[HN Gopher] Designing a Lego orrery
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       Designing a Lego orrery
        
       Author : _Microft
       Score  : 588 points
       Date   : 2024-06-09 19:23 UTC (1 days ago)
        
 (HTM) web link (marian42.de)
 (TXT) w3m dump (marian42.de)
        
       | h2odragon wrote:
       | Art is often enhanced by the constraints of the medium in which
       | it is realized.
       | 
       |  _wow_ thats cool. Lego should pay him lots of money for the plan
       | and sella few kits of it.
        
         | mortos wrote:
         | As he mentions in the article, LEGO does sell a kit already,
         | set 42179. I find it unlikely they'll adopt his design when
         | they already sell one of their own, even if his has
         | improvements that he mentions.
        
           | eichin wrote:
           | Though it looks like it's not _strictly_ against
           | https://ideas.lego.com/guidelines , under "PLEASE ONLY
           | SUGGEST NEW IDEAS. NO IDEAS TO "BRING BACK" OLD LEGO SETS."
           | they say:
           | 
           | > Don't submit product ideas requesting we re-release or
           | "bring back" discontinued LEGO products or themes in their
           | original form, and don't submit product ideas that are
           | "modifications," "improvements," or "expansion sets" to
           | existing or past LEGO sets. If you're submitting a product
           | idea based on a discontinued LEGO theme or brand (for example
           | Blacktron or Octan), it must be your own new, creative work.
           | 
           | simply because this design _predates_ the official re-
           | release... but given that the official one is from this year,
           | it seems really unlikely they 'd run with it this soon
           | anyway.
        
       | flafla2 wrote:
       | This is so awesome. There's a lot to geek out about here, but I
       | was personally enamored with the extra effort to make good
       | renders/visualizations in software. Thanks for the read!
        
       | CaptainOfCoit wrote:
       | The gear ratio calculator is great and will be of great use!
       | Thanks!
       | 
       | Extra + for making the form variables controllable by URL params:
       | https://marian42.de/gears/?targetratio=2/8&dst=any&gears=def...
        
         | dolmen wrote:
         | The project is open source: https://github.com/marian42/gears
        
       | HenryBemis wrote:
       | I love Legos, I usually make them and give them away. Now, this
       | one surprised me and I was amazed. I will never do this, but
       | WOW!!!!
        
       | _Microft wrote:
       | The creator of this also made a tool to design custom,
       | 3d-printable Lego-compatible pieces:
       | 
       | https://marian42.de/article/partdesigner/
        
         | jb1991 wrote:
         | Now if only we can reliably 3D print the gears also, and ensure
         | they still work well with other pieces.
        
       | IshKebab wrote:
       | I have the not-Lego(tm) orrery he mentioned at the start and it
       | is great. Very good value for money & fun to build. It is sad
       | that you can't use it to explain seasons though, like you can
       | with his serious upgrade. Nice work!
        
       | juliangamble wrote:
       | The author spends lots of time modelling axial tilt to represent
       | the seasons.
       | 
       | Then there was this gem:
       | 
       | > I also used this program to create digital building
       | instructions. My takeaway from this is that it works really well
       | for small models, but it has serious usability problems on larger
       | models. When you make changes to the model or change an early
       | step in the instructions, it will often break the layout of the
       | instructions in many places so that most of it needs to be
       | redone. This was a lot of tedious work, but I ended up with a 264
       | page, 436 step instructions PDF.
       | 
       | Wow.
        
         | dclowd9901 wrote:
         | That actually doesn't seem that bad for a model this complex.
         | The larger sets can have well into the hundreds of steps with
         | manuals reaching into several hundred pages on 8x10 paper.
        
           | iwontberude wrote:
           | I used a Lego product this past week and the instructions
           | were actually omitting 1-2 steps explicitly and expecting you
           | to see the difference between the current and previous
           | figures in the print.
        
             | pimlottc wrote:
             | In the old days, "spot the difference" was the standard
             | practice in Lego instructions [0]
             | 
             | 0: https://www.toysperiod.com/download.php?file=h4d4k5w544a
             | 4h4n...
        
