Blakbird

This is exactly why LEGO is used as a medium in so many learning institutions. Particularly in robotics, the ability to quickly mock-up and test your idea is invaluable. For learning any mechanical prinicple, seeing it in practice is infinitely better than reading about it, and building and holding it with your own hands is better than seeing it. For example, I was aware of the basic principles of a differential for many years, but I didn't really thoroughly understand it until I saw my first LEGO version. In a few seconds of playing with it, the function becomes obvious.

Given that China has a couple of billion people, it is not too surprising that they have lots of people in every category, good and bad. My guess is that the extent to which their government controls Internet usage makes it much harder for them to buy legally than for people in other countries. But in any country there are plenty of reasons someone might not have a Paypal account or any money.

I had wondered about the timing aspect. So the brain needs to run slowly just so it doesn't issue commands faster than the mechanical part can execute them. And the Geneva wheels are necessary so that the commands are discreet and never overlap eachother. I see. I was thinking that the last cam resulted in a continuous 3/4 turn actuation, but it must actually be 3 discreet actuations (the three 2x2 plate stacks). Thanks for the diagram; I was actually going to ask if you had something like this. For example, when you start a new drawing it is important to know where you can set the model to get a result that will fit. That requires a knowledge of where the current state of the machine lies on the final curve. Do you always set the machine to a particular state before starting a drawing? The state shown in the LDraw file (with all the Geneva mechanisms horizontal) can actually never happen in normal operation.

While I can't disagree that pirating is illegal, I think there is a difference between downloading something for your own use and actually selling someone else's product. This website is selling something that doesn't belong to them, so they are not just stealing but also profiting from the theft. There is nothing wrong with reselling a physical product (buying a LEGO model and then later selling it), but selling copies of instructions prevents them from being purchased from the actual owner. In a way it is even worse than stealing someone's physical property and selling it because they can sell as many copies as they want and it costs them nothing. At least a car thief has to do some work for his profit!

The model is split into two main modules: top and bottom. The bottom contains the motor, the drive system, and the pen. It waits for a command and then executes either a right or left turn. The top is the brain and controls the logic of the model. It's input is a rotating axle from the motor, and it's output are two links which command either a left or a right turn. So the whole function of the top is to determine whether a left or right turn should come next, and then to command it at the appropriate time. Let's take a closer look at the top. In green we see the input gearing which is powered by the motor. In orange and purple we see the Geneva mechanisms. In blue we see the cams which drive the yellow rockers. Let's start with the input: The blue axle comes from the motor and drives a worm gear. This provides for a large 1 stage reduction and also prevents any backdriving. There are 4 stages of gearing here: blue-red = 8:1, red-yellow = 1.67:1, yellow-green = 3:1, green-orange = 5:1. Overall ratio is therefore 200:1. This means there is LOTS of torque available to drive the Geneva mechanisms, and that's important because they are not as efficient as gears. The orange gear drives the first Geneva mechanism. There are a total of 5 Geneva mechanisms in series. Let's take a closer look at them: A Geneva mechanism is like a gear system in that there is a rotating input which drives a rotating output. However it is different than a gear system in that the rotation of the output is intermittent. In this case, the purple assembly is the driver and the orange assembly is the follower or wheel. As can be seen in the animation, each revolution of the driver rotates the follower 180 degrees, so it is something like a 2:1 reduction. However, the follower stops at a 45 degree angle and then waits for input before rotating 90 degrees to the next stopping point. The 2x2 macaroni piece serves to hold the follower in place during the portion of the cycle when it should be stopped. The Geneva mechanisms are arranged in series with the output of each driving the input of the next. Each is connected to a pair of cams shown in blue. Each cam pair is clocked so that they face opposite directions. This is important because you don't want to command both a left and right turn at the same time. As Alexander previously explained, the cams are shaped differently to provide sharper lift in the early stages and more gradual lift in the later stages. The very last cam (shown upper left) is different than the others. The others are designed to lift only for about 1/4 of their rotation, but the last is designed to lift for 3/4 of a rotation. So what's the point of all these cams, intermittendly commanded by Geneva mechanisms? The cams serve to lift the rockers, shown in yellow. There are two rockers, one for a left turn command and one for a right turn command. ANY of the cams on a given side can command a turn by lifting the rocker. The cams bear against 2x2 round rollers to minimize friction. After going through the logic of the top assembly, but without the benefit of having actually built it yet, I find myself wondering about a few things: What drives the need for the Geneva mechanisms? What if you just used 2:1 gearing at each stage instead? I think the problem would be that all the cams would be moving all the time, and this would make for duplicate commands. The model needs to sit still while waiting for the next command. This leads me to the next question: Is there ever a time when more than one cam is commanding a turn at the same time? For example, could two cams on the left side both be pointing up? It seems like this would be inevitable. Is there evere a time when a right and left turn are commanded simultaneously? The last 3/4 turn cam leads to believe that this must happen while it is engaged. What is the effect of this? Why was it important that the Geneva wheel stop at a 45 degree angle instead of a 90 degree angle? Is this because Technic axles are cruciform and you don't want a cam "up" and commanding a turn when a wheel is stopped? I think it would be quite interesting to watch an animation or video of the top assembly alone running at high speed, perhaps with the 40 tooth gear as direct input. There is a snippet of this in the main video, but it is not long enough to see the motion drive all the cams. Sadly, such an animation is more complicated than I have the time to simulate manually.

