What Size Of Drill Bit Should Be Used For A #8 screw?

Finding the correct drill bit size for drilling the perfect fit for a hole is difficult. Each application will likely need a different drill bit size, so there is no one-size-fits-all here. You will find several choices as soon as you arrive at the hardware store. It makes it challenging to find home improvement items.

Knowing the specific materials you need will lessen the challenges of purchasing in-store or online.

4 screws on a table

What is tap drill size?

Getting a strong understanding of the tap drill size is important in fully understanding the topic. You will encounter this term several times, so knowing its meaning will help you along the way. We utilize the tap drill for cutting a cylindrical opening, typically in metals. Why is this process significant? The threads created as part of the process allow it to accept a screw.

The tap is a hard metallic material with threads. It acts as the female part of the mating pair because you insert it into the hole created by the tap drill. The male part is either a screw or a bolt. Manufacturers cut the threads in metal cylinders using a special die, a process we call threading.

On a different note, humans have long used screws, nuts, and bolts to secure parts together. Since the middle ages, the industry has acknowledged it as a global standard. Modern fasteners use metal, while earlier versions use wood. The fastener’s size is directly proportional to the load. A heavier load requires a larger piece, while a lesser load requires a smaller one. A table or chair requires a smaller one than a ship.

Accurate measurements are the most significant factor during the size selection process because it uses a hardened bit to drill a hole in a metal surface. Removing excess metal decreases tension and stress in the application area. We need to avoid these imbalances to prevent inaccuracies in the measurements.

We take the length and diameter when sizing the tap drill. It is a countersink hole, making it wider on the top and tapers through the tip.

6 Piece Slotted & Phillips Screwdriver Set

Drill bit size for a #8 screw

We do not recommend guessing the tap size for a #8 screw because it will lead to inaccurate measurements. Getting precise measurements is important to prevent issues from happening. The drill size translates to the thread count.

Screw SizeDrill Hole Size for SoftwoodDrill Hole Size for Hardwood
#51/ 16”5/ 64”
#65/ 64”3/ 32”
#73/ 32”3/ 32”
#83/ 32”1/ 8”
#93/ 32”1/ 8”
#107/ 64”1/ 8”

We recommend using a 3/32-inch drill bit on softwood and 1/8-inch on hardwood. These are for a #8 screw.

The 1/8-inch drill bit is the closest you will find that matches the diameter of the #8 screw. It measures about 0.125 inches or 3.175 millimeters. You can use a tapered bit with a larger diameter if you need to drill a pilot hole. We suggest using a 0.071-inch / 11/64-inch / 4.36 millimeters bit. 

Best drill bits for a #8 screw

A curated list of the best bits for the #8 screw is what most people need. These are some of the best drill bits for a #8 screw. You will find all these products on Amazon, so you only have to look in one place for everything you might need.

DEWALT Countersink Drill Bit Set 3-Piece (#6, #8, #10)

The DEWALT Countersink DW2535 is a three-piece set containing bits #6, #8, and #10. You can counterbore, drill, and countersink in one step.

Unlike other brands and models, the Dewalt 3-piece set works excellently on softwood and hardwood. It provides enough countersinks to sit on the surface of your application. We recommend using a 3/8-inch plug cutter with this set.

FTG USA Countersink Drill Bit 5-Piece Set (#4, #6, #8, #10, #12)

The set contains a four-flute cutter #45 carbon steel countersink with an HSS M2 tapered bit. It contains the following sizes.

  • #4 (7/64-inch)
  • #6 (9/64-inch)
  • #8 (11/64-inch)
  • #10 (3/16-inch)
  • #12 (7/32-inch)

It also has an improved countersink connection drill bit to a 1/4-inch hex shank. We can replace the tapered drill bit with an FTG replacement taper bit countersink. We recommend using it for wood surfaces.

You can also adjust the countersink bit with the adjustable counter bore that attaches to a flat shank.

FTG USA provides test reports from the US Third-Party Accredited Testing Laboratory, ensuring all products have passed quality standards and inspections.

AUTOTOOLHOME 6 Pack Titanium Combination Drill Tap Bit Set

The AUTOTOOLHOME set uses HSS 4341 taps, which are fast, durable, and sharp. The surface has a titanium alloy coating, improving cutting performance and promoting wear resistance. These effectively extend the product’s service life, making it worth your money.

It has a three-in-one operation, including tapping, deburring & countersinking, and hole drilling on the most common materials, such as sheet metal, copper, aluminum, brass, and plastic.

