What Size Drill Bit for a 1/2-13 Tap?

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½-13 taps are considered small for drill bit sizes. However, you still need to know the specific measurement. To know what size drill bit for a ½- 13 tap is, continue reading and know more about how this tap is used.

What Size Drill Bit for a 1/2-13 Tap?

A ½- 13 tap uses a drill bit size of 27/64 inches or 0.4219 inches in diameter. ½- 13 taps are National Coarse threads which means they belong to the UNC. UNC or Unified National Coarse is a classification of threads mainly used in the United States and Canada.

½- 13 taps are generally used to make new threads or re-thread damaged threads similar to that of ¾-10 taps with a drill bit of 21/32″. They are also versatile when it comes to hand use. However, they can’t cut oil like the ⅝” tap with a drill bit of 17/32”.

Tips for Using Medium Drill Bits

Measure Your Drilling Depth

When you are drilling, you often need to measure the exact depth as you don’t want to drill through or leave it shallow. Sometimes, you need to make a partial hole in a workpiece so measuring the exact depth is essential.

You can measure the depth you want to drill into by placing the drill bit next to the material. Mark the exact depth you want the drill bit to go and wrap a piece of tape around it as a guide.

The tape acts as a gauge as to when you should stop drilling. This makes the drilling easier since you can accurately gauge when to stop drilling for the right depth.

Rely on Drill Guides If You Have Low or No Vision

You can buy drill guides built for medium drill bits from hardware stores. It makes drilling with medium drill bits easy as the guide will accurately place the bit into your workpiece.

If you have a drill press, you can make a set of drill guides by drilling holes with medium-sized diameters into small blocks of wood. It’s like a DIY drill guide that you can use to better your drilling accuracy.

If you can’t do either of the two options, you can ask a friend to help you make drill guides using your drill and a built-in level.

Wear Protective Eyewear

Since I’m dealing with medium drill bits, debris could fly away and land into your eyes. Accidents related to eyes are one of the most common mistakes people do when handling drills. It’s important to protect your eyes from flying debris, which might lead to serious injuries.

Wear safety glasses as a precaution. There is a lot of protective eyewear you can choose from that has different designs. Choose one that fits snugly in your head so it doesn’t slip off as you are drilling.

You can put it in a checklist before drilling so you won’t forget to wear them.


½- 13 taps have a specific drill bit size of 27/64 inches. Make sure you follow this as there are no other variations so the drill bit size is the only standard. This tap is also mostly used for making new threads and re-threading so using it other than that isn’t a good idea.