alt.hn

7/22/2026 at 2:16:44 PM

The Beam Engine

 https://glinscott.github.io/beam-engine/

by glinscott

7/22/2026 at 2:23:50 PM

Author here. The beam engine created power from steam, and was a key part of the early Industrial Revolution. The article is a deep dive into the engine: how it works, the history behind it, and the engineering tradeoffs the builders faced. There are quite a few interactive figures that I hope make the concepts easier to see.

by glinscott

7/23/2026 at 11:16:51 PM

This reminds me a lot of the articles at: https://ciechanow.ski/archives/

Not just in terms of presentation, but also quality.

Amazing!

by spartanatreyu

7/23/2026 at 11:30:53 PM

Thank you, a lot of research went into it :).

And 100% inspired by Bartosz's articles - he is the first line in the credits section.

by glinscott

7/24/2026 at 10:52:17 AM

Indeed, and what amazing work it is. Fingers crossed you'll create more of this.

by pratio

7/24/2026 at 5:54:08 AM

A fantastic website/person to be inspired by. You also did a great job.

by spiderfarmer

7/25/2026 at 6:08:38 PM

anyone knows what Bartosz is working on these days? miss reading his articles.

by anunay_i

7/24/2026 at 10:49:53 AM

I know right, I clicked on it and thought Bartosz got a new website.

by pratio

7/24/2026 at 4:32:04 AM

Excellent work, glinscott. Thank you for sharing! I am about to send this to all my pals who are parents to schoolkids (um, and also pals who are still, like me, basically a schoolkid :p XD).

Building things up from first principles, and ideally also tactile / visceral examples, is my absolute favourite genre of explanations. Alas, a rarefied genre, because it is so much harder to do well (without doing disservice to the learner's intellect and ability) than expert talking to (presumed) expert. So thanks for contributing to it.

People like George Polya [0], Richard Feynman [1], Grace Hopper [2] are exemplars of this tradition.

[0] https://www.youtube.com/watch?v=h0gbw-Ur_do

[1] https://www.youtube.com/watch?v=EKWGGDXe5MA

[2] https://www.youtube.com/watch?v=ZR0ujwlvbkQ

(And I too try in my own meagre way through my blog and source code, albeit it's all plain text because visual explainers, animated ones that too are ridiculously difficult. So I have some idea of how much of a labour of love your piece is. <Claps hands, Whistles, Doffs hat>.)

by adityaathalye

7/24/2026 at 6:16:01 AM

You are welcome! I agree, it's a really nice way to learn about something. Digging into the transfer of power with belts may have been one of my favorite parts here, even though it's not really steam directly :).

by glinscott

7/24/2026 at 7:22:58 AM

The capstan winding animation is beautiful.

The key thing to understand about early steam engine technology is that they didn't have steel. Good steel in quantity wasn't available until the Bessemer converter around 1880. The converter itself is simple. It took about 10,000 melts to get the metallurgy right, and analytical chemistry to get consistent ingredient mixes.

Without steel, the early engines were cast or wrought iron. So everything was very low pressure, or blew up. That's why "atmospheric" engines such as Newcomen's were built. That doesn't use steam pressure at all. It just uses condensing steam to create a partial vacuum so atmospheric pressure can push the piston. The technology got stuck there for 75 years.

Higher pressure engines made of iron were tried. They blew up frequently at first. This led to a useful institution, The Hartford Steam Boiler Inspection and Insurance Company, founded in 1866.[1] They still exist, owned by Munich Re. Hartford Steam Boiler had a tough approach to insurance. They'd insure risky things such as steamboats, but only after their inspectors had inspected them. Their insurance policies gave them the right to inspect at any time, which they used. The usual arrangement was that they inspected something, produced a list of things which had to be fixed, and came back for a second inspection after the fixes. Only then did they provide coverage. Steamboats mostly stopped blowing up.

