What Size Of Drill Bit Should Be Used For A 8-32 Tap?

Finding the correct tap drill size is daunting, especially if you are new to the space. You might find some charts over the interview, but those are confusing because of several figures. It may still become a challenging task while looking through several size availabilities.

Looking for the correct size in a hardware store is a daunting task because of the several items on display. Finding a tap drill size is a challenge, especially for people who do not know much about it. This article focuses on the best 8-32 tap drill size.


The most commonly used drill bit for an 8-32 tap is a size #29. It is 0.136 inches in diameter.

In this article, we’ll also take a look at the following:

  • The best drill bits out there
  • Why do you need a pilot hole?

Several sections in this article will contribute to a better understanding of it, which will be helpful in the long run. Some topics we will cover are how to drill and use an 8-32 tap. 

What is tap drill size?

It is challenging to wrap your head around a tap drill size if you don’t know it. This article mentions the term several times, so knowing what it means and its practical uses will go a long way.

We use a tap drill to cut a cylindrical opening through a metal material. It creates threads through the hole, accepting a screw and holding it in place. Essentially, it is an attachment tool used for the metalwork technique of tapping. Moreover, we can use the attachment to rethread or repair damaged fixings. You can use it with a die tool to create external and internal threads.

Humans use screws, bolts, and nuts to clamp two or more parts together. This practice has been around since the middle ages. The early fasteners use wood, but modern ones are mostly metal. The load is directly proportional to the size. As such, a larger size means a heavier load. A table requires a smaller fastener than a ship or cargo. These craftsmen use handmade mating components.

A tap drill bit has three main types – taper, intermediate, and bottoming tap. Metal machinists are hugely familiar with these parts, so they know more about them than others. 

The bottoming has a flat head with little to almost no tapering. You will notice a little taper from the shaft to the tip of the bit. It can form a fully-threaded hole in the material, but it does not go through the other side of the application area. A good example is when you need to screw the legs into the platform or base. The machinist will need to start the process by using a tapered bit.

On the other hand, taper and intermediate taps have a significant taper from the tip to the bottom part. Between these two, the intermediate is the more common one. They assist in aligning the threads while tapping through an unthreaded hole. We recommend using the tapered bit for harder materials because of a more gradual taper. 

Drill bit size for an 8-32 tap


The best-fitting size for an 8-32 tap is the #29 drill bit size. It is equivalent to 3.454 millimeters or 0.136 inches. We recommend against guessing the size because this will lead to issues in the long run. 

Best products

Most people prefer looking into a curated list of the best products. The following items we will cover below are the best for an 8-32 tap. You can find everything on Amazon, so you only need to look at one site.

BOSCH BDT832 Combo Set

The BOSCH BDT832 is a drill bit and tap combo, providing a secure drilling method through a hole size before the right-hand internal threads. The inclusive drill bit matches the tap, which does not contain a no-skate tip.

A heat-treated carbon steel tap ensures maximum speed and durability. Moreover, the rolled tap threads are cleaner and more accurate than machined threads.

The set should contain one 8-32 high-carbon steel plug tap and one #29 wire gauge drill bit.

NameBOSCH BDT832 8-32
Item Weight‎0.81 ounces
MaterialHigh Carbon Steel
Package Dimensions‎5.9 x 1.8 x 0.2 inches
Shank TypeStraight


  • Bosch is a great brand.
  • It’s been treated for additional durability.
  • It worked great on aluminum.
  • Drilling holes with it was a breeze.


  • The Bosch BDT832 is sometimes not available on Amazon.
You can trust Bosch.

TEMO 2 pc Combination Set

The TEMO 2-piece combination set offers several sizes, including the 8-32 option. It uses high-speed M2 steel for surface applications that include copper, steel, aluminum, and brass. It offers a three-in-one deburr, tap, and drill operation. The tapered design prevents thread damage due to over-drilling.

The 135 self-centering split point tip guarantees accurate drilling for its size. For maximum longevity, we recommend cleaning the tap after use. You can also reverse drill after completing it.

TEMO offers US-based customer service through phone, chat, email, or in-store. You can drop by the customer service center in La Crosse, WI, as of the time of this writing. We recommend checking their website for the most updated address before proceeding to the center.

The company offers a wide selection of goods and specialized equipment for business applications and home improvement.

