firmly into the pilot hole. Apply downward pressure on the extractor while turning it counterclockwise to remove the damaged screw.
If the extractor slips and loses its bite in the screw, try tapping the extractor again to get a better seat in the pilot hole. Push down more firmly as you turn the extractor counterclockwise. If that doesn't work, slightly enlarge the pilot hole and try again.
If a screw extractor doesn't work, you can still get the screw out without an extractor. Before anything, try twisting the screw with pliers to remove it. If that fails, drill out the screw completely by slowly screwing into the old screw with a smaller bit. Slowly reverse or drill counterclockwise and get the pieces of old metal out. Re-thread the hole and use a larger screw.