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Tamas Juhasz

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Everything posted by Tamas Juhasz

  1. Tamas Juhasz
    That doesn't makes a lot of sense. That would be a single propeller. (before this I made single propellers to fly with these motors) I wanted to get a flying machine with frame/body and one or more propellers.
  2. Tamas Juhasz
    Interesting point of view, thanks for sharing it. If I thought about this, I'd make a video about the pull back process with some geared down Lego motor. It's easy to make a simple machnism with Lego, which pulls back the motors, and when finished, it connects off. It would be more comfortable, it was pretty wearing to pull them with hand. If I can innovate the flying part, I'll make this electric back pulling part also. "Looks like you made them counter-rotating to keep it reasonably stable." The two propellers turn in the same direction, that's the biggest problem with this, and the reason, why the whole flying thing spins after a while (this decreases the flying time). There is no inverted of this propeller. But other one would be too heavy, which can be inverted (built propeller).
  3. Tamas Juhasz
    Thx Horace T. You are absolutely right. That's why I connected all motors to channel one and to the same colored output. So I can control it with the speed remote controller (except in 1-3 level, those have little torque with this gearing). You can see an example in the video from 0:21 to 0:25 - typical case, when low rpm is needed to win against tricky terrain.
  4. Tamas Juhasz
    Hi! I posted this moc a while ago in a specific topic as an example, but I never made an own moc topic for it. JFAIR "contest" has "no rules", and the theme is about really flying Lego things, or things related to fly, so I think it's a good opportunity to present this moc: http://www.brickshel...ry.cgi?f=500935 The machine has a very small frame (7L beam), and two propellers for propulsion: http://www.brickshel...y.cgi?i=5432844 Here you can see it flying and raising: (I don't know it's the first, or not, it just flies. ) I think a flying Lego machine can raise from it's own power. It's easy to throw or spin something with your hand. I made some experiments with pull back motors, because they are pretty powerful compared to their size and have lot of rpm, which is very needed to generate raising force. So it can raise/flying off only with Lego parts. The motors with the base structure, the flying thing are all 100% Lego. Yes, it can't raise too high (0,5 m max.), but the flying itself was my goal. Flying time is about 1 sec. The accelerating unit contains two pull-back motors: http://www.brickshel...y.cgi?i=5432841 (I used these motors, because with (even with overvolted) Lego electric motors it seems, it's impossible to fly without wires between the ground and flying machine. And, If I use wires, then it's not a flying machine, because it's connected to the ground.) The video was recorded with 600 FPS. We made some 1200 fps videos, but they have pretty low resolution. Camera: Casio EX-F1
  5. Tamas Juhasz
    I'm afraid I don't fully understand your first sentence.
  6. Tamas Juhasz
    Thanks guys. Shock absorbers: It depends on the builder, if you like them, you will use them. The truth is, in 99% of 4x4 off roader constructions, shock absorbers are unnecessary. A linked suspension is always more stable and gives more optimal weight distribution, better center of gravity in terrain. Lego vehicles in this speed (under few km/h) don't need shocks. We use them in suspensions to make the axles/wheels back to the original position, once they are moved by terrain. But there are so many different constructions, sometimes it' much better to use springs (Lego shocks are only springs, except for the one in 8466 door mechanism), e.g. for crawlers, realistic models, Tatra. I don't think non spring suspensions will be more popular in the future. Yes, in this weight one LiPo is enough. The terrain in the video was pretty hard, but had enough power to go through. Falling back or rolling down is the real problem (as in every crawler). With two it would be more powerful, but more heavy, and I have only one LiPo. It would be difficult to place a second LiPo under the small body.
