Fair Wind Fasteners
Silicon Bronze Square Nuts
Silicon Bronze Square Nuts
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Hard to find square nuts in 655 Silicon Bronze alloy, and we have them here at Fair Wind Fasteners!
Beautifully machined, and will look great on your application. Square nuts have a larger surface contact area than standard hex nuts. The machined edge chamfers both front and back making this a true square nut, as famously used on Hereshoff vessels but also used all over in the traditional boat building world.
Your square nuts will come un-polished, but they do polish up to a gorgeous shine just like any of our silicon bronze hardware.
| Size | Width across the flats (inches) | Width across the flats (mm) |
| 1/4-20 | 0.432" | 10.98mm |
| 5/16-18 | 0.558" | 14.15mm |
| 3/8-16 | 0.610" | 15.51mm |
| 1/2-13 | 0.790" | 20.06mm |
Don't forget to add some Screw Lube to protect the threads on these nuts against galling and corrosion, making them easy to undo years later.

It's hard to write a review for a nut, but I am not using this for any machinery use. I am a craftsman who makes all sorts of products from industrial goods. I am going to make this nut into a silicon bronze ring and the square form will be unusual compared to other similar rings.
The finish is excellent and the ring will form fine with a heavy duty grinder disk in my jeweler's handpiece grinder (it's like a dentist's drill, but for grinding/polishing).
If you need a SOLID square silicon bronze nut, this measures exactly as described in the description, is very solid with no pitting or voids. It looks like it would be a strong nut to use where such a nut is needed.
... and I am a retired mechanical engineer, so I'm not just making this up. This silicon bronze nut is higher quality than I expected.
Excellent products, great service and very timely shipping. What more can I say! Thank you.
fast shipping, great web site.
my preferred place for fasteners
Silicon Bronze Square Nuts
High quality as expected
Glad to find slot head silicon bronze screws!
Looks ok, may get to apply today.
"Miss Behave", my recently acquired 1986 Caliber 33 sailboat, sat for years uncovered on the hard before she became mine. A persistent leak in the companionway hatch had created a rotten spot in the cabin sole at the bottom of the companionway and running into the galley area, high traffic in other words. My quick fix was to cut out the rotted section, about the size of my hand, and patch it in temporarily until I could do a proper nice looking repair. Problem is, the sole was flexing badly in that area due to the loss of material and integrity. My solution was to make up a couple of white oak stringers to insert under there to shore things up. These were installed athwartship and fastened by a single 1/4-20 x 4 inch carriage bolt at the end of each stringer, which were well back into the sound part of the sole. I chose silicon bronze and secured these with square nuts. I am not sure why I chose square, but they worked well. This temporary repair could do the job for a decade or longer. So I can take time with the proper nice repair at the time of my choosing.
