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aeh5040

Eurobricks Knights
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Everything posted by aeh5040

  1. aeh5040
    It's a pity no-one seems to be working in complex self-actuating pneumatic circuits these days. There was quite a lot of activity in this a few years ago, but the art seems to have almost died out. Check out: http://www.brickshelf.com/cgi-bin/gallery.cgi?m=kclague http://www.brickshelf.com/cgi-bin/gallery.cgi?f=82736 http://www.brickshelf.com/cgi-bin/gallery.cgi?m=sigurd18
  2. aeh5040
    I see! Still, I suspect the string could easily slip off a half-stud pulley. It would be interesting to see some pulley block systems using these wider pulleys...
  3. aeh5040
    Perhaps I misunderstood, but it seems to me that Lego offers plenty of free-spinning wheels:
  4. aeh5040
    That's probably because your connections are not strong enough. The LBG right-angle connectors do not make for rigid connections, because their pins are frictionless. You need some cross-bracing liftarms. For high torque situations it's also a good idea to brace the gears on both sides of their axles. I think a chain would be in danger of rubbing on the 20t, and it would not solve the underlying problem.
  5. aeh5040
    Indeed!
  6. aeh5040
    USA: www.amazon.com has 42009 down from $220 to $178 (20% reduction) as well modest discounts on a few other sets.
  7. aeh5040
    Wow - that is an epic and beautiful model! Also the most unusual use of axles I have ever seen!
  8. aeh5040
    Incredible! Amazing to see something of that size moving at that speed!
  9. aeh5040
    As always it's beautiful and works flawlessly, but I feel like this is one of his simplest designs yet. A genius like Akiyuky can probably put together a module like this before breakfast! Not intended as a criticism - just interesting to see him going back to basics.
  10. aeh5040
    Here is a schematic of the simplest feedback loop from Mark Bellis' brickshelf. (This system actually appeared in the B-model of 8868). Depending on what you want to achieve, things can also be much more complicated...
  11. aeh5040
    Excellent "remake" - well done!
  12. aeh5040
    Looks great! I hope the functionality of the actual set is as good as yours!
  13. aeh5040
    Wow, that is amazing and beautiful! How would it look if the motor was fixed in place?
  14. aeh5040
    Wow! Yet another one, and also very impressive. I like the intermittent drive of the two rotors. The minimalist construction makes it look simple, but it is not at all!
  15. aeh5040
    Nice find! Such angles can be computed using the Cosine Rule. With a bigger triangle one can get even closer. Here the first three numbers are the side lengths of the triangle, starting with the one opposite the angle (the first line is Erik's triangle): 3 4 4 44.0486256741 5 7 4 44.4153085972 5 7 5 45.5729959992 5 7 6 44.4153085972 6 8 8 44.0486256741 7 9 9 45.7707609523 7 10 7 44.4153085972 7 10 8 44.0486256741 8 11 6 45.2071662976 One can also get an almost exact 30 degree angle: 3 6 5 29.9264348666 4 8 7 29.9947255274 And it is interesting that there are some exact 60 degree triangles besides the equilateral triangle: 1 1 1 60.0 2 2 2 60.0 .... 7 8 3 60.0 7 8 5 60.0
  16. aeh5040
    Very neat mechanism! I thought that was basically how it worked, but wasn't sure. Besides Nico's (which as Blakbird said is not true braiding, although it's very impressive), other Lego examples include these: There are also some interesting Meccano implementations with more than three strands. It would be good to see one of these in Lego...
  17. aeh5040
    This is an interesting topic! Of course you can use although it is bulky and the attachment options are not great. In the Pen Dragon I used 3/4 pins as studs fitting into the bottom of a round plate to get a 45 degree offset on an axle. This method could probably be adapted in other ways (thanks to Blakbird for the render): There is also the old 1/2 bush, with allows 22.5 degree increments:
  18. aeh5040
    Wow - great work! I've seen a few of these (and it is on my list to try building one of my own), but I think yours is the most elegant I have seen. I'd like to see more details of the mechanism. In particular, the reciprocal motion mechanism (to swipe the bobbins to and fro) looks interesting and unusual...
  19. aeh5040
    That's a lovely machine! I have been experimenting with various designs for large wheels for some time. I am surprised by how sturdy these appear to be. Great work!
  20. aeh5040
    In addition to the Power Functions components, there is a wide variety of other Lego motors, most of them no longer in production. You can find very detailed information about them on Philo's page. All are "compatible" in the sense that they use standard lego attachments (studs or axle holes) and standard lego axles.
  21. aeh5040
    Many thanks for the further data, Blakbird. I have been away for a while, so have not been able to experiment further. I suspect that the "prying apart" of the wheels may well be the major reason for the difference between your picture and mine. I am using relatively rough "art paper", and you say your paper is quite "sticky". Sticky paper could easily result in more prying apart. It would certainly by worth a try going back to the knobbly motorcycle tires. The "prying" and "squishing" effects might be less. The knobbly tires are very slightly thicker (in the direction along the axle), so with the half-bush spacing there is a bit of a danger that they might rub on the structure. I need to check this. Another potential solution would be to use a much bigger wheel such as 88516, and mount it much further out (more than a stud further in this case). I'm less keen on this as it would require major redesign and might cause other problems. I would also like to see how much of the inaccuracy can be "hidden" by staring from the center of the curve, as I did. (I may try a simulation for that). Again, I want to find the best possible set-up, so that it can be incorporated into the final instructions!
  22. aeh5040
    Hm - I am also a bit surprised that Blakbird's version didn't quite join up right, and I don't have a good explanation at the moment. As I mentioned, I fine-tuned the wheel spacing by trail and error. After doing a rough version of your calculation, I just got it to do a bunch of left turns in succession, and adjusted until the angle was right. This test was done on a wooden floor with no paper and no pen, whereas the final run was done on fairly rough paper, so I'd be surprised if the paper is responsible for the difference (but it's possible). It might help to start in the center of the curve rather than the corner. I did this partly because I wasn't sure of the exact size and orientation, to maximize the chances of it staying on the paper. Many thanks for the instructions! I am aware of a few issues, and I'm keen to make them perfect. I have already started making a few improvements, both in the stepping and, in one case, to the actual build, to make it easier to put together. I would like to know exactly what issues you had - I'll PM you... One thing I found is that uneven floor can have a big effect. It did not work so well on a hardwood floor, which has some imperfections. The video is from a tiled kitchen floor (with thick paper), which is also not perfect, but flatter than the wood floor. It looks like you are using a wooden table, which ought to be very flat. It also looks as if your wheels and casters have gone of the edge of the paper at times. That caused alot of trouble for me, because the casters can get stuck under the edge of the paper. It's possible that caused some inaccruacy.
  23. aeh5040
    Wow - Akiyuky proves he is a genius yet again. If there is a better use for the red sliding 8t gear, I have yet to see it! At first I thought the video must be speeded up, but no; it is just insanely fast! And making the sorting arm push the release mechanisms is pure comic gold (as well as very ingenious).
  24. aeh5040
    Stunning model and very imaginative back story! I only wish it was all motorized. I do realize that would be very very difficult...
  25. aeh5040
    Cute! Keep up the good work.
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