8-32 Tap Drill Size

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If you have all the charts but are still confused about what drill bit you should use for an 8-32 tap drill size, how to calculate, and how you can use an 8-32 tap, you’re in luck! Because we have been working hard to bring you all the facts you need to complete your project.

What Size of Drill Bit Do I Need for an 8-32 Tap?

The #29 drill bit is needed for a #8-32 tap. It is the same as a 3.454-millimeter drill bit, which measures 0.136 inches.

How to Know the Drill Bit Size for 8-32 Taps

Decimal measures, in both inches and millimeters, are employed for drill bits. For instance, a #29 drill bit has a diameter of 0.136 inches (or 3.454 millimeters). Additionally, this drill bit can also be used with the #8-36 NF tap.

Drill Bit Size for 8-32 Taps

Not to be confused with fractional tap sizes (such as 7/16, 3/16, 5/16), #8-32 is a solid size. There are drill bits that you must measure in inches and millimeters rather than the closest fractional size, so keep that in mind.

8-32 Tap Sizing

There is little difference in how a tap is used, no matter how big or small the object is. As you would any other drill bit, attach the #8-32 tap drill bit to your drill as you would any other drill bit. 

Regarding threading metals for screws and bolts, an #8-32 tap can be your best bet. Before forging any metal together, this is the most important step. You’re on the correct path if you build anything out of steel or aluminum [1].

How to Calculate the Tap Drill Size

To calculate your tap drill size, you only need basic calculations and the size tap you’re using. To begin, measure the diameter of the tap. You can physically measure the diameter or refer to the tap’s specifications.

Tap Drill bits

Once you know the diameter, you can use the formula DH=DMB -.0130 (% of thread desired/Ni).

How to Drill With an 8-32 Tap

If you’re working with smaller metal objects, be sure they’re fastened down. Utilize a corded or cordless drill, though inexpensive cordless drills may not be powerful enough. But, you can still drill precise holes with threads for little screws and bolts.

We recommend creating divots or holes before the drilling process. You can accomplish this with a center punch. It’s also a good idea to add drilling lubricant before you start. Center punches will make drilling holes easier and more precise.

You can also use a hand tap or T-handle to connect the 8-32 tap. If you’re working with a thin metal, you can make the threads by hand. If you’re short on time, it is faster to drill holes with a power drill and a #8-32 tap drill bit.

Drilling on a piece of metal

A #8-32 tap can be helpful when working with metal. Use a portable drill for drilling tiny pieces of metal. For larger parts, you might wish to use a metal drill press.

For a drill press, make sure that huge metal parts are fastened down with a vice or C-clamp suitable for such objects. As previously stated, if you have a #8-32 tap drill bit (#29), attach it to the drill and get to work immediately.

What is the Pitch of an 8-32 Tap?

The pitch of a #8-32 Tap is 0.794 mm. To measure the distance between two points on a screw thread, measure the distance between them. When dividing by the thread per inch, the pitch is determined by multiplying by one. 


What is the diameter of an 8-32 tap?

The diameter of an 8-32 tap is 0.164 inches or 4.166 mm. You can measure the diameter of the thread using a ruler, then measure the length of the thread. 

Using your tap thread measurement, you can determine which tap connector is compatible with your device.


We hope our guide has been useful if you’re looking for a drill bit appropriate for a #8-32 tap drill size. The more durable a drill bit is, the more metalworking projects it may use. 

Thus, using the right size drill bit for your woodworking projects is important.

Robert Johnson is a woodworker who takes joy in sharing his passion for creating to the rest of the world. His brainchild, Sawinery, allowed him to do so as well as connect with other craftsmen. He has since built an enviable workshop for himself and an equally impressive online accomplishment: an extensive resource site serving old timers and novices alike.
Robert Johnson
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