No special tricks, just patience and a lot of practice. I start by inling the whole thing with MPD Center, then I create a blank submodel for each function and just cut-paste parts into them from the top level. Of course, I can't do any of that without first understanding which parts move with which other parts, and that can take quite a while if I've never built the model. I thought about all that coloring stuff. The pictures I have posted so far are just an attempt to use colors to group the functions, not the explain everything. If I tried to do that all in one image, there would be too many colors and it would actually be harder to follow instead of clearer. As I go through each individual function, I'll add more colors to explain the details of that function. I hope that makes sense. I did the same thing with my review of Akiyuki's ball factory.

As I am wont to do, I have dissected the file and simplified it by removing all the structure and leaving all the moving parts. In the case of this model, it looks almost the same with only the functional parts included. Then I separated the functions into logical groups and color coded them. The results are shown below. This helps a lot in understanding how everything works. The more I look at it, the more I understand and the more impressed I am. In the future, I will step through each of the colored functions and explain how I think they work. The phrases "Geneva Mechanism", "Scotch Yoke", and "Tomy Armatron" are all mentioned in the description, but it may not be at all obvious to many how those things work or how they work together to achieve the desired result.

Personally, I wouldn't put myself in a small tub with motorized propellers.

Thank you for your sentiment. It is always good to remember that we can't condemn a whole group of people for what one (or even many) are doing. It is refreshing to hear your attitude.

I used to own a 1984 Fleetwood, so this really brings back memories. Yours is a lot nicer than mine ever was!

There aren't any rules stating what sort of methodology the transformation has to use. Whether or not it needs to be motorized has already been asked and answered (it doesn't). So I think you have your answer.

If you want to motorize a supercar, 8448 actually came with instructions for adding a motor. The motor is not suitable for actually moving the car, but you can put the car on jacks and watch the wheels speed up as you run through the gears.

Your topic title of "Is there a MOC" doesn't tell anybody what this thread is about. MOC means "My Own Creation" and this is obviously a MOC like everything on MOC Pages. I have changed the title to "Are there instructions for Francisco Hartley's Aventador?" which is what I think you are really asking. The answer is no. Francisco doesn't do instructions. If there were, you probably would have found a link on MOC Pages.

Yes, that looks challenging all right. I like a good challenge. I'll go through the file and see if I can make it any more "buildable". One difference I note in the file is the tires. The file has the knobby tires because I think the smooth versions are not in LDraw. Some of the lift cranks use cams, and others use 1x3 thin liftarms. Why the difference?

Yes. Regardless of what words you want to use to describe what it does, it is still one of the best mechanical creations I have ever seen. It will be on my shelf.

Obviously it is impossible to create an infinitely complex figure mechanically. The machine makes an approximation of the full fractal, and a very good one.

I'll test it!

I'm moving this to the Buy and Sell forum.

I fixed your video links. You just needed to change https to http. Those are some pretty impressive videos. I'll be looking forward to your dinosaur!

No, two battery boxes in parallel would not change the voltage. It would just change the available current.

That's some amazing styrene work. You are a master.

The topic has been discussed from time to time. The drive and suspension system in 8880 is not well suited to motorization. Not strong enough and too much friction. In order to do it you would have to totally change the car. I suppose you could do it to a model that looked like 8880, but it wouldn't be 8880.

May I please be a Dutch person?

Agreed. Done.

Not any time soon. I got distracted by too many of those side projects which prevented me from working on and completing the main body of the site. The fundamentals page is already in pretty good shape so I probably won't get back to it until the rest of the site is done.