What Size Drill Bit For a 3/8″ Concrete Anchor? [Answered]

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A 3/8″ concrete wedge anchor is a handy tool used for fastening static loads. It is a mechanically designed wedge anchor with four primary parts. It is specially designed for fixing loads to static concrete.

However, the process can’t be completed without knowing what size drill bit is needed for a 3/8″ wedge anchor.

Wedge Anchor vs Concrete Anchor: What’s the Difference?

Wedge anchors and concrete anchors are both designed to fasten objects to concrete, but they function differently and are used in different scenarios.

Wedge Anchor

These are a type of mechanical anchor primarily used for attaching objects to concrete. The name comes from the wedge that is expanded inside the hole once the anchor is installed.

This expansion gives them their holding strength. They are used when the hole you are drilling into the concrete is a through-hole (meaning the hole goes all the way through the material).

Some unique features of a wedge anchor include:

  • They provide a very strong connection and are often used in heavy-duty applications.
  • Once installed, they cannot be removed without damaging the concrete.
  • They come in various materials, including stainless steel and galvanized steel, for different environments.

Concrete Anchor

This term can refer to a variety of anchor types that are designed for use in concrete, including wedge anchors. However, when contrasted with wedge anchors, “concrete anchor” usually refers to concrete screws, sometimes known as Tapcon screws.

Concrete screws are designed to thread directly into a hole drilled in concrete, brick, or block. They are often used in situations where you want the ability to remove the screw later without damaging the concrete.

Some unique features of a concrete screw include:

  • Unlike wedge anchors, concrete screws can be removed and reinserted without causing significant damage to the concrete.
  • They are typically used in lighter-duty applications compared to wedge anchors.
  • They require a smaller hole than a wedge anchor for the same diameter screw.

So, while “wedge anchor” refers to a specific type of concrete anchor, “concrete anchor” is a broader term that can refer to any type of anchor (including wedge anchors) that is designed for use in concrete.

 Wedge AnchorConcrete Anchor
DefinitionA type of mechanical anchor primarily used for attaching objects to concrete. They expand inside the hole once installed.Refers to a variety of anchor types designed for use in concrete, usually refers to concrete screws when contrasted with wedge anchors.
RemovabilityCannot be removed without damaging the concrete.Can be removed and reinserted without causing significant damage to the concrete.
ApplicationUsed in heavy-duty applications and through-hole drilling.Used in lighter-duty applications, no need for through-hole drilling.
MaterialsCome in various materials, including stainless steel and galvanized steel.Usually made as concrete screws, sometimes known as Tapcon screws.
Hole Size RequirementRequires larger hole for the same diameter anchor.Requires smaller hole for the same diameter screw.

How to Install a Wedge Anchor

Step 1: Select The Right Tools

You need a hammer drill to create an initial hole in the concrete.

Remember to operate the drill in hammer and rotation mode. This is important to ensure that the drilling process is simpler and the hole created is perfect.

A hole made without a hammer drill may result in the imperfect fitting of the anchor. In addition, the process of drilling is much more tedious when done without the hammer drill.

Hammer drill

Step 2: Take Necessary Measurements

The sum of the thickness of the material to be attached and the diameter of the anchor to be installed needs to be calculated. Take the space required for nuts and washers into consideration.

The sum of the above two quantities determines the minimum length of the wedge anchor that is needed.

  1. To have more holding value, installing the wedge anchors at a much deeper depth than the minimum value calculated.
  2. The diameter of the bit must be the same as the anchor to be installed.
  3. Chuck an ANSI standard carbide-tipped masonry bit into the hammer drill. 
  4. ANSI standard bits should be used to maintain proper hole tolerance. This is needed to have an appropriate hole and anchor diameter.

The minimum holding value will be determined by the hole tolerance and needs to be properly measured. This article has more information on wedge anchors.

Step 3: Drill The Hole And Check Its Depth

After you have taken the necessary measurements, it is time to proceed with the actual drilling. If you have doubts regarding the measurements, it is best to repeat the process.

