Davidz90

Thanks. Indeed, wristwatch mechanisms are certainly a sight to behold. Here's an example how a high-quality large scale model of one operates. Much smoother and wider swing arc than in my attempts. To think that they date back to XVIII century... Thanks! First things first, I plan to do some measurements (and maybe computer simulations as well) to choose the best escapement type to mate with balance wheel. Eventually, I want to write a big chapter about wristwatch mechanisms for 2nd edition of my book.

Yes, I tried this as well! It sort of worked in this arrangement: 20241223_165650 but it's definitely inferior to the hose.

Rather unsurprisingly, I decided to build a clock. However, to make things more interesting, it will not be regulated by a pendulum. Instead, a balance wheel like in a wristwatch wil be used. This poses a lot of interesting technical problems: -Pendulum can be made very efficient; much harder to do this with balance wheel without high quality bearings (like jewel bearings used in wristwatches) -Pendulum is very accurate - just setting the proper length takes care of 99% of accuracy. Balance wheel, on the other hand, is very sensitive to driving force and spring characteristic. The use of balance wheel should allow me to build a small, desk clock powered by pullback motor. However, this source of power makes things even more difficult due to limited energy and uneven spring force. Neverthless, my goals are: 1. Make it work for at least half an hour on a pullback motor (so it can be called a clock, not "egg timer" XD) 2. Make it reasonably accurate (I aim for under 1% error; trivial with pendulum, but real challenge here) Right now, I'm testing various escapement options: The second design works for 5 minutes on a full rewind, 30 minutes seems possible.

Ok, thanks!

A question regarding the rules: I'm considering submitting a desk clock with wristrwatch-like mechanism, with balance wheel oscillating on a spring. For that, I needed a very weak spring, which I made out of flexible hose. Specifically, I submerged the hose in hot water so that it took a spring shape permanently, as depicted here: Does this count as modifying bricks? Cutting hoses is OK, so bending them should be OK too?

Well, research submarines do have bright colors typically. Also, this is smaller set aimed for younger kids, of course it is colorful. In this case, many colors don't bother me at all.

Another youtuber tried a few solenoid engine concepts: Pretty much the same conclusions: it is extremely underpowered unless enormous magnets and coils are used. BTW, it's a very cool, mad scientist vibe channel.

Thanks for letting me know! I had no issues with the specified weight, but apparently got lucky. I'll add this change to instructions in a future edition of the book.

Hi! It is a bit hard to see, but the lowest liftarm is considerably shorter. Also, 9.8 inches is the distance between pivot and center of mass, which is a little above the top of the weight. That makes the 6 inches of difference. In the end, fine tuning with a stopwatch is needed to really dial the speed in. If the clock works for a while before stopping, then: 1. Make sure it is leveled; when it is, the gears should recoil the same amount on left and right swing 2. Driving weight may be a little too light. I used that exact weight, but it is a little optimistic. Even a little friction somewhere between gears can stop it.

Thank you very much! Your builds have been an inspiration for me as well, especially pneumatic engines and intricate machinery like the loom.

From my experience, they work with the chain but have a little less grip on it than larger gears, so that the chain will be more prone to skipping teeth if not tensioned well. Also, for some reason, 20t spur gear also has considerably weaker grip on the chain than 24 or 16.

No problem, You can post in this thread. At first I was confused about starship, but it seems like a very cool project! I'll write down the gear ratios in the larger (black/white) and smaller clock: 1. Black/white clock Pendulum has a period of 2 seconds (125 stud length). 40t gear make one rotation in 80 seconds Front has 16:12 gear ratio to make it 60 for seconds hand On the back, 16:24 makes it 120 seconds (2 minutes), then 8:40 makes it 10 minutes, then 8:24 makes it 30. Final 12:24 makes it 60. with 70 studs (1.5 second) pendulum, 40t gears make one rotation per minute so the front dial needs to be 20:20. on the back, 16:24 could be changed to 12:24 to get two minutes, but it needs a different gear spacing. Direct replacement with 20:20 will leave us with one minute, so extra 1:2 reduction has to be added somewhere. There's space for it (for example, in the place of the three 16t gears). Mind the rotation direction. 2. Red clock This one uses one second (31 stud) pendulum and both in front and on the back, there is 16:24 gear ratio to change 40 seconds to 60. Here, exactly as you said, it can be replaced by 20:20 for 1.5 second (70 stud) pendulum.

Wow, amazing find!

Yes, this sounds about right. The amplitude is about 5 degrees, which equals to 2.7 studs displacement to left/right. Of course it's always a good idea to have some margin; building the mechanism, measuring the displacement and then designing the case accordingly is the safest option. Also keep in mind that weight distribution on the pendulum and driving torque affect the period somewhat, so actual proper length may be 32-33 studs.

Gear ratios will need to be altered to account for a shorter pendulum. For a one second period, the ideal length is about 25 cm (31 studs). For 1.5 second period, 56 cm (70 studs). For two seconds, 100 cm (125 studs). Escape wheel has 40 teeth, so it does 1 rotation per minute with 1.5 second pendulum. The smaller, red one is designed with a short 1 second pendulum in mind.

Yep, they are the same mechanism. The concern about size is understandable, my mom complains a lot about it XD In terms of cost, weight on a string is considerably cheaper option than Lego chain. A smaller case is an option, in the most minimal version it can be a column of bricks, with pendulum hanging in front and weight at the back.

Awesome! Which one, exactly? The black and white one has been built recently by one person, with transparent backing instead of wood, and it looks better than mine .

They are reused. I have 4 clocks in total: the ones in the photo, one red (the one with 19 functions) and one black (accuracy world record). Red one will probably get a rebuild next :)

I have a question: Does Cada produce any gears in different sizes than Lego? Recently, I bough cheap "Clementoni mechanics" brand bricks and while most of them are not Lego compatible, gears and axles are. I got gears with 10, 18, 26 and 42 teeth. I'd love to expand my gear ratio options with something higher quality such as Cada.

My new, large project is complete! Clock tower with 3 faces featuring striking mechanism, world time, moon phase indicator and calendar.

Thanks for a cool link! So far, I cobbled together a basic Theo Jansen style walker with no extra gearing. It is stable and walks, but by clumsily dragging feet on the ground. I got a new appreciacion of how much torque is involved in this.

One option for slower-faster motion is this arrangement with two offse axles. (I hope I'm not hijacking the thread, just throwing some ideas)

Yes, noticed that as well. Thanks to this, only one leg is lifted at a time. While there is no direct Lego analogue, there may be some ways to create such an intermittent motion. Seems like an interesting problem, I'll look into that.

Recently, I stumbled upon this video that may be relevant: This design seems to be exceptionally stable.

A new, large project in progress. A clock tower that will have 4 faces with various functions. Right now, regular time and striking mechanism are finished. I managed to make pipe chime with pretty good sound. The idea to encode 1,2..12 strikes in a chain is not new, my improvement is a triggering mechanism that needs a very little force and is not grabbing the chain directly to stop. More details here: Finally, the chime is one of the set of four, which will be used for Westminster chimes (the same melody that Big Ben makes)