Davidz90

Eurobricks Vassals
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  1. Awesome! Such a creative idea :D Good thing the string is quite thick - at 6m/s, a thin one might be a serious hazard to the fingers
  2. The big crossbow has got a little brother :D
  3. Now THAT is powerfull! It would be interesting to calculate the efficiency - the water mass per second (in kilograms) * 9.81 m/s^2 * pump height (metres) should give approx. mechanical power in watts, neglecting the kinetic energy of water. Then, one can compare it with electric imput power. In this case (25cm, 10 litres/minute), it would be about 0.4 Watts. This site confirms this value (I had to multiply the flow rate by 1000 because result cannot go below kilowatts) http://www.engineeringtoolbox.com/pumps-power-d_505.html
  4. That works suprisingly well I always thought that the casing must be round and very tightly fitted to the impeller to get any sort of efficiency.
  5. Working electric guitar

    Thanks guys!! BTW are there any tehniques to make a stiffer guitar neck, or generally strong technic beam? I have 4x8 plates near the body and then 2x8 plates and 1x8 plates sandwiched between technic bricks, with ocasional 2x3 plate to connect them, making some sort of a H-beam (see image). What could I do, apart from using longer plates and bricks?
  6. Interesting mechanism! As far as I understand, the differential rotates because even without a jam, there is some resistance in the mechanism so that the torque is split between output axle and the "gearbox". This problem may get even worse when actual load is connected to the axle. Two solutions that come to mind: -link the differential with another gear that provides some resistance (for example, by clutch). -add some latch or friction setup to the gear shifting mechanism (specifically, the arm moving on the black, vertical axle between red parts), so that it needs a small push to start moving.
  7. [WIP] Fastest Lego Technic Motorless Car

    How about using two pullback motors for front and rear wheels, with different gear ratios? For example, the rear, high torque one provides fast start and the front, geared up "sustainer" provides some extra speed. Also, reducing mass would help. For example, by using single motorcycle wheel on the back and two small wheels in front.
  8. Working electric guitar

    Thanks for feedback! I use electromagnetic pickup and a metal string. However, a piezo pickup is a great idea, I'll definitely try that! Changing pressure on the back string significantly affects the tone. Now, the string on the back is tied to the same tuning key as the front one - the tension is changed on both sides at the same time, keeping forces balanced. This is important because even a small bend on the neck significantly changes the distance from the string to the neck surface. I'm thinking about adding a vibrato lever to change the tension of the back string .
  9. Wow, great job! I'm surprised how well it manages obstacles with the tracks. A mobility comparison with wheels would be interesting.
  10. This is a fully functional electric guitar. Unlike some other ones that can be found on Youtube, the whole body and neck are 100% Lego (only the pickup and string are not). Despite my best efforts, its rigidity is somewhat lacking - as a result, the tone changes quite a bit depending on how it is held. Not to mention I can't play guitar... I have decided to use one string, because: -easier to play -less tuning -the body cannot really take much more tension The pickup is connected straight to the computer by audio jack. There, the software (Guitar rig 5) acts as an amplifier.
  11. I have finally done some half-decent video. Enjoy :D
  12. Mini desk clock

    Just a small update. I have reworked the clock to extend the operating time to 50 hours. This was possible with very small and reasonably efficient Arnfield gravity escapement. Basically, the pendulum lifts small weight (right arm) from upper position to the lower position. The difference in height, which equals to difference in potential energy, is transferred to the pendulum. Then, the pendulum swings free. In the meantime, the weighted arm unlocks the escapement wheel and is lifted by it back to the upper position. The smooth, shock free operation allowed for very light pendulum and good overall efficiency.
  13. So many functions :O The cabin interior is a marvel of engineering.
  14. 1:18 ouch, it seems that some passagers are banging their heads on the arch :P Truly fantastic!
  15. [MOC] H-24 Engine

    Putting this in Hawker Tempest model would be cool! Simple but efficient, nice job!