Wow. Not only does it look great on my phone, but it loads quickly and the movements are seamless. Compare that to the 360 view of furniture on any big box website or cars on a dealers website.
This one's my favorite (although I haven't read the whole thing):
"This movement is designed to double the speed by gears of equal diameters and numbers of teeth—a result once generally supposed to be impossible. Six bevel-gears are employed..."
It's like an automobile differential --- if one wheel stays still, the other wheel turns faster than the input. Hence the warnings to not exceed a certain speed when one wheel is slipping, because the other one turns much faster than what the speedometer indicates.
I read and re-read this for a solid 5 minutes and I have no idea how it produces the result. I get that gear D spins orbitally around the left-right axis instead of rotating clockwise, but I can't seem to grok how that would produce 2x rotations.
Thanks for that video. Very informative... like many of the videos from that age. There's something about training videos and physics videos from the 50s / 60s that makes them much better than what people produce today; it's hard to say exactly what it is, but they do feel cruft-free.
Educational videos today tend to go to one of two extremes. Either they're a talking head with PowerPoint, like most of the "massively online" courses. Or they have way too many jump cuts, like theatrical movies which want your attention, not your understanding.
There's also an annoying tendency to have distracting music and irrelevant graphics during narration.
Here's an old Jam Handy film, "Spinning Levers", on how a transmission works.[1] There's a whole series of these Chevrolet films on the Internet Archive, covering major vehicle systems. Things to note:
- There's a narrator and a demonstrator. We never see the narrator, and the demonstrator never talks. So the viewer can focus.
- The demo models of parts are really good. They start with a simple version and add features until a full transmission has been built up.
- There's some simple animation. Animation is used to point out how power flows through the gears. This is much clearer than someone using a pointer.
- The editing and narration are very well synchronized.
- There's an entertaining part at the beginning and end, so you don't feel like they're beating you over the head with the boring stuff.
Oh yes, that's legendary! I forgot it was pre-war! Speaking of war, I also recall pretty well-made video explanations for bomber pilots, about how to fly the planes to avoid anti-aircraft fire.
So I guess I should extend my original statement to the 1930s-1970s range.
Not a mechanical engineer but I think this is what is happening.
Note that Shaft F and shaft D are made to rotate in opposite directions.
Then another gear is made to pit those motions against each other, by means of that wacky rotating frame A.
To see why let’s unwrap it from a polar coordinate to something more linear.
Imagine a wheel with gears resting on a rail with teeth. The wheel has an axle going through it. If you drag the wheel’s axle forward horizontally that’s like what Frame A does to impart 1x rotation. But then the rail is also moving backwards, giving you 2x rotation.
You're entirely correct - it's a modified differential drive.
The two shafts are coaxial to each other and drive their corresponding gears in opposite directions. The frame is fixed relative to one shaft but mobile relative to the other, which is where the extra 1/2 of relative motion comes from.
The traditional way to do this was with a crossed belt. This is the higher-friction lower-slippage version of that.
I think what happens is that E is moving the whole gear D move around. I think you realize this. In other words the motion of E does not change the teeth of E and the teeth of D which are in contact with each other.
But then the gear LeftC is making D rotate around the circumference of E i.e. changing the teeth of E and teeth of D which are in contact. Since this is in the same direction as above, you get 2x speed.
Essentially imaging you sitting on the edge of a plate. E is making the whole plate spin. And leftC is making you run around the circumference of the plate in the same direction as the direction of rotation. So your angular speed becomes twice as much as the speed of the plate.
E is the output gear, and B is the input. The arrangement on the right is to make the frame A and gear C turn in opposite directions, and D adds the two rotations together again to turn E twice for each revolution of B.
I think I got it. The simplest way I can describe it is the gear on the far right is turning the whole square frame on the left because the little shaft turns inside the big shaft. The 2nd gear from the right (that is connected to the big shaft) is turning the "thing-thats-already-turning", so you get 2X rpm.
Great for assisting with mechanical engineering problem solving. I just sent this to my team. If you like this sort of thing, we also discovered an awesome set of mechanical animations on Youtube done by an experienced Vietnamese mechanical engineer in a similar vain (but 3D drafted). URL not handy, hopefully someone can find/share.
