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How to Use Left-Hand Drill Bits?

Back when the option of reverse gear was not available on drills, left-hand drill bits were used for this purpose. Nowadays left-hand drills are used to extract broken fasteners.

While normal bits have clockwise twists, left-hand drill bits have counter-clockwise twists.

If you are ever stuck in a situation where you have stripped or broken a screw or bolt, left-hand drill bits can actually save you from the frustration of dealing with a broken fastener that does not budge.

Broken fasteners are one sticky situation to be in and if not extracted properly can manage to ruin your work material.

If you are left with a broken fastener or are in general curious about the use of left-hand drill bits, I have answered all the questions in your mind in this article.

How to Use Left-Hand Drill Bits? For removing a broken fastener first make a mark in the fastener with a center punch. Now drill into the fastener using a left-hand drill bit with a drill on reverse gear. Drill 2/3 times the length of the fastener into it. If you have not already been able to remove the fastener, you can now use the hole for using other extractors.

Throughout my DIY journey, I have had to deal with a number of broken fasteners and have tried every other tool under the sun. While there are several tools and tricks available on the internet, left-hand drill bits are my first choice for removing a broken fastener.

In this article, I have compiled a comprehensive guide for using left-hand drill bits as an extractor.

What are Left-Hand Drill Bits For?

left-hand drill

At times you end up breaking or bending a fastener and it doesn’t really matter. But in some situations, you just have to get that fastener out and that’s exactly when you are going to need a left-hand drill bit.

A left-hand drill bit is the easiest and most efficient tool for extracting a broken fastener without damaging the work material.

If used probably, a left-hand drill bit alone can do the job for you. But if the fastener doesn’t budge with the left-hand bit, you now have a hole available for using other extractors.

I personally suggest that every DIY enthusiast should invest in a left-hand drill bit set as it proves to be worth every penny you spend on it. And while you might not need them too often, they will really ease your job once you do.

You can easily find left-hand drill bit sets (Check on Amazon) as well as left-hand drill bits with screw extractors (Check on Amazon). You can select any of these options according to your use and budget.

How to Use Left-Hand Drill Bits for Removing Stuck Bolt?

A stuck bolt can be really difficult to extract, based on why exactly it is stuck. Bolts that are stuck due to corrosion tend to be more difficult to remove as compared to bolts that are stuck due to material failure.

I have compiled a foolproof step-by-step guide for you to accomplish this task without breaking a sweat.

Step 1: Gather Tools

The first step for any task is gathering all the tools that you are going to need. For removing a stuck/broken bolt with a left-hand drill you are going to need the following tools:

  • Left-hand drill bits
  • Cordless drill with reverse gear
  • Center punch
  • Hammer
  • Thread cutting oil or penetrating oil
  • Safety glasses
  • Safety gloves
  • Screw extractor(optional)

Step 2: Safety Precautions

left-hand drill bits

Now that you have gathered all the tools, you need to make sure you are taking the necessary safety precautions.

As you will be drilling metal, there can be flying metal shards during the process. Wearing your safety glasses and gloves will protect you from any injury caused by the debris.

Step 3: Mark the Center

left-hand drill bits

There is one main factor that can decide the success or failure of your extraction. This factor is whether or not you manage to drill in the exact middle of the bolt.

To avoid making any mistakes in this regard, use a center punch and a hammer to mark the center of the bolt. This indentation will help guide your drill bit.

If you have an automatic center punch it will make your job much easier and you will not need to use a hammer.

Step 4: Drill it

Now you need to drill with a left-hand drill bit with a diameter less than that of the bolt. Even if you are not able to remove the bolt at this step, using a left-hand drill bit will ensure that the bolt is not driven in tighter.

Follow these steps for drilling:

  • Add some thread cutting oil to the bolt. It will really facilitate the extraction.
  • Now fix the left-hand drill bit in the drill.
  • Put the drill in reverse gear.
  • Put your drill bit on the indentation mark and hold your drill straight.
  • Drill at a slow speed and apply pressure.
  • The bit will bite into the bolt and it will start unfastening with the rotation of the drill.
  • Even if the drill bit doesn’t bite drill 2/3rd the length of the bolt.
  • Remove all the metal fillings.

Now if you have managed to get the bolt out at this point you do not need to move to the next step.

And even if you have failed to extract the bolt with the left-hand drill bit don’t worry, you are now one step closer to extracting the bolt.

How to Use a Screw Extractor?

For using a screw extractor you have to follow the steps given in the above section first. Now assuming that you were not able to extract the said bolt you will now follow the instructions given below to use a screw extractor:

  • Turn the screw extractor into the hole you have drilled.
  • Screw the extractor until it grabs hold of the bolt.
  • If the extractor doesn’t bite the bolt try using one size bigger.
  • Once the extractor is holding the bolt, keep screwing slowly to take out the bolt.

One thing you should keep in mind while using a screw extractor is that you do not want to break it inside the bolt. Screw extractors are made with hardened metal and are even more difficult to drill out.

You can avoid breaking your extractor by using it manually instead of using a drill at slow speed.

Related Questions:

What is the purpose of left-hand drill bits?

Left-hand drill bits are mainly used for extracting broken bolts and screws. They are either used as a facilitator for an extractor or work as an extractor themselves.

How to sharpen left-hand drill bits?

Many drill sharpener manufacturers also provide left-hand chucks for sharpening left-hand drill bits. Using these chucks you can easily sharpen your left-hand drill bits with your normal drill sharpener.

Which way do you drill with left-hand drill bits?

With a left-hand drill bit, you have to use your drill in the reverse gear. You cannot use left-hand drill bits with a forward gear on your drill so make sure you are using the reverse gear.