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Didumos69
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Everything posted by Didumos69
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A final test before I take it apart. And the final teaser. -
I don't think I could have phrased it much better, thanks @kbalage ?. I also don't think this model will be faster than your remake with buggy motors of @agrof's class one buggy, the main difference will be the way it behaves. The way it tilts in turns, the way it responds to bumps and small curbs and the way it takes bigger obstacles. Apart from pursuing performance, this model explores what's possible when it comes to robustness and durability. This has much to do with the fact that this is a 4WD model with 2 Buwizzes. A lot of power is sent to both the front an the rear wheels. That puts high demands on the strength of all kind of things; the steering, the suspension, the chassis, the bodywork. I had to think outside the beaten track on all these aspects, while holding on to requirements such as Ackermann geometry, small turning radius, extensive suspension travel and minimal slack in moving parts. But adding strength and coherence comes at the price of using more parts, which adds weight, which requires even more strength, etc. With this model I have tried to find a balance between performance, robustness and weight. A balance that fits the power of 2 Buwizzes and 4L motors on the one hand and a 4WD model built from LEGO on the other hand.
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Thanks for the hint! More renders here. The latest digital files: Stud.io, LDD and LDraw (I removed the old files to avoid confusion). The LDraw-file can best be used as parts list, because it does not contain placeholders for the BuWizzes. I will only update things now, when I find inconsistencies while making the photo sequence instructions.
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@boochydog, I can sense the excitement! Have fun!
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This has come to a great finish! Like others pointed out, this could be a real set. If you need help converting from ldd to stud.io, you can pm me.
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I find it miraculous too. The Tower Of Hanoi is a school example of recursion, because the problem of moving N discs is easily decomposed into the problem of moving N - 1 discs and a simple case: moving N - 1 discs from source peg to auxiliary peg moving the Nth disc from source peg to destination peg moving N - 1 discs from auxiliary peg to desitination peg The fact that this will lead to a solution is not hard to comprehend. However, the insight that something as trivial as swapping the smallest disc between two pegs, while iterating over peg pairs in one direction (like source-axiliary, auxiliary-destination, destination-source, source-auxiliary, etc.) will solve the problem too, feels like solving the issue without the need to understand it. It reminds me of a quest where blue and red midgets, which can't communicate with each other and don't know which color they are (they can see the color of other midgets though), need to line up with all red ones on one side and all blue ones on the other side. They can solve the problem by lining up one by one, with each one lining up right inbetween the already lined-up red ones and already lined-up blue ones, or simply at the end as long as there is only one color present. But in that case it makes perfect sense that the simple task each midget has to perform, will eventually solve the problem. Opposed to that, I can't comprehend why iteratively swapping the smallest disc between two pegs solves the Tower of Hanoi problem.
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This is truely awesome. If I'm correct the pseudo-code of this solution reads as follows: piles = pile[3]; // move discs from piles[0] to piles[2] for (i = 0; i < 2^n - 1; i++) { swap smallest disc between piles[i mod 3] and piles[(i + 1) mod 3]; } A very nice way to produce the same step trace as the recursive solution would.
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Aha, I get it. Indeed a useful tip ?! Thanks! The fact that I couldn't finish this before the summer actually turns out fine. Making instructions triggered me to make it more worth the effort for end-users. I also made some changes that allow for a more easy building experience, but it will still be really challenging. Thanks and I would be honored if you build this. I'm sorry, but most files are out of date. The only file up to date is this one, but it does not include building steps. I don't expect much will change now though.
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Thanks guys! Thanks for thinking with me! I would have to insert the bar ends into half pins, which was tested by @agrof and turned out to be no good. And I can't figure out a way to change the structure to have axle holes instead of pin-holes for the tow-balls. The structure is very small and ties together the gearrack, a slider and the steering links. However, I added a static structure (suggested by @Lipko) to lock up the ball-joints. This actually makes for a self-healing setup: When it happens that the pins with tow balls are no longer fully inserted, steering will push them in again. With the new steering links the model can take a serious frontal beating: I think I'm ready for making instructions now... (At the end of the video one BuWizz is empty).
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You're welcome! I will follow you're advice regarding WD40. I will use that for the bigger turn-tables I'm using now. I guess I was lucky with the silicon-spray I used, because the smaller turn-tables didn't get damaged. Btw, you might want to consider using the latest file. It has all the latest changes (big turn tables, strong steering links). Thanks! I tested the brick controller app v2 today, but there is still too much lag to make it work for this model. Especially steering is a problem.
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The newer is much stronger. The plates of the old one disconnect sometimes when the front wheels hit something. Others have reported that as well. But the most important change is the way the steering link is mounted to the wheel hub. By using 8L axles with stop the connection is firmly locked. The pin with the hammer inserted was the weak link in the old version. This new connection could however still be combined with the plates approach. About the blue half pins. Strictly taken, it is illegal, but practically spoken, installing the 2 5L thin levers with the half pins inserted can be done with the least of bending; the bottom side of the suspension arm already has some cutouts that make the installation easy. You should try. EDIT: I actually think the new steering arm would still be better, even without the blue half pins inserted. I will also try with the half pins inserted from outside, with the knob sticking out. If I find the legal version to be equally strong, then that would still be preferable over an illegal solution.
