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Comment by alexpotato | Hacker News Reader

I was in Hong Kong several years ago and saw some of the scaffolding up close.

As a former Boy Scout with a lot of experience in knots/lashing etc, I was VERY curious to see what kind of ropes, knots and lashing they use.

Turns out it's just some flat nylon ribbon and mostly a couple quick wraps and overhand knots.

Really is amazing that it all stays together. I imagine the friction between the ribbon and the wood surface of the bamboo must be high enough to be "sticky".

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The post below got flagged, but they the link they shared has some really nice visualizations of the scaffolding:

https://multimedia.scmp.com/infographics/culture/article/318...

Wrapping a rope under tension for several turns around a cylinder can make very strong assemblies. Relevant concept:

https://en.wikipedia.org/wiki/Capstan_equation

Note that the exponent is proportional to the number of turns.

It's a simple square pole lashing knot (also known as a japanese square lashing). It works well with almost any kind of cordage. The knot holds the poles in a 90-degree orientation and the finish of the knot tightens the main cord to lock it in place. Natural fiber actually locks better than nylon as it has more 'tooth'. The use of nylon is mostly to resist the elements, adds a bit more strength, is cheaper to manufacture and easy to cut for disassembly.

Nylon degrades relatively quickly under UV exposure tho. It's a well known thing in climbing/mountaineering to not trust the gear that's been sitting in the sun for a while and people have died ignoring this advice (famously, Dan Osman). Interesting choice for outdoors setting...

It's only about 60% degraded after 36 months exposure. The scaffolds aren't up for that long (they're taken down immediately once work is complete). The nylon joint is several times stronger than it needs to be to keep the poles together (2.5 kN per joint; point-loaded beam is spread between two joints, so 5 kN; max rated beam load is below that).

Just fyi, the guy who did the analysis of Dan Osman's failed rope (Black Diamond's QA manager) concluded the rope was not affected by UV or weather exposure. (https://groups.google.com/g/rec.climbing/c/gW92OrNs7_o?pli=1)

As I lived in HK back in the 1970's I'm pretty sure that was not flat nylon ribbon at all in those days, but simply strips of split bamboo or shavings from the surface of a broken pole. It would make sense to transition to nylon, since that could be made on a spool rather than having to be created on site.

I've got used to how scanty UK scaffolding is now but at first it worried me that it would not be robust enough.

keep in mind that for tying around things and binding, that the knot is really there to maximize the friction of the line against the thing - and to do so under various circumstances. Ideally the knot itself is holding very little load.

You might be inclined to peruse The Ashley Book of Knots (ABOK).

> mostly a couple quick wraps and overhand knots.

"The toughest part of the job, though, is tying a proper knot to secure bamboo poles, which can take years to master"

Cool sketches of the knots - https://multimedia.scmp.com/infographics/culture/article/318...

I'm sure the years to master includes where and which way to do the knots.

> some flat nylon ribbon

Over 0.5 kN per strip, blah blah boring specs for the scaffolding which at 25 pages would be... 100 times shorter than the EU?

Any who, my bamboo wilted after cutting, you have to treat it it seems... so not even close to the knot stage, but did find the spec'ed lashes, then remembered I hate knots, like just the basic reef knot ones... screw years. Zip ties FTW

Years to master a knot? I understand it's critically important that they be tied properly, but years to master a knot just doesn't seem possible.

It can't be right. I could understand architected the scaffolding itself on a large scale would take a long time though, to be safe and reliable.

Knots and construction with poles and rope lashing was always my favourite part of scouts. The sketches of the knot looks cool on the surface but don't tell me much about how they are tied or what other lashings they are similar to. Not much detail and the second image has three running ends?

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