How to Drill Out a Broken Bolt (5-Step Method)

Stuck or broken bolts can be a nuisance in any project or repair, but there are ways you can easily pull them out!

In some situations, the bolt can be lodged deep in a metallic hole or exposed to the surface. Some people like to either forget them leave them in or try to remove them incorrectly, damaging the parts around them. I have been on a few repair jobs where broken or stuck bolts have been forgotten and neglected, causing rust and other damages. Knowing how to remove them can serve you well in avoiding shelling out on a handyman.

Drilling out broken and stuck bolts from metal holes is easy.

  • Use a center punch to make pilot holes at the center of the broken bolt
  • Drill the pilot hole with a left-hand drill bit until the broken bolt grabs onto the drill bit extracting the bolt
  • You may also use a hammer and a chisel to bite the broken bolt until it is removable
  • Heating the broken bolt with a flame weakens the broken bolt
  • Welding a nut on the broken bolt also works fine

I will go into more detail below.

What You Need

Fetch the following tools to make your work easy

  • Reverse or left-hand Drill Bit
  • Pliers
  • Hammer
  • Source of heat
  • Welding equipment
  • A nut
  • Chisel
  • Spanner
  • Penetrant

Method 1: Turn the Broken Bolt the Right Way

turning broken bolt the right way

The simplest technique to use to extract a bolt from a metal surface or hole is by turning it in the right direction.

This technique is quite applicable where the bolt is not strongly attached to a surface, and when it is somewhat projecting above the surface.

Simply grab the bolt with a pair of pliers and turn it in the right direction.

Method 2: Remove the Broken Bolt with a Hammer and Chisel

You can still remove a broken bolt with a hammer and a chisel. Proceed as follows:

  • Grab the correct size chisel that fits in the hole and incline it at an angle favorable for hammering.
  • Hit the chisel with a hammer until it goes into the broken bolt.
  • Keep doing that around the broken bolt until it becomes possible to remove the broken bolt.
  • Once the bolt is exposed above the surface, you can weld a nut and remove it (method 3).

Method 3: Weld a Nut Onto The Stuck Bolt

Welding a nut onto a broken bolt is another viable solution for stuck bolts. It is the easiest technique so far if you have a welding machine.

However, this method is not suitable if the broken bolt is lodged deep in the recess or where it was fixed. The steps below will guide you through this method:

Step 1. Scrape off the metal fragments or dirt from the stuck bolt using any relevant object.

Step 2. Next, identify the correct size nut that matches the broken bolt. Align it on the surface of the broken bolt. To prevent the nut from sliding off, you may apply super glue and fix it on the broken nut before welding. You can use any other technique to secure the nut during welding.

Step 3. Weld the nut on the broken bolt until it sticks firmly. The heat generated during welding will also help in loosening the nut. Weld on the inside of the nut for effectiveness.

Step 4. Use a correct size spanner to remove the broken bolt welded on the nut.

Method 4: Use a Reverse Drill Bit

Reverse Drill bits can also be crucial in removing broken bolts. Unlike the welding technique, you can use this method to remove even the deep-lodged bolts.

However, you will need the correct drill bit to suit your situation. Follow the steps below:

Step 1. Position a center punch close to the middle of the stuck bolt. Hit it squarely with a hammer to enable the drilling of the pilot holes. Then, use a reverse drill bit to cut a pilot hole in the broken bolt.

Making a precise pilot hole is critical to avert any damage to the bolt threads. Damaging the threads can cause major issues or even render the entire extraction process impossible.

Step 2. Use a reverse-drilling setting such as 20 RPM to drill into the pilot hole gently. The drill bit is made of hardened steel. So, if it breaks off while drilling, you may experience more problems extracting it.

While reverse drilling, the stuck bolt will eventually grab onto the drill bit, extracting it. Go on steadily and slowly until the whole bolt gets extracted.

Step 3. Use a magnet to remove the broken bolt’s metal shaving or debris left behind during reverse drilling.

Caution: do not insert a new bolt without removing the metal debris. It may seize or sheer off.

Hover a powerful magnet above the hole to capture the metal debris. Alternatively, you can use compressed air to blast the metal shaving. (1)

Method 5: Apply Heat

Here, the broken bolt is weakened by applying heat and then removed. Procedure:

  • First, spray the joint with PB Blaster penetrating oil and wait a few minutes.
  • Use a rag to soak the excess penetrant. The oil is not super-flammable, but it will catch fire if there is plenty of unelaborated liquid.
  • Next, light it up with a propane flame. Always aim the torch to point away from you for safety reasons.
  • After igniting the stuck joint, heat the bolt. Repeated heating and cooling are highly effective. (2)
  • When the bolt is loosened, you can use a spanner or any other effective tool to pull it out.

applying heat to broken bolt
Video | Hagerty

Take a look at some of our related articles below.




References
(1) metal debris – https://www.sciencedirect.com/topics/engineering/
metallic-debris
(2) heating and cooling – https://www.energy.gov/energysaver/principles-heating-and-cooling

Video References

Hagerty

Ultimate Handyman

About Sam Orlovsky

b1d87d2ee85af3e51479df87928bdc88?s=90&d=mm&r=gI realized early on carpentry was a huge passion for me and I’ve stayed in the industry for over 20 years now. This gives me a unique ability to really be able to tell you what the best tools and recommendations are. I’m not only a carpenter but I also like machinery and anything to do with electrics. One of my career paths starting off was as an apprentice electrician so I also have a lot of experience with electrical products and anything related.