What Size Drill Bit for a 5-40 Tap?

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5-40 taps are often used for many things related to tapping. If you don’t know what size drill bit for a 5-40 tap should be, you’re probably doing a bad job at re-threading. You should know the proper drill bit size for it to work effectively.

What Size Drill Bit for a 5-40 Tap?

A 5-40 tap needs a size drill bit of 0.1015 inches in decimal or a number 38 drill bit. The 5-40 tap much like the 2-56 tap, is part of the National Coarse or the UNC, which stands for Unified National Coarse, which is a standard thread followed by the United States and Canada.

Drill with an attached drill bit

5-40 taps are generally used to re-thread or clean up threads, much like how ½- 13 taps are used with the sizing as the only difference. They can also be used for general purposes and have excellent wear resistance, making them good for through or blind hole tapping.

Tips for Using Large Drill Bits

Make Use of the Hammer Action

Some drills have the hammer action feature. This allows you to “punch” on a hard surface repeatedly. For example, if you’re drilling through concrete, you might want to turn on the hammer action to make the drilling efficiency.

Hammer action is a great feature, especially when using large drill bits for concrete. Concrete is hard to drill without the right equipment.

The hammer action makes a vibration that transfers to the drill bit that, gives it better penetration. This will lessen the time for you to drill on concrete and be less taxing on the drill bit since it’s supported by the hammering motion to penetrate the surface.

Avoid Jamming Your Drill

One common thing when using large drill bits is jamming. It’s a common mistake amateur drillers make since they usually apply more pressure when drilling, which leads to jamming. You should learn how to avoid jamming your drill.

When you jam your drill, you might have to replace the tip, and your drill’s lifespan will shorten. You want to avoid spending more than you should when it’s avoidable. One thing you can do is not apply too much pressure when drilling.

Different kinds of drill bits placed upright

Also, feel the drill and spot when you think it is slowing down. Pull it out when you think it’s slowing down and let it cool for a while, cleaning off any debris stuck in the drill.

Learn the Proper Safety Precautions

When handling large drill bits, it’s important to practice safety to avoid accidents. You don’t know what might happen when drilling, or you might have overlooked something.

That’s why it’s not bad to learn about safety practices when drilling. Practice them and make it a habit when working on a drilling project.

One thing you can start with is wearing protective gear such as:

  • Drilling hand gloves
  • Masks
  • Safety glasses or goggles
  • Tight clothing

Starting with these and making it a habit to wear one will minimize the chance of accidents. Reading the manual before you start using the drill is also a great habit.


5-40 taps are commonly used since they are around the medium-sized range. Now that you know the actual drill bit size, which is #38, you should follow the proper dimensions to produce good handiwork