(Today, Hartford Steam Boiler also sells business interruption insurance against cyberattacks, and even AI liability insurance. They probably still inspect first. That may be the good path to AI safety - liability lawyers suing for damages on one side, and an insurance company into tough inspections on the other.)

[1] https://www.munichre.com/hsb/en.html

by Animats

7/24/2026 at 3:04:11 PM

Thanks, yes the capstan animation is one of my favorites :).

Great point on steel not being an option, I should have mentioned that.

RE: Hartford Steam Boiler Inspection - cool, thanks for the details!

by glinscott

7/24/2026 at 8:38:23 AM

Despite all the details, you still left out a lot. Safety valve, pressure gauge(s), regulation of the water pump, water level gauge for the boiler, lubrication (you only have two of the glass/metal can reservoir types for the main axle), and then maybe also the valve gear (the control mechanism for the valves which takes into account where in the cycle the machine is and maybe also how fast it is going, how fast it should be going, and in which direction). And a way to drain water from the bottom of the cylinder + maybe a way to make the steam as dry as possible.

And each of those could be expanded to much more than the page you already made.

Things are almost always a lot more complicated than they seem. It seems so simple -- "water + heat makes steam, steam pushes piston, back and forth motion makes rotary motion" -- but it is really anything but.

by peterfirefly

7/24/2026 at 2:58:38 PM

RE: Things are more complicated - I totally agree. My favorite part of the article is probably the belt transmission section. I wasn't sure how it was possible for a leather belt to transmit so much power. Super fun to just dig in deeper and deeper to see how it works. Even there though, I left out a lot - the material properties of leather that let it work, how they attached the belts, the problems they had with gears transmitting power (partly leading to the development of the involute shape for gears), etc.

RE: safety valve, pressure gauge, etc. - yes, there is definitely another article to be built here :). Another fun aspect is safely starting the machine, warming it up appropriately, flushing water from the system, and the bigger engines even had a small engine to get the wheel turning.

by glinscott

7/24/2026 at 1:07:57 PM

I don't have much to contribute to the conversation but I wanted to congratulate you on the work and thank you for sharing.

This is impressive work!

by Otterly99

7/22/2026 at 2:31:29 PM

Really cool site! Did you create the animations with videos of assemblies in a CAD package? Very noice!!!

by monkmartinez

7/24/2026 at 10:52:47 AM

This looks like a labour of love - fantastic

by lifeisstillgood

7/24/2026 at 10:29:23 AM

> This push on every wall is pressure, and we will measure it in atmospheres, multiples of the ordinary pressure of the air around us.

No, don't do that. Because the pressure of the atmosphere isn't constant. It varies with weather and how high you are.

Instead use Pascal (Pa) or Hectopascal (hPA). I really pays back to use SI units for physical things. Suddenly you have formulas without weird constants, like 1 Pa = 1 N/m^2

It's a sad thing that new articles still propose units that are (since many, many years) outdated: the metric system is from 1793, the SI is from 1960.

BACK then people didn't knew better and used the varying atmosphere as base. But today ?!?!?

by holgerschurig

7/24/2026 at 1:49:50 PM

An Atmosphere (atm) is a standardised unit of pressure.

1 atm = 101,325 PA

It is not an SI unit but it is widely used and very useful in situations, such as this, where pressure relative to atmospheric pressure is relevant.

by biorach

7/23/2026 at 10:26:42 PM

One of the unexpected pleasures of having a 3 year old has been learning far more than I ever planned to about steam locomotives. It turns out steam engineering is fascinating, this article emphasized it for me even more. It really amazes me how much ingenuity there is in just connecting the right shapes and joints up so that the right thing happens at the right time, creating perfect cycles, regulators, etc. Seeing it explained in an iterative way like this is fantastic because you can understand what problem is solved by each part. I would love to see a piece like this strictly about locomotives.

by radarsat1

7/24/2026 at 4:06:29 AM

One of my treasured toys - probably from a few years older than your 3 year old though - was a rocking cylinder steam engine my father gave me. It was a present from his father as part of a steam powered boat they built together probably in the late 1940s.

