Why Frames Tilt Forward (2015) | Hacker News Reader

Why Frames Tilt Forward (2015)

chcollins.com

131 pointstheospears48 comments

This sentence is very funny to me: "Most people in the Northern Hemisphere hang their pictures on a wall."

I guess OP did some research but perhaps wasn't exhaustive and didn't want to generalise to below the equator. People write funny and quirky things. I'm glad things like archive.org exist to save the quirkiness for future generations.

Or maybe the author is not discarding the hypothesis that, in the southern hemisphere, frames tilt backward due to the Coriolis effect ;)

I've heard that at the equator, people put pictures on the ceiling; they're held there by centrifugal force.

It is very well known that Down Under the roof is down and the floor is up. Thus, the pictures are not hung to the wall: they are anchored to it!

Jubal called out, "That house on the hilltop--can you see what color they've painted it?"

Anne looked, then answered, "It's white on this side."

Yes, in this case, it's quirky and possibly endearing. When people feel like they need to document trivial comments by writing "Edit: typo", less so.

Nice Heinlein reference. That particular concept stuck with me after reading SIASL

OP kinda has a point though they did not phrase it effectively. From my experience, here in Asia we generally don't hang paintings/drawings/anything on walls. Most framed images are photos and these are more likely to be placed on shelves, tables suchlike.

TIL Asia is in the southern hemisphere

There are many who place frames on top of mantles, piano or other objects....

I am the OP of the referenced article... I'm here because I saw a large spike in interest in the article and traced it back to this post. A few responses to these comments, if I may, without getting abuse...

* Of course I was having fun with the "North America" comment. And the Coriolis Effect did in fact come to mind when I wrote it.

* The article was not "advocating" for pictures to be hung on wires -- or flush against the wall for that matter -- but was rather a response to some inaccurate/misleading advice on other websites about how to hang pictures flat against the wall. There seems to be great interest by others in doing that, as it is one of the most frequently-used search terms that link to my article.

* Specifically, some sites claimed that the forward tilt had to do with the weight of the frame, and I thought I would do laypeople a service by demonstrating that the weight has nothing to do with the frame's equilibrium position.

* I enjoy recreational math, and this was a situation that (to that point) had not been answered on the internets. If it's TL;DR to others, so be it.

* Finally, while iteration is indeed within the capability of computers, it is not within the capability of the wordpress on-line calculator plug-in that I provided for the convenience of readers.

In any event, Happy Monday, HN, and thanks for your interest. - Craig

A professionally hung painting would not be on wires but on a dedicated wall mount. But Cable mounts are easy to reposition.

True story... I once went to a public museum in Malaysia to photograph a painting I had an interest in. The light was bouncing off the glass, so I raised its lower edge by placing a cigarette packet behind the frame. Worked a charm and I got the photo I wanted, all without the guards seeing. I came back a year later and later lo and behold the cigarette packet was still there.

try a polarizer next time.

https://en.m.wikipedia.org/wiki/Polarizer

https://en.m.wikipedia.org/wiki/Polarizing_filter_(photograp...

The relevant physics phenomenon goes by Brewster’s angle, as mentioned in Feynman’s rant against rote memorization[1] that essentially describes another common use for polarizing filters in photography—reducing or amplifying the reflection of the sky in bodies of water.

[1] https://calteches.library.caltech.edu/2255/

My strategy was the add a pair of clear stick on bumpers to the back bottom corners of my frame (the kind you stick on cupboard doors so they close softly) to push the bottom out a little bit and straighten them out.

Seems hug-o-death'd; wayback link: https://web.archive.org/web/20180608222850/https://chcollins...

Because they can't tilt backward?

They clearly can, but the forces tend to pull them the other way.

> Because the calculation requires iteration (i.e., the answer cannot be found simply by plugging in the known quantities), I had thought this was impractical.

Since you know, computers are famously bad at iterating. (Hint: they are not)

GP should name his method the "Runge-Kutta" ;)

Author discovered value of free body diagrams.

Maybe we can all learn the value of diagrams. Drawing on paper is not cheating!

The article seemed like a common sense concept overthought, so I knew there just had to be a well trodden path that someone in the HN comments would bring up by name. Thanks for this!

Do you know where I could find a free body diagram for a door with hinges? I don't understand why my doors are trying to close themselves. I think something is not level, but I don't understand the hinges though to draw a diagram myself.

Good discussion and an okay diagram in this thread

https://engineering.stackexchange.com/questions/43338/how-do...

They auto-close when the top hinge is more to the outside then than the bottom hing, or the whole frame is tilted towards the inside (where the door does not swing into). You can try adjusting the hinges with a tool.

In an ideal situation everything is level in all directions.

This hurt my brain. I guess we envision inside and outside on different sides.

Not sure if this is any clearer, but the door will close itself if the bottom hinge is offset from the top in the direction the door opens. Picture the angle of the bottom of the door when it is open 90 degrees and it might be easier to visualize why it falls shut.