These types of books are helpful and proof that it’s hard to innovate mechanisms. However the animated GIFs are not the clearest. I’m more of a fan of this guy’s Youtube channel with carefully modeled animated 3D CAD of tons of amazing mechanisms. https://www.youtube.com/user/thang010146
For example, I predict the increasingly suffocating digital zeitgeist will give rise to a form of competition which would be the mechanist's version of a demo scene.
People will compete to "hack" non-digital mechanics as far as they can go, from analog sensors to mobile, programmable, multi-function automatons such as Theo Jansen's Strandbeests [0].
Resources like this, even if their maintainers have long gone, will become coveted gold mines.
Already sort of happened in the mechanical watch space. When the quartz crisis hit in the 1970's all the traditional Swiss watchmakers had to move upmarket with fancier complications.
I expect the same thing to happen to ICE automobiles. To become luxury/jewellery pieces.
Fantastic (and expensive) works of mechanical movement art, but it goes well beyond this.
Some "watches" (the fanciest ones aren't really wearable, but could be considered "portable") contain an amazing number of various mechanical functions and movements (called "complications"), of utter insane complexity:
Similar such works are done in the clock space as well.
I wish I had the wealth to be able to afford such a piece (then again, if I did, I'd probably have a 3rd iteration of the Difference Engine commissioned first - sigh).
> For example, I predict the increasingly suffocating digital zeitgeist will give rise to a form of competition which would be the mechanist's version of a demo scene.
I think it's not just that. The internet allows niche hobbies to thrive where previously they would die out, because it makes it easier for people to find peers who are into the same thing. Hence it's easier to maintain the minimum required "population" for a subculture to "survive". The people involved are just dispersed across the planet.
I kinda hope this branches out into complex automata; I tend to wonder, though, if such mechanisms from the 17th thru 19th century could ever be improved upon in purely mechanical terms, but to me it's a fascinating thought.
Do you think Leonardo Da Vinci have been a programmer and digital artist instead of a mechanist/inventor if born today? And would his contributions have the same impact?
So I could see him continue explorations of that nature.
> And would his contributions have the same impact?
Aside from his art, and possibly the various engineering commissions or consultations he was involved in - what was in his notebooks didn't see the light of day until long, long after his death. They were essentially "lost" until rediscovered much later. While he was alive, they were probably only seen by himself, and/or maybe a few students (speculating).
On the art side alone, though - would his works have the same impact? That's difficult to say. If they were collected, preserved, and viewed by their owners properly.
I don't know this for certain, but my guess is that most of the artwork of people like LDV of that era, their art were all private commissions, for the most part, outside of a very few pieces that were "publically viewable" - for various terms of "public". Those private commissions would have only been viewed by their owners, family, and maybe a few friends or acquaintances. Outside of those, the works would not have been public, until far later, as they were sold or otherwise "moved around" in the marketplace. Their value would increase or decrease almost at a whim, but also depending on how known the artist was, and other works by the artist. What we see today of these artists is probably mostly survivor bias. There's a good chance that there were others out there of a similar note who just didn't make it because of various reasons (along with a whole host of others who weren't as good, and their art - mediocre or whatnot as it may have been - became "trash" and didn't get passed down to us, but was thrown away over time).
So - if such digital works were created - in 500 years or so, if the work was preserved (migrated from media to media, from machine to "machine", platform to platform) - it's quite possible they would have the same impact - after enough time passed (and everything else being the same).
Back then there was less noise. Today there is such a high ratio of noise that you have to wonder if the geniuses like Newton, Da Vinci, Einstein, etc. would have found a platform and similar level of exposure today, through modern means of communication like YouTube and podcasts.
You have to wonder what disciplines they would have chosen, what their acute insight would have to offer to the modern frontiers of physics, medicine, biology, computer engineering, etc.
It's not a dying art, it's "abstracted away". The servos are still internally utilizing these designs. You just don't have to worry about the gritty physical details, just some basic control code.
Yup, it's in the same way that working with transistors is a
dying art. The use of transistors is not dying at all. Millions and billions of transistors were involved in the creation, transfer, and delivery of these words to your screen or speaker.
Two identical gears start moving at the same speed. Suddenly, one gear slows down, then lurches forward at a much faster speed, and then returns to its starting speed.
While the other, identically shaped gear, spins at a constant speed the whole time.
It appears that the left gear is the driving gear and the right is the driven. This means that the angular speed of the right gear is the ratio of the left radius to the right radius (speed_right = speed_left*radius_left/radius_right). Because the angular speed of the left gear is constant the only change to the angular speed of the right will come from the changing radius ratio of the two gears.
