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A nut screws on to a bolt, creating pressure. This pressure fastens components together. There are a variety of different types of nuts. The main types of nuts used in robotics are hex nuts, wing nuts, crown nuts, and lock nuts.


Hex Nuts

Hex nuts are used most frequently during prototyping because they are easy to remove. As their name suggests, they are hexagonally shaped and have a threaded hole in the center. The size of the nut, the diameter of the hole, and the nut's thread count come in a variety of sizes.

A hex nut.

Wing Nuts

Wing nuts are very similar to hex nuts but they have two "wings" that may make it easier to tighten and loosen the nut by hand.

Wing nuts.

Crown Nuts

Crown nuts are a normal hex nut with a metal "crown" on one side. Crown nuts are not lock nuts! When tightened against metal, the crown bites the metal, holding the nut in place and allowing the bolt to be tightened with a single wrench. This is useful for prototyping, but should not go on the final robot, as crown nuts shake loose and come off.

Lock Nuts

Lock nuts cannot be tightened by hand after a certain point where they lock. Unlike other nuts they resist loosening by vibration and a certain amount of torque. After the nut locks, a ratchet or wrench is necessary for further tightening.

Lock nuts.



To tighten a nut, simply place it on the bolt you wish to tighten. Turn the nut to the right using either your hand or a wrench.


To loosen a nut, one will need two wrenches or a wrench and a ratchet. Place one of the wrenches over the head of the bolt, and either the ratchet or the other wrench over the nut. Keep the first wrench in place to prevent the bolt from turning, as you turn the other wrench to the left, loosening the nut. Loosen the nut until it can be removed.

Safety and Other Tips

  • Righty-tighty, lefty-loosey!
  • Never lock nut anything until you are sure that it is in its final position.
  • Only lock nuts go on the final robot.
  • If you are having trouble tightening a nut, you may need to add some washers to increase surface area and allow the nut to screw on tighter.
  • Do not over tighten as this may cause the material to bend. This is especially important when using thin aluminum.