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Didumos69

Eurobricks Dukes
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Everything posted by Didumos69

  1. Didumos69
    Indeed, many custom wheel hubs suffer from this issue. You could indeed add half bushes, but eventually - after some playing around with the model - you will get slack in such setups too. The point is that the wheel and half bushes only need to slide a fraction of a mm to introduce substantial slack. Nevertheless, this remains to be a great idea, also because it reduces the wheel offset. Does the wheel actuallly touch the outer circle of the portal hub? If it does, I can imagine this really works great!
  2. Didumos69
    Nice idea! The only problem I see is that the wheels are not secured and will slowly slide off the axle.
  3. Didumos69
    Slack.
  4. Didumos69
    Thanks! Yea, I guess I'm a bit of a perfectionist . It does return by itself. That's what I just added. Or do you mean return by itself without silicon bands? Feel free to share your ideas . Or maybe you're referring to the stepper video.
  5. Didumos69
    The mechanism itself does not rely on perfect centering. When returning the lever manually - without the return-to-center pushers - you can return it to the center position or a little beyond. For the user this doens't come very precise and feels very intuitive, see the video below to illustrate this. It is the fact that the pushers would interfere when they would push beyond the center, which requires a perfectly centered return-to-center feature. To make sure they don't interfere, they both need to return to the exact center and not further. After some more trial and error I figured out how to make it work. The cause of the problem was that the way the pushers are stopped (with the attached half bushes) did not work out the same for both pushers. The rear pusher inserted a little deeper into the 5x7 frame than the front pusher, which was why I needed to extend the front pusher a little. Apparently the sides of a 5x7 frame are slightly thicker than a normal beam. To resolve this I used this part to stop the pushers. Now the pushers are perfectly symmetric and work flawlessly. And the shift lever is perfectly centered. I hope this also pleases @Ludo Visser . When the shift lever is in upright / centered position, I can put a nail between the rear part and the adjacent beam, whereas the front part touches the adjacent 5x7 frame.
  6. Didumos69
    I'm still in doubt whether to make the 'return-to-center'-feature part of the final model. IMO it's a little too sensitive to small displacements of other parts, where the rest of the model is not sensitive to such a thing at all. I have to improve it before I will include it. I have unlisted the video on YouTube to temper expectations.
  7. Didumos69
    @Jon61, great to see the instructions for the cube being redone, thanks! I'm happy this helped you to start off with MLCad.
  8. Didumos69
    Video recap: Yep, you just won yourself eternal fame ! Yea, I shot the video right after getting it to work. Not a good practice. Btw, I'm happy to know you're back in 'instruction' business . Thank you very much. I hope you'll get a chance to build it someday. I tried changing it from left to right but that doesn't make any difference. Also, the silicon bands are off-axle on both sides, so I wouldn't expect that to make the assymetric behavior mentioned by @Ludo Visser. But I took a closer look tonight and now I know where the difference comes from. The lower knob gear needs to pass the end of an 3x5 L-beam with a half pin inserted when it returns. The L-beam at the front is slightly better secured than the L-beam at the back. The L-beam in the front doesn't go anywhere when the knob gear returns, but the L-beam in the back shows a little movement when the knob gear passes the end of the half beam. As a result the knob gear returns slightly more easily when coming from the back, which explains why in that case the pusher does not need to push as far to make the knob gear return as when the knob gear comes from the front.
  9. Didumos69
    I just checked and it works exactly the same without the 1l beam. Doesn't work with the bush swapped to the other pusher though. Still have to figure out why exactly. Btw, there was an error in the build shown in the video, who can tell what?
  10. Didumos69
    Good point. It is not attached, but it didn't fall out so far. The 3L beam in the middle moves only a little more than half a stud in both directions. So far I had to pull the pusher out and move the shift lever in the opposite direction to take the 1L beam out. But I will check again tonight. I can probably do without the 1L beam, because it doesn't really extend the pusher. I was waiting for someone to comment on the symmetry . Yes, the entire mechanism is symmetric. Besides having the shift lever in upright position, it was important that the two pushers almost squeeze the 3L beam in the middle - it should have no room to move - while completely eliminating interference between the two pushers. I tried all kinds of combinations, for instance with two 1L beams and with two bushes, but this was the only way to get it to work flawlessly. The shift lever can handle being a little out of ideal position. It leans slightly forward, but you have to look very accurately to see that. But this doesn't explain why this doesn't work when I swap the 1L beam and the bush. This has to do with the fact that when the shift lever is in idle position, it 'likes' to lean a little forward, also without the return-to-center feature. This has to do with the fact that during the final stage of returning the shift lever, it gets a little help/kick from the knob gears getting back into idle position. Together with play in the connections this causes the horizontal lever connecting the shift lever and the knob gears to be slightly squeezed, no matter from which side you return the lever. This causes the shift lever to lean forward a little. EDIT: This doesn't make sense. I have to look into this a little deeper. I will try once more with the 1L beam and bush swapped. I'm not even sure whether I tested that after getting this to work.