This behavior can be seen a bit more clearly with nautilus gears that have constantly changing radii.
I imagine the red gear is the one backed with a motor rotating at a constant speed. Which would explain why it never slows down or speeds up.
The blue one is being entirely driven by the red. It slows down because moving 2 notches at a greater diameter requires less rotation than moving 2 notches at a lesser diameter. It then speeds up because moving 3 notches at a lesser diameter requires more rotation than moving 3 at a greater diameter.
Others have talked to the changing ratio, however I think the possible implications(use cases) of this are also interesting. I'm imagining making room for something, also rotating at a the same speed, to slip into place by arresting the second gears speed before catching it up.
I'd love to get into watch building which likely utilizes a lot of these tricky movements.
I have recently became interested with the inner workings of watches and found this 1949 video to be a perfect explanation of the underlying concept of a watch movement mechanism: https://www.youtube.com/watch?v=WYBvt9kA3bE
By adjusting the distance from the center the ratio can be changed. Closer to the center on the driving cog (the left red one) will reduce rotation ratio and further away, will increase the rotation.
Only relative speed will be determined by the geometry (these gears, in effect, change the gear ratio throughout one revolution).
In this animation, the author decided that the left gear is driving the right one (while itself, presumably, being driven by a motor at constant speed or something similar).
As others have mentioned, the movements make perfect sense intuitively as soon as you realize that the red gear is rotating constantly (driven by a motor), and the blue gear is spinning freely.
It does indeed thinking about it like that. But since the gears would be bumping into each other rather than just pushing each other would that cause them to deteriorate faster?
Gears are always bumping into each other, one tooth at a time. In practice, the friction of the teeth sliding on each other causes much more wear than the impacts.
In a properly constructed (shaped) gear, the teeth should roll against each other rather than sliding (i.e. the velocities of the contact points are the same).
The left wheel rotates at fixed speed, it's the source of the movement (connected to the source of power). The right wheel rotates according to the relative radii between them, the constant speed of the left wheel dictating its speed.
They are indeed identical but they're spinning in opposite directions, which in effect means one is flipped (going small->big instead of big->small). I believe that's how they can behave differently.
the gear on the left is the driving gear, moving at a constant rate. When the gear on the left allows the gear on the right to fit closer to the center of that left gear, the gear on the right moves more slowly. Similarly, when the gear on the right fits farther from the center of the left gear, the gear on the right moves more quickly
I used to spend a lot of time chasing a mower around the yard while trying to design a continuously variable transmission that used (for lack of the term of art) direct engagement (eg gears) rather than friction on bearing surfaces like belt-based cvt’s.
Came up with a few tantalizing geometries but would always find a problem after thinking it through.
Makes me wonder how many if these were deveoped under similarly mindless activities. Also makes me wonder what a genetic algorithm or ML-based optimization/search algorithm could find.
There is significant research into overconstrained 6, 7, 8+ bar linkages. For reference, an overcostrained 4 bar linkage is quite common, your standard “4-bar linkage”. The fun continues as you add more and more linkages.
I’m no expert, but I understand that there is no closed method for determining viable overconstrained sets past 4. So the research has a large amount of analytical/exploratory research. Very active field:
https://www.google.com/search?client=safari&hl=en-us&ei=1bvk...
I'm curious, I saw this ratcheting CVT on YT[1], and since I have no experience with mechanical engineering wasn't really able to judge how useful it was or whether it was practical, but it looked like the real deal?
There is some information about ratcheting CVTs (and CVTs in general) here [0], although the page looks a bit sketchy. From what I've seen, they are not very practical or widely used. Maybe there is a niche where their capabilities and drawbacks are a good fit but I have not come across it.
One thing to keep in mind is that these days it's not hard to beat (both on price and power/torque capabilities) sophisticated transmission mechanism (meaning - expensive and containing many fragile mechanical parts) by simply using a larger electric motor with variable speed control and fixed gearing. Torque output at low speeds (which would be the advantage of CVT) is going to be limited by mechanical design and weight constraints of the transmission mechanism.
It's useful and practical for some applications (despite what the author says in the video) and has been on sale for decades. But if you use ratchets for the ratcheting, the variability isn't continuous but discrete (as he explains in the followup video you'll presumably watch soon) and if you use sprag clutches or something, the drive is friction-based.
"CVT" in Prius is better described by the term "power split device". It is a very different thing from the belt CVT or ratcheting CVT, as it will not multiply your torque beyond the capabilities of either of the motors.