NameTEMO 2 pc 8-32 Combination
Item Weight‎0.634 ounces
Manufacturer‎Golden Coulee
Product Dimensions‎3.5 x 4 x 0.25 inches
Size‎2pc bright 8-32


  • It made 15 threaded holes with no problems.
  • Great value product
  • It seems very durable.
  • It worked on steel tubing.


  • Temo is not a big name in the space.
  • A few customers have had these break relatively fast.
Have you heard of Temo?

IRWIN (80217)

The IRWIN 8-32 drill set is ideal for threading and creating fasteners for metal applications. It makes about 32 threads per inch of measurement. The drill bit takes advantage of high-speed steel for precise and accurate drilling. On the other hand, the tap uses high-carbon steel for general applications.

Finish TypeBlack Oxide
Item Dimensions LxWxH0.2 x 1.52 x 5.54 inches
Item Weight‎0.48 ounces


  • Irwin has been around for almost 150 years.
  • We tried finding these at the local hardware store but could find the drill bit at Amazon.
  • We like both the drill and tap are in the same package.


  • They will eventually break.
  • They don’t remind you to use drilling oil.
Irwin is big in home improvement.

Century 95305

The Century Drill & Tool uses a high-carbon steel machine screw tap, making it a durable tool for daily use. Its precision-cut threads promote accurate threading.

The combo pack contains a drill and tap combination, which are compatible. The tap threads have a precision cut, allowing exact and consistent threading throughout. It is heat-tempered and treated for a longer life.

On the other hand, the drill bit features premium-grade high-speed steel for all your drilling needs. A 135-degree quick-cut point promotes self-centering. It also penetrates faster while requiring less pressure.


  • Century Drill is based in America.
  • It’s a great set with both drill & tap.
  • The price of this Century Drill product is great.
  • It’s sharp and works great.


  • We wish it were possible to see how it came packaged.
  • Remember to use lubricating oil.
Century Drill & Tool
Let's get you started with your projects.

Drill America, POU Series

The Drill America #8-32 tap and bit kit utilizes a high-speed plug hand tap with a matching high-speed steel bit. These are great for CNC and general machine-tapping applications. A plastic pouch comes with every purchase for easy storage and packing.

These are black oxide high-speed steel drill bits, making them an excellent choice for general-purpose applications. Its hardness and toughness combined promote wear resistance. 


  • They seemed high quality.
  • They achieve what you need them to.


  • There have been some issues for some of the other users.
Steel plugs
Do you need to make holes?

What to consider

man using a drill

Reading through a set of guidelines is beneficial before drilling. There are a few things worth considering before getting into it.

The first step we recommend is knowing the correct drill and tap sizes for your application. Several dimensions are available online, so finding the exact one you need is important. Make sure to get the correct size because it makes or breaks the next steps. If unsure, we recommend using scrap metal first to get an idea.

Using the correct size helps avoid getting into problems and costing more.

Why use a pilot hole?

We encountered a pilot hole in this article, but we have never discussed its relevance. This section explains the importance of it and why drilling one is important.

Driving a screw through a material without a pilot hole is like pushing wood to make room for the screw. It displaces wood and puts pressure on its surroundings, leading to cracking and splitting in the long run.

In several cases, having a pilot hole is important because of several reasons. It guides the screw as you drive it into place. It makes it easier, whether using a screwdriver or a power drill. Not having a pilot will require you to apply more force, making it a chore. Moreover, applying too much force may cause the screw to break. However, it only usually happens with cheap, low-quality screws. 

How to

You start by gathering all the tools and materials you need for the project you are planning to do. We recommend mounting two clamps for the piece you are working on to prevent slipping and twisting.

Wear safety equipment and protection before engaging in any activity. It prevents injuries and accidents from happening. Gloves and goggles are some of the important gear we recommend because it protects your eyes and hands. You can also wear a long-sleeve shirt to protect your arms from debris.

We recommend positioning your tool at a 90-degree angle from the material’s surface. A good angle prevents issues from driving the screw onto the application surface.

drill bit

How to use the products above

You have the option to use a cordless or corded drill. However, inexpensive ones may not be powerful enough for your use case. Before starting the process, prepare a pilot hole. We also recommend using a drilling lubricant to ease things.

Connect the 8-32 tap using a hand tap or T-handle. You can make the threads by hand if working with a thin metal. A power drill is a way to go if you are short on time.

The 8-32 tap is an excellent size when working with metal objects. You can use a portable drill for tiny metal pieces. You might need a metal drill press when working with bigger parts. 

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