How To Remove A Broken Bolt (With And Without Drilling)

Nothing can bring a project to a halt quite like the discovery of a broken bolt. Whether it's something as simple as replacing an old mower blade or a more involved task like building a deck, one snapped bolt can derail progress. Fortunately, there are ways to remove a broken bolt, even if it's stuck deeper down.

First, it's a good idea to use a product like Blaster 16-PB Penetrating Catalyst, as it can make it much easier to move a seized bolt, especially if you still have threads to grab onto with a vice grip. PB Blaster is different from WD-40, so you'll want to pick the right one for your needs. 

If the bolt broke off inside the material and there's no part of the thread sticking out, you'll need to use a left-handed bit or even a bolt extractor in a process that involves a few steps. You'll want to be especially careful if you attempt to drill out the broken bolt, as doing damage to the internal threads could prevent you from using a new fastener after removing the broken one.

If the threads of the bolt are protruding out of the material, you don't need to drill to remove a seized bolt with no head. Instead, you'll need a good pair of vice grips that have plenty of teeth in good condition. If there isn't as much material on the teeth, such as those typically found on a well-worn tool, it'll be much more challenging to get a solid hold around the bolt threads. If you find your vice grips are lacking, you might want to consider a replacement from one of the best hand tool brands.

If you can't twist out the broken bolt by gripping around the threads with a vice grip, you can employ another method called the double nut. First, twist one nut over the threads until it's flush with the material, then twist on another until both nuts are tightly twisted together. Then, using two wrenches (one in each hand), simultaneously twist both nuts left, reversing the bolt out.

If you have the misfortune to snap a bolt inside the material, making it impossible to grab onto, you'll need to drill. However, you'll first need to start a hole as close to the middle of the bolt as possible. Use a hammer and punch to form your pilot hole into the bolt's center.

Once the hole on top of the broken bolt is started, you'll need a left-handed bit, which is unique because the threads are reversed. With the proper left-handed bit securely in your drill, you'll want to set it to reverse (like when you're loosening a fastener spinning counter-clockwise). DO NOT set the drill to tighten or spin clockwise, as this could force the bolt even tighter into the material, making your problem worse.

Place your drill with the left-handed bit over the bolt and into the pilot hole you created. Once you start drilling, don't spin the bit too fast; this process works much better at a slow speed.

If this fails to dislodge the broken bolt, you'll want to swap out the left-handed bit for a specialty broken bolt extractor. Usually, these come in a set with a wide assortment of sizes to suit a variety of jobs. While an extractor bit also features reversed threads like a left-handed bit, it includes a shape ideal for gripping broken fasteners. It isn't just broken bolts you can remedy either, as screw extractor sets can also remove stripped hardware.