A449 Round Head Bolts Appropriate For Wood Connections

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Questions And Answers On Round Head Bolts

Where Are Round Head Bolts Used?

Round head bolts are commonly used to fasten wood to wood or wood to metal. They are frequently chosen for projects like connecting guardrails, fencing, and wooden infrastructure components.

They are appropriate for light-duty and standard-duty applications involving wooden pieces. Heavy-duty applications may require a different fastener choice.

What Is The Difference Between Round Head Bolts And Carriage Bolts?

The shape of the neck beneath the head of a bolt distinguishes a carriage bolt from a round head bolt.

A carriage bolt has a square neck, unlike a round head bolt. The square neck on a carriage bolt reduces the possibility of the fastener turning after it has been tightly installed.

What Are The Advantages Of Round Head Bolts?

Round head bolts offer the advantage of eliminating the need for washers when making wooden structural connections. Their wide, dome-shaped heads provide sufficient surface area to distribute force like washers.

Although they are ideal fasteners for structural components, they are appropriate for light-duty wood connections as well.

What Are Round Head Bolts?

Round head bolts are ideal fasteners for connecting wooden structural elements. Their dome-shaped heads result in a smooth, low profile after installation. Their shafts are fully threaded, and the necks have a cylindrical shape.

The rounded heads work similarly to a washer in that they distribute force and enhance the stability of structural connections.

What Are Round Head Bolts Made From?

Round head bolts are usually manufactured from carbon steel. Medium-carbon steel is used to make ASTM A449 bolts that are rigid and strong.  Low-carbon steel is the source material for ASTM A307 round head bolts.

Treatments that resist corrosive elements, like hot-dip galvanization, are an available option for round head bolts.

What Are ASTM Standards For Round Head Bolts?

ASTM standards describe the material, dimensions, and mechanical properties of round head bolts.

ASTM A449 round head bolts are made from medium-carbon steel.  ASTM A307 round head bolts are made from low-carbon steel. Both kinds of bolts come in lengths of 6 to 18 inches and diameters of 1/2 to 1-1/4 inches.

How Long Are Round Head Bolts?

Long round head bolts are needed for industrial construction applications that require fastening metal to thick pieces of wood. Their lengths start at 6 inches and go up to 18 inches.

Round head bolts in lengths below 6 inches are intended for light-duty fastening on structures or equipment.

How Are Round Head Bolts Measured?

The sizes of round head bolts are determined like other structural bolts.

The measurement from immediately below the head to the end of the threading forms the length. The thickness of the shaft, including the threads, represents the diameter. Thread sizing varies according to thread pitch and number of threads per inch.

How Are Round Head Bolts Installed?

Installation of round head bolts requires placing them through pre-drilled holes. They are then tightened by threading on a nut from the end.

Their smooth, rounded heads cannot be loosened or tightened like a hex or socket head bolt. When adjustment of a round head bolt is necessary, the nut must be turned.

Are Round Head Bolts And Button Head Bolts The Same?

Round head bolts and button head bolts are not identical.

Button head bolts and screws have a higher curve on their dome-shaped heads compared to round head bolts. Button head fasteners also have a recessed drive where a screw bit fits to complete the installation.

Round head bolts have lower head profiles and are usually tightened with a nut.