  7. Tamas Juhasz
    Hi! I made a few crawlers until now, and I wanted to create something new, with more fun. So I decided to add a lot of power in a lightweight chassis to be the crawler fast, but also capable. My goal was to make the most simple and effective Lego rock crawler: http://www.brickshel...ry.cgi?f=538615 I used a flexible frame as suspension, this helps to keep it lighter, there is no need for a lot of parts to create a 4 link or other suspension. As you can see below in the video, this "suspension" also works well on terrain. Has LiPo battery, and V2 IR receiver. There are two receivers, two XL motor is connected to each, there are 4 XL motors in total. After the motor's output, a 24:12 gearing (deceleration) is built in, so the wheel spins about 85 rpm, which allows to reach 1,7 km/h. The wheelbase-width ratio is similar to real RC crawlers. I tried to add a big ground clearance, there was no problem with it. It's an advantage of this flexible chassis, there is nothing under the middle of the vehicle. The wheels are RC4WD 1,9" Rock Crusher XT's, their weight helps a lot of the stabilization of the vehicle. The XL motors are placed low, they also help to have a better center of gravity. I added a simple body, with more crawler-like look, than in my previous crawlers. Steering: One M motor steers the two XL motors in the front axle. These motors are connected to mini turntables to be more stable and robust. The steering ratio is 5:1. http://www.brickshel...16_1280x960.jpg I used strong pins from 8842 to make stronger connections in the axles. All the motors and the main parts are connected together with these: Weight: 1105 g. I don't know yet the number of pieces, but it can be about 200. A 720p video: Most interesting parts: 01:11 ; 01:37 ; 03:16 What do you think?
  8. Tamas Juhasz
    Thanks! I think the stairs would be possible also with PP tyres, you just need more ground clearance, a bit different geometry, and more weight on the front axle. If the tyres becaome dusty, then there are only a little difference between custom tyres and PP tyres. We prooved this in our last crawler race. There was nearly nothing difference between the climbing of a PP wheeled crawler and a custom wheeled one (rc4wd tyres). Maybe I'll make this crawler. Until now, this PP crawler was made: http://www.eurobrick...showtopic=72950 Anyway, I don't understand why my crawlers have this lack of interest. If they aren't good, feel free to tell me. Should I made the pictures or the video in different way?
  9. Tamas Juhasz
    Ok. I uploaded the instructions some days ago, here is the link: http://ge.tt/9dxJFaA1/v/0 Was made only from the 9398's parts. Not too fast, and I would make for myself (if I needed a similar vehicle) something better, but imho it's good to see the basics.
  10. Tamas Juhasz
    @Doc_Brown: Thanks. I even surprised when it passed the stairs. For a long time, it was me the impossible terrain section.. @Gzzig: Thanks to share your opinion. If it seems climb better with longer wheelbase (without that I don't think, the stairs section can be passed), then why you suggest the short wheelbase? Nobody can proove, why it's good, and I tell the reason: it's not better or worse. There are simply long and short wheelbases. There are terrains/sections where long or short wheelbase is better. But I wrote one reason for the long wheelbase: "With a long one, it's more stable against falling backwards." We are allowed to think outside of the box. RC crawlers have short wheelbase, because: - they have relatively low ground clearance for better center of gravity--> with short w.b. their abilities are better - to get better turning circle --> my crawler is light, don't need a lower center of gravity --> big ground clearance can be made --> long wheelbase also Turning circle: I don't care much about it, but the front wheels can be steered in big angle, so I had no problem with it. ( I would be happy, if this topic wouldn't turn into fight against long/short wheelbases... )
  11. Tamas Juhasz
    @Oteshima: I made few days ago exactly what you need, also for someone from our LUG (Hunagrian Lego club), who asked about this type of technik car. If you need the instructions, send me your email adress in private message.
