The Space Needle's Nuts

Wikipedia has a picture of someone rudely touching one of the Space Needle’s nuts:

They’re smaller than I expected.

I’m afraid Tikki last posted here about eleven years ago.

Welcome all the same!

I imagine they used a wrench about 100 feet long to hold the nut fixed in place and tightened the bolt from below with a 100 foot screwdriver . If you take the Underground Seattle tour, I assume you can see the screw heads.

I wonder if it’s metric or US customary. It would be annoying if the nuts turned out to be 250 mm when all you have in the toolbox is a 10" crescent wrench.

Those are fairly normal “nuts”. I am used to seeing such bolts being tensioned (tightened) using pneumatic or hydraulic bolt tensioners :

That’s what she articulated.


As the actress said to the bishop.

Always fun when your entendres get doubled.

That’s what she said

wait, what?

So … not so much a space needle as a space weeble,

It was difficult to see exactly how that hydraulic tensioner applied torque to the nuts, but the cool thing was seeing that it could torque multiple nuts at the same time to assure even pull-up around the entire flange perimeter.

Some years ago I saw a documentary that I think showed a large naval vessel on which many fasteners along the length of a shaft had to be tightened in close synchrony. Every few feet along its length there was a sailor with a wrench on a fastener, and every few seconds a particular individual called out a command - and every sailor would give his wrench a single turn.

It’s been tried.

I haven’t been there to check, but all the photos I can find make them look more like 12", 16" tops.

I’m sure I’ve seen photos of ginormous nuts, that were indeed in the vicinity of 6’, at the base of a tower, but it might have been a different tower. I think it might have been the CN Tower in Toronto, but I can’t find any images on that.

Space Needle nuts (and bolts) aren’t really all that impressive.

I agree that this particular video does not show the whole process very well. The hydraulic tensioner does not apply torque to the nut, it applies a tension (stretch) to the bolt. Then the nut is tightened manually.

The goal is to provide clamp force on the joint by stretching the bolt.

It the usual bolted application, this is done by tightening the nut, which acts through the ramp angle of the thread to stretch the bolt. There’s a lot of things that can affect how that torque translates to tension in the joint. For example, friction between the mating surfaces.

Hydraulic tensioners pull directly on the end of the bolt to create a certain amount of tension. Then the nut is tightened to maintain this tension. There’s still some variation in the results, but much less as compared to a simple torque tightening.

There are lots of other methods to tighten a bolt/nut connection: torque-angle, turn of the nut, and now exotic computer-controlled methods that monitor the joint as the bolt is being tightened. But this is getting a bit off-topic.

Here’s a video that shows the two methods of tightening:

How about raising an entire building, with “600 men using 6000 jackscrews” in 1860?

I realize this is 15 years old and it turns out the Space Needle’s nuts aren’t as large as originally thought, but teams of burly men actually kinda are how they tighten the “pilgrim nut” on a large ship’s propeller. There’s a good example at the 31:00 mark in this video.

They use handles to spin it Price or Right style until it’s hand tightened, then hydraulics to torque them down.

I was able to personally confirm that the Space Needle’s nuts are quite small indeed:

In fact I think the person in the Wikipedia picture has very small hands since the nuts seemed quite a bit larger in comparison.

Can you post a pic of your hand next to a piece of string so we can get some idea
of scale.
Also, why is the nut on the left half the size ?