How to Remove a Stripped Bolt

How to Remove a Rusted Bolt

Rusted bolts are tough to remove because the iron oxide hydrate deposits on the bolt bond with deposits on the nut or other female threads. Applying penetrating oil breaks the bond and helps to remove most rusted bolts.

1. Brush Off Rust

   With the wire brush, clean the rust, paint, and corrosion off of the bolt head. Cleaning the bolt head will provide the wrench with a firmer grip on the bolt head. Also, you'll want to remove rust to give the penetrating oil easier access to the shank's threads.

2. Use a Hex Closed-End or Socket Wrench

   Open-end C-shaped wrenches will not provide the tightest grip on the bolt head. Similarly, tools like Crescent wrenches, locking pliers, and slip-joint pliers are not ideal for gripping bolt heads. If you previously used any of these wrenches or pliers, switch to a closed-end O-shaped (or box-end) wrench. Also, make sure that the wrench has a 6-point (hexagonal) end rather than a 12-point end.

   Tip

   If the bolt is not turning, do not force the bolt. To avoid rounding the bolt head, stop and move to the next step.

3. Tap the Bolt Head

   Gently tap on the bolt head with a smooth-faced hammer or a ball peen hammer. Tap straight down or from the side. Regulate the force of the blow to avoid bending or distorting the bolt, which could make the bolt even more difficult to remove.

4. Apply Penetrating Oil or Heat

   Penetrating Oil: Shake the can of room temperature penetrating oil. Attach the applicator straw, if any. Completely saturate the bolt with the penetrating oil. Gently tap the bolt a few more times. Spray more penetrating oil and let it sit for about 20 minutes.

   Heat: Light the propane torch and heat the bolt for about 30 seconds. Carefully try to remove the bolt. Intermittently tapping the bolt with the hammer may help as well.
   

   Warning

   With a low flashpoint of 150°F, penetrating oils should not be used around open flames. Penetrating oil can be applied to a heated bolt, but avoid using heat and penetrating oil at the same time.

5. Remove the Rusted Bolt

   Fit a hex closed-end or socket wrench over the bolt and turn counter-clockwise.

How to Remove a Broken Bolt

A broken bolt is one where the bolt head has snapped off, leaving the bolt shank flush or nearly flush with the top of the nut or work material.

1. Turn the Bolt by Gripping It

   If the bolt has not sheared off perfectly flush, you may be able to grab a small section of the bolt with pliers to turn it out, at least partially. Needle-nose locking pliers are capable of gripping small amounts of bolt material.

   Turn the pliers to the side. Open the pliers, then tighten the adjustment screw until the pliers can grip firmly. Close the pliers with the handles. Turn counter-clockwise until about 1/4-inch of the bolt emerges. Then switch to regular locking pliers and turn the bolt the rest of the way out.

2. Use a Screw Extractor Set

   With reverse-threaded bits, a screw extractor set can remove broken bolts.

   Apply a drop or two of thread-cutting oil. Drill a pilot hole in the center of the bolt. Drill perfectly plumb about 1/4-inch or deeper, if possible.

   Switch to the screw extractor. The extractor bits may either fit into a T-shaped handle for manual removal or they may be chucked into an electric drill. Turn the extractor counter-clockwise until the bit reaches the bottom of the pilot hole. The bolt will begin to emerge. If the extractor bit's grip is still solid, continue turning out the bolt is out. If the grip is weak, switch to a set of locking pliers.

3. Create a Groove in the Bolt

   Attach a metal-cutting tip to a rotary cutting tool like a Dremel. Holding the tool to the side, groove the top of the bolt head. Be careful not to continue down to the bolt shank. With a flathead screwdriver, turn the bolt out as if you were turning out a slotted screw.

How to Remove a Rounded Bolt

A rounded bolt is one where the bolt head is intact but its flat sides and corners have been rounded down, usually from overturning with an improper tool. These can be removed with locking pliers or a bolt extractor kit.

1. Use Locking Pliers

   Hold a pair of standard locking pliers to the side. Turn the adjustment screw on the pliers so the teeth grip the rounded bolt head with maximum force. Lock the pliers. Turn the bolt counter-clockwise until enough of the bolt is exposed to switch the pliers to a lower section of the bolt.

2. Use a Bolt Extractor Set

   A bolt extractor set has reverse-spiral sockets that fit over the top of a rounded bolt, gripping the rounded portion so the bolt can be turned out.

   Apply penetrating oil to the bolt. Place the socket over the bolt head. Tap the socket down with a hammer. Fit the socket wrench handle onto the extractor socket. Turn counter-clockwise until the socket grips into the metal and the bolt turns out.

3. Create a Groove in the Bolt Head

   If the bolt head is rounded or flat by design—like a carriage bolt or button head bolt—grooving a slot and removing it with a screwdriver is the best option.

   With the metal wheel in the rotary tool and the tool held sideways, create a groove in the bolt head large enough for a flathead screwdriver. Add some penetrating oil as a lubricant. Then, turn the bolt out with the screwdriver.

Tips to Avoid Stripping or Breaking Bolts

• Use a wrench size that correctly corresponds with the bolt size.
• Avoid mixing Imperial and metric wrenches and bolts.
• Avoid turning the bolt with adjustable wrenches.
• Use hexagonal wrenches or sockets to avoid rounding the bolt head.
• Keep the bolt free of rust by covering it, painting it, or applying penetrating oil.