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Bolts are threaded fasteners with a head on one end and a nut on the other. They join objects together and can be tightened or released using the nut. Bolt fasteners are commonly used in engineering, manufacturing, and building.

Types of Bolts

Do it Best carries multiple types of bolts, each suited for a different purpose. Consider the type of materials being fastened and the overall project goal when selecting the proper bolt.

  • Hex bolts have a hexagonal head and are used with a nut and washer. 
  • Anchor bolts are used to connect materials to concrete.
  • U bolts are U-shaped with threading on both ends. They support pipes, tubing, and ropes.
  • Retrofit bolts (RFBs) are threaded rods with a nut and washer that are secured into concrete or masonry using adhesive.
  • Carriage bolts attach wood or metal to metal. They feature a slightly domed head and are self-locking.
  • Screw bolts have threaded shanks like screws with a larger head similar to a bolt. Bolts screws can be used in hard materials like concrete where a traditional screw would not hold.

Bolt Materials and Finishes

Bolts are made of steel which is known for its strength. 

  • Steel is the most common material for bolts. It is strong, inexpensive, and is best used in applications where aesthetics are not important.
  • Stainless steel is more visually attractive, corrosion-resistant, rust-resistant, non-magnetic, and hygienic. For these reasons, it is often used in cookware,  appliances, and surgical equipment.
  • Low-carbon steel is very high strength and is often used in shipbuilding, oil and gas pipelines, and automotive applications.

Steel bolts can have additional coatings applied. Zinc provides added corrosion resistance. Hot-dipped galvanizing creates a thicker coating of zinc for even more durability. Chrome adds a polished appearance and corrosion resistance but is higher cost.

Choosing the Right Bolt Size

Selecting the proper bolt size is important. The diameter of the bolt should either be one recommended by the manufacturer of the part being bolted or a diameter that fits and fills the hole. As a general rule, the bolt diameter should be 1.5 - 3 times the thickness of the material being bolted together. 

The length of the bolt should be long enough that a couple of threads are sticking out of the nut at the end. 

The threading on a bolt can be coarse, which is thick, durable, and unlikely to strip. Alternatively, it can be fine or extra fine, which provides better tensile strength, shear strength, and vibration resistance. 

Bolt Strength and Grades

Long bolts, small bolts, and all in between are measured in tensile strength or psi (pounds per square inch).

  • Grade 2 - Low-stress, general use for non-critical joining. 60,000 - 74,000 psi
  • Grade 5  - Medium strength and automotive applications. 105,000 - 120,000 psi
  • Grade 8 - High strength for industrial machinery and automotive suspension. 150,000 psi

Head Type

Bolts have a variety of head shapes that are made to grip the tools used to tighten them. 

  • Hex heads are easy to grip and turn. They are installed with a wrench or socket.
  • Hex caps are shaped like domes and used for decorative purposes. They are installed with a crescent wrench.
  • Round caps can be used in light to medium-strength applications and provide a finished look.

Brands

Quality brands make stronger products. Do it Best carries bolts from trusted manufacturers:

Browse Do it Best’s wide selection of bolts for upcoming projects.