Something similar to this: https://en.wikipedia.org/wiki/Oscillating_cylinder_steam_eng...

And you can still get them reasonably inexpensively: https://www.aliexpress.com/item/1005007964198565.html

I bought one for a friend's 5 year old a while back and became BEST UNCLE EVER!

The run well on compressed air (like an electric car tyre inflator or small air compressor), or for a bit more high temperature danger they run great attached to the steam wand of an espresso machine. When I was a kid dad built me a steam boiler out of a steal aerosol can and some copper tubing with a folded brass sheetmetal alcohol burner. That's not a 5 year old friendly thing though, from memory I'd have been maybe 10 or 12 when he started letting my light alcohol on fire in that garage or backyard. (Modern parenting may disapprove...)

by bigiain

7/24/2026 at 4:04:29 AM

High performance "modern" steam engines are fascinating, they're not necessarily simpler than their internal combustion successors, just different. Monotube boilers create superheated steam that pushes 1200°F, which is right around the same temperature as the exhaust gasses in truck's diesel engine pulling a large hill at maximum power. Hot enough to melt aluminum save for the presence of oil jets to cool the piston and a jacket of cooling water surrounding the cylinder. However, since there's no combustion happening in the cylinder of a steam engine, you don't have any cooling water surrounding it--that would be totally counterproductive. So steam engines operate in a thermal regime that is far more extreme than internal combustion engines. Consequently, bores are often cut slightly tapered to account for the temperature gradient across the stroke, in a double acting engine the cylinder bore has a slight hourglass shape, otherwise the thermal expansion would cause the piston to bind at the ends.

For a fun rabbit hole to dive down, check out Doble steam car technology or the Besler airplane engine.

by 27183

7/24/2026 at 4:29:15 AM

Thanks for the pointers! That is an area I've not explored much - reciprocating steam using modern technology. Using modern electronics, sensors and valves to optimize steam expansion would be a fun project. Perfect cutoff every time :).

by glinscott

7/23/2026 at 10:48:44 PM

Thank you! I have a few ideas for the next article. Locomotives are up there on the list, but they are the final challenge of steam engineering, there is so much to cover.

Also considering the origins of precision - the intertwined evolution of machining tools and measuring systems that allowed these machines to be built.

RE: 3 year old - yes, mechanical systems are wonderful for children (and adults). There is something incredibly satisfying about watching them in motion doing work.

by glinscott

7/23/2026 at 9:26:17 PM

Ever hear the phrase "Balls out" when referring to pushing something to the max? Comes form the balls of the centrifugal engine governor. At maximum speed the balls extended all the way outward giving us the term "Running balls out."

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

edit: I once said this phrase at a work meeting and someone objected to my use of a crude term which I then explained much to everyone's surprise. They thought it had something to do with testicles.

by MisterTea

7/24/2026 at 12:54:41 AM

While fun and satisfying, this is extremely unlikely to be true.

The first attested use is from 1945, on the nose of a P-47 Thunderbolt flown by Captain Milton Thompson of the 509th Fighter Squadron. And his art was exactly what you'd expect: a charging bull with the words "balls out".

by bos

7/24/2026 at 1:39:51 AM

Maybe he's thinking of "balls to the wall"?

by inigyou

7/24/2026 at 3:58:09 AM

Could be, for which the first attested use is in 1965 or so. Still doesn’t help.

by bos

7/23/2026 at 9:51:50 PM

Definitely a fun note :). I think I heard it first from a Jay Leno youtube video where he was showing his amazing collection of steam powered machinery.