I am a bit nostalgic/sad about the fact that many young people who would've wanted to learn this craft a century ago are today choosing software engineering.
> The piston and crank connections are such that the steam acts on each piston during about two-thirds of the revolution of the crank, and hence there are no dead points.
Quite a clever solution to allow startup in any position!
This type of thing is very dangerous for me. I can end up browsing these for hours. Very similar to knots, how each one is tied, what it's pros and cons are, the history behind them, etc. I wish like knots these mechanical movements had names instead of just the index number.
As a completely unrelated remark: it felt strange for me to see a so ancient text but without Yat[1] and hard signs[2] at end of the most words. You know, I've never seen so old english text, only russian ones. Typography is recognizably ancient, but where are those old letters. Cognitive dissonance as it is.
Here's the start of the Wycliffe Bible from the 14th century:
> In þe firſte made God of nouȝt heuene and erþe. Þe erþe forſoþe was veyn wiþ ynne and void, and derkneſſis weren vpon þe face of þe ſee; and þe ſpiryt of God was born vpon þe watrys. And God ſeide, Be maad liȝt; and maad is liȝt.
NIV Bible (20th century):
> In the beginning God created the heavens and the earth. 2 Now the earth was formless and empty, darkness was over the surface of the deep, and the Spirit of God was hovering over the waters. And God said, “Let there be light,” and there was light.
By the way, I just say this because you're obviously not a native English speaker: Although your meaning is clear, "ancient" is too strong a word for a text from 1871. Ancient means a very long time ago, like maybe 1000 years or more (there's no exact definition). For this book you might just use "old", or "antique".
Also, interesting to see the old letters of Cyrillic, so thank you for the links.
> "ancient" is too strong a word for a text from 1871
> use "old", or "antique"
Yes, thanks! I knew the precise meaning of "ancient" (it is like in "Ancient Greece" or "Ancient Egypt", it is about times that were really different), it seems as an exaggeration, but thought that "old" is not specific enough and "antique" didn't came into my mind. At the same exaggeration is a valid literacy device.
Thank you, for pointing at that. I really appreciate that, because I feel that my English is not perfect, and the lack of feedback in internet conversations doesn't allow me to improve it.
No problem. :)
And yeah, as you say you can use it as intentional hyperbole as well. "Wow, the first version of The Art of Computer Programming came out in 1968 - that's ancient!"
I like http://507movements.com/mm_398.html which is a programmable drive system. Constant rotation input can give you a cyclic but irregular and arbitrary output movement.
Another good programmable mechanism is a spring made from sheet metal. Take a flat piece and cut a spiral with the width of the material proportional to the force you want at that part of the spring's travel. Stretch it out to form a little tower, with the base on a solid surface, and the load carried on the center of the spiral.
And SmallParts I think is now Amazon Supply or something, but dear god would I not trust Amazon for that sort of purchase. Especially PPE like allegedly 3M respirators. Who knows how much of this is counterfeit.
Small Parts used to be an indispensable source of well cataloged parts for my projects. They shipped quickly and reliably and had a nice parametric search system.
Sadly they were acquired by Amazon and effectively ruined. In theory Amazon sells the same parts but Amazon's search for specialized parts is dreadful, and when you find a part it's often out of stock or available with a long lead time from a dubious supplier.
To me Small Parts is the classic example of how Amazon is systematically stamping out smaller but better suppliers. I'm not sure why Amazon even needed to acquire them. They could have sold those types of parts anyway. I wonder if they simply wanted the smallparts.com url, which now leads to Amazon.
I should clarify why I liked Small Parts vs McMaster Carr: I'm in Canada and Small Parts would ship to Canada, but McMaster Carr would not ship here unless you had a business, but my work was for a hobby.
They were a life saver when I was going to school for furniture. We would order everything from them. Screws, bits, inserts, random bits of metal.
Later I discovered that they provide CAD drawings for everything they carry. That was immensely helpful when designing things in say, Solidworks. If there were some screws that were called for it only took a visit to McMaster-Carr to get a 3D version of the real part.
Given that these animations aren't interactive and run continuously as well as have a fixed resolution (I thought they were SVG at first, but zooming in disproves that), I feel like plain old GIFs would be far better for accessibility and maybe even bandwidth --- GIF's delta-frame encoding is surprisingly effective, especially for art like this.
s/accessibility/generic utility/ - I'm not sure I understand why would one want to use Canvas and code the animations where a GIF would do. Only two reasons come to mind - maybe the future plan is to make them interactive, or maybe the authors found it easier to hand-code the animations rather than bothering with an animation editor.
