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Can You Install A Lag Screw Into Concrete?

Can You Install A Lag Screw Into Concrete?

The short answer is Yes! You can install a Lag Screw into concrete. Installing a lag screw into concrete is not a difficult process but it does require an anchor to install properly.

Lag Screw and Lag Shield

Lag shields are concrete anchors that expand near the bottom to hold the shield inside of a drilled hole. They are made specifically for the installation of lag screws into masonry materials.

To install a lag shield into concrete first drill a hole that is the same diameter as the outside diameter of the lag shield. Before drilling you will also want to measure the length of the lag shield and drill down the length plus a little extra space .

Next take a hammer and tap the lag shield down into the hole you’ve drilled until its flush with the surface. Since the hole is the same size as the outer diameter, this should create a snug fit for the anchor.

Installing A Lag Screw Into Wood

Next make sure you have a lag screw long enough for the installation. For example, if you wanted to install a 2 x 4 to the lag shield, you would need to make sure the lag screw had 1-1/2″ of clearance and then about another 1″ to 1-1/2″ to install into the shield. This means you would need roughly a 3″ lag screw to complete this installation.

Once you have the proper lag screw, begin fastening the lag screw into the installed shield. This will push the lag shield apart in the hole creating a strong hold to keep your installation in place.

Types Of Masonry Anchors

Types Of Masonry Anchors

There are many types of masonry anchors available today. The problem for many is determining which of these anchors they need to perform the job. Listed below are some of the more common fasteners found in the masonry field.

Drop In AnchorsDrop In Anchors With Setting Tool

A Masonry Drop In Anchor is mostly used in poured concrete.  They are used in high strength applications by fastening a bolt into the internal threading of the anchor. They are also available in coil threading (a coarser thread for coil threaded rod). Some masonry anchors have a lip to prevent the anchor from dropping too far into the concrete.

To install the drop in anchor, drill a hole the same diameter as the anchor and only as deep as the anchor itself. Then drop the anchor into the hole and seat the setting tool inside of it. Then hit the setting tool with a hammer. The bottom portion of the anchor will deform resulting in a wedged anchor that cannot be removed.

Lag Shield AnchorsLag Shield Wedge Anchors

A Lag Shield Concrete Anchor is used in combination with a lag screw to create an anchor in concrete. Lag shields are made of two parts and when the lag screw is driven into the shield, it expands resulting in a tight wedge in the concrete.

Lag Shield Anchors are very similar to a drop in anchor but are designed specifically to take a lag screw. Lag screw anchors also do not require a setting tool to install.

Masonry Concrete Screws

Masonry Concrete Screws, sometimes referred to as Tapcons, are probably the Tapcon Masonry Concrete Screwsmost common concrete fastener used. Concrete screws are easy to identify based on their bright blue coating. They are used for fastening wood or metal to different masonry materials. They are available in both Phillips flat head (for flush finishes) and hex head (for ease of installation).

Installing a concrete screw is very simple. First, drill a hole through both materials and then simply drive the screw into the hole. Make sure you use a screw that is long enough to reach through both materials otherwise you will not have a firm hold.

Sammys Hanging AnchorsSammys Screws

Sammys Screws are a common anchor used for hanging applications. Most often installed vertically or horizontally, these anchors have a threaded opening used to receive threaded rod. Sammys are commonly used in HVAC applications for hanging duct. The term Sammys, much like Tapcon, is a brand name. There are many types of these hanging anchors available.

To install a Sammys screw, first drill a hole into the material and use a wrench or socket to drive the anchor into the material. Once installed to the silver head, remove the wrench and screw in a piece of threaded rod.

Hammer Driven Pin AnchorHammer Drive Pin Anchor

A Hammer Driven Pin Anchor is a small anchor which is mostly used to fasten plywood to concrete. These anchors are very simple to use. They have a lip over the head making it compatible with holes that may have accidentally been driven too far into the material.

To install one of these pin anchors, drill a hole through both materials and drop the anchor into the hole. Once the lip is seated against the top of the material, hit the exposed pin with a hammer. The pin is driven down through the middle of the fastener pushing both sides out in a wedge fashion holding the fastener in place.

Toggle Wing AnchorsToggle Wing Anchors

A Toggle Wing Anchor is used when a hollow wall is present. This is common when cinder blocks are used to create the walls of a building. They are also commonly used in drywall applications. It is not recommended to use heavy weight on these anchors especially in drywall as they will rip through the material.

To install one of these anchors, first a hole must be drilled big enough for the toggle portion of the anchor to push though. Once in the hollow part of the wall, the toggle wing will expand. Then using either a Phillips or Slotted head screwdriver, the bolt is driven into the toggle wing pulling it against the other side of the wall. This allows the bolt to tighten down on the material being hung.

Double Expansion Shield AnchorDouble Expansion Shield Anchor

Double Expansion Shield Anchors are used primarily used in brick and block. As a screw is driven into the anchor, it starts to pull down towards the middle resulting in an expanded anchor. These anchors only expand so much. The reason for this is to prevent brick from cracking.