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Sorry, but as part of preparing for making instructions, I'm still improving things. I finally found a way to properly fix the steering links to the wheel hubs. Before: After:
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@SamuelYsc It is of course attractive to bring as much power as possible from the Buwizzes to the wheels, but this puts unreal requirements on the drivetrain. I'm afraid you will destroy gears and U-joints even when they are braced well. @brunojj1 About AWD and Buwizzes. I have such a setup in my Greyhound (4 L-motors and 2 Buwizzes). Based on the experience of others I started off with a separate drive train for each wheel. The biggest issue I encountered when putting a lot of power to the front wheels in a model that has some weight (approx. 2kg), was the slack and weakness of the standard LEGO wheels hubs and steering links. Slack causes a lot of too-in when driving forward and too-out when driving backwards. This introduces a lot of tire scrub, which means friction and worse performance. Weakness of the standard wheel hubs caused (in my case) wheels to come off in turns. The dbg pins of the standard wheel hubs are the softest pins out there. I had to come up with all kinds of tricks to make it work, like for instance the use of turn-tables as wheelhubs (my Greyhound is not only a rigidity-fest ?). @SamuelYsc So getting the best out of 2 Buwizzes and 4 L-motors in a 4WD vehicle is already very hard to do, let alone using 4 Buwizzes and 8 XL-motors.
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I managed to do the same thing by using the 44771 tire as inner tire. A bit harder to assemble, but significantly lighter. You need to follow the following steps to get the tires into place: Place the rim with the 44771 tire installed into the CLAAS tire (or first the 44771 tire and then the rim). Make sure the 44771 tire connects to both the inner and outer ridges of the rim. Now carefully push the CLAAS tire over the outer ridge of the rim. Finally, make sure the inner tire still sits on the inner ridge of the rim. When in the final setup (after tightening) the 5.5L axles don't stick out a little, your inner tire probably got pushed off the inner ridge somewhere. In that case, go back to step 4.
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That seems like a great challenge and I'm really curious to see where this goes. Even more so given the fact that this rework is in good hands ?. I have been thinking about doing something like this with 42056, but eventually I opted for building a completely new model where I had complete freedom.
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Thanks for the complement. I don't see myself as more genius than anyone else here though. I just have different objectives than most of us. In this case I simply strive to reduce slack as much as possible. In a powerful RC model slack in the wheelhubs is really annoying, especially in a 4WD model. All kinds of undesired too-in, too-out and camber, which in turn adds to tire scrub and thus undesired friction and loss of speed.
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These are the hubs that I currently use in my Greyhound 4WD Buggy. Also on Rebrickable.
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Thanks! Here are some final images:
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I did not password-protect it. Maybe it's because I'm using Stud.io 2.0. I'm still making updates btw. One thing I had to do to make it foolproof was inserting Unimog tires inside the CLAAS tires. The CLAAS tires attach to the outer ridges of the rims and the Unimog tires attach to the inner ridges. That way the CLAAS tires can be nicely squeezed against the turntables. It works very well and it looks very cool too, because of the flat flanks of the tires, but it adds quite some weight too. After some abuse nothing got displaced.
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I reserved time to make photo sequence instructions in the first days of this week. However, things worked out a little differently. I found myself completely reworking the wheel hubs, both in the front and in the back. I've mentioned before that the front wheel hubs were the most vulnerable part of the model. They relied on (extensive) friction locking only. Eventually, I replaced the small turn-tables in the wheel hubs with large turn-tables. After a few iterations I found a setup that feels really strong and rigid: The inner side of the tyre is squeezed between the turn-table and the rim. The outer side of the tire connects to the rim normally. The rim is attached to two 5L axles with end-stop sticking out the turn-tables. The rims are locked as before; by squeezing rubber connectors that are slided over the axles with end-stop. That works very well and if the rim would slide over the axle while driving at all, it is very easy to re-secure it. You only need to squeeze the rim back on, while giving resistance to the turn-table. I installed these new wheel hubs on one side of the model and they perform really well. I will soon install the hubs on the other side and make a more abusive test-drive. I also plan to lubricate the turn-tables. Not decided whether I will do that with WD40 or with graphite. The pros: Completely form-locked front wheel hubs Way less slack in the wheel hubs Tyres look less balloonish, because they are drawn to the inside of the rim by half a stud. Reduced chances of tyres running off the rims in fast turns (this happened only a few times with the old setup) No need for silicon bands to keep the front wheel hubs together No need for belt wheel tyres to reduce slack in the front wheel hubs No need for the rare shorter 5.5L axles with end-stop The cons One stud wider track width, half a stud more width on each side. Here is a temporary development version of the Stud.io file in case you would want to study this more closely.
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Technic Pub
Didumos69 replied to jantjeuh's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
When I was young I only played one game: Block out, a kind of 3D Tetris. There's a remake here. (search for Dydimus ?). I always imagined a similar game with Technic pieces that connect when they are dropped correctly. -
Will there be a solution for the V2s with hardware bug that have already been shipped?
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Thanks! I pass.
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Can one controller be used to control 2 units? For my Greyhound this would only be useful if I can link outputs of two different units to a single control channel.
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@piece, it amazes me that your gears broke after 10 seconds. In my build I use the same gears and axles for over half a year now. Without any problems. Did you use this part?