Picture Hanging Knot (2017) | Hacker News Reader

Picture Hanging Knot (2017)

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141 pointspolm2351 comments

If this were a taught unstretchable string, the tension in the string ends up infinite and the compression in the picture frame also infinite.

Obviously the string has a little stretch, but even so, the tension in the string is proportional to 1/sin(angle), which for very small angles makes very large amounts of tension, which will eventually bend or warp the frame.

Instead, you should deliberately leave a reasonable amount of slack, and the tension in the string will then stay under 3x the frames weight, which it will be able to handle forever.

I've seen it in a FB math group with the text: Applications of knot theory :)

I watched it 5 times and can't figure it out. Explain to me this sorcery.

This is topologically equivalent to pulling your hand out of the "cuff", letting the blue cord fall free, and then putting your hand back in.

Perhaps you find the reversed gif helpful: https://imgur.com/a/hwzePnS

I started using a taught line hitch with cotton cord for hanging pictures.

The taut line hitch makes it easy to adjust the height without moving the nail and the cotton cord helps keep the taut line hitch from slipping (vs says monofilament).

Agreed, any "knot explainer" that includes the step "Tie a few ‘granny knot’ L over R, then R over L to secure the underlying knot" immediately disqualifies it as an actual knot.

The taughtline hitch is a much better knot for this.

I never could master the trucker's hitch[1] though :-)

[1] https://www.youtube.com/watch?v=TUHgGK-tImY

But doesn't alternating L over R then R over L make it actually a square knot? That's pretty classically an "actual" knot, albeit poorly described in this case.

Agreed, L over R then R over L is a square knot or reef knot.

L over R, L over R would make a granny knot.

But maybe in the UK both are called a granny knot?

Interestingly, when a granny knot is collapsed (the cord on one side gets pulled taut), it becomes two half hitches. When a square knot is collapsed, it becomes a larks head or cow hitch knot. In the balanced state, the granny is a weaker knot and the square is stronger. In the collapsed state (then cleaned up a little bit), two half hitches is a stronger knot than a cow hitch.

>L over R, L over R would make a granny knot.

Same in the UK.

I don’t think so, they’re just repeating half hitches for stability. This is very commonplace. I’ve never seen a reason to alternate the direction of the half hitches though.

Well, one comes undone easily and the other is more secure, compare here [1] or here [2] for example.

[1] https://en.wikipedia.org/wiki/Granny_knot [2] https://www.fieggen.com/shoelace/grannyknot.htm

If you can't tie a knot, tie a lot?

Also, it's a taut-line hitch:

https://en.wikipedia.org/wiki/Taut-line_hitch

taut, meaning tight, not taught, the past tense of teach.

The taut line hitch is a great knot to know for lots of situations; once you learn it, you'll find yourself using it in a number of different ways. It's great for adding guy lines to a tent fly, or hanging a tarp in the woods for camping. I've used it to tie small gifts together at the holidays.

I like the Farrimond Friction Hitch[0] for this.

It's essentially a quick release Prussik tied with the working end.

You can use a toggle, or slip a second bight through the first to prevent accidental untying.

Big benefit is that it is faster to tie in longer lengths of cord and it's faster to undo, being quick release.

[0] https://en.wikipedia.org/wiki/Farrimond_friction_hitch

Agree, the taut line hitch is amazing and an excellent knot to know. I also love the "trucker's hitch." I often use the truckers hitch in situations where having easy control over the tightness with minimal risk of slippage is my goal. If I need to adjust it much then taut line hitch is preferred, otherwise I truckers hitch is my favorite knot (and seems magical the first few times you use it).

Indeed. And with an alpine butterfly loop, you have basically tackle. So it's great for tying stuff, because tightening doesn't require retying.

For anyone like me who is thinking, "Gosh, I used to study knots and taut line hitch sure sounds familiar, but I can't quite place it right now..."

https://www.google.com/search?q=taut+line+hitch

I've always used a twisted wire, or Ashley's bend

https://en.wikipedia.org/wiki/Ashley%27s_bend

Came here to say this. Top tip: wire can be twisted by using a drill or electric screwdriver.

Alright, I really don't get this. Where does the final nail go? Is there anything that prevents the picture from becoming un-level? Is there a tiny hole for the nail?

The nail goes in the wall, then you put the string over the nail. You can move the frame left and right on the nail to make it level. You can also have more than one nail for more stability, in which case you just use a level to make them straight.

So it seems like this project is quite literally, how to tie a very tight cord between the edges of the frame.

Yes. And your comment is quite literally just words in a specific order.

Close-up photos sure would help me see the details better, particularly whether the cord is passing over or under.

For any heavy or large art I tend to use a french cleat(s):

https://www.govart.com/cleat-flare-10-inch-pair.aspx

I feel like that merely reduces the problem to figuring out how to mount a 10"/25cm wide Al extrusion on a piece of potentially arbitrary width. Where would you mount that on a stretched canvas, for instance?

On the stretchers, of course. Not all french cleats are 10". Some of mine are 1/2" and I use two sets. Once hung, the art never gets crooked.

