Slotted Hex Nuts in Plain Steel

Slotted Hex Nuts are hex nuts with slots protruding from the top, similar to castle nuts. To use a slotted nut, a hole is drilled through the threaded portion of a bolt or stud. A cotter pin is then placed through the slots and hole and deformed so it cannot easily be removed. This creates a locking effect that prevents the nut from spinning free of the bolt or stud.

Slotted nuts are similar to castle nuts but usually have a lower profile than a castle nut of the same size. Slotted hex nuts are generally preferred to castle nuts due to their lower profile. The cotter pin locks the slotted nut into place, which eliminates the need for other locking-type fasteners. This means no lock washers are needed when using a slotted nut.

Plain Steel

Having a plain "finish" means this fastener is very vulnerable to corrosion. Plain fasteners are best used in non-corrosive, indoor environments and are the most economical choice for such applications. After all, if it isn't going to be exposed to corrosion, why spend extra on a plating or coating?

Using A Slotted Hex Nut

  1. Slide the Pre-drilled threaded fastener through the installation material
  2. Rotate the nut onto the fastener(slotted portion away from the installation material)
  3. Apply the appropriate torque to the nut
    1. *If the bolt has no hole, once it is torqued properly drill a hole between two of the slots
  4. Rotate the nut +/- 30% to align the hole with the slots in the nut
  5. Slide the cotter pin through the slots, into the hole and out the other side
  6. Using pliers, bend the cotter pin so that it cannot freely come out of the hole

Maintenance

  • Check the fastener assembly to ensure the cotter pin is in place
  • When removing the nut, bend or cut the cotter pin so it can be removed
  • When re-installing, use a New cotter pin
Shop Cotter Pins

FAQs

What are slotted nuts used for?

Slotted nuts are used in applications where vibration or torque might unfasten the assembly. They are a kind of locknut that can be used interchangeably with castle nuts in most applications.

What is the difference between a castle nut and a slotted nut?

Functionally, both slotted and castle nuts work much the same and can be used interchangeably in most applications. The difference comes in the slot style. Castle nuts have turret geometry, which allows cotter pins fastened through the slots to be bent closer to the nut, allowing for a less protruding pin.

Why do castle and slotted nuts have slots?

The slots in castle and slotted nuts are for accepting a cotter, split, or taper pin or wire to prevent the nut from loosening. The pin, threaded through a hole at the end of a bolt and a slot in the nut, is bent around the castle or slotted nut to lock it down.

What fasteners are used to lock slotted nuts?

Traditionally, slotted nuts are locked with cotter pins or split pins. R-Clips and safety wire have also been known to be used for installing castle nuts.

What are locking nuts for?

Lock nuts are an easy to use, cost-effective solution to protecting against vibration-related loosening. They're used to protect applications from loosening over time.

What is plain steel?

The term "plain steel" usually refers to carbon steel or mild steel with no plating or coating.