To install a double expansion shield anchor, simply drill a hole large enough for the anchor to drop into and then install the screw into the anchor. As you fasten the screw it will pull the bottom towards the middle and force the top down to the middle as well. The result it a limited but effective amount of expansion on the anchor. The limit of expansion highly reduces the chance of cracking brick or block.

Sleeve AnchorsSleeve Anchors

Sleeve anchors are fairly simple to use and are primarily used in brick or block. They can be used in concrete but are not considered as strong as a wedge anchor. So, for light to medium holding applications, a sleeve anchor is a good choice. There are two common types of sleeve anchors. They are the Nut Drive which is commonly used for extra strength and Phillips/Slotted Combo Driven Flat Head which is used when a flush surface is required.

To install the nut driven style, drill a hole and place the sleeve anchor into the hole. Then place the washer and nut onto the exposed threading and begin fastening the nut. As the anchor is pulled up out of the concrete, the sleeve around it begins to expand wedging the anchor into place inside the hole. You can install the Combo Flat head style in much the same way except you are using a Phillips drive and the installation will leave the top flush with the surface of the installation material.

Wedge AnchorsWedge Anchors

Wedge Anchors are extremely popular and are one of the strongest anchors for hold strength. Wedge anchors look and function like a sleeve anchor but have a much smaller sleeve near the bottom of the anchor.

To install a wedge anchor simply drill a hole that is the same size diameter as the anchor and place it into the hole. After placing the material being held to the concrete on the exposed portion, place the washer and thread the fastener onto the anchor. As the nut is tightened against the washer, it will begin pulling the anchor up. This will result in the wedge skirt catching the concrete and expanding and digging into the concrete as the anchor is pulled.

Thread Pitch Vs. Threads Per Inch (TPI)

Thread Pitch Vs. Threads Per Inch

Thread Per Inch (TPI)

Threads Per Inch (TPI)

Threads per inch, commonly abbreviated as TPI, is a term frequently used when talking about fasteners.

TPI is a term used to help identify how many threads are in an inch. To determine treads per inch an inch of the bolt is measured and then the peaks on the fastener are counted. In the picture you can see there are 5 peaks in the inch measurement. This means the TPI of this fastener will be 5. When looking at an example bolt measurement:

1/4″-20 x 2″

The 1/4″ refers to the bolt diameter (in inches), the -20 refers to the threads per inch meaning that there are 20 threads per inch on this bolt, and the 2″ refers to the length (also in inches).

Thread Pitch

Thread Pitch

Thread pitch is the term used to calculate the difference between two threads. For metric fasteners, thread pitch is used in place of TPI. The distance is also measured in millimeters.

To measure thread pitch, use a caliper and measure from the peak of one thread to the next.

M2 x .4 x 5M

The M2 refers to the diameter of the bolt (in millimeters), the .4 refers to the thread pitch in millimeters meaning that there are .4 millimeters between each thread peak and the 5M refers to the length of the bolt it millimeters.

Why It Matters

Thread Pitch and Threads Per Inch are both used to measure the threading of a bolt or nut to ensure that they are going to couple together properly. If the threading of a bolt and nut are different they will either seize or strip the threading resulting in an unusable connection.

A Word About Fine And Coarse Threading

Fine thread fasteners have a tighter helical structure and are usually less pronounced. A coarse thread fastener has larger deeper and more forgiving threads (meaning if the threading gets lightly damaged they may still work). Most standard fasteners and metric fasteners have a fine and a coarse thread version. You can identify each of them by using the TPI or Thread Pitch.

For US Fasteners, you might see 1/4″-20 and 1/4″-28. To determine which of these is coarse thread and which is fine, simply take the TPI number (the 20 and the 28) and compare. Remember a coarse thread means the threads are bigger so less will be able to fit within an inch so the 20 means the fastener is coarse thread and the 28 means the fastener is a fine thread.

*The TPI and Thread Pitch will change based on the diameter of the fastener so you will not always see 20 and 28.

For metric fasteners, you will see a M8 x 1.25 or an M8 x 1. For thread pitch, the distance between two points is the second number meaning the higher the number the fewer threads there are. This means the M8 x 1.25 is the coarse threading and the M8 x 1 is the fine thread.


For more information about fasteners check out Fasteners 101.

Black Oxide Coating: What Is Black Oxide?

Black Oxide Coating: What Is Black Oxide?black oxide treated lock washers

Black Oxide, sometimes called blackening, is the act of converting the top layer of a ferrous material with a chemical treatment. Treating fasteners with a black oxide coating not only adds a nice clean black look but can also add a mild layer of corrosion and abrasion resistance. To achieve the maximum in corrosion resistance, black oxide can either be waxed or oiled to add an extra layer of protection. The wax coating may dull the color of the treatment but provides the best resistance. The black oxide treatment is also referred to as gun bluing.

When fasteners are dipped into the black oxide bath materials (warm and hot processes) the harsh chemical components convert the top layer into magnetite. Black Oxide Stainless Steel Nuts Bolts and Washers are the most common form of black oxide fastener available. Prized both for the corrosion resistance of stainless steel with the added benefits of the black oxide treatment.

