Jam Nuts and How to Use Them

Jam nuts are nuts that are about half of the size of a regular nut. In practice, these nuts are both screwed onto the bolt and then they are tightened against each other.

There are a couple of different reasons you might want to use jam nuts. The first is if you are fastening to a very soft material and cannot risk hurting the material by fastening against it. The second is when you need to attach something to the bolt but let it move around on the bolt.

How to Use Them

The process of installing jam nuts is very simple. We’ve chosen to use our trusty vice to hold our bolt in place for this example. So once your bolt is in place simply screw the first nut onto the bolt. Make sure the bolt is far enough down to allow room for the second one. After you get the first nut on far enough you can begin spinning the second one. These nuts should both slide onto the bolt very easily.

Before tightening you need to set the bottom nut, the one that is closer to the bolt head, to the desired height. Next take an adjustable (or the correct size) wrench and slide it onto the bottom nut. You will the proceed to used either a wrench or socket as we do here, to tighten the top nut against the bottom one. These nuts tightening against each other will lock the nuts in place on the bolt. We also recommend using threadlocker to keep these nuts in place during an installation.

The main differences between a jam nut and a regular hex nut is that they are tightened against each other instead of against a material, and that they are about half of the size of a regular nut.