Davidz90

Eurobricks Vassals
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About Davidz90

  • Birthday 01/09/1990

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    <p> Technic </p>

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    Poland

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  1. Davidz90

    Quadruped kinematic workbench

    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.
  2. Davidz90

    Quadruped kinematic workbench

    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.
  3. Davidz90

    Cards sorter

    Wow, that's some seriously impressive image recognition algorithm!
  4. Davidz90

    Portable Nintendo Arcade Cabinet

    Very interesting idea! Maybe a stupid question, but with all that stuff packed closely together, isn't heat an issue?
  5. Davidz90

    My mechanical clocks

    A final version of my Arnfield clock, and my first wall-hanging design. And here are building instructions for escapement:
  6. Davidz90

    [MOC] Mechanical Game of Life

    Incredible . Very interesting idea and great execution!
  7. Davidz90

    How much weight does a liftarm hold?

    I think it should work ok as long as the zeppelin is more or less hanging on them. In pure tension or compression, even a single liftarm can withstand 3+ kg. I had a gravity powered clock where the 2.5 kg weight was hanging on two liftarms. There was no damage after a week.
  8. Davidz90

    My mechanical clocks

    Thanks! Figuring out gear ratios took me more time than actually building the thing :D Lining up u-joints is definitely a good idea. Another thing I'd like to improve is to use a large turntable for frame rotation - that would be much less wobbly. Sure, I have few photos on Flickr: Orrery_5 by David_Z1, on Flickr Orrery_1 by David_Z1, on Flickr Orrery_2 by David_Z1, on Flickr Orrery_3 by David_Z1, on Flickr Orrery_4 by David_Z1, on Flickr
  9. Davidz90

    My mechanical clocks

    And now something slightly different: an orrery! It was a challenge to get proper orbital periods with possibly simple gear ratios. The result: 99.87% accuracy!
  10. Davidz90

    [MOC] Reverse draw crossbow

    Thanks! This is my own design, not a set. No clue how much all the bricks would cost, but I guess not that much. The construction is actually simple: There are no rare/expensive parts, only bunch of beams, plates and technic bricks :P
  11. Davidz90

    My mechanical clocks

    Ken Kuo has many excellent animations of various escapements: https://www.youtube.com/channel/UC2h07cGBpJs8bF3OkgtJICg Other than that, there are many other animations. As for books etc, unfortunately I don't know any good references. The Arnfield, while conceptually a bit more advanced than other escapements, is actually pretty easy to pull off. The critical part is making sure that unlocking the escape wheel takes less energy than the wheel delivers by lifting the gravity arm back up. Basically, the escapement tuning is like this: gravity arm fails to lift? -> it has to be lighter or more torque is needed gravity arm jumps erratically? -> less torque or heavier arm is needed escape wheel fails to unlock? -> needs heavier gravity arm or less unlocking friction pendulum works for a while then stops? -> needs heavier gravity arm or less unlocking friction I have done recently an instruction for my Arnfield escapement:
  12. Davidz90

    My mechanical clocks

    Another design in microwatt power range. Combines very long period pendulum with "spring" made of carbon fiber strip.
  13. One thing comes to mind: Everything worth doing is worth overdoing Interesting idea and great build!
  14. Davidz90

    [MOC] Reverse draw crossbow

    Thanks! Limb strength is a major problem here. Ideally, they should be a single piece - a connection in the middle of a limb is just asking for trouble. Keep in mind that while the string has 5 kg pull, this is after the compound system - the limbs hold some 15-20 kg. I'm thinking about something like Ravin R15 crossbow - I'm arleady pretty close to it in overall dimensions, and the limbs are short.
  15. Congratulations @MegaRoi, @Didumos69 and @Anto! That was a very fun contest