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Didumos69

Eurobricks Dukes
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Everything posted by Didumos69

  1. Didumos69
    A limited slip diff is open by default and closes when slipping occurs. This one is closed by default, that is, the friction between bevel gears and diff housing is allways present and is not initiated by slip. This is not an LSD imo. I ever made the same mistake btw. You could have obtained the same effect without modifying parts with a linear clutch outside the diff:
  2. Didumos69
    So I decided to revert to none-toe geometry. I'll keep the idea of toe-out in the back of my mind when I start test-driving. This meant I needed to adjust the steering rods, which was quite challenging, but this setup seems to do the job perfectly: It may seem that I'm working with a lot of space, but it all comes very precise. The steering rods tilt a little while steering, with the suspension fully expanded/compressed. So I had to remove and replace some parts to prevent the rods from sticking behind small ridges, for instance at the sides of these connectors. Also, the steering rods disappear partly inbetween the A-arms while steering, which confines them two max 2 studs height. I'm not planning to. They feel very smooth running. I hope the reduced slack will compensate for the little extra friction. Btw, I will eventually be using the Unimog tires or Claas tires. I know Claas tires don't have the right profile, but their size fits better I think. Thanks! For me the main idea behind this model is to integrate all motors in the suspension. I realized it would give me max 7km/h in advance, but when I see the last scene in @kbalage's test video, where the vehicle climbs a 33 degree slope, I know what I'm aiming for. I want this vehicle to ride a rough off-road track with the same ease. Well, I am much inspired by this model (even though it has a solid rear axle) and I noticed that a modest caster angle is actually quite common for 4WD buggy's.
  3. Didumos69
    Wow @kbalage,.that's an awesome comparison, thank you very much! I'm afraid I'm not going to wait buying motors etc. until I know the exact weight. It will most likely be the two BuWizzes setup.
  4. Didumos69
    Thanks! When I have a section that is inclined properly and want to add a subassembly, like for instance the steering rods in the front axles, I copy-paste an axle from that section with the correct rotation. Then I add a new bush and place it somewhere floating. Then I select the subassembly and the bush, and shove the bush over the axle. Now the assembly has the same inclination and can be added without causing problems. Maybe interesting to know: I made use of this type of connection between the beams running on top and underneath the front module to the 4 axles holding the suspension arms. This does not obstruct the arms or the motors in rotating and makes a nice rigid connection. The axles sit tight against the connectors without stressing any parts.
  5. Didumos69
    Thank you very much for these compliments @Timewhatistime! I would be interested to see what you have designed with a similar steering mechanism.
  6. Didumos69
    Thanks @kbalage, also for your response in the other thread. I'm new to RC anyway, so I might as well get adjusted to the touch interface anyway. I'm more and more tempted to go BuWizz, because performance is the main objective for this model. I still have one question. With 4 L-motors and 1 servo, do I need two battery boxes or can I work with one? Update: I have built the front axles. I used custom placeholders for the motors, for I don't own any yet. I had to make a few minor adjustments to make it work, but I'm actually quite content with the result. It has more travel than I expected: 6+ studs travel . I played a little with the steering rods. The steering angle and Ackermann effect are optimal when I move the steering pivot one stud forward. That gives a little toe out (independent of suspension compression), but I have learned from @nicjasno's videos that a little toe-out for driven front axles is actually quite convenient. Due to slack in the setup (yes, there still is a little slack ) traction will pull the wheels forward and align them perfectly parallel when driving forward. So if there are no objections, I will stick to a little toe-out. I used a 2L friction pin and it works. It doesn't influence the suspension .
  7. Didumos69
    @kbalage, I noticed you are using two BuWizz units as battery boxes. Is it advisable to use two battery units for a model at this scale. If I'm correct you could have routed two L-motors to one channel. Or is that not the case. I'm asking this for my 4WD RC buggy of course.
  8. Didumos69
    Thanks, that makes sense. Today I also looked into the BuWizz. For someone that doesn't have any motors, battery boxes, receivers etc, having a battery box and controller in one unit might be quite convenient.
  9. Didumos69
    Great start! Excited to see a new WIP from your hands !
  10. Didumos69
    Now that I have a good feeling about the front axles, I started working on the main structure of the chassis. The front axles are somewhat inclined (about 5 degrees) to obtain caster. A little more modest than @agrof's class 1 buggy, because 4WD ususally comes with less caster than RWD. The tail is - again - based on the (5,12,13)-triangle. The length-wise structure is more or less done. Now I need to work on the width-wise structure. In that process I will also connect the trailing arms in the back. They are still floating now. One question I'm playing with, is what kind of battery box I should use. And can I pair two battery boxes? I'm planning to use SBrick and will probably not do anything with BuWizz.
  11. Didumos69
    +1
  12. Didumos69
    I redid most of the front axles. I had a hard time installing large shocks in a way that doesn't rise far above the rest of the unit. The shocks are placed upside-down with reason. I needed the axle holes to make a good connection with the wishbones. Depending on the final weight I will use two hard shocks or one hard and one soft shock on each side. I had to replace the thin suspension arms and as a consequence I had to get rid of the bottom and top frames. And finally I changed the Ackermann geometry such that the steering rods are aligned perfectly transversal.
  13. Didumos69
    Great pictures @MegaRoi! And nice colors! I hope the steering is enjoyable. Thanks for sharing your version.
  14. Didumos69
    Very cool looking and nicely put together! I prefer.the solid axle in the back. One critical note: The front wheel drive won't allow more steering angle than 20 degrees, otherwise the motor will eat up the CV-joints.
