Buying Guide

Types of Nuts and Bolts

Bolt Types
Description Feature/Benefits Recommended For
carriage bolts Domed, enlarged head shape Designed to keep bolt from pulling through Attaching metal to wood
hex bolts Also called hex cap screws, have six-sided heads and machine threads Works with a tapped hole or a nut Construction and machinery applications
u-bolts Shaped like the letter "U" with screw heads on either end Works with pipes and other round materials Plumbing and HVAC applications
lag bolts Also known as lag screws, not used with a nut Extremely sturdy and tough, can handle a lot of weight Framing lumber, installing floors, heavy-duty jobs
specialty bolts Various sizes, from less than a millimeter to over 20 inches long Specifically designed and manufactured for a particular commercial use Electronic, military, marine, mining and construction fasteners
Hardware Nut Types
Description Feature/Benefits Recommended For
axle hat nuts Also called an acorn nut or cap nut, has a domed top Hides edges of bolts, gives seamless appearance Electrical panels, stereo cabinets, automotive
hex nuts Six-sided, used with hex bolts, attached with a wrench Can access them from any angle, easy to loosen and tighten Works with any fastener with threaded rods
jam nuts Half as tall as standard hex nuts Size makes it easier to fit in tight spaces Securing an item onto a bolt without applying torque or force
lock nuts Also known as prevailing torque nuts Locking action, resistant to loosing from vibrations Washing machines, automotive, prolonged vibration uses
push nuts Can be capped or uncapped, installed with a special nut driver Distributes load, reduces stress to surface, speedy assembly Secures unthreaded bolts and other fasteners
rod coupling nuts Hollow threaded fastener, also called extension nuts Joins two male threads together, can be used as a spacer Tightening rods, installing plumbing pipes
speed nuts Also called a sheet metal nut, has two metal pieces that function as one Does the job of both a nut and a locking washer Hard-to-reach locations, blind assembly situations
square nuts Threaded nut with four sides, has various internal platings Makes other fasteners stronger, minimizes damage from rough edges Used in furniture, metal channels
tee nuts Has a flange at the end of a long, threaded body Leaves a flush surface Fasten composite materials, wood or plastic
u-nuts Made from one piece of rolled thread Reliable and strong, can be made of plastic to prevent scratching Hold two or more sheet metal panels together
wing nuts Has two projected pieces of metal or "wings" Easily loosened or tightened without tools Good for uses that require periodic tightening or loosing
Common Bolt and Nut Finishes
Two hex bolts lying beside one another

Bolts and nuts can be made of various materials such as steel, titanium or plastic. The finish or plating on a metal bolt or nut affects its look and durability. Below are some common finishes and benefits:

  • Zinc - Most common, low cost, resists corrosion and rust
  • Nickel -  Very hard finish, higher investment, good corrosion resistance
  • Chromium – Bright finish, good rust and corrosion resistance
  • Chromate – Adds color, shine, superior rust resistance
  • Anodizing -  Aluminum, hard oxide surface, excellent corrosion resistance