This is from the article, but governors also played a role in kicking off modern control theory! """ In 1868, James Clerk Maxwell studied when these oscillations grow or die away in his paper “On Governors”[https://www.damtp.cam.ac.uk/user/gold/pdfs/teaching/old_lite...]. This became one of the beginnings of modern control theory. """

by glinscott

7/24/2026 at 2:33:06 AM

Indeed, and of course "governor" in Greek is κυβερνήτης (kubernetes).

by emmelaich

7/23/2026 at 9:44:05 PM

tbh, any time i've said it i've been referring to testicles, but thanks for the helpful excuse in future.

by dijksterhuis

7/23/2026 at 9:30:06 PM

Similar to balls to the walls (or similar). Coming from the analog aviation controls I believe.

by jscott817

7/23/2026 at 9:46:18 PM

Example, throttle controls on a Dogulas DC3. All engine controls forward is the typical convention for full power. (At sea level, neglecting the altitude effect on required engine fuel/air mixture.)

https://www.douglasdc3.com/dc3throt/dc3throt.htm

by buildsjets

7/23/2026 at 9:53:05 PM

That said, i'm sure the pilots were aware of the double entendre

by conartist6

7/23/2026 at 9:43:10 PM

Balls to the van der Waals

by CalRobert

7/23/2026 at 11:08:58 PM

Engaging in a little hydrogen bonding, eh?

by taneq

7/24/2026 at 12:54:46 AM

There is also a steam engineers term called "high-balling" which referred the little ball in the steam pressure gauge used in the early days. So high-balling was travelling at high speed.

by lebuffon

7/24/2026 at 1:48:58 AM

plausibly related to a "high ball" (cocktail glass shape, or slang for a personal-use amount of cocaine)

by chrisweekly

7/23/2026 at 11:07:51 PM

> When the engine slows, the balls fall and open the cock again.

The choice of wording makes me suspect that they intended both entendres. ;)

by taneq

7/24/2026 at 2:26:19 AM

Euphemisms are weird, what was originally intended as a way of saying a thing without actually saying that thing, becomes the unspeakable thing in the first place. and the original meaning fades.

The one I like is why do we use birds to refer to female anatomy? I also heard something the other day and had an epiphany, but the sort you can't really tell anyone. "Oh... it means pouch that makes so much more sense, it's not a cat."

by somat

7/24/2026 at 2:48:24 AM

[dead]

by yunnpp

7/23/2026 at 9:58:18 PM

I suppose this is also the less colorful true origin of "balls to the wall" than the phrase itself suggests?

by goodmythical

7/23/2026 at 10:01:26 PM

Nope. Balls to the wall refers to the balls on the end of throttle levers in aircraft cockpit.

Going balls to the wall means pushing the throttle and mixture all the way in to the firewall/instrument panel for maximum power.

by dghlsakjg

7/23/2026 at 11:17:39 PM

Nit: I believe this originated with locomotives, predating aircraft by quite a bit!

by teachrdan

7/24/2026 at 1:56:04 PM

Every source I can find says it was a mid century phrase first found written in the 1960s from pilots. Pre aircraft locomotives would have been steam driven. Largely operated by a complex series of valves, mostly rotating so no wall to push them to. They did have a governor balanced by rotating balls, which when at full RPM would be fully extended, or: balls out.

https://www.thedrive.com/news/the-phrase-balls-to-the-wall-c...

by dghlsakjg

7/24/2026 at 1:01:46 AM

What about the phrase "testicles out"?

by akoboldfrying

7/24/2026 at 1:41:00 AM

That one, although widely believed to refer to the steel balls in a centrifugal governor of a steam engine, actually refers to testicles.

by inigyou

7/23/2026 at 11:30:53 PM

and i suppose “fuck” is actually an acronym for “fornicating under command of king,” right?

by icase

7/24/2026 at 1:50:09 AM

For Unlawful Carnal Knowledge is the acronym I've encountered most

by chrisweekly

7/24/2026 at 1:32:08 AM

[dead]

by Daz912

7/23/2026 at 11:16:30 PM

Ancient Greeks had a steam engine. They called it a Hero's engine. They used it as a toy.

They couldn't use it as anything else than a toy. The reason they couldn't because they didn't have the metallurgy and the machining to create pistons, valves, etc.

