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Hrafn

Eurobricks Knights
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Everything posted by Hrafn

  1. Hrafn
    Strange! The rubber on all of mine is transparent.
  2. Hrafn
    Which piece, or ?
  3. Hrafn
    No, not at all.
  4. Hrafn
    Black wheels, definitely. Looks great!
  5. Hrafn
    That looks good! Black is hard to photograph, but on the other hand it conceals the seams between liftarms better than any other color. I don't think you need to put any canvas on it - it looks good as-is. How well does it perform?
  6. Hrafn
    OK, I have made some good progress. Steering is currently done with a combination crank and rack-and-pinion setup which is sort of hard to explain; I will eventually post photos but there's so much stuff crammed into the front axle assembly that it's hard to see what's going on. Meanwhile the front and rear suspension modules are now very robust, and (with a dummy chassis) I've got a turning circle of about 4 feet (~120 cm). I'd like it to be tighter, and could probably squeeze a few more degrees of steering lock out of the current design, but right now the effort required to do that redesign doesn't seem worthwhile. 4 feet is still reasonable for a model of this size, I think, though in this scale the turning circle should be more like 100 cm. For comparison the wheelbase is 30 studs (24 cm) and the width including wheels is 21 studs. For steering, I'm probably going to use a geared-down PF-M motor, possibly with return to center. The train remote just introduces too much lag when using the servo. My initial plan was to use 2 buggy motors for propulsion, with an AA battery box for power. It sounds like the current limiting circuits on the battery box and the receivers will be an issue in getting as much power as I'd like, though. I'd rather not modify the battery box, but the RC control unit is so large it would really impact the design of the vehicle if I used it. 4 L motors (with no gearing) or 2 XL (geared up) are also options, but it looks like getting enough current to them could still be an issue.
  7. Hrafn
    I knew there had to be a better way to do it than with tweezers. Thanks, Zblj and skppo!
  8. Hrafn
    I did this one the other day. You can take it apart using a sharp tool (tweezers or something similar) but it's a pain.
  9. Hrafn
    Looks good! White, yellow, or tan would look good, or (if you can do two stripes side by side) blue or red look good when paired with white or light bluish gray. Red and yellow together is another good option. In what colors do you have the parts you need for a stripe?
  10. Hrafn
    Thanks! I'm having a little trouble making out what's going on in those photos. I also misunderstood you - I thought they were Lego vehicles. The concepts behind bellcrank steering I think I get pretty well; implementing them in Technic in a way that's rigid and robust is what's tricky for me.
  11. Hrafn
    Do you have any photos of your setup in either vehicle? I was looking at a single crank system (well, two parallel ones connected as a four-bar linkage) but haven't yet figured out how I want to connect them to a steering motor.
  12. Hrafn
    I was surprised to discover that after I improvised a crank-based steering method on my own and then googled to see if any real cars used anything like it. It's good to know it's not a crazy approach to take!
  13. Hrafn
    Nice! I really like the way you made the bow with panels.
  14. Hrafn
    Thank you! I'm glad to hear it's useful. I think I'm going to abandon the rack and pinion, and instead do the steering with a bell crank system. It's not true to how the real vehicle works, but it does seem more robust for this application. Now the trick is going to be making everything very robust and rigid so the wheels don't wobble.
  15. Hrafn
    Thanks for the further detail, but I'm still not entirely sure what you mean. The current setup results in no toe in or out, though I may add some toe in later since the inherent slack in Lego means the wheels experience a bit of toe out when moving forward. When the control arms are horizontal there is no camber; as the wheels move up relative to the body, the camber becomes negative, which is what I want in a corner. There is some caster angle at all times. When the wheels turn to maximum steering lock, the wheel on the inside of the turn does experience some positive camber due to the kingpin inclination, but it's fairly slight and seems to be an acceptable feature in real vehicles. I realize the photos are not very good - my intention was just to show that I am (slowly) making some progress. I hope to take better photos as I make more progress. Right now it's definitely hard to tell from the photos what all the angles actually are. I think a big part of that is that I'm taking close-in photos of a small object, which results in distortions of the angles due to perspective.
  16. Hrafn
    #2, in any of the lengths available (any of the part numbers starting in 5306 on BrickLink). Note that in the 9V system, the polarity of the motor (which way it spins) depends on how you orient the connector plates at the ends of the wire where they connect with the motor and with the RC unit. If it's spinning the wrong way for what you want to do, just turn a connector 90 or 180 degrees.
  17. Hrafn
    It does seem to work very well indeed - thanks for sharing it! I'll have to see how it works when the vehicle is finished and there's more weight on it, but so far it seems quite robust and I really appreciate how little friction there is in the drivetrain.
  18. Hrafn
    Given how slowly I work, I'm afraid you're going to have to!
  19. Hrafn
    Thanks! Yes, I do - but I'm not planning on revealing which until I've gotten a bit further, especially with some of the bodywork. Thanks! That's a good point, they should be angled inward. I haven't decided on the final configuration of the springs because I'm not sure how much weight will be on the front wheels and therefore how stiff the suspension should be. I'm not sure I understand your question (or why you included that link) - could you explain? What I'm trying to do is twofold. First, I want the vehicle I'm building to have good handling, and the geometry of the front suspension and steering will factor into that. Second, I'm using this project as a way to learn about suspension in general.
  20. Hrafn
    Time for a quick update. The rear axle has been largely solved by using a modified version of the rear axle from Thirdwigg's 8081 MOD. The "floating differential" allows for fully independent, driven suspension in 21 (or, in his model, 19) studs' width. The front suspension is nearing completion. I've successfully incorporated - kingpin inclination to give near-zero scrub radius - caster - short long arm suspension to give increasingly negative camber as the body moves down - Ackerman steering Here is the current hub: And here, stripped of all the supporting structure and the steering motor, is the general setup of the front axle, showing the basic geometry: Stripped down like this, the maximum steering lock is about 45 degrees for the inside wheel (30 for the outside wheel): The angles look a bit off in this photo because of perspective caused by the camera; slight positive camber on the inside wheel; and the fact that the suspension is not depressed the way it will be once the vehicle adds some weight on the springs. So far, so good. The 7L steering rack will probably have to go, though - its 4L stretch of teeth doesn't allow for enough travel to get to the full steering lock. Instead the inside wheel ends up stopping at about 30 degrees, which isn't nearly as much as I want. I'm also still working on making sure that the steering links don't collide with anything during suspension travel, and that the steering rack is secured in a track so it doesn't wobble. The latter two goals keep conflicting but I'm sure there's a good solution out there.
  21. Hrafn

