Most common drill bits are of the twist bit variety and are called this because the flutes on the bit twist around and up the bit.
Typical twist drill bits have flutes that twist to the right in a clockwise direction. Less commonly seen are left-handed drill bits, which have flutes that twist in a left-handed or counter-clockwise direction.
The most common use of left-handed drill bits is for drilling out bolts, and if that’s what you’re here for I put together a 5 step guide halfway through the article below.
Left-handed drill bits were once used when it was easier to change the drill bit than to change the drill rotation.
Left-handed drill bits are available in many sizes and lengths, but their limited use can make them difficult to find.
General-use twist bits are the most common left-handed drill bit, but some have flatted shanks to prevent twisting in the drill chuck.
Removal of broken fasteners is the most common use for left-handed drill bits. Since right-handed fasteners are loosened by turning to the left, the torque applied by a lefthanded drill bit loosens the fastener.
Fasteners that have broken off in a threaded hole can be a time-consuming problem to repair. Left-handed drill bits can save time and money by easing the removal of the broken fastener.
Use of the Left Handed Drill Bits
Left-hand drill bits remove broken screws, bolts, and studs. I’m planning to discuss removing a broken bolt in this how-to guide therefore, this guide will be about bolts.
You can loosen the right-handed bolts by turning them to the left. So, left-hand drill bits use the same principle. These drill bits rotate bolts to the left, and eventually, the bolt will loosen. If you get it right, this is one of the easiest ways to remove broken bolts.
Tip of the Day: Never store your right-handed drill bit with your left handed ones. Keep them separately. Once they get mixed up, it is hard to figure out which one is which.
However, in some cases, the broken bolt won’t come out easily. If that is the case, I got a few tricks up my sleeve that might come in handy for you. To learn them, follow the below guide.
Be mindful of: Unlike right handed drill bits, the lefthanded drill bits rotate counterclockwise.
5-Step Guide on How to Use Left-Handed Drill Bits to Drill a Bolt
The most common use of left-handed drill bits is for drilling out bolts. That’s why we couldn’t create a guide about left-handed drill bit uses without a detailed guide on drilling out bolts with them.
If you aren’t familiar with the lefthanded drill bits, this guide can greatly help you. But remember, follow the below steps precisely. Sometimes, you won’t get the broken bolt out the first time. In that kind of situation, don’t get frustrated. Try it again. This process demands pinpoint accuracy and some training.
Step 1 – Gather the Necessary Tools
First and foremost, you should collect the necessary tools. You’ll need the following tools.
- Drill with a reverse gear
- Left handed drill bit set
- Center drill bit set
- Manual or automatic center punch
- Safety gloves
- Safety glasses
- Thread cutting oil
- Screw extractor (optional)
- Spanner (optional)
Step 2 – Wear Safety Gear
For this type of drilling process, wearing the necessary safety gear is necessary. Wear safety gloves to protect your hands. After all, you are dealing with sharp objects.
Also, safety glasses can protect your eyes. During this process, small metal pieces can break off and jump up and go inside your eyes.
Step 3 – Mark the Center on the Bolt
Then, mark the center of the bolt. You can approach this in two ways. You can use a manual or automatic center punch.
If you use a manual center punch, you’ll need a hammer too. Place the center punch on the center of the bolt and tap it using the hammer.
If you use an automatic center punch, you don’t need a hammer. Place the automatic center punch on the bolt and press the switch.
However, some automatic center punches are not powerful enough. So, you might have to use the manual center punch and hammer after using the automatic one.
Be mindful of: It is vital to place the center punch close to the bolt’s center as much as you can. The success of this entire process largely depends on that.
Step 4 – Start the Drilling Process
Now, you can start the drilling process. I’ll break down this step into two parts.
- Drilling with the center drill bit
- Drilling with the left handed drill bit
Drilling with Center Drill Bit
Before using the left handed drill bit, it is wise to use the center drill bit. When you use a center drill bit, you can accurately drill the marked center. For some, using the drill in reverse gear (while using the left handed drill bit) on a flat surface can be challenging. But it will be much easier on a drilled hole. So, first, drill the bolt using the center drill bit. Only drill a few centimeters.
Be mindful of: Here, only use the center drill bit to create a hole.
Drilling with Left Handed Drill Bit
Now take the left handed drill bit and connect it to the drill.
Remember to use similar size drill bits for this process. Also, both drill bits should have less diameter than the bolt. After connecting the drill bit, put the drill in reverse gear. That means the drill bit is now rotating counterclockwise.
Be mindful of: Ordinary drills and drill bits rotate in a clockwise direction.
Then, start the drilling process. Maintain a slow speed and apply pressure. The drill should be straight during this process. (1)
Slowly the drill bit will go into the bolt and will loosen the bolt.
But in some cases, the bolt won’t loosen. If so, go to the next step.
Step 5 – Use the Screw Extractor
In this step, I’ll show you how to loosen the bolt using the screw extractor. Follow these steps.
- Make sure the bolt is drilled over half of its length.
- Remove all the metal filling on the drilled hole. (2)
- Insert the right-sized screw extractor into the drilled bolt.
- If the screw extractor grabs the bolt without much effort, your job will be much easier. If it doesn’t, take the hammer and tap on the head of the extractor.
- After tightening the bolt and the extractor, take the spanner and rotate the screw extractor counterclockwise to loosen the bolt.
Don’t break the screw extractor inside the bolt during this extraction process. If you do that, loosening the bolt might be nearly impossible. Most screw extractors are made with hard metal. Because of that, drilling them is no easy task. So, avoid such a situation in any way possible.
You can use the same technique to loosen a screw. But remember, if you plan to loosen a small screw, you’ll need drill bits with a smaller diameter than the broken screw.
How Can I Sharpen My Left Handed Drill Bit?
You can sharpen your left handed drill bit by using left hand chucks. Using these chucks is pretty easy.
Do All Drills Come with a Reverse Gear?
Unfortunately, no. Some drills only rotate in a clockwise direction. With these drills, you can use the right handed drill bits. But you cannot use the left handed drill bits.
What Does R and L Mean On a Drill?
If you need to drill forward (in a clockwise direction), you should put R gear. To drill in reverse, put L gear. In other words, for cutting or screwing, put the R gear. Put the L gear for unscrewing.
Take a look at some of our related articles below.
- How to cut electrical wire
- How to drill out a broken bolt
- How to drill out broken bolt in engine block
(1) apply pressure – https://www.sciencedirect.com/topics/engineering/
(2) metal – https://byjus.com/chemistry/metal/
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