  12. Tamas Juhasz
    Hello! I present my latest crawler: http://www.brickshel...ry.cgi?f=538333 I wanted to make something totally new crawler construction. During the last months, some variation was made (little upgrades), this wast he first: My goal was to made a very simple and reliable crawler, which is able to take apart in competitions. It was succesful in Malug crawler races. Crawlers are relatively free-made, so the bodywork isn't made after a picture from reality. One important thing: you may noticed, it has a relatively large wheel base. To have the good wheelbase/ground clearance ratio, I also increased ground clearance. All depends on the terrain, it can be as good as short wheelbase. With a long one, it's more stable against falling backwards. It has "no" suspension, the chassis is strong enough but felxible to give articulation for the axles: (this makes it simplier) The next varation (V2) was made with longitudinal strenghtening to prevent the decreasing of ground clearance in the middle: The non Lego tyres: RC4WD 1,9" rock crusher XT. The chassis shows the innovation: It's driven with two XL motors (in the axles), on M motor steers. The additional M motor and ship weight in the front axle is only for weight, they have no functions. More weight on the front axle helps a lot in terrain. The bodywork in not too strong, but who cares with that in a crawler. Lightweight construction was important. In the video below, you can see some high-speed recording about a falling of a piece from the body. More pictures: In competition: http://www.brickshel...ler-No2/019.jpg http://www.brickshel...ler-No2/020.jpg http://www.brickshel...ler-No2/021.jpg Video: This is totally different than my previous videos. Was made with 30 fps (instead of 10) and 1080p HD resolution. I don't say, I will make every video in this way (requires a lot HDD space, sometimes unnecessary), but the more important or bigger mocs will be recorded similar. So the video: Hope you like it.
  13. Tamas Juhasz
    The strength of 14t gears is also an experienced "fact". Me and some technic clubmates in Malug (hungarian Lego club) also found that they are the strongest, during the last 10 years. They are strong because of the center part, because of the amount of material in the center (the bevel 12t gears brake mostly in center). 12t gears has a weak cross-section in the center, 14t don't. 14t gears were phased out, because they can be used with less gears properly, they only fit well (seen with TLC Lego technic model builder eye) with the 28t old style differential, and each other. They aren't exact stud wide (less than a half), and have 14 teeth, you can make with them "strange" ratios. But for these properties, many of us like them.
  14. Tamas Juhasz
    Guys, don't be so naive. IT'S FACT, IT'S FAKE. Blakbird has right with the stability, but it doesn't matter, if it flies for 2 seconds, then it can fly. BUT: I write again: a single M motor has 1 W power. With that you can't even raise the motor's weight. And this thing is heavy. Very heavy. The creator simply lies, when he says, it's made with 100 % Lego and there is no modification. --> I can only quote Darth Dino: "Even with a high resolution camera and a very good lens at perfect focus point it is hard to see in the final image a thin Nylon string, fishing line. It is just a pixel or something wide in the final high resolution image. If you clone the neighbour pixels over the string carefully AND reduce the resolution down like this image, you will never see it."Non Lego propellers doesn't increases the power, which is needed to raise this weight. The propellers can increase the efficeincy of flying. Again: M motor HAS 1 W OF POWER. Power is the keyword. There is physic, no wonders.
  15. Tamas Juhasz
    One very important thing: if you gear up before the diff, then down, then the efficency of the drivetrain will be very bad. You should use this as the last opportunity. lego motors have relatively less power, so every percent of power which can go to the driven wheels are important. Anyway, measuring how much torque can handle a 12t bevel gear, is very easy: just fix the gear in a vise, then use a big lever arm with a weighing scale. From the displyed weight (in the moment when the gear breaks) you can count the force, and you know the arm's length --> M = F*l. Then you can count with the motor's maximum torque and the drivetrain's gearing until the 12t bevel gears, how much torque go to them. If it's higher than the measured one, you should modify the construction. The old 14t gears are the strongest. The tan, new 12t gears are a little bit stronger (not prooved fact, only experiments), than the grey ones. The 90's years light grey 12t bevel gears are the weakest, imho. You can't say this if you don't say which wheel do you want to use. If you use a small wheel, then you need no or less gearing. With a 94 mm wheel you need more. RC buggy motors are enough strong to drive with no gearing a car with 62 mm wheels. It all depends on, what is your goal with the vehicle (going uphill, or only driving in a flat surface in the room, etc.).