  1. Drill a hole in the concrete that is deeper than the minimum depth required.
  2. The minimum depth embedment for the anchor diameter must be met for the process to be completed seamlessly. The minimum depth for a 3/8″ wedge anchor is one and a half inches.
  3. Place a tape on the bit at the required depth to check the depth of the hole made. You can also set a depth gauge on the hammer drill.
  4. The bit should be in a retracted position when you set the depth gauge on the hammer drill or when you place the tap. 
  5. The bit is retracted when it is in its most inward position inside the chuck of the drill.
Man holding drill bit pieces that fits a 3/8 wedge anchor

Step 4: Clean The Hole And Install The Edge

Clean the hole properly after it had been successfully drilled.

  1. Remove all dust and debris from the hole you have drilled, as this helps to enhance the holding value of the wedge anchor. A vacuum cleaner or a wire brush can be used for cleaning the hole.
  2. Use the wire brush to initially clean the hole and then use a vacuum cleaner. Repeat this process multiple times to ensure that all the dirt has been removed.
  3. Now that the hole is cleaned, you are ready to install the anchor wedge. The anchor wedge comes with the exact number of nuts and washers needed. Make sure you don’t lose them.
  4. Place one washer over the threaded end of the anchor body.
  5. Thread a nut in a clockwise direction onto the anchor body to flush the top of the nut with the top of the anchor body to preserve the anchor’s thread during installation. 
  6. Place the fixture on the anchor after installing it through a hole in the fixture. You can install it on the concrete directly as well.

The drill bit size needed for a 3/8″ concrete wedge is 3/8th of an inch. Make sure you have the drill bit of appropriate size before you proceed further.

This video on using an anchor wedge will help you understand the process better.

Some measures need to be taken, which depend on the material of the surface being drilled.

Through Fixture

Use the hole in the fixture to insert the anchor’s clipped end and attach it to the concrete.

Tightly fix the nut and washer to the concrete’s surface. Strike the end of the anchor’s nut with a hammer to make sure that the attachment is firm.

The anchor should be embedded to the minimum embedment depth recommended in data sheets available on the internet.

Person changing his drill bit

Direct Through Concrete

Pass the clipped end of the anchor through a hole that is already drilled in the concrete. 

  1. Embed the anchor into the concrete to a minimum depth by using a hammer. Use it to strike the nutted end of the anchor.
  2. There should be enough threads above the concrete to ensure proper attachment and at least three to five threads inside the concrete.
  3. Tightly set the anchor in the concrete by rotating the nut in a clockwise direction.
  4. Turn the nut further with a wrench in the clockwise direction. Do this till the specified value of anchor depth is reached.

Do not turn the anchor too much as it may cause damage to its threads and reduce the holding value of the anchor.

Frequently Asked Questions

Can You Remove a Wedge Anchor From Solid Concrete?

Yes, you can remove a wedge anchor from solid concrete like ductwork or light posts. There are essentially three ways to do this. First, pound the anchor with a hammer into the concrete if the hole is deep enough beneath the anchor. Second, cut the anchor from the surface using a cutoff wheel, and flatten the pound with a hammer. And lastly, simply use a bolt breaker to break the excess rod off from the surface. 

What Is the Correct Drill Bit Size for ⅜ Concrete Anchor?

The drill bit size for a ⅜ concrete anchor should always be the same as the diameter of the anchor. Keep in mind that the terms “concrete anchor” and “wedge anchor” are the same.

How to Choose and Use Drill Bits | Ask This Old House

Conclusion

Choice of the drill bit size is a simple but essential step before the drilling operation. If you carefully find the model of your drill or make sample holes, you will find the perfect drill bit size and have an easy time drilling.

An expert at home repair, remodel, and DIY projects for nearly 40 years. His first experience came in completely restoring an antique home. Completely redone from the inside out, and restored to its original form, the home is a featured design by renowned Southern California Architect Cliff May, considered to be the father of the California Ranch Home. Now Dennis spends his time on fine woodworking projects and tool comparisons.