- Requirements for Drilling out a Broken Drill Bit
- Safety Measures Before you Begin
- Procedure for Drilling Out a Broken Drill Bit
- Tips to Prevent Drill Bits from Breaking
It is not uncommon for a drill bit to break. It can be very frustrating when it snaps while drilling a hole and gets stuck inside. This guide is for drilling out a broken drill bit without causing further damage. Locking pliers can also be used to take a drill bit out, but only if the bit’s end is clearly visible and there is enough space to grab it with the pliers. If the bit is embedded deeply or is coated with lubricating oil, you will have to drill it out.
Requirements for Drilling out a Broken Drill Bit
You will need the following seven additional items to drill out a broken drill bit besides showing a little extra patience:
- A screw (or tap) extractor that is smaller than the hole
- A tapered drill bit with reverse threading (conical shaped)
- A centerpunch
- A hammer
- A wrench
- A chisel or file
- Cutting (or lubricating) oil for lubrication and preventing overheating (optional)
Safety Measures Before you Begin
A few precautions before you begin to extract the broken drill bit: The two snapped ends of the drill bit may be sharp or hot, or both, so work carefully! Also, it is recommended to wear eye protection for your own safety in case a tiny shard or other object flies in your face. Another thing to note is that this method is only likely to be successful if the bit is at least ¼” in diameter. If it is less than this, you may have to use another drill bit roughly the same size as the broken one but stronger to drill it out completely.
Procedure for Drilling Out a Broken Drill Bit
Here is the procedure for drilling out a broken drill bit in six steps:
Step 1 – Smoothen the Surface
Chisel or file off jagged edges, if any, to flatten and smoothen the surface of the broken drill bit’s end.
Step 2 – Create a Divot
Create a small divot (hole) on the bit’s broken end by striking a hammer on a center punch placed on it. There should be a small guide hole at the end of the broken bit.
Step 3 – Attach a Smaller Drill Bit
Insert a drill bit into the drill machine (or power drill) shorter in diameter than the broken one you are trying to extract. Apply lubricating oil on its tip, if necessary, and position it directly on the divot you created.
Step 4 – Drill Into the Broken Bit
Drill straight and slowly into the broken bit’s end to a depth of around ¼” to ½” as necessary. Gradually speed up the drilling while applying stronger pressure. In case the drill heats up, wait a few minutes for it to cool before resuming. (1)
Step 5 – Fit the Screw Extractor
With the cone-shaped end of the screw extractor placed in the divot, tap its end with the hammer so that it is securely in place. Then, slide the extractor’s metal collar down, as far as it will go so that the extractor holds tightly onto the broken drill bit.
Step 6 – Remove the Broken Drill Bit
With the wrench on the top end of the extractor, slowly turn the extractor in an anticlockwise direction. The broken bit that was stuck inside the hole should slowly start turning until it is completely removed. If it does not come out easily, apply more cutting oil to lubricate the threads of the broken bit before trying again.
Tips to Prevent Drill Bits from Breaking
Having removed the broken drill bit out of the hole, it would be wise to know how to prevent this from happening again in the future. Removing and replacing broken drill bits can be time-consuming and costly. Here are some prevention tips you may find helpful to make your drill bits last longer:
- Lubricate the Drill Bit – Always lubricate your drill bit before using it, especially when drilling into a hard material such as steel, or other rough surfaces where it could break. The oil reduces friction, prevents overheating, and thus minimizes the chances of the drill bit breaking. (2)
- Attach Drill Bits Firmly – Always insert the drill bit inside the drill machine as far as it can go for a strong grasp, and tighten the chuck firmly. A loose drill bit has a greater chance of breaking no matter what type of surface you drill into because you cannot drill straight with a wobbly drill bit attached.
- Speed up the Drill Machine Gradually – When drilling, start slowly and speed up gradually. Drilling immediately at a high speed can cause overheating and increased strain on the drill bit due to which it is more likely to break.
Take a look at some of our related articles below.
- How to use left-handed drill bits
- What size drill bit for 3/8 lag bolt
- What is a step drill bit used for
(1) Gradually speed up – https://www.ncbi.nlm.nih.gov/pmc/
(2) reduces friction – https://www.sciencedirect.com/topics/physics-and-astronomy/friction-reduction
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