  16. Tamas Juhasz
    A lot depends on the motor. I'm sure, it's totally fake. With one M motor, you have far less power than even a super light machine (= only the motor's weight) can be made to fly. As Zblj and others said, there is one way to be not fake: a modified M motor. But in this case, it's fake because of the motor. Compared to RC motors, a Lego motor is very weak, isn't able to raise it's own weight. Then how could it raise such a heavy (yes, this machine is very heavy in the Lego flying machine world) machine? I made some experiments some years ago, the maximum with 100% Lego was this: As the video prooves, Lego can fly, raise from it's own power, but with a battery box and Lego motors, I can hardly imagine.
  17. Tamas Juhasz
    9L links: they are pretty strong aginst bending, it's no problem. I still don't understand why to use this ( ) piece in a linear gearbox, there are some better one. If you push it with it's ball joint, then appears what I wrote: "I don't think it's good because of the ball joint. That can only transmit force, so it stresses more the sliding gear and axle."
  18. Tamas Juhasz
    This simply doesn't works. A motor can be controlled in this way, but a receiver can't. The old 9V system is unable to work with PF receivers (except after the receiver).
  19. Tamas Juhasz
    I wrote something wrong about the PF receivers and switches yesterday. You CAN power them thorugh a PF switch, all of my switches give current to them (and the green led lights), but you can't switch off the receivers with PF switches. And for my system, the switching off is indispensable. That's the rason, why I use more than one BB, and no PF switches. LTC has right, the PF switch with a receiver works only as an extension wire between the receiver and the BB. So we can turn back to the original theme. Would you use it in a moc?
  20. Tamas Juhasz
    Very good moc. I see you used CV joints for driving the wheels. Aren't they weak for 5,6 kg in terrain? How can do it an uphill stage? 5,6 kg is a really serious weight.
  21. Tamas Juhasz
    Mindstorms for mass control? My system can control 24 motors, that can be called mass. Here are pictures about internals: http://s186.photobuc...9?sort=3&page=1 It seems to me that only two channel can be switched on: http://s186.photobucket.com/user/NXTLiftBoy/media/Internals%20of%20LEGO%20Power%20Functions%20Switch%208869/IMG_2056.jpg.html?sort=3&o=6
  22. Tamas Juhasz
    I wondered too, maybe the switch has no output (even it can be seen on the connector) for receivers, only two, for motors, like the old 9V system.
  23. Tamas Juhasz
    Thanks. Maybe it's surprising, but this doesn't works. You can't power the receivers through PF switches. At the beginning, I thought also at switches and one BB, but it's simply doesn't works. Each block needs a battery box.
  24. Tamas Juhasz
    Hello! I had an idea nowadays how to control a lot of PF motors without very complex and space requiring mechanical switch: http://www.brickshel...ry.cgi?f=537994 The conception is simple: I used only electric components to switch between the motors. There is two receiver blocks, each contains 3 receivers. The fourth receiver has the swicthing motor, and the 13th motor can be connected to the other output. So the system in the pictures can be control easily 12 + 1 motors. One advantage is that the switching itself is very fast. If you connect two switching motors to the 4th receiver, you can use 24 motors. Indicator LEDs are recommended, so you always can see, which block (=which functions) are switched on. The blocks can be switched on individually, because the controller motor(s) pushes the battery box's on/off button. To control 13 motors, you need 7 receivers, 3 battery boxes, and 1 M motors. To control 24 motors, you need 13 receivers, 5 battery boxes and 2 M motors. I don't think the amount of PF parts is a problem. If somebody makes a huge moc with so many motors and functions, then 7 or 13 receivers and 3-5 battery boxes aren't so much in money and requiring space. A lot of builders are still have these. More pictures: Video: Hope you like it. Edit1: I forget to say, you can't switch off the receivers through PF switches. At the beginning, I thought at switches and one BB, but it's simply doesn't works. Each block needs a battery box, the receivers can only switched off with them.
  25. Tamas Juhasz
    It works also with older 16t gears, you just have to find a loose one. I have a few. I also have a very loose 20t gear, I used it in a moc to build a sliding gear gearbox (not uploaded yet). I don't think it's good because of the ball joint. That can only transmit force, so it stresses more the sliding gear and axle.
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