DrJB

Eurobricks Dukes
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Everything posted by DrJB

  1. The tread links are also available in TAN (Elves Set) and Silver (very rare/pricey)
  2. There are multiple reasons for using a planetary reduction set vs. other options. 1. Planetary sets offer relatively high gear reduction ratio than others 2. They're often used in 'final drives/reductions' for many construction machines. 3. You can also find them in typical automobiles transmissions (automatic only) Gear are made to transmit power, power = force × speed = Torque × Angular Speed. Often, the gears/shafts/bearing sizes are dictated by the load applied on them. As such, if you have an engine driving a vehicle, you want to keep the components' sizes as small as possible for the same power. Thus, let the speed be high. But once you get to the tires (or tracks), you need very high gear reduction, and that is why planetary sets are often used in wheel/hubs of large construction machines. In lego though, we rarely talk about torque and thus, replicating a planetary drive is just a curiosity for many of us mechanical engineers to try and reproduce real life mechanisms.
  3. I've found many 'inconsistencies' in Bricklink's inventory and parts' names. I used to double-check with peeron but that site is no longer maintained regularly.
  4. While this is for sure a very interesting finding and discussion, I am not sure of applications. Let's face it, most of the designs/machines we use out there (in real life) are not truly 3D, but more like multiple 2D layers stacked on top of one another. If you think of an automobile engine, it consists of several crank mechanisms (2D) stacked on top of one another. The only two real world applications I can think of in real life include trusses (as in large cranes, static) and multi-link automobile suspensions (mechanisms) where the various links actually articulate around one another. Yes, again, very nice finding/discussion.
  5. Those larger balls were introduced with the Bionicle theme. They are far more common than the soccer/basket-ball balls, but unfortunately they are not interchangeable.
  6. Any chance you can release some 'instructions'. I could do an LXF file if more photos are provided.
  7. I've personally been exposed to the Mindstorms 'theme' a long time back, officially with the RCX 2.0, but also a bit before that during a course/project at MIT, which developed the predecessor to the smart brick. Fast Forward 15-20 years, I took part in a FLL event few weeks back and while it is always exciting to see kids invent and perform, it is a bit 'disappointing' that the hardware/software was not used to its full potential. For example, to complete some of the missions, the kids could have very well used some sort of proximity sensors or line tracking (the markings on the mat are for a reason). However, many of them resorted to simple 'open-loop' approaches where the left/right motors were given specific inputs/speeds to go around a given curve. Some of this can be blamed on credited to the coaches, but that's a different story. Of course, one cannot expect young kids (middle school) to understand yet let alone apply concepts of closed-loop feedback with PID control and the like. But nonetheless, such capability IS there, and the smart brick is REALLY smart. In fact, while at MIT, a greater emphasis was put on feedback control as otherwise, the robot would simply be another fancy RC toy. Now, all of this 'prelude' is to ask the community to share whatever contraptions they've come across that DO USE feedback control (or smart use of sensors' readings, besides motors' rotation angles). To me, the 'best' examples I have seen so far are: 1. Line following, a classic topic, seen in every released version of mindstorms (RCX/NXT/EV3) 2. Balancing bot (inverted pendulum) released in the EV3 Educational Version. So, what can you add to the list?
  8. Thank you very much. That's quite a reference you've dug out. I'll sure enjoy reading it.
  9. I've been exploring (playing with) both the Arduino and Raspberry PI over the past few months and I agree fully, those two platforms offer possibilities way beyond the Mindstorms brick. The one advantage of the brick is that you can do mechanical constructions/designs as well with lego components. Unfortunately that is not so easy with the Arduino/PI. Well, there are some attempts out there, such as BrickPI, but those are very 'limited' and expensive. In all honesty, I'm hoping TLG 'notices' the potential offered by the Arduino platform and ultimately develops a theme on that, through some joint adventure with the Italians :) PS. That Tank/Beer video is amazing. Is that done by mechanical/passive means or there are some electronics (active control) in there?
  10. Very unique, and I like it even more as it is NOT a vehicle. Now. to change the melody, would changing the location of the specific bells do the trick?
  11. Let's go back to the very beginning: 1. What happens when you engage the drive? ANything moves, you hear some parts 'fighting' against each other ... ? 2. If it is easy, I would disconnect one part (gear) at a time, and see if there is motion. That will tell you which gears are working 'against' each other. 3. Do you have an LXF or better yet, some schematics of the drive-train only (motors+gears+axles) with all supporting structure removed? This is the easiest way to 'diagnose' likely issues.
  12. Interesting. Are you sure you're not operating the motors in cold conditions where the rubber/elastomer becomes more brittle? It could also be 'fast' aging of the rubber as many of the old Mindstorms cables were prone to. I'm sure TLG would happily replace those if it is the case. Does not hurt to ask though.
  13. This reminds me of the Mindstorms RCX. The official lego version included instructions on how to build a bionicle disc shooter. Philo upped it real good and built a CD/DVD disk shooter. I'm guessing he wanted those disks to behave as frisbees :) but not sure the aero-dynamics were there.
  14. One possible upgrade: Gyroscopic Stabilization.
  15. Neither the 8043 nor the 42009 uses the 16L axles ... I'm confused :(
  16. I rarely comment on MOCs but this one is sure a beauty. The attention to detail, and reproduction of main working functions is very commendable. I like how you used parts from many themes (old vs new technic, old gray vs. bluish gray, ...) to fulfill all the functions and looks. All you need now is a harvester to complete an agricultural trio masterpiece. Thank you for sharing.
  17. These were first introduced with the Unimog, for the so-called 'portal' axles. The goal there was precisely to increase the ground clearance (distance between ground and truck's underside). They seem like they do not do much, but you can install a gear reduction AND a spindle (below) for a wheel (wheel hub connects to spindle). +
  18. You need to flip one of the differentials.
  19. The elliptical mechanism (and the SW figure) is a fun contraption. Thank You for sharing.
  20. It's a tough call, as to what challenge to put him up to next. From my experience, pushing those complex sets onto younger kids, while bolsters their self-esteem, might cause the interest to disappear soon. I had my son do challenging Technic builds as well at an early age. Now he's not interested in Lego anymore. So, tread 'carefully'.
  21. Go for 8043, without any doubt. That set is slowly becoming rare (and expensive). Plus, the number of functions (playability) are second to none (well, except 8455).
  22. Reminds me of the one on display at the UN building in New York. If I recall, the change of orbit is due to the earth's rotation i.e., Coriolis force. Hence the question: How much time it takes to go through a full cycle?
  23. With all the anticipation for the $300 Porsche and longest speculation/critique thread ever (what a polarizing set that was !), I somehow took a break from Lego and have not bought any of the newer sets. In fact, my last set was the Mercedes Truck. Yes, I took my time and explored other hobbies such as Arduino, Raspberry PI, and lately the DJI drones. In all honesty, I do not miss Lego as much as I thought I would, except perhaps for the curved gear racks of the BWE and BlackBird's unrelenting dedication to Akiyuki's GBCs. To you all: Yes there is a whole world out there beyond Lego Technic and TLG. And yet, not with any remorse, I find myself wondering what is it I might have missed. Yes, I watched Sariel's reviews of the 2017 H1 sets and that ubiquitous white/printed 3L liftarm for the 40th anniversary. Is that it, anything with more substance than that?
  24. never seen any Technic sets on costco.com ... only City. :(