Metallics JSFN1420 Nuts 1/4-20 Serr Flange Locknut St-zn (Jar 100)

No separate washer is needed. The Metallics JSFN1420 locknut has an integral flange measuring 0.574 to 0.594 inches across, so it spreads clamp load like a washer would and will span oversized or poorly aligned holes. The serrations on the flange bearing face bite the mating surface as you wrench it down, which is what resists back-off.

It is a 1/4-20 nut, meaning a 1/4 inch diameter screw or bolt at 20 threads per inch, the standard coarse UNC pitch in that diameter. It will not run on a 1/4-28 fine thread fastener.

That is the intended use. The flange serrations displace material on the mating surface when tightened, so it takes more torque to loosen the nut than it did to tighten it. Metallics lists the application as high vibration areas plus electrical, plumbing, and heating and air conditioning work.

No. The JSFN1420 is not Buy American compliant and is not ARRA compliant, with country of origin listed as multiple. On a federally funded project with domestic sourcing requirements you will need a domestically produced fastener instead.

The serrated flange type locks mechanically against the mating surface, so the clamped part needs to be a material the serrations can bite, and it leaves witness marks on a finished or painted surface. It is reusable-unfriendly for that reason, but it does not gall screw threads and it gives a more uniform bearing-stress to clamp-force ratio than other low carbon lock nuts. A nylon insert nut locks on the thread instead, so pick that where you cannot mar the surface. For strut, channel, enclosure, and bracket work in vibration, the flange nut is the one to use.

Yes, Metallics rates a panel thickness of 0.04 inch for the JSFN1420. The flange spreads the load over a 0.574 to 0.594 inch diameter footprint, which keeps a thin panel from dimpling the way a plain hex nut can.

Dimensionally they follow ASME B18.16.4-2008, the spec for prevailing-torque and free-spinning flange nuts, so they interchange with any other nut built to that standard in 1/4-20. Hardness is Rockwell HR15N 78 to 90.

They are steel with a zinc finish. Zinc plating handles indoor, damp interior, and protected exterior conditions. For direct weather exposure, standing water, or coastal air, go with a stainless flange nut instead.

They ship in a jar of 100, and the jar is the order minimum, so you buy in 100-piece increments. Jar weight is 0.93 lbs. Metallics offers other sizes and quantities by request.

Wrenching height on the JSFN1420 is 0.14 inch out of an overall nut height of 0.222 to 0.236 inch, so the usable grip is shallow. A deep socket or a box wrench seats fine, but a worn open-end wrench can slip. Keep that in mind on overhead or blind work inside panels and gutters.