What Size Drill Bit for a 9/16-12 Tap?

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A 9/16-12 tap is rarely used since they are mostly for re-threading and cleaning. Hence, it’s no wonder you’re here checking what size drill bit for a 9/16- 12 tap. If you want to know more about the sizing, read further.

What Size Drill Bit for a 9/16-12 Tap?

A 9/16- 12 tap requires a size drill bit of 31/64 inches or 0.4844 inches in decimals. The 9/16- 12 tap is classified as NC or national course just like the 4-40 tap. This means it’s a coarse thread or also known as UNC (Unified National Coarse).

UNC is the term commonly used in the United States and Canada. They have lesser threads per inch and are usually applied deeper compared to fine threads. 9/16- 12 taps are generally used for re-threading or cleaning up threads just like the 5/16- 18 taps with a drill bit of 17/64″.

9/16- 12 taps can also be used for general purposes if needed. It can cut into most metal and plastic so it’s ideal for small-scale tapping jobs. They’re not like the ⅝ taps with a drill bit of 17/32” which can either be NC or NF.

Tips for Using Medium Drill Bits

Deburr the Hole

Most medium drill bits are used for drilling holes. So, deburring the hole is a sensible thing to do. After you’re done drilling, make sure the hole does not have sharp edges or burr left in the hole. Feel the hole until it’s smooth.

It ensures your hole is smooth and clean, so you produce quality work. You can deburr a hole by running it in a bit of power and running the bit around the edges of the hole.

You can also use deburring tools to make the process simpler and easier. Most of them come with an instructional, so you should have no problems learning to properly use them.

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. 

Consider Using Stud Finder

A stud finder ensures you are not drilling into a water pipe or electric cables. Drilling through electric cables can create a huge accident, like electrocuting yourself. So, it’s best to use a stud finder as a safety precaution.

It’s also useful to avoid hitting water pipes which can cause leakage and flooding in your home. You should use a stud finder when drilling with hazardous materials near the drilling spot.

If you’re drilling into an unfamiliar surface, it’s best to use a stud finder to ensure you are drilling precisely and accurately. It’s better to be safe than sorry.


9/16- 12 taps use 31/64 inches for drill bit sizes. It’s mainly used for re-threading and cleaning up threads. Make sure you use the right sizing for it to work effectively. Other than that, you can also use it for general purposes as long as you use the right material.