Early nuts were made of wood and were used with wooden pegs. The square shape made it possible to form a tool to tighten the nut in place. Square steel nuts were common on machinery from the late 19th through to the mid 20th century.

Square nuts were common in early applications because they were easier to make with the tools, metals and techniques of the time. When machinists used cast iron and cruder forms of steel, the square shape was easier to produce. As machinery became smaller and more compact, however, the hex head evolved to meet the need for more compact heads.

In the 1830’s, square headed nuts were superseded by hex head. The widespread use of hex nuts and bolts came because of innovation in engineering and metallurgy. Hex nuts and the tools to use them require close tolerances, whilst square heads required less accurate tolerances.

To complement our range of fixtures and fittings, we have sourced a range of vintage style industrial black oxide square headed nuts. These come in variety of sizes to suit various application such as furniture construction, woodworking projects, lighting design and any general vintage industrial project.

These square head bolts will create a more authentic appearance for your project. 

For those of us who struggle with imperial measurements, we have included metric equivalents next to the sizes, usually in brackets [].

Make installation of your lag bolts, pyramid head door screws and square head machine bolts easier and safer with our 8-point sockets.

https://littleanvil.com/nuts-bolts-screws/8-point-socket

Currently we carry a limited range of sizes and a small amount of stock. We will continue to increase our range and stock levels over time. Contact us if you require a specific size not in the list or a larger quantity. Please allow a 2-3 week lead-time for delivery.