Keps K Lock Nuts

Hex Nuts with an Attached Free-Spinning Washer

A Keps K-lock nut is a nut with an attached or captive, free-spinning washer. They may also be referred to as Keps Nuts, k-lock nuts, star nuts, or captive lock washer nuts. They are used to make an assembly more convenient as they combine both a hex nut and a lock washer into a single fastener.

K Lock Nuts Feature a conical external tooth washer attached to the bottom of the nut. This integrated lock washer bites into the surface material, providing increased breakaway torque and decreased likelihood of the nut loosening.

Keps Nuts are available in both US and Metric sizes in 304/A2 Stainless Steel and Zinc Plated Steel.

Stainless Steel

18-8 or 304 grades of Stainless steel are suitable for many general purpose applications, especially freshwater and non-salt water wet environments. Corrosion-resistant and durable, 18-8 stainless steel is equivalent to the A2 grade of stainless steel.

Zinc Plated Steel

Zinc is by far the most common and economical type of plating for fasteners. The zinc plating adds a protective "sacrificial" top layer against corrosion while also adding a shiny finish to the fastener. Zinc plating is ideal for indoor use where it won't be constantly exposed to harsh elements.

Not sure what material you need? Check out our Material Guide to find the right material for your needs!

How to Install Keps K Lock Nuts | Fasteners 101

Installing Keps K Lock Nuts
How to Install Keps K Lock Nuts Transcript

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Bob: This is called a K lock nut or Keps lock nut.

These have these little wings that are here, and this is a free-rolling washer lock nut. So those little wings get tightened and the key to this is not to over tighten them. Once you over tighten this, it's no longer a lock nut and that free-rolling washer gets crushed and it just doesn't work for you anymore. So, the key to this is not to torque it down too tight. Very common, this is a very common lock nut.

Okay I have a K lock nut here. I'm going to demonstrate it. I have a hole that's in this piece of steel. I put my hex cap screw through and I'm going to hand-tighten this k lock nut or Keps nut onto this piece of steel.

As you can see here, I just snugged it up with my hand. Then I'm only going to turn it a couple times (with a wrench) to tighten it. Alright, so I'm just going to tighten this up a little bit. That was it right there. I just snugged it up, not overpowering the nut.

If you had something that this just had to be tightened up to and it would free spin, that washer-the nut will turn, but the washer will stay in its original spot. You can see right there, you can see the nut keep spinning, also if you over tighten this it's just going to flatten out that locking mechanism on this lock washer thus it's just going to become loose over time; it'll just vibrate loose.

That's the k lock nut.

FAQs

How do K nuts work?

Keps K lock nuts are standard hex nuts with a free-spinning captive serrated washer attached. This washer bites into the surface material to help the nut resist vibration. Keps nuts effectively combine hex nuts with external tooth lock washers into a single fastener for ease of use.

What is the main difference between a KEPS nut and a Nylock nut?

Keps nuts use a serrated captive washer that's attached to the nut to bite into the surface material to create tension and resist vibration. Nylock nuts use a nylon insert that the screw will cut threads into, creating friction between the screw threads and the nylon to prevent loosening. Both are lock nuts, but their methods of locking are their main difference.

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.

How do you use lock nuts?

Most lock nuts are used the same way traditional nuts are; by simply fastening them to the opposite side of a bolt. The locking action activates after the nut is fastened down. The exception to this is castellated nuts and slotted nuts, which needs a hole drilled into the bolt and a cotter pin to finish installation.

Can lock nuts be removed?

They're not designed to be removed easily. If they were, they wouldn't be very good lock nuts! That said, it is possible to remove locknuts. It may require some patience and, in some cases, power tools to remove them. The exact method will vary based on application and lock nut.