FAQs For Infrastructure Construction Bolts

Galvanized, HDG, Stainless And Zinc Carriage Bolts For Construction

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Top Questions And Answers For Carriage Bolts

Why are they called carriage bolts?

Carriage bolts are named such because they were commonly used on the frames of carriages. The square neck of a carriage bolt is compatible with the square-shape holes that are punched into a carriage’s wood frame. While they are still called carriage bolts, they are used in the fastening of wood to metal in many different applications.

What is the difference between a lag bolt and a carriage bolt?

Carriage bolts and lag bolts have some similarities, in that they are both used in wood construction, but the main differences are in their form. In carriage bolts, the threaded portion is consistently cylindrical and ends in a flat edge at the bottom. They feature a domed head and a square neck, which prevents turning after they are tightened. The threaded portion of a lag bolt ends in a point. This part of the bolt is also wider. They feature a hexagonal head.

Do carriage bolts need washers?

Carriage bolts can be installed without a washer. The dome-shaped, round head of a carriage bolt will help to more evenly distribute load across a softer material like wood. The square-shape of their collar or neck prevents the assembly from rotating and better secures it in place. If a material buffer is needed between fasteners and the installation, a washer can still be used.

How are carriage bolts measured?

Key measurements for carriage bolts are length and diameter. These measurements are taken in the same way as other types of bolts. The length is taken directly from the base of the head of the bolt to the end of the threaded portion. The bolt’s diameter is the measurement of the width of the threaded portion.

What are grade 5 carriage bolts?

Grade 5 carriage bolts are suitable for use in tougher settings. Common applications include wood to metal connections in construction, industrial, and manufacturing. As a standard, they are manufactured from medium tempered carbon steel. Grade 5 carriage bolts provide a tensile strength capacity of 120,000 psi and are compliant with SAE J429 strength and hardness requirements and ASME B18.5 dimensional requirements.

What are carriage bolts used for?

Carriage bolts are used to connect wood to metal in various lumber, timber, and other wood-based structures. They provide added stability and security through a domed head. This feature provides an extended bearing surface that prevents the fastener from losing tension and pulling through the wood in which it is installed.

What are carriage bolts made from?

Carriage bolts are most commonly manufactured from structural-grade metals, which are used to make many types of bolts. Standard carriage bolts are made from carbon steel, alloy steel, and stainless steel. They are sometimes finished with various treatments to enhance their resistance, such as hot-dipped galvanization and zinc-plating.

Do carriage bolts have shear strength?

A carriage bolt’s shear strength, tensile strength, and weight capacity are determined by the bolt’s grade, material, and diameter. When looking at grade 8 plain alloy steel carriage bolts, they exhibit a shear strength of 90,000 psi and a tensile strength of 150,000 psi. The varied strength limitations of carriage bolts will factor into the reliability of an assembly.

How do you install carriage bolts?

The installation of carriage bolts starts with the insertion of the bolt into a wood workpiece. This is done through a pre-drilled hole that’s comparable to the diameter of the bolt. The bolt’s square-shaped neck will help to prevent turning when the nut is threaded and tightened. This can be done using a hand wrench or electric tool.

How do carriage bolts work?

Carriage bolts are used in the fastening of metal elements to wood forms and frames. Their head is rounded and smooth. As a result, they are not tightened from this side but are instead secured from the nut side of an installation using a wrench. They are placed in pre-drilled holes. They have a square-shaped neck, which prevents them from turning and maintains tension