Materials That Can Get The Black Oxide Treatment

blackening finishing cup washers

  • Stainless Steel
  • Copper
  • Copper Based Alloys
  • Zinc
  • Powdered Metals
  • Silver Solder

The Black Oxide Processes

Blackening can be achieved in a number of different ways. There are three main ways to do this. If you are interested in the specifics of each type check out this article from Wikipedia.

Hot Bath

The process of treating the fasteners in different chemicals in order to convert the surface material into magnetite. The process is completed by dipping the fasteners into different tanks and occasionally placed in water. Once the process of dipping is completed the top layer of the fastener is porous and a layer of oil is applied. The oil seeps into the material adding that extra corrosion resistance to rust. This process creates a black oxide bath that complies with MIL-DTL-13924, AMS 2485, ASTM D769 and ISO 11408 standards.

Cold Coating

The cold process applies a compound (copper selenium) onto the fasteners at room temperature. This process is more convenient for working in house as it does not require many chemicals at heated temperatures to apply. Once applied it is considered weaker than the other forms of oxidization until a layer of oil or wax is applied to the surface.

Mid-Temperature Bath

Like the hot bath treatment method but does not produce the same toxic fumes of the hot bath and the surface is converted to magnetite at a much lower temperature. This method can also meet the same military standards that the hot bath version produces.

Benefits Of Black Oxide Fastenersblack stainless steel socket set screws

  • Does not significantly change the dimensions of the fasteners as hot dip galvanizing does.
  • A cheaper alternative to other methods of corrosion resistance such as electroplating.
  • An appealing look when a bright shine is not desired.
  • The process can normally be done in large quantities which makes it faster and cheaper for smaller sizes.
  • Reduces the risk of galling by adding an oil finish
  • Decorative finish
  • Adds a layer of mild corrosion and abrasion resistance
  • Paint sticks well to the black coating if painting is required

Will Black Oxide Bolts Rust

Black Oxide adds a mild layer of corrosion and abrasion resistance to fasteners. Like any material, black oxide treated fasteners can rust in the right environments. It will depend on if the fastener is damaged or marred, the type of metal with the black oxide treatment and environmental conditions.

Disadvantages Of Black Oxide

Black oxide is not nearly as corrosion resistant as some of the other options available to improve corrosion resistance.

The black oxide finish can be easily rubbed off. To prevent this, put some painters tape over the tip of your bit to create a tighter fit and prevent scratching in the event of a slip out of the drive.

The Black residue from the fasteners may come off of them so for certain applications it is recommended that they are wiped down before use. This extra step can be labor-some if many fasteners are needed.

Black oxide fasteners are largely used in the automotive industry due to their sleek black look. This look can deteriorate very quickly though in hot environments. Often, after a black oxide coat is applied to a fastener, they are placed in an oil bath for an extra layer of protection. The oil residue that stays on the fasteners will begin to turn brown when in high heat environments. So many users find they bolts look like they rust prematurely. It is not recommended to place black oxide bolts on or near engines.

Custom Coating For Fasteners

black stainless nylon insert lock nuts

Our company offers custom black oxide orders VIA phone orders. Can’t Find what you need in black oxide? Give us a call at 866-573-445 for pricing and availability!

Custom Fasteners and Hardware

How To Avoid Breaking Spanner Bits

Avoid Breaking Spanner Bits

Broken Spanner Bit

The spanner drive style is still an uncommon drive style for most people to just have lying around.

This uncommon bit makes screws more resistant to tampering and removal without the proper bit. Due to this, a spanner bit is often referred to as a “tamper-proof” or “security” bit.

The Problem With Spanner Bits

As great as spanner “snake eye” bits are for adding security to an assembly, they also have some downfalls. Spanner bits are made to fit a very specific drive size. If they are used with the wrong size it becomes increasingly likely that the bit will break.

Spanner bits are also more prone to snapping than any other bit type. The spanner bit has two prongs that are inserted into two holes in the head of the screw. Pressure is then directly applied to only those two prongs (across a very small area) which causes the screw to turn. Other bits can have as many as six sides pushing on the head making it less likely that they will break by spreading the load across multiple points of contact.

Spanner bits are commonly avoided for this reason but there are actually a few easy steps you can take to avoid most of the common reasons spanners break.

Steps To Avoid Breaking Spanner Bits

Always Pre-Drill Into Hardwood

Hardwood can be particularly difficult for screws to cut into. We recommend pre-drilling a pilot hole even when the screw has a self-drilling tip. Pre-drilling a hole removes much of the wood that would be in the way and allows a screw to more easily install.

Avoid Coming To A Hard Stop

Drilling into knots or using a screw that is too long where it can hit metal on the back of the installation surface can cause the screw to seize in place. This sudden seizure will place all of the pressure upon the bit prongs and more than likely cause them to snap.

Avoid Over-Installation (Over-Torquing) Of The Screw

When installing the screw, make sure to stop once the head reaches the installation material. Attempting to screw the fastener in further will increase the amount of torque required to turn the screw dramatically.


Watch As Bob demonstrates this with one of our own spanner bits.

*No spanner bit regardless of quality will stay in tact if you do not take care when installing spanner drive screws. It’s the nature of the bit design.

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