               | dumbo-octopus wrote:
               | As it should be. I credit LEGO for my acing the ASVAB
               | spatial reasoning sections.
        
       | Tokkemon wrote:
       | They make a model of this exact thing: https://www.lego.com/en-
       | us/product/planet-earth-and-moon-in-...
        
         | jnsie wrote:
         | The author describes their experience with this set
         | 
         | > Two years later in 2024, Lego released their own orrey
         | design. I was quite excited at the prospect of an official Lego
         | orrery, but I was disappointed by the execution....
        
           | trgn wrote:
           | The lego one is actually pretty nice, and cheaper than most
           | ready-made models.
           | 
           | The one part that isn't quite right, and I'm not even sure
           | I've ever seen a model that does this right, is the moon's
           | orbital tilt, so the earth isn't blocking the moon for full
           | moon, and the moon isn't blocking the sun for new moon. The
           | distances probably don't scale to make it practical, the tilt
           | would have to be extremely exaggerated. The phases of the
           | moon is the only thing that I've never seen an orrery show
           | very well.
        
       | OptionOfT wrote:
       | > To make matters worse, the axis always points in the same
       | direction.
       | 
       | I don't understand how this was never explained to me in high
       | school. Of course we learned that the tilt of Earth is what
       | causes seasons, but I never understood why. Now I know why I
       | didn't understand it, some part was missing.
       | 
       | And I literally thought I wasn't smart enough to understand.
        
         | gnramires wrote:
         | It follows from conservation of angular momentum :) If the axis
         | direction changed (for a fixed orbit), then Earth's (or Solar
         | system's, etc.) angular momentum would be changed, not be
         | conserved.
        
           | dumbo-octopus wrote:
           | Unless the Sun's tilt moved ever so slightly in compensation.
           | 
           | Around one one billionth of a degree to be exact. Impossible
           | to detect.
        
             | gnramires wrote:
             | Indeed. Another fact you can use is that in Newtonian
             | mechanics (although not in GR due to frame dragging, only
             | approximately), a rotating spherical body has the same
             | gravitational field as a static one. So there would be no
             | mechanism for the axially tilted rotating Earth to
             | influence the Sun (different from a non-rotating Earth).
        
         | eru wrote:
         | I guess a good animated 3d model, either digitally or one you
         | can touch like this orrery, would have cleared up a lot of
         | confusion. Especially if you can play with it in a darkened
         | room with a flashlight.
        
           | mikepurvis wrote:
           | Yeah, the critical insight is that the tilt impacts how high
           | in the sky the sun is, which in turn affects the length of
           | the day and the incidence angle of the sunlight.
        
           | KolmogorovComp wrote:
           | You do not need a complex 3d model, very simple illustrations
           | show it well.
           | 
           | https://kidspressmagazine.com/wp-
           | content/uploads/2014/04/dre...
           | 
           | And then explaining that the hemisphere that receives the sun
           | energy perpendicularly get more heat from it.
           | 
           | https://scitechdaily.com/images/Earths-Seasons-Tilt-
           | scaled.j...
        
         | Perz1val wrote:
         | It does rotate, but it's slow enought to not matter in most
         | cases. Afaik some ancient, star aligned constructions do not
         | work anymore because of this
         | 
         | https://en.m.wikipedia.org/wiki/Axial_precession
        
         | KineticLensman wrote:
         | The thing I spent some time puzzling about recently is why the
         | changes to sunrise and sunset times through the year aren't
         | symmetric about midday and why they have different rates at
         | different time of the year. This led me to the equation of time
         | [0], another fascinating rabbit hole.
         | 
         | [0] https://en.wikipedia.org/wiki/Equation_of_time
        
         | ClumsyPilot wrote:
         | I noticed this often happens in school. A key piece of
         | information is just missing and you just learn the right answer
         | to pas tests, but never know why
        
         | gmiller123456 wrote:
         | They used to tell us you could stand an egg on its end on the
         | equinox because the Earth was standing straight up and down. It
         | really wasn't part of class, just something people mentioned. I
         | even remember seeing a short news story of kids actually trying
         | it in school. Then at one point one of my teachers pointed out
         | people figured out you could do it any day of the year.
        