  11. Didumos69
    I finally managed to get a return-to-center to work for the shift lever, without taking anything away from the stiffness of the mid-console or the 'bare' feel of the shifter. Until now the shift lever had to be returned manually. This wasn't a problem, because the actual shift is completed before returning the lever. You could actually leave the shifter out-of-center until the next shift without causing any trouble. Not completely sure whether this should be part of the final build, but it might pave the road for a HoG shifter on top of the roof. For driving the shift axle other than via the shifter requires the shift lever to be exactly in upright position when idle. To make this work I had to find a way to make two return-mechanisms - one on each side - that do not affect eachother. To be able to play a little around with my shifter I rebuilt the entire drive train without the front and rear axles. This is what I managed to do (it only works with a 1L beam for the rear mechanism and a bush fro the front mechanism):
  12. Didumos69
    Yea, riding with diff locks only makes sense on a surface that allows wheels to slip or even spin. There have been army trucks around without diffs and when these were driven on a normal road the driver had to ride with one side through the verge of the road every once in a while to take out windup in the drive train.
  13. Didumos69
    Wow! I didn't know there was so much detail in it. I am not often tempted to build otherones MOCs - I started some but stopped because I had different ideas - but this one really makes a chance!
  14. Didumos69
    Poor truck, but I have to admit I could not suppress a laugh .
  15. Didumos69
    Many wise things have been said here already. To me there are several aspects to building a sturdy car: Cohesion, bend rigidity and torsional rigidity. Not all three are always important, for instance in a Unimog chassis torsional flex is desired. Cohesion - To me, building something that doesn't fall apart and doesn't require any fixing of connections after using it, is more important than building something that is very rigid. To obtain a highly cohesive structure, you have to think about the forces the connections in your structure are exposed to. Make sure the most substantial forces work orthogonal to your connecting pins. For example: When you have several connected beams spanning the length of your chassis, it is better to have them oriented with their pinholes horizontally than with their pinholes vertically. Otherwise your vehicle is likely to fall apart under its own weight. @Jeroen Ottens refers to this practice as using form-locked connections rather than friction-locked connections. Now the example I gave is very simple, but it can be extremely hard to make everything relevant form-locked. When I was testing my rugged super-car I found out that the connections in the left and right sides of the hood slowly declined. So I added a width-wise construction keeping the parts together. I did similar things wherever it was needed, until I was satisfied. Bend rigidity - To avoid bending in your chassis it is important to have some kind of bridge or console running through the middle of your chassis from the front all the way to the back. The higher, the better. I would say at least 5 studs high. Torsional rigidity - When your bridge / console consists of several beams (or 'rails') that are not connected somewhere halfway, the four beams together will easily twist. To avoid this torsional flex, you have to make sure the beams remain squared. This is where triangles and squared elements come into play. In my rugged super-car I wanted to have no more than 5 studs space between the seats. After tying my bridge / console together with 5x7 frames there was still quite some twist in the narrow section between the seats. To avoid torsional twist in this section I integrated several 3x5 frames. In addition I used this: part in the top side of the bridge. This 'squaring' reduced torsional flex significantly. As a source of inspiration, here is the LXF-file with the main structure of my rugged super-car.
  16. Didumos69
    Looked into it a little deeper. The fact that the angles match has to do with the fact that the angles defined by the ratios 4 / 6 and 2 / 10 add up to the angle defined by the ratio 1 / 1 (45 degrees): Arctan sum identity: arctan(x) + arctan(y) = arctan((x + y) / (1 - xy)) arctan(2/10) + arctan(4/6) = arctan(1)
  17. Didumos69
    Great MOC with some very nice features, such as the McPherson strut suspension, the trailing arm suspension and the pneumatics of course. But I do think it could have been better. The bodywork is not consistent, some areas are perfect (tail lights), some are off (doors and roof). And I keep wondering whether the CV-joints in the front drive will stay inserted in the diff over time. At least these CV-joints could have been secured better, for instance in a way similar to this:
  18. Didumos69
    Excellent model, with great functions! The vehicle has a modest yet very recognizable look and you managed to capture that perfectly . Great job, as usual!
  19. Didumos69
    Given your proof in the 'perfect fit' thread for the fact the sharp angle of the (5,12,13) triangle equals the sharp angle drawn by your stacked frames, it's no coincidence that the deviation of the 157.38 angle is the same as in the 112.62 angle: .12 degrees. Together they make exactly 270 degrees.
  20. Didumos69
    Great! Thanks @aeh5040!
  21. Didumos69
    I know. I should have been more clear. My question is actually: Why does the sharp angle of the Pythagorean triangle match the angle defined by the pattern with two frames from @aeh5040?
  22. Didumos69
    I had to study this one a little, but it's also a perfect fit. Can anyone tell me why? LXF-file here.
  23. Didumos69
    This construction follows the lines perpendicular to the sides of the Pythagorean triple (5, 12, 13). The hole of the connector coincides with the center of the triangle's in-circle with r = 2. The angle produced with this construction is 180 - 2 arctan(2/10) = 157.38 degrees, whereas the connector is 157.5 degrees. LXF-file can be found here.
  24. Didumos69
    So the Pythagorean triple (5, 12, 13) has an incircle with radius (5 + 12 - 13) / 2 = 2. Only realized this just now .
  25. Didumos69
    Thanks for pointing that out . I will take your advice for the final video. Haha, I get it now.
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