Each piece has an engraving with a label, making it convenient for you to choose the size you need. The quick change hex shank tapers through the end and prevents excessive knocks from occurring. The back taper prevents damage and over-thrilling.

The set comes with a durable and lightweight storage case, so everything is safely kept in one place.

COMOWARE Left Hand Drill Bit Set, 13 Piece

The COMOWARE drill bit set has a 135-degree twist and split-point design, increasing cutting speed. Its self-centering feature prevents walking and clears chips quicker.

The bits utilize a high-speed M2 steel with a titanium nitride coating for durability. You can use it as a screw extractor, removing broken fasteners. The reversible drills remove studs, screws, and bolts around different applications, such as the garage or house.

You will find the following bits in this set – 1/16, 5/64, 3/32, 7/64, 1/8, 9/64, 5/32, 11/64, 3/16, 13/64, 7/32, 15/64 and 1/4. A metal case houses all these bits, allowing for easy carrying and storage.

Drill Hulk 13-Piece M35 Cobalt Drill Bit Set

The Drill Hulk 13-Piece cobalt set uses high-speed steel and 5% cobalt material, increasing heat resistance. The cobalt provides more durability performance than the typical HSS drill bit.

You can sharpen it several times without damaging the drill. We recommend using it on hard metal surfaces, including stainless steel.

The set contains 13-piece cobalt drill bits ranging from 1/16-inch to 1/4-inch (increments of 1/64-inch). A plastic case protects it from damage and loss. 

What to consider when drilling?

box of self-tapping screws

Our recommendation is to read through some guidelines before starting the drilling work because there are several things worth considering before it.

You can proceed with drilling as soon as you find the correct tap drill size and material. Using scrap metal before performing the process on the actual product is ideal if it is your first time. Getting the idea of it is important so you know what exactly to do.

Using the correct bit size is the best way to do it. You can avoid unwanted costs and errors if you have enough knowledge of the work you will be doing.

Researching for the correct diameter and length is an important step to knowing the exact one to pick and use. 

Why drill a pilot hole?

Here are the top reasons why drilling a pilot hole is an important step to take:

  • It prevents jacking from occurring
  • It tightens the joints
  • It prevents wood pieces from splitting
  • Easy joint alignment
  • It keeps the screws from misaligning
  • You can easily countersink the screw
  • You can prevent the breaking and splitting of the screw

How to drill?

This section provides a high-level summary of the correct way to drill. You start by gathering all the necessary tools and materials for the project. We recommend using mounting clamps to keep the piece in place. It prevents slipping and spinning from happening. Moreover, it minimizes injuries from occurring.

We recommend preparing and wearing protective clothing and equipment. Gloves and goggles are some of the most common protective gear you can use. A long-sleeve shirt is also a good idea to prevent debris from contacting your skin.

Use a painter’s or masking tape to mark the area where you wish to create the hole. Ensuring a stable foundation and solid support is vital when working with flexible or thin materials. It will prevent deformation or slipping from happening, but this is not unavoidable. 

How to use a #8 screw?

Here is a step-by-step guide on how to use a #8 screw.

  1. Create a threaded pilot hole, allowing a screw or bolt to slide in easily. It is almost impossible to get it inside without creating a pilot hole.
  2. Have the bolt and tap available for a visual comparison.
  3. Practice making a hole into a scrap material to know if you have the correct sizes.

You can apply the same steps with other tap sizes available in the market. Researching prior to application is our recommendation because there might be other things worth considering or knowing. There might be slight differences in how to use a specific size, so figuring it out firsthand is beneficial.

FAQ

The following are the frequently asked questions.

What size hole do I drill for a 3/8-inch 20 tap?

The diameter of the drill bit should be 5/16 inches and have a length of six inches.

Why are most drill bits kept at a 118-degree angle?

Maintaining a 118-degree angle allows for a more aggressive cut, which is most favorable with wood. On the other hand, a steeper angle dulls quickly. 

What size hole do I drill for a 5/16 tap?

We recommend using a G or F drill for this tap size. The sizes of these are 0.2610 inches and 0.2570 inches, respectively. 

What is the pitch of a 10-24 tap?

The pitch of a 10-24 tap is 0.1629 inches.

What size hole do I drill for a 10/32 tap?

The accurate drill bit size for a 10/32-inch tap is 5/32 inches or a #21 drill bit. In other words, you need a small amount of allowance to keep your glass items from breaking. 

What is the next size up from a 5/8 drill bit?

The next size up is 11/16 inches.

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