The answer is a bowline or sheet bend (same knot). They show how to do it with pictures.

It depends what material you're tying. For twine, sure; if you're hanging a 30 kg artwork you probably want to use steel wire, and pretty much any kind of knot is unsuitable here.

Rubbish. Stuff like e.g. boats in the multi-tonne weight class are secured by tying knots every day. Spearfishers. Mountain climbers. I could go on.

Get some 2 mm Dyneema rope, which has an average breaking strength of 300 kg, run it through some D-rings and tie it with an Alpine Butterfly. You will be able to do pullups off that artwork if you want.

This all depends on what you're hanging. If hanging art worth more than $100, use steel cable. Museums and galleries all use steel cable because it is easier and nicer to work with. dyneema is strong, but not chemically stable and will degrade over time with exposure to atmosphere and light (though obviously there isn't a lot of light behind a piece of art on the wall).

I agree that it's easier to work with - you don't need to know any knots, just twist it and it stays. So that's a definite benefit.

But when it comes to UV and chemical resistance, I don't see how one would get any degradation in a museum setting. Dyneema is used in heavy industrial applications like mooring lines and tugboats for very large ships with lifespans over ten years. Unless you're hanging up something that you're not taking down for a century, it shouldn't be a worry.

> hanging art worth more than $100

To add to this; this is the vast majority of art.

As a climber I place my life in the hands of knots all the time, but tying a knot in steel cable is generally a bad idea since it is unlikely to bind properly.

For better or for worse steel is often used instead of synthetic rope for picture hanging.

>Rubbish. Stuff like e.g. boats in the multi-tonne weight class are secured by tying knots every day. Spearfishers. Mountain climbers. I could go on.

Oil rigs are towed to location using steel cables. Steel wire rope is substantially stronger for its weight and for it size but generally harder to work with than plastic things of similar capacity. Both materials can hang pictures just fine. It's not exactly a dynamic load. People will argue over anything.

> Steel wire rope is substantially stronger for its weight and for it size but generally harder to work with than plastic things of similar capacity.

That is not true. The tensile strength of kevlar and dynema is higher than that of steel, while they have a density that is several times lower.

Steel cables are at high risk of corrosion in off-shore environments and are rarely used. Tug operations will use simple synthetic cables (spectra, dynema).

Platform anchoring cables are often a rather complex combination of synthetic cables and weights to obtain neutral buoyancy.

Neat, thanks for introducing me to Dyneema rope. I just ordered some. I suspect it will come in really handy.

It's also has a huge benefit for towing or wrenching over steel cable - there's virtually no recoil if it breaks.

Steel cable will slice people in half and send wrenches through car windows and to stab the driver when it breaks.

“slice people in half”

Why I won’t drive over the cable car slot. Slice cars in half, that.

As an amateur sailor I beg to differ.

First, you can tie knots with steel wire, too.

Second, I would be much more comfortable hanging artwork on a thin twine than on steel wire. Steel wire tends to be sharp and scratch and punch holes in anything it gets into contact with. Rope that will be durable and can withstand the stress of hanging 30kg artwork is still very thin. Just google it and be surprised. (https://www.ingersollrand.com/pt-la/lifting-equipment-materi...)

Relatedly, this seems like a good place to mention the wonderful Ian’s Shoelace Site: https://www.fieggen.com/shoelace/

Knots have always fascinated me. I keep "The Morrow Guide to Knots" handy to look at when I'm bored and I think mentally tying the knots is as much (or even more) fun than physically doing it.

If you are interested here is a non-affilate link:

https://www.amazon.com/Morrow-Guide-Knots-Sailing-Climbing/d...

Huh. Me, I've always used soft iron twisted wire.

Parents were photographers for ~40 years and I've framed countless pieces.

We always just used wire.

I use wire in place of string. It is easier to hook wire onto a screw in the wall than string. Also... I always use two screws instead of one. That way the frame remains level.

What? No. A reef knot will never pull apart under tension and allows you to have a flat knot with a loop. Its also way easier to tie and you could make multiple passes if you want.

This knot traps the two lengths together. If you just use a reef knot, a) you'll have more slack, because there's no pulley mechanism to take advantage of to tighten the string, and b) it's easy to accidentally hang the picture by only one of the lines, so the slack has twice the effect, and the picture hangs lower than it otherwise would.

this isn't just bad advice, it's dangerous. i wouldn't want to drive behind somebody that tied down an external load with only reef knots.

Everyone should learn a tie down knot. Way too many people use unsafe knots (such as an overhand) to tie loads down because that’s all they know.

A truckers hitch is as simple as it gets:

1. Tie a loop in the middle of the cord (I like the alpine butterfly but any loop, eg a figure 8 is fine)

2. Put the cord through your anchor point and the newly made loop.

3. Pull it tight and tie it off with a half-hitch.

You now have a 2:1 mechanical advantage, meaning you can tighten a load twice as much as you normally can. It also won’t loosen itself, and you only have to untie one knot to remove the entire system.

Step 6 is a doozy.

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