There's an important lesson that can be applied to every technology, I think: technological progress is always iterated, never revolutionized. If your novelty - a programming language, a framework, a methodology, whatever - doesn't stand on the shoulders of the giants, then you have simply nothing to apply this novelty to.

by AndriyKunitsyn

7/24/2026 at 2:35:59 AM

That was a reaction engine, something like a steam rocket confined to rotate in a circle, and not a positive-displacement engine: https://en.wikipedia.org/wiki/Aeolipile

They couldn't use it as anything else than a toy. The reason they couldn't because they didn't have the metallurgy and the machining to create pistons, valves, etc.

IMHO they definitely had the processes to basically add a PTO to one, but it was probably dismissed as impractical.

by userbinator

7/24/2026 at 1:44:10 PM

> The reason they couldn't because they didn't have the metallurgy and the machining to create pistons, valves, etc.

It was a turbine. You don’t use pistons in a turbine. They lacked knowledge of turbine blades, the metallurgy to make pressure vessels, and the tools to make parts with the tolerances needed to spin at high RPM and withstand high temperatures.

by mr_toad

7/24/2026 at 5:09:27 PM

Probably could've connected it to some tiny device, and then someone surely would've thought, what if we made a really big one a d connected it to our Archimedes screws?

by inigyou

7/24/2026 at 9:27:28 PM

The Romans didn't have a need to pump water from coal mines because they hadn't yet cut down all their fuel forests or exhausted all their surface deposits of coal. Newcomen's engine was so inefficient, it needed to be at a coal mine to power it and this jet screw engine would have been even worse. If they wanted to turn an Archimedes screw, it would have taken less labor to just have a person turn it by hand.

by foxglacier

7/24/2026 at 9:32:13 PM

I'm sure they could afford to build one or two as an experiment.

by inigyou

7/24/2026 at 8:47:40 AM

[dead]

by peterfirefly

7/24/2026 at 12:06:00 PM

Whenever I see an explanation of an old technology, I don't wonder "How do that work" but rather "How did they even build this"

How did they make vacuum and be sure it was indeed a vacuum ?

How did they melted that metal alloy into the right shape ?

How did they built those precise mirrors ?

How many times did they fail before succeeding ?

How did they lubricate and seal properly all components ?

I know I could explain 80% of those inventions easily by studying them for a few days each. I know I would never be able to build 1% of those machines myself, I'd constantly run into technical issues and it'd take me years for each

by ttoinou

7/24/2026 at 5:07:14 PM

One of the most conceptually simple ways to make a vacuum is a Sprengel pump. You have, from top to bottom, a pipe full of mercury, a restriction so it comes out in drops to the next stage, a chamber where the vacuum is developed, and an exit pipe. Mercury drops fall through the chamber, trapping air between them as they fall down the exit pipe. The energy comes from lifting the mercury back to the top.

A way that's easy to execute, but doesn't produce a perfect vacuum, is to fill a chamber with steam (actual high temperature steam, not the clouds coming off a kitchen pot), seal it and cool it. This is only a near-vacuum because it's filled with low pressure water vapor, but it's very easy to do.

by inigyou

7/24/2026 at 12:42:58 PM

For this reason, I always point out that toolmaking was an essential and often forgotten part of Manchester’s Industrial Revolution.

by davidpapermill

7/24/2026 at 12:33:45 PM

You might enjoy How to Make Evertything on YT.

by Sophistifunk

7/23/2026 at 9:05:17 PM

This reminds me a lot of https://ciechanow.ski, down to the body typeface. (IBM Plex Sans?) Also, the SI units everywhere here make me beam. Thank you :)

by delta_p_delta_x

7/23/2026 at 9:08:51 PM

100% - his articles were a major inspiration, and first line in the credits: - Thanks to Bartosz Ciechanowski, whose exceptionally well written and designed articles inspired this one.