Yes, we are saying the same :)

TL;DR - because the wire attachment point is usually to the rear of the center of gravity.

when a succinct John Nagle TL;DR is worth a handful of animated diagrams.

The graphs and diagrams are more useful because they show what variables the tilt depends on, ie how to reduce the tilt if you want to.

And it's hard to fix without poking something through the wall that you probably want to keep pristine, because glass weighs a lot.

Unless you modify the frame. Or screw into the top of the frame. Or loads of options that aren't taken for one reason or another because "the frame has a wire across it" is utterly dominant.

Slight forward tilt can be desired, eg. to help with dust accumulation.

And just you wait until the author of the article tries to work out why the wire isn't straight across but has a bend in it when the painting is hanging on a hook.

The tension on cable strung between two points is a function of the weight pulling down on it, and the reciprocal of the sine of the angle the cable makes where the weight hooks on. For it to be straight, the latter becomes infinite...

Yes, however the discussion is more valuable than that. I once bought a framed poster at a garage sale and discovered when I got it home that it had a steel plate across the bottom of the frame. I thought it a bit of over engineering for adding frame support (it attached to the back of the frame with machine screws) but when you hung the poster it hung flat against the wall. I took me a couple of weeks to figure out the person do did that was moving the CG of the framed print closer to the wall which made hit hang nearly flat on the wall.

When reading the referenced article I realized it also allowed for an arbitrarily tightly stretched cross wire because the steel plate would bear all of the stress, not the art. That was something I had not thought of!

> I took me a couple of weeks to figure out the person do did that was moving the CG of the framed print closer to the wall which made hit hang nearly flat on the wall.

As it was at the bottom of the frame, it also moved the CG lower, which also helps to reduce the tilt, even if the CG remains a little bit to the front.

> When reading the referenced article I realized it also allowed for an arbitrarily tightly stretched cross wire because the steel plate would bear all of the stress, not the art.

I don't really get this, if the plate was at the bottom. I assume the stretched wire would be attached somewhere at the top half, so the rest of the frame would need to bear at least some of the stress.

It was a plate, probably 3" "tall" and as wide as the frame, attached in four places at each of the corners. As a result it held the frame rigid (much like a corner bracket would). If you pulled the top toward each other, in addition to the top bar of the frame resisting that pull, the bracket would resist and attempt to make the bottom/side angle less than 90 degrees.

My naive answer to this problem would be "well, then don't use a wire to hang them, use something that forces the frame against the wall". Which leaves you with the issue that the frame might pull the nail out of the wall - but that also seems to be a solved problem: you can either use special picture hanging hooks which have up to 3 nails, with the nails angled upward so they won't be pulled out by a force facing downward. Or you can overengineer it and use a wall plug. This might not solve the author's problem, who seems to swap the pictures around often, but I assume most people don't do that...

My money would (at least partially) be on the guy having bought a duff hanging system, or had it poorly installed.

I've just returned from a holiday where I visited a few art museums.

They all had hanging systems. None of them had frames tilting as excessively as the one in the photo on this guys blog. In fact, the tilt was barely perceptible (if it was there at all).

I'm sure he's making a perfectly valid point in this blog. But I'm just saying it doesn't have to be like that, or at least not so extreme.

https://www.alamy.com/stock-photo-paintings-hanging-inside-a...

Here's a random photo of Louvre, place with both the art nerds and money to hang things "properly". You can clearly see they tilt forward on the cables, maybe not as much as OP but still.

And this is why I just don’t hang pictures like this. Instead, I put a pair of eyehooks on the inside of the frame, a pair of picture hooks on the wall, and just slot it on. For heavy works, mirrors weighing 100kg+ etc., I use heavier duty fittings, but the same method.

Pictures and paintings were supposed to tilt forward a lot, to make viewing them better. It fell out of fashion. Look at old photos from inside homes, and you see wall paintings very tilted.

The old houses of the people rich enough to own paintings in the past had much taller ceilings than the houses that are affordable now for most people, while now anyone can have a copy of a famous painting or a cheap original painting or photograph.

So it was normal for the paintings to be hanged at a place higher on the wall, so you had to look somewhat upwards to admire them. In this case, a significant tilt forward was just right to view the painting as orthogonal to the line of view.

Exactly, and when photos and paintings became affordable for normal people, they would hang them in the same style as the rich. Even if they didn't have tall ceilings.

I thought it was to minimize dust deposition on its main surface. No matter whether there is a protective glass or not.

Could it be this simple?

I love the level of detail put into exploring something so simple. The details are interesting to chew on for a bit.

But is the “undue” stress of a taught wire actually a problem for typical weights?

I don't understand the concern for having heavy tension on a wire for a large piece of art. Can't a cross-brace on the back of the frame be used to negate this issue?

It's amazing somebody would write, draft and plot so much on a 7th grade physics problem.

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