Standard nuts and bolts let the Crystal Palace rise in 190 days
For centuries each nut was made to fit one particular bolt, and no other. Lose one and you had to make a replacement by hand. Then, in 1851, the builders of London's Crystal Palace faced a 190-day deadline and gambled on nuts and bolts in standard sizes, a radical idea that let them finish on time.
A nut is a fastener with a threaded hole that screws onto a matching bolt. What keeps them together is a blend of friction between the threads, slight elastic give in the metal, a small stretch in the bolt and the squeeze on the parts being clamped. Because vibration can slowly undo that grip, engineers have invented many ways to lock a nut in place, from spring washers and a second jamming nut to nylon inserts, thread-locking adhesive and split pins through slotted castellated nuts.
Shape matters more than it seems. The earliest nuts were square because they were easy to make by hand, and square nuts still turn up where maximum grip is needed, since their long sides give a spanner more leverage. Six sides became the norm as a compromise. A spanner can find a new grip after only a sixth of a turn, helpful in cramped spaces, yet the corners are not so small and numerous that they round off. Special shapes serve special jobs, such as wing nuts for turning by finger.
Before standardisation, every hand-made pair was unique. Joseph Whitworth proposed a common standard in 1841, but nobody adopted it immediately. The turning point came with the Great Exhibition in Hyde Park. The contractor Fox Henderson had to erect the enormous glass Crystal Palace quickly and cheaply, and chose interchangeable, standard-sized fasteners; research on the building's remains in 2024 identified this as the key innovation that made the schedule possible. The success spread the Whitworth standard widely, although Britain did not formally adopt a national standard until 1905.
Today nuts are graded to match the strength of their bolts under international systems. An ISO class 10 nut, for example, can bear the proof load of a class 10.9 bolt without its threads stripping, and critical joints in cars and machinery are tightened to a precise torque with a torque wrench.
Source: Nut (hardware)