       | ropable wrote:
       | One of those examples where a community creation is miles better
       | than the "official" Lego design.
        
         | NeoTar wrote:
         | Better by some measure - LEGO is probably optimizing for
         | different metrics:
         | 
         | - Number of distinct pieces (fewer is better),
         | 
         | - Complexity of build-process,
         | 
         | - Robustness,
        
       | ashton314 wrote:
       | Daaaaaang that's amazing.
       | 
       | I want to build this as the first bit of a clock like the one in
       | _Anathem_.
        
       | pimlottc wrote:
       | Great article! I would also highly recommending following the
       | link at the end for the video on Akiyuki's clock [0]. It's a
       | masterpiece, and that's saying something for how brilliant his
       | other designs are.
       | 
       | 0: https://www.youtube.com/watch?v=GUdlSYC1cCE
        
       | hubraumhugo wrote:
       | Whenever I see a project like this that involves hundreds of
       | hours of engineering and craftsmanship, I think: Doing nothing
       | after retirement doesn't appeal to me, so this is how I'd love to
       | spend my time (even sooner if circumstances allow).
        
         | fragmede wrote:
         | What do you think retirement _is_?
        
         | bdjsiqoocwk wrote:
         | That's retirement.
        
         | HenryBemis wrote:
         | Retirement = you bought (pension/savings/investments) yourself
         | time in your 20-30 last years in life to enjoy. You are paying
         | yourself to do what pleases you.
        
           | piotrke wrote:
           | You paid everyone in life first. Now you pay yourself. Last.
        
             | marcusverus wrote:
             | Naturally. Retirement is the most expensive thing you'll
             | ever buy!
        
         | p0seidon wrote:
         | The picture at the start of the article just says it all. I was
         | just looking at it for minutes and didn't dare to scroll down.
        
       | ragebol wrote:
       | This is great, also the various calculators and parts designer.
       | 
       | I've been looking to build an articulated clock, which is pretty
       | much an orrery like this but without planets and different gear
       | ratios.
       | 
       | Difficulty is that I'd like to have the second hand keep straight
       | from minute hand at whole minutes. And I think I need a gear
       | ratio of 61 for that. Or Keep it straight up at whole minutes,
       | which needs a gear ratio of 59 IIRC. Both primes, so not easily
       | achievable with gears.
       | 
       | It's been a while since I spent time on this though.
       | 
       | EDIT: I could add/subtract 1 rotation via a differential gear I
       | think.
        
       | jb1991 wrote:
       | I too am disappointed by the direction Lego has gone away from
       | the classic Technic gears and pulleys. And the cancellation of
       | Mindstorms without an adequate replacement. It's the end of an
       | era. Now everything is mostly focused on brand deals with all the
       | popular themed kids toys.
        
         | qzio wrote:
         | What about wedo and spike? I think they look pretty ok...
        
           | jb1991 wrote:
           | Well, "pretty ok" is not a great bar coming from the
           | mindstorms system. But even if you exclude that entire
           | category, the Technic series overall is not the same as it
           | used to be.
        
       | TechDebtDevin wrote:
       | This is lame, the world needs smart people like you solving real
       | problems. A cool project but dumb as hell at the same time.
        
         | pootempy wrote:
         | How many smart people run marathons, do all night drink binging
         | sessions, travel to exotic cities and other such follies?
         | 
         | My belief is that a project like this (and probably the
         | marathon and travel too!) make you smarter. You need to do
         | something that ain't work sometimes!
        
         | isametry wrote:
         | Ignoring most of your comment and only focusing on this part:
         | 
         | > the world needs smart people like you solving real problems
         | 
         | It has them. And they're doing pretty much exactly this. What's
         | described in the OP resembles a pretty standard machine design
         | process - the key is splitting up the complex goal into smaller
         | manageable units. (And using tools for the tedious parts such
         | as gear math; if the tools don't exist, you of course develop
         | your own!)
         | 
         | The author was presumably able to do this _because_ they've
         | already solved a real problem or two.
        
