Davidz90

Eurobricks Citizen
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About Davidz90

  • Birthday 01/09/1990

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    <p> Technic </p>

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  1. Actually, I did XD In fairness, it is quite a bit more convoluted and makes use of multiple differentials, but for me that's a plus. The, moon is the most puzzling - a simple 1:28 would be better. I'l definitely make a mod implementing better gear ratios & limiting the color vomit on the model.
  2. I got the set. Very pleasant build. Unfortunately, my Earth prints are also slightly displaced, Africa experienced catastrophic tectonic shift. After studying the gearing, I can confirm the earlier findings about gear ratios: 1 lunar month = 27 days (should be 29.53059 solar days) 1 sun rotation = 27 days (technically OK, some parts of the sun rotate at this speed) 1 hand crank rotation = 3 days Regarding the year, earth is atached in such a way that without input, it will remain stationary in relation to the base (not the arm). So it will gain an extra solar day throughout the year (from the perspective of earth, sun will do 1 full rotation). This means that the year length is 364.5 sidereal days (2:729 gear ratio, rotations in relation to fixed base/stars) + 1 solar day. Since the earth rotations are in relation to the fixed base, all the days in calculations are sidereal days, which are shorter than solar days (they are 23 hours, 56 minutes long, so approx. 0.997222 of a solar day). Therefore, the final periods, in solar days, are: 1 lunar month = 26.9249 days (should be 29.53059 days) 1 year = 364.4874 days (should be 365.2425 days) In short, year length is a little worse than the earlier calculations.
  3. This one is truly jaw-dropping. Absolutely brilliant engineering.
  4. A working calendar. The first obstacle was devising way to encode the length of the months. My "eureka" moment was using a days dial with 32 positions and a hand that skips 1-5 days at the end depending on the month. A 12-sided cam with 5 possible heights turned out to be quite doable and compact.
  5. Indeed, the orbit eccentricity of Earth is less than 2% so including that would be just extra complexity with no visible difference. For moon, on the other hand, it would make more sense to add eccentricity, which is not that complicated mechanically. The comment about inaccurate sun size was hilarious; it should be about 100 times bigger than earth, good luck doing that (still simpler than realistic distances, would be a few kilometer radius lol).
  6. Ok, here's a decently working stepper mechanism with 8t gear, now properly aligned with beams: I'm not 100% satisfied with the reliability, but the idea seems viable.
  7. Yes, I understand, valid point. I'll try a few things tomorrow.
  8. Here's my quick and dirty prototype. Works just fine in one direction, adding second pallet below is problematic.
  9. I wonder if it's possible to build something like this but with 8t gear. Did some experiments, I could do a single direction stepper no problem, but two-directional one eludes me. Also, rubber connectors are great for replacing rubberbands when flexible components are needed.
  10. I agree, IMO it is a technic set, and one of the better ones recently. I'm working on a motorized version right now, although wing flapping takes a lot of power; that's why regular helicopters are somewhat more practical :P
  11. Well, axle is "achse" in German. These two languages are surprisingly similiar, leading to many interesting misspellings on both sides. Another early review, here print alignment seems pretty ok:
  12. If you are talking about Earth's axis precession, it is 1 rotation in 26000 years so basically stationary for all intents and purposes. So the part does rotate, but in the sense that it remains fixed in relation to the base, properly demonstrating seasons. I'm eager to get this set and do some improvements. Too bad about the print mismatch, and I don't understand why there are pins at all - axle going all the way through would hold two hemispheres just fine?
  13. And good thing it isn't, the forum is already saturated with vehicles. It definitely has inspired me. I've also considered building a lathe, with a turntable-based chuck. In my case it would be even smaller, which could possibly allow it to work with wood and even soft metals like aluminium, despite limited power. The lack of motor power can be compensated for to some extent by adding a heavy flywheel and doing the cuts in small steps, allowing the lathe to spin up. Another possibly interesting thing to do is a drill press.
  14. Wow, this is amazing! Surprisingly strong too. Very neat design of the chuck.