Glad you enjoyed the units :).

by glinscott

7/24/2026 at 2:55:22 AM

Are you a graphics programmer? That js/glsl is no joke.

by yunnpp

7/23/2026 at 9:00:46 PM

For those in London who want to see one of these in the flesh, as it were, there's one in Tottenham: https://www.mbeam.org/

by frereubu

7/24/2026 at 6:56:44 AM

There’s also the amazing Crossness, which does have occasional steaming days. And if you’re in Manchester the Museum of Science and Industry has a great collection of small and large engines which they run

by blipvert

7/24/2026 at 12:45:07 PM

Yes, Manchester has a good collection but the exhibits are sadly lacking on technical details, be warned.

by davidpapermill

7/23/2026 at 10:07:29 PM

Quinn (Blondihacks) on youtube is a model engineer machinist and has, IMO, the most outsider-watchable content on building boilers and steam engines like this.

Highly recommend this primer titled "The Model Engineering Learning Curve" https://www.youtube.com/watch?v=Ps_BQJEMnGA

She's been building a model locomotive for years now, there are over 100 videos: https://www.youtube.com/watch?list=PLY67-4BrEae-xhrvZX33gPk4...

One more: a little engine I'd never encountered before called a wobbler is, apparently, the hello world of machining model engines: https://www.youtube.com/watch?v=HrHDrIms7-0

by eleventen

7/23/2026 at 10:28:15 PM

Blondihacks is amazing. Beware though, you may be buying a lathe and a milling machine soon after you start watching :).

It's a great hobby. Manual machining is totally different from writing code, but you get into a similar state of flow.

by glinscott

7/24/2026 at 10:58:47 AM

Blondie hacks guided me on how to lathe, which was grand as I'd only ever done router CNC before.

by KaiserPro

7/24/2026 at 6:04:06 AM

Wow, that Blondiehacks video opened my eyes to a whole unknown world. Thanks!

by aryehof

7/24/2026 at 1:34:42 AM

I'm only ~5 minutes into that first video and every single thing she has said so far rings so stupid true that its almost painful hearing it said so bluntly. Making things takes a lot of time, requires lots of fundamental skills, is expensive to do yourself, generally isn't going to be better than something other people are selling, and should be fun the entire time you're doing it.

This should be the comment that people read on this post. Watch these videos.

by shit_game

7/23/2026 at 11:51:50 PM

See also Wreck2Restored, a channel that documents the ongoing restoration of a 2-foot gauge steam locomotive. Crossheads and sliding valves featured!

https://www.youtube.com/@Wreck2Restored

by pfdietz

7/24/2026 at 1:53:47 AM

The interactive article is so good!

(Sorry I am pasting my old comment.)

Some Model Engineering related resources:

Engineering drawings of small model engines used in model aircraft making. These designs are intended for manufacturing and practical operation, rather than merely for display, and can be used to build fully functional engines.

https://www.modelengineeringwebsite.com/Beam_Engine_drawings...

https://modelengineeringwebsite.com/Classic_ME_beam_engine.h...

https://outerzone.co.uk/plans.asp?cat=Engines&Xcardsperpage=...

https://modelenginenews.org/midge/index.html

https://modelengineeringwebsite.com/Midget_gas_engine_1.html

https://www.adriansmodelaeroengines.com/catalog/product.php?...

by pillars

7/24/2026 at 1:43:21 AM

The first steam engines were vacuum engines, fill a cylinder full of steam and as it condenses it sucks the piston down, Watt's improvement and patent was on a separated condenser unit so you did not have to reheat the whole cylinder each time. This doubled the efficiency, that is, reduced the amount of coal you had to burn by half. But Watt would not sell manufacturing rights to his patent he sold operating licenses, If you had an engine that utilized Watts patent idea you owed him half the price of the coal you did not have to burn by using it. Consequently there were a lot of "pirate" engines, the most common method of working around Watts patent was to claim that your condenser was integrated into(as opposed to separated from) the cylinder some how.

by somat

7/24/2026 at 4:33:00 AM

Yes, great details! Not sure if you've read it, but "Richard L. Hills, Power from Steam: A History of the Stationary Steam Engine (1989)." is a truly wonderful overview, that really digs deep into the business. It has many letters directly from Watt, including the problems they had getting these huge engines built (before any decent roads!).

by glinscott

7/24/2026 at 10:48:04 AM

why are you badly summarizing the post?