         | another-dave wrote:
         | it's a bit like Richard Fenyman's wobbling plate -- you don't
         | necessarily know where you'll end up (maybe with a Nobel
         | prize).
         | 
         | -- https://www.asc.ohio-state.edu/kilcup.1/262/feynman.html
        
       | dolmen wrote:
       | See also this older LEGO orrery produced by the University of
       | California as an educational project for NASA Kepler mission:
       | 
       | https://www.nasa.gov/wp-content/uploads/2016/09/table-top_tr...
       | https://www.nasa.gov/wp-content/uploads/2016/09/table-top_tr...
       | 
       | Also: http://mrob.com/pub/lego/orrery.html
        
       | hoseja wrote:
       | How about a nice metal non-LEGO orrery that doesn't cost a
       | gajillion dollars.
        
       | snowwrestler wrote:
       | About an hour after reading this blog post and the thread here on
       | HN, I opened Instagram. The very first ad was from Lego, for
       | their orrery.
       | 
       | It was so specific and unique (I can't recall ever seeing an ad
       | from Lego on IG at all) that it must have been targeted by some
       | behavioral data on me.
       | 
       | But from where? HN and the blog do not seem to be running the
       | Meta pixel, and I was using Safari on iOS, which blocks 3rd party
       | cookies.
       | 
       | After some recollection, I remembered that I had clicked play on
       | one of the YouTube videos that are embedded in the blog post. So
       | Lego must have Google ads running that target people who view
       | these orrery project videos.
        
         | johnmaguire wrote:
         | Do you even need to click play on a video, or is the act of
         | loading the embed enough?
        
         | et-al wrote:
         | EFF's Privacy Badger shows a few potential trackers when
         | loading that page.
         | 
         | https://github.com/EFForg/privacybadger
        
       | lawlessone wrote:
       | The is wonderful
        
       | larodi wrote:
       | Schools should teach Lego and such mechanics in particular as
       | mandatory classes. Starting from first year with increasing
       | complexity. Of course alongside classes for graph networks and
       | their applications.
        
         | meristohm wrote:
         | Counterpoint (from the perspective of a science teacher who has
         | used LEGO as part of teaching, and who still has about 70
         | pounds of LEGO): LEGO pieces reinforce "blocky" engineer
         | mindset, reinforcing the idea that we can "fix" climate change
         | with technology.
         | 
         | We're up against a population boom enabled by access to fossil
         | fuels. Our nigh-insatiable appetite for energy conversion has
         | serious consequences for life on earth.
         | 
         | I'd far rather teach basketry & other fiber arts, foraging for
         | food & medicine, land stewardship, how to hunt kill and process
         | animals for food, and other primitive (using this word non-
         | pejoratively) skills done as a tight-knot group (such as what a
         | classroom can be with good leadership- not saying I provided
         | that to the degree I value now, but if/when I go back to
         | teaching, I will). LEGO is a distraction, a luxury enabled by
         | the Industrial Revolution. We don't have plastic interlocking
         | bricks without coal and petroleum and long (and easily-
         | disrupted) supply chain.
         | 
         | Until a few years ago my LEGO collection, amassed in childhood,
         | was a prized possession. Now I'd have sold it or given it away
         | were it not for my wife advising we keep it for our child. In
         | light of what I wrote above, while I can get down on the ground
         | and immerse myself in creative parallel play, I'll also promote
         | the old ways to plant the seeds of a wonderful, effortful,
         | meaningful life that also has a more down-to-earth carbon
         | footprint.
        
           | bigstrat2003 wrote:
           | Climate change is not a reason to not enjoy Legos. Life is
           | for enjoying, not for worrying about whether one's hobby is
           | environmentally friendly enough.
        
       | MrTurvey wrote:
       | This brings me back to young me and my mechanic dad making a
       | hydraulic car with Lego Technic. Isn't Lego just the best, for
       | all ages and all walks of life?
        
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