Which was rather laborious; perhaps his CAD and programming knowledge made it so that creating a physical animation engine was easier than other methods?
Regardless, I wish he'd open source it; he mentions that he might - but it's been a few years now, so...
There's also DMG-LIB[0] and KMODDL[1] which contain mechanism animations along with CAD models of some mechanisms. It's been mentioned before, but thang010146's youtube channel also has many of these mechanisms, sometimes they even have CAD models available of their models. I suspect that thang010146 might actually have the largest digital repository of mechanisms.
If your 2D vector graphics system has support for rendering a path style with diagonal hashes across it, and to continue that path across different primitives (line segments, circle arcs) it seems that then the problem is then easy. You just render the entire cable as a path, starting at the fixed end. You render that path that for different positions of the pulleys and there you have your frames, with the diagonal hashes moving at their apparently correct respective speeds.
The smallest pulley on the bottom betrays how it is done.
The rope is a line along the side closest to the pulley, the other side of it // the wire pattern are made by attaching triangle(-ish?) shapes to it. Only the bend at the smallest pulley is so tight it shows.
Right, the animation is wrong; power is 1:7 if the bottom pulley is fixed and the top is movable, while the animation shows the other way around, which makes it, as you say, 1:6.
There is only cable. Unless the pulleys are stuck due to friction, the tension is equal in all sections of the cable. The load is being lifted by six segments of the cable, so 6x the tension: the machine's advantage is 6x.
Even so - it's "just" a compound pulley system. The advantage of White's pulley seems to be the reduction of friction by only having two axles, and synchronized rope movement so that the rope doesn't need to slip over the sheaves.
Those who find it interesting may also be interested to check out Polhem's mechanical alphabet [1], which was created nearly two centuries earlier. Fun fact: I learned about it from a Pettson and Findus tale I read to my children, and I was lucky enough to see parts of it in the museum in Stockholm [1] during last summer.
What a great project. I have a very similar book (1800 Mechanical Movements, Devices, and Appliances) and have a blast flipping through it. It is great to see the illustrations come alive. Great great job!
There are actually a great many of these "mechanical movement" books from that time period, circa 19th to early 20th century.
They are contemporary with similar books on "electrical machinery" (generators and motors, mainly), "steam engineering", "home and farm improvements/implements", and many other similar subjects.
Some were aimed at the professional engineer, while others were meant or accessible to the ordinary person with such interests or needs.
I enjoy discovering and adding these books to my collection when I can find them at used and antiquarian bookstores.
A few months ago, this video [0] from the 30ies explaining a differential was posted on HN. It also is extremely interesting to watch. Minute 5 is very illuminating.
This is the only link I’m always happy to see resurface when posted here on HN. Every single time (maybe this is the 5-10th time?) I end up watching mesmerised for 50 movements or more.
Some of them would be virtually impossible to build with Lego, as they rely upon machining just not really available in the Lego space (unless there's a wizard of Lego out there that could fashion such parts using certain strange Lego parts from certain sets, like the Bionicle series and such).
But a lot of the more basic mechanical movements could be easily constructed; those with simple pulleys, gears, levers, etc.
So you might not be able to construct all of them, but you probably could construct a great many.
It’s surprising that this crowd seems uninterested in the non-https status of the (otherhwise very cool) site. Have we decided it doesn’t matter? No sarcasm intended. I’d really like to know.
HTTPS Everywhere is dumb security theater that desensitizes users to potential issues when it should otherwise matter.
When only important shit you really wanted to encrypt was encrypted and you get a cert warning you took notice. Now one in 10 sites with an "easy/free ssl cert" that expired has normalized cert warnings on pages with cat pictures and bank sites alike.
Are you worried someone is going to inject a false movement into the page? I'm not giving the page any personal information. There isn't even a login. What would you be guarding against by switching to HTTPS?
In practical terms it doesn't matter, which is probably why HN doesn't seem to care. But in my opinion, it's free and easy to get an ssl cert and so from a norms perspective it should be viewed as non-negotiable today. It doesn't actually add much to the website but it's best practice, like changing the default password on a raspberry pi even if you never plan to network it.
[0] https://animagraffs.com