Hex Jam Nuts in Black Oxide Coated 18-8 Stainless Steel
Hexagonal Thin Nuts For Locking Against Each Other
Jam nuts, also known aptly as thin nuts, are low profile hex nuts about 2/3rd the thickness of a standard hex finish nut. They are commonly used as a kind of locknut but may also be found in situations where a standard nut would not fit.
A jam nut is often used when a nut needs to be locked in place without clamping against another object. The jam nut essentially acts as the "other object," as the two nuts are tightened against each other. They can also be used to secure an item on a fastener without applying force to that object. This is achieved by first tightening one of the nuts onto the item. Then the other nut is screwed down on top of the first nut. The inner nut is then slackened back and tightened against the outer nut.
This locking action helps to avoid compression of the part being fastened while also locking it in place but still rotate freely, such as in bearings. The idea behind a jam nut is that a thin nut exerts less overall force than a fully torqued standard nut. They're the opposite of most heavy styles for nuts.
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.
Black Oxide Coating
18-8 stainless steel hex nuts are available in a black oxide coating, which adds mild corrosion and abrasion resistance, but is mostly used for the color.
| Nut Sizes | Flats | Thickness |
| 1/4"-20 | 7/16" | 5/32" |
| 5/16"-18 | 1/2" | 3/16" |
| 3/8"-16 | 9/16" | 7/32" |
| 1/2"-13 | 3/4" | 5/16" |
FAQs
What is a jam nut used for?
Jam nuts are low profile nuts commonly used as a type of locknut, where it is "jammed" up against another nut. With both nuts being fastened towards each other, this effectively locks the assembly in place. You may also find these nuts used in applications where a standard nut won't fit.
What is the jam nut method?
The jam nut method, sometimes known as the "double nut" method, is a friction locking method that uses two separate nuts fastened towards and against each other. Thus, the two nuts are bearing in opposite directions on the threads creating the "jam" effect.
How do you loosen jam nuts?
To loosen jam nuts, you can either take the outer nut off first and remove it like any other nut, or put a wrench on each nut and turn them in opposite directions to unfasten them from the assembly.
Why are jam nuts thinner?
Jam nuts are thinner because it helps save space when locking a pair of nuts together. The thinner size also means the jam nut exerts less overall force when fully torqued, so the standard nut can exert more force on the jam nut when they are fastened together without potentially damaging the material you're fastening to.
What is black oxide used for?
Black oxide is used to add mild corrosion resistance, abrasion resistance, for appearances, and to minimize light reflection.
What does 18-8 mean?
In regards to stainless steel, 18-8 (sometimes written as 18/8) is the composition of chromium (18%) and nickel (8%) in the stainless steel alloy. 18-8 also refers to the 300 series of stainless steel grades, including 302, 303, 304, & 316. Though you'll often find it used interchangeably with the 304 grade because it's the best known stainless grade in the series.