It wasn't a vacuum engine, as per post the water just cooled the cylinder. And it wasn't half of the coal, it was a third.

by GeoAtreides

7/24/2026 at 12:28:25 AM

Ha. The title lead me to believe this was about Erlang. But this is great too.

by pstuart

7/24/2026 at 12:39:34 AM

When I clicked on the link, I first thought it was going to be about, well, steam engines. Then I realized this is Hacker News, so it's probably about the Erlang VM. Turns out my first thought was actually the correct one!

Glad to not be the only person to expect Erlang instead of steam.

by jcranmer

7/24/2026 at 8:50:43 AM

Yes, I also got briefly very confused about the top comment.

by vidarh

7/23/2026 at 9:03:52 PM

Cool! If you're in New Zealand, there is a massive, two story Double Woolf beam engine at MOTAT museum in Auckland, along with an array of other steam driven engines that they run from time to time.

by constantlm

7/23/2026 at 9:10:42 PM

This is what finally made the idea behind Watt's condenser click for me.

by a_shovel

7/23/2026 at 9:14:33 PM

Awesome! It's pretty amazing all the concepts that need to come together for even these very old engines. I found I built a better understanding of what was going on as I built out the animations as well.

by glinscott

7/23/2026 at 9:18:19 PM

First off, this is very cool, I love these kind of breakdowns from first principal.

This is sending me :)

> One cup of water becomes roughly 400 litres of steam, enough to fill two bathtubs

Three units of measurement in one sentence, my favorite unit is bathtubs.

by bullfightonmars

7/23/2026 at 9:32:11 PM

Thanks!

RE: units - Good catch - there is almost certainly a better way to phrase this one. I always tried to give physical examples to make things more concrete. But who knows, maybe the bathtub will take off as a unit :).

by glinscott

7/23/2026 at 9:50:27 PM

Those damn imperial measurements.

by LoganDark

7/23/2026 at 10:30:07 PM

Love this article!

One nit: All three animations that show the governor and the flywheel have the governor turning the wrong way, causing the gears that join them to do physically impossible things.

by diggernet

7/23/2026 at 10:35:52 PM

Oh my. Yes, you are totally right. This was tricky because I needed to merge two different animations (the governor moves independently from the rotation of the wheel), and I seem to have messed that up.

Fix shall be deployed shortly!

by glinscott

7/23/2026 at 10:53:44 PM

Fixed!

by glinscott

7/24/2026 at 12:26:24 PM

If you enjoyed this and haven’t been, you need to plan a trip to Paris to spend a day at Musée des Arts et Métiers.

by jonstewart

7/23/2026 at 11:47:22 PM

Nice replacement since B Ciechanowski joined OpenAI, we don't get those high quality articles anymore.

by brcmthrowaway

7/23/2026 at 10:40:55 PM

How did you do the figures? Iterative design with Three.js and an agent? What did that process look like?

by Evidlo

7/23/2026 at 10:53:35 PM

It was a mix of techniques, this article has been in progress for quite a while :). The first part was modeling all the relationships for an accurate beam engine in onshape (great cad tool). Then, I built a custom exporter to cleanly export it to three.js. This ensured physical realism for the hero of the article. All of these are linked from the article.

For the figures, I had prototyped some by hand, and it was slow going. Fable was the first LLM I found that was actually able to understand and model mechanical linkages correctly enough to be useful. I built a style guide, and iterated many times on each figure and animation until we arrived at something useful. There are also quite a few backing tests to ensure physical correctness of the animations (as far as reasonably possible :).

by glinscott

7/23/2026 at 10:00:13 PM

my grandpa had a table top model of a beam engine that he would power with a pressure cooker

by tingletech

7/24/2026 at 12:41:55 PM

This is SO cool!

How do you make those animations?

by ciefa