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Hex Jam Nuts in Zinc Plated 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.
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.
| Nut Size | Width Across Flats | Height |
| 1/4" | 7/16" | 5/32" |
| 5/16" | 1/2" | 3/16" |
| 3/8" | 9/16" | 7/32" |
| 7/16" | 11/16" | 1/4" |
| 1/2" | 3/4" | 5/16" |
| 9/16" | 7/8" | 5/16" |
| 5/8" | 15/16" | 3/8" |
| 3/4" | 1-1/8" | 27/64" |
| 7/8" | 1-5/16" | 31/64" |
| 1" | 1-1/2" | 35/64" |
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 zinc plated steel?
Zinc plated steel is steel that goes through the process of adding a layer or coating of zinc to protect the steel from corrosion. The added layer of zinc sacrifices itself to keep the steel from rusting, even if the plating is damaged.
Is zinc plated steel rust proof?
No. Zinc plating adds a layer of corrosion resistance for rust protection. Still, it's a thin plating, and it's not as rust resistant as hot-dip galvanizing, which also uses a zinc top layer. While not the most corrosive resistant of materials, zinc plating is easily the most economical and commonly used.
Can zinc plated steel be used outside?
Zinc plating is not a good form of corrosive protection for outdoor use, especially near saltwater or in marine environments. For those applications, stainless steel or potentially hot-dip galvanized steel would work better. Zinc-plated steel is better for indoor use.
