Davidz90

Maybe you can disable the striking mechanism but keep it running? Or the ticking is the problem? The amazing thing is that not only you can make a Lego clock, but actually you can match the efficiency and accuracy of "real" grandfather clocks, at least the lower quality ones.

Thank you very much! I agree, that is what Lego Technic is for, at least for me. I'm not a fan of cars or vehicles in general, but always liked clocks and other contraptions with complex gear ratios. Thanks! I was afraid I might have gone too far with the music XD

Seeing so much positive feedback and nice comments in my recent clock topic, I decided to revive this one (I hope it's OK) with some new mechanisms. Grasshopper escapement This is a type of clock mechanism invented by John Harrison in 1622. The name comes from the fact that the moving parts resemble legs of a grasshopper. Its remarkable property is the fact that the pendulum is in constant contact with the mechanism, so it is driven all the time, instead of short pushes that most other mechanisms deliver. In my Lego rendition, I tried to simplify the design by tying it directly to the pendulum. The result is a remarkably simple and efficient design: You can see that the escape wheel (40T gear) moves mostly forwards, but goes back (recoils) for a brief moment. This recoil, caused by the pallet engaging the tooth, causes the other pallet to disengage. To allow this recoil, the resting points of the pallets need to be movable - this is acomplished by the black T-brackets. And here is an even simpler rendition, designed for very small swing angles: My goal here was to find out how efficient it can be; I wanted to make a clock that runs for 1000 hours on single rewind. This proved to be a bit too ambitious, in the end I settled on 170 hours:

Thank you very much! I'm afraid not, for several reasons: 1. That would take a lot of time 2. Clock needs several custom pieces (steel nuts for pendulum weights, steel block for driving weight, printed dials) 3. Mechanism is a horrid mess of almost 100 gears, with axles going in various directions and questionable building techniques to get some gears to mesh together. However, I have a series of videos where various components are shown in detail:

Maybe there is some simple way to advance 20 tooth gear by 2 teeth at a time.

Thanks! John Harrison was a genius, no doubt about it. Grasshopper escapement is an uncommon mechanism, but actually one of the simpler ones to pull off in Lego. Also, it can be extremely accurate; this clock is not made for accuracy and keeps time up to 5 minutes/day, but under 10 seconds/day is possible with a regular, long pendulum, temperature expansion compensation and fine-tuned escapement. Thanks!

A dual-pendulum clock with grasshopper escapement, inspired by John Harrison's H1 clock that was intended to be used aboard a ship, for accurate navigation. Two pendulums swinging in opposite direction cancel out forces due to the ship moving on waves. My model includes several extra complications: -separate seconds hand -moon phase indicator accurate to 1 day in 19 years -calendar, with year length of 365.2484 days (accurate to 1 day in 170 years) -star map (planisphere) showing the night sky at the given date and time -equation of time (the difference between mean time and solar time, which is +-15 minutes depending on the time of year; accurate to 2 minutes) -time of sunrise/sunset, accurate to approx. 15 minutes -motor powered self-winder Video:

Yes, they tend to break all the time, even when not stressed at all. It seems that better structural solution is there arleady - I've never had issues with the shortest half beams (with two x holes).

Maybe a battery box? The black bricks are around 50g each, AFAIK a full box is 250-300.

I believe it would definitely help with jumping - ideally, with sufficiently long rope (and maybe heavier projectile), the trowing arm brakes almost completely, with no energy left for any jumping. Lightening the arm is an option too - that would also help with throwing power. Motorized rewinding would be cool, waiting for results [EDIT] You inspired me to make some experiments. Here's a quick and dirty prototype: I have used longer rope and there is dramatic difference when firing with and without projectile. The counterweight is somewhat overdone - it is over 2x heavier than the rest of the machine :D As You said, there is a lot of physics involved - light arm allowed me to move pivot point closer to the weight and get more velocity despite shorter drop.

Awesome! How about making the sling ropes longer? This might also increase the efficiency of energy transfer, besides the base wheels. The "stone" is many times lighter than the trebuchet arm and with such short sling, not much faster than it - this results in rather low efficiency and lots of energy wasted in jumping.

Happy new year! Maybe go a step further and make an actual Lego cannon - that is a sure way to beat absolute speed record

I'd try to find a way to connect both sails to single axle, effectively halving the weight here. It would be less rigid, but less mass = way slower speed = smaller forces. The classical, triangular paper airplanes work well ONLY because the wing loading (e. g. mass divided by wing area) is small. One can test this by adding mass to the paper airplane while keeping the COG - the speed (and the so-called Reynolds number) will increase and at some point, this type of wing will just refuse to work, basically producing more drag than lift. You are right that reducing mass at the rear is critical - every gram at the rear means few additional grams at the front to keep COG. Unless the front sticks out far away, but that tends to destabilize the aircraft. Flex hoses are worth trying. Alternatively, maybe hold the rear sail tips with rope only?

This is super cool! Now I want to get those sails :D I'm also curious how this works out. How about replacing some axles with hoses (the thin, rigid ones)? Might save some weight.

Now that is something unusual. Cool!

For more German insanity, I can recommend this page: http://www.luft46.com/

Very interesting linkage, a bit like Theo Jansen's, but not quite. Very smooth and fast! (and yes, a bit creepy :D) Nice job!

The engine looks great! If You want a twin engine with radial and twin boom configuration like P38, there is P-61 Black widow. For single engined fighters, I'm a big fan of Polikarpov I-16. That thing is cute

Fantastic build and brilliant engineering! I'm also curious if the mechanism is inspired by some other mechanical solvers or original. Either way, fantastic

The legs are very narrow (seems like 2 studs to me), but somewhat wide in the other direction. There might be enough leverage for linear actuator to do the job.

I mean something like this: https://www.youtube.com/watch?v=GUsOouwjsL4 One leg is moving at a time. The tree legs form a stable base, and the centre of gravity (Cg) is moving to keep within this base. I've made schematics: walk by David_Z1, on Flickr Blue circle is the moving leg. Triangle is the current base. Note that Cg could simply move in a circle, either by rotating counterweight or by leaning whole quadruped on the standing legs.

That's a great idea! I'm a big fan of walking Lego contraptions and actually used Algodoo in the past, but this is much more convenient. I always wondered if one could make a quadruped with walking pattern similar to star wars AT-AT e.g. moving only a single leg at a time, while standing on the remaining three. Potentially, that would be more stable than usual solutions.

Wow, that's some seriously impressive image recognition algorithm!

Very interesting idea! Maybe a stupid question, but with all that stuff packed closely together, isn't heat an issue?

A final version of my Arnfield clock, and my first wall-hanging design. And here are building instructions for escapement: