Davidz90

A neat way to slow the pendulum down without making it longer is to add a secondary mass above the pivot. This method can slow it down considerably. Also, You may consider using a more subtle escapement that is less power hungry. Something with regular gear as an escape wheel, for example. The one in the video is extremely inefficient.

Whoa, it sounds amazingly well! Those are nylon strings? How thick? In my guitar, I really struggled with making the structure stiff enough to not bend under the string tension, but that was with steel strings.

You are right that two line segments is a somewhat surprising shape, and a parabola would be the more expected outcome; at least assuming that the period depends somewhat linearly on torque. Then again, torque characteristic of a pullback motor is not that linear either. It seems that instead of changing continously, the torque jumps between values (which corresponds to a jump in the slope of the error, giving that segmented look). To really properly analyze the torque dependence, I'd need to switch to gravity power and do multiple runs with various driving weights.

The new escapement design is reliable and efficient enough, runs for about 10 minutes with a single pullback motor and 1:25 gear ratio. Now let's see if it is stable enough. Thanks to loud, clean ticking sound, I can use sound recordings for measurements (incidentally, that is how technicians troubleshoot real wristwatches). They look like this: audio1 By measuring the time between ticks (more specifically, the last, highest peak), one gets the period: periods_1 Right now, it is slightly below 2.2 s; I'll either reduce the inertia of the wheel a little to aim for 2 s, or increase it to go for 2.5 s. At any rate, it seems rather stable, with +-0.05 s variation. A histogram confirms this: periods_2 Finally, assuming for a moment that the mean period of 2.19 s is the ideal value, here is the error: periods_3 One can see that the clock is never more than 0.35 seconds off during the 7 minute test run, despite the fact that pullback motor torque decreases by over 50% during that time; an impossible feat without chronometer escapement.

Really interesting, this topic seems to be a real rabbit hole! I wasn't aware that there are so many different algorithms!

Wow, that's a very interesting and ambitious project. I believe You would need some way to encode the length of individual months to make this work?

Yet another small update. I came up with a more robust design where all parts are mechanically linked, so it no longer depends on separate moving pieces hitting each other the right way.

Wow, I love the steampunk aesthetics! I'm anticipating a video of the real thing, especially the escapement; there's quite a jump from building it digitally and actually getting it to work reliably.

Thanks! Yes, the whip is surprisingly consistent, it shows no signs of wear after a few days of testing various escapements. Time will tell how accurate the timing can be, but I don't expect miracles; my plan is to do rough tuning by tweaking the inertia of the wheel and fine tuning by slightly twisting the whip.

Another small update, experimenting with new, more compact mechanism.

Sure! The role of the balance wheel is the same as the pendulum - it oscillates at some frequency, regulating the speed of the clock. The whip piece acts as a very weak spring, which is necessary to make it oscillate back and forth. Frequency is proportional to the stiffness of the spring and inversely proportional to the inertia of the wheel. Speed can be regulated by altering the inertia - in wristwatches this is the job of a set of screws on the wheel's rim. Pullback motor, as You guessed, is the main source of power that sustains the oscillations. The job of the escapement is to deliver the pullback motor's energy to the wheel in a way that doesn't disturb the oscillations too much, so that the speed is not too torque-dependent. Otherwise the clock would run slower and slower as the pullback unwinds. Yes, in wall clocks usually one weight acts as a driver and the second one powers the chime. Not sure what the spring may be for in this arrangement. One option is so-called maintaining power - it acts as a interim power source when the weight is rewinded. It's also possible that the clock is purely spring-powered and weights are just for show.

More progress today. I managed to implement a proper chronometer escapement, where the wheel receives a push when passing through middle point, in one direction. The difference from Galileo escapement may seem superfluous at first, but in fact it results in considerably more harmonic, slower motion that doesn't depend on the driving torque. Exactly what is needed for spring-driven clock.

Thank you very much for this outstanding work! I had a lot of fun tracking down early-mid 1990's sets that I had but no longer remember clearly. The decision to end the project is understandable, writing a book is indeed a time-consuming work.

Wow, very interesting. So, gravity power + electric auto-rewidner. I like the oscillator a lot. The part at the top, left to the motor, is escapement? Good luck with the striking mechanism, chiming the exact number of hours is sure ambitious, such mechanism may take more space than the rest combined!

Another great idea, so exciting! Nice jaws structure. Indeed, finding something that can be machined with Lego could be challenging. Styrofoam? Butter?

I'll follow this one with interest.

A little more progress. The heat-formed hose proved to have poor long-term stability. It still keeps the shape, but became more stiff and seems to have more damping. Thus, a switch to the whip piece:

-Steam engine model (or even working steam engine, technically steam is a little below Lego melting point XD) -Mechanical calculator (either general-purpose or ballistic calculator like ones on WW2 era battleships, could be connected to some shooting thing) -Some more exotic types of catapult/trebuchet (never seen one powered with electric motor) -Any sort of wind instrument (if that is possible; I have seen Lego air raid siren, so some sort of whistle/flute doesn't seem too far fetched) -Recreation of the internal mechanism of tape recorder (easier) or VHS player (hard) I already made a functional electric guitar and a crossbow in the past, and drilling press is on my list of future projects :).

Okay, contest is over, we already have the winner What an amazing and unique idea! I wonder how far this concept can be pushed; Do you plan to test some other diaphragm materials apart from Ducati windscreen? Also, some sort of resonance chamber (like in string instruments) may work as well.

Yes, these are very hard to separate with regular pieces and almost impossible with transparent ones.

I got the Formula 1 Alfa Romeo set for christmas and just finished assembling it. I'm very impressed with overall looks and brick quality is completely on par with Lego. However, I ran into a problem: the drivetrain runs poorly, with audible clicks. Seems like the knob gears are jamming, but can't pinpoint the issue. Anyone else had similar experience? A few other minor nitpicks: -the stickers are slightly translucent, so white parts don't look very nice -steering radius is kinda poor -engine seems undersized (maybe it's not, haven't measured it), there's no gearbox (and yet, there's a problem with friction in transmission) In short, 10/10 display model, 7/10 mechanical features.

I got some simulations up and running. The chronometer escapement (wheel receives a short push when passing through neutral point) is the way to go, everything else works rather poorly with high friction and is better suited for a pendulum. Wristwatch manufacturers know what they are doing, what a surprise so back to the drawing board.

Second day of trying various stuff. Managed to make it run with 40t gear instead of propeller piece, but at much smaller amplitude, faster speed and with more torque needed, so there is no big gain in efficiency.

Merry Chistmas!

Wow, that's amazing! Very cool and unique idea. The reversing mechanism is very interesting as well.