  15. Didumos69
    Thank you! I appreciate it.
  16. Didumos69
    I think I understand now. You're version is the one to the right, right? That's an option too and it fits the smaller rim too. However, I wanted to have a solution with pins through the turn-table pinholes and not with axles. Just to minimize slack to the max. I discussed this in the turn-table hub thread.
  17. Didumos69
    Thanks Tommy. I don't really understand what you mean. I don't see what is different in your image, besides the omitted belt wheel and 2l pins. Would you care to elaborate on what's the difference? It's the axle-bush connectors that are not allowed by LDD. However in practice the assembly fits well. It sits tight, but that adds to stability. I tried replacing the axle-bush connector with a and use a 1.5l pin instead of the pin with axle, this fits in LDD, but it feels less rigid. I tried to do that, but it's not easy to mesh with a 28 tooth turn table inside the rim. For this model I will not be using the turntable for gearing. That's the type of info I need! I'm planning to use the SBrick, but I'm a.newbee when it comes to motorized building, so I can use this kind of info. This way I can experiment with different gearing in the back. Thanks!
  18. Didumos69
    I think so too. Btw, part of the problem of the LEGO wheel hubs being sloppy are the DBG pins that don't sit very tight in the rim. They won't sit tight in this metal piece either.
  19. Didumos69
    Thanks for the suggestions and remarks guys! I guess I will have to try this and see how it behaves. If it would make steering sloppy, I will have to figure out another way or skip Ackermann steering. I'm doing my utmost best to eliminate slack in everything moving: turn-table based wheel hubs, gear rack sliders etc., so it won't make much sense to introduce sloppyness in this connection. Stll, if anyone could test how a bar inserted in the frictionless pin would effect it's sloppyness and it's friction, that would be very useful. I don't have any parts with bar-ends myself. Thanks Victor and @kbalage! Gearing up the front-axles sure won't fit. In the back I could make the gear ratio 12:20. Would it make sense to only gear up the rear axles? As for the size and weight, it may seem big, but it really is only 1 stud wider (due to the custom wheel hubs) and 1 stud longer than @agrof's class 1 buggy.
  20. Didumos69
    I just figured that when you would replace the two 3L pins by this (see image), the wheel will never come off the turn-table (idea of replacing a 3l pin with this from @agrof's class 1 buggy, and probably used by others too).
  21. Didumos69
    Excellent work an nice to read about the hurdles you had to take. It's good to know building this kind of models is still a challenge for you too . I feel honored to be mentioned for the stepper idea .
  22. Didumos69
    Yes and it's not the only thing that limits the travel. The LBG 5L suspension arms collide with the motors when the A-arms are inclined more than depicted in the renders. When held flat, the front axles have a ground clearance of 5L. The suspension travel is 4.5L, so when compressed completely, the bottom hangs 0.5L above the ground. Nevertheless, when the frame on top will turn out to be the bottleneck, I will change it. Yes, the unsuspended weight is intended to increase performance. However, I would argue that the motors are not completely unsuspended. Their center of gravity sits much closer to the 'suspended side' of the A-arms than to the 'wheel-side' of the A-arms. My conclusion would be that the motors are less suspended, but not unsuspended. I agree I should include Ackermann steering. I looked into that before, but couldn't find a proper way to implement it without obstructing other requirements. For instance, I don't like having steering links that are shorter than the A-arms, because that would result in toe-out when the suspension fully expands or fully compresses. But I looked into it again and found a way to have Ackermann geometry without introducing toe-out. I could split the horizontal rotation and the vertical rotation of the connection between the steering rod and the wheel hub. My only concern with that is that the 2L pin without friction could come out easily and that the whole steering will suffer from more slack. On the positive side, it does solve my issue with the massive steering rods being able to rotate freely. Their orientation is now defined by the position of the wheel hub. It would give about 32 degrees max steering angle for the inside turn and about 24 degrees for the outside turn.
  23. Didumos69
    Thanks @DugaldIC. I hope it's all going to work out fine. I should replace it with a 11L axle. The two 5,5 axles at the other side of the rack should not be replaced, otherwise the assembly with the tow balls could slide over the axle. But luckily those don't run through a frame. I hope to know more soon. But I'm actually more concerned about the massive steering rods (with 4x2 liftarms) that can freely rotate, because they are attached to two balls at both ends. My guess is that it should work as they will first (and only) collide with the gear rack assembly which moves along with them. If all works out fine, the max steering angle should be 30 degrees. Something that would never be possible when making FWD with standard wheel hubs and CV-joints.
  24. Didumos69
    Cool! That new part would be better I think, less friction. That part opens up some nice possibilities. But what about the gearrack? There is a 3l gearrack with tow balls attached, but can you integrate it?
  25. Didumos69
    I honestly don't know yet. I usually have more fun with the chassis-part, so I might copy more ideas from the body eventually. Yes I did. I prefer to make everything rely on perfect fits (not that I would mark the original as illegal, all fits close to perfectly), so I modified the trailing arms to match the Pythagorean (5,12,13) triple. If you zoom in on the trailing arms in the top view, you'll recognize the larger pattern below: I fixed the gear rack travel: I managed to lower the gear rack by half a stud so I can control it with a servo motor using a 20t gear. This will give me the required 1.5L travel. The gear rack has two sliders. A bit overkill, but it was the only way I could find, to lock the sliders properly. Everything needs to be rugged of course .
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