    Trip Ideas

    Hrafn replied to Zerobricks's topic in Community

    Annecy (in France, near Geneva) is right on your route and - according to family I had who lived there - it's really beautiful.
  22. Hrafn

    Trip Ideas

    Hrafn replied to Zerobricks's topic in Community

    Most of the travel I've done in Europe has been in Western Europe, which unfortunately tends to be expensive. Also, other than a few places that I've gone in the last few years (Vicenza, Rome, Sicily, Spain, London) most of the travel was 14 years ago so it may well be out of date. That said: Rome is just amazing, definitely my favorite city in Europe. See the Forum and the Coliseum. They're famous for good reason. And then wander the back streets, get a square of the local pizza, have an espresso, and watch the scooters zoom by. Venice is otherworldly, with its canals and slowly sinking buildings. It's very touristy, though, and very expensive. Barcelona is fun, and Gaudi's architecture (including the Sagrada Familia, but not limited to that) is amazing in person in a way that photographs of it can't convey. Stay away from the central section of town at night, though - as of 2007 there was lots of shady stuff going on there. Budapest is beautiful; I'm not sure how it is to navigate if you don't speak Hungarian, though. When I was there I was with Hungarian-speaking family. Prague has an amazing mix of beautiful architecture in the center of town. London, frankly, just feels like another big city to me. That said, the British Museum is incredible if you're at all interested in ancient art. Paris is also huge but I found it much more charming. Go to Montmartre, but watch out for pickpockets. Eat lots of croissants. In 2000, Berlin was very exciting and had a lot of interesting art stuff going on; I gather it's gotten a bit more sedate but is still a fun city. For an antidote to big cities, go to Bacharach on the Rhine in Germany. There is (or was, anyway, in 2000) a hostel there that's in an old fortress. And you can't exactly get there by rail, but I had an amazing time everywhere I went in Iceland.
  23. Hrafn
    If you want to avoid having to buy the Unimog portal axles, it's very possible to build robust portal axles that use smaller gears using basic parts. Sariel for example did so in his Hummer: Or see the instruction photos for his Jeep Wrangler. I realize that might not have the clearance you're looking for, but it does show that you don't need the Unimog parts.
  24. Hrafn
    Oh no! I'm sorry to hear that. To stray off-topic briefly, if physical therapy is an option, I recommend it. It's slow and painful, but it can bring huge results over time.
  25. Hrafn
    There are 1x2 Technic (studded) bricks with two holes in them, instead of one hole in the center. Used with standard Technic bricks, this gives a half-stud offset.
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