aeh5040

Amazingly, it turns out that the "impossible cube" CAN be made using 3L push pins, even with all of the bushed ends internal to the 5x7 frames, despite the fact that two such pins may not be inserted directly opposite each other (as mentioned earlier). All the relevant pin holes are filled, and no bending was necessary to assemble this! The method is left as an exercise...!

Wow, that's beautiful - I don't remember seeing it. These remind me of this , which the maker claims is impossible to open or take apart without the combination.I think a new kind of puzzle might be possible among these lines - models that CAN be taken apart (without pliers etc), but only if the steps are done in exactly the right order. If some of the steps involve some parts pivoting or sliding, it might be very difficult to discover the right sequence.

How about this? I have actually used this - it was essential for the rotating knot. I found that a crown gear gives a tighter fit (which I needed). I can confirm that the turntables can be taken apart easily without damage to lego or the user.

Incidentally, this can also be modified to give an "auto-reverse" mechanism (e.g. to make a LA continually expand and contract): connect the two outputs of the gearbox so that they turn in opposite directions, and put the differential _after_ the gearbox in the drivetrain.

I love these challenges! Here is a very reliable solution that does not rely on friction. (Bracing and compactness could certainly be improved). The basic mechanism is: motor -> one side of differential other side of differential -> selector gearbox with changeover catch differential housing -> spring-loaded axle with two stable positions -> "clutch" with large amount of slack -> changeover catch

Here is version 2! Found a way to make the anchor points much more rigid, greatly reducing the wobble that was present in the previous version.

Wow, that's amazing performance! The stripped-down chassis looks simple, but getting something to work this well is anything but.

That's awesome! This trike setup (2 steered wheels in front, 1 powered behind) is great for stability. Maybe you could use 2 wedge wheels + 3 pins in place of those crown gears to keep the wheels on better?

That is interesting. It's amazing what can be done with 3D printing!

Edit: scroll down for the improved version. They said it couldn't be done! Well, actually, no-one said that, but I had serious doubts whether it could work. After the rotating ring, I'm sure everyone has been thinking "that's very nice, but can it be tied in a knot?" I'm happy to report that the answer is yes! Enjoy!

Wow! Awesome work, Jennifer and Blakbird! Wonderful to see this incredible model and its builder reappear! :thumbup: Is there any chance we might see the legendary Compact Excavator resurrected at some point?

Wow, this looks amazing, looking forward to further progress! I imagine controlling it will be quite challenging!

Wonderful!

I would like to see a technic dolphin! You might take a look at mahj's Da Vinci flyer - the wings achieve an amazingly fluid-looking motion with only one internal joint:

Yes, the chain one was inspired by exactly this. (Arthur Ganson's other sculptures are also well worth checking out). I tried for a while to send the chain upward, like this, but found it too tricky. That's a great idea! I believe this could be made to work. There's actually very little friction. The more delicate point is that the internal ring of axles needs to be held rigidly in place, and to hold up under the weight. So adding too much more weight is not a good idea. But I think your "scissors" could be done! A few GBC ideas are indeed in the pipeline...

Awesome work, Burf! As a child it was my dream to own enough Lego to do this... Have you examined your axles after this? Is there any significant wear or bending?

Thanks all for the encouragement! Lost_In_Noise: Thanks! Actually there's no differential, just two back-to-back turntables. lego muppet9: A smaller one definitely should possible, but tricky. The technic frames seemed perfect for the purpose, which is why I chose this scale. Fitting everything in to the driving section at the bottom was also challenging, so making that part smaller would certainly require some thought...

Just a few things I've been playing around with...

I expect most people have seen akiyuky's astonishing 20 unit GBC loop, although I didn't notice it posted here: I could just sit and watch this for hours... But most amazing of all, in my opinion, is his "Automatic crane loader" module. All the functions you see here are driven by one motor, located on the train itself. It really is hard to believe this is possible....!

Nicely done - the splitter is working very well!

Both the loom and the Digicomp I are absolutely fantastic! Awesome work! The Digicomp was actually on my long-term list of things to make, but you beat me to it! :) Many thanks also for making instructions. I'll definitely be making one of these...

I don't have any instructions or parts list at the moment. I could perhaps take some more photos to make the construction clearer. Is there any particular part of the construction that you would like to know more about?

Actually I don't think that should be a problem. If there is resistance on the output then the "floating" gear gets pushed harder onto the correct side. I tried to show this in the video. (If the resistance is VERY high in your application then you will want two liftarms, one either side of the floating gear, so that its axle is held more firmly. You might also want to limit the movement of the liftarms so that the gears are not pushed together too hard. Like I said, lots of experimentation needed!) One potential issue is not enough resistance - in that case it's possible that the floating gear will not engage at all. There needs to be a bit of friction between the drive axle and the floating liftarm to avoid this.

It would be hard to improve on akiyukiy's amazing construction:

This is an interesting challenge. Here is a mechanism I just put together that might work for you. The output is powered when the motor is on, and free to rotate when it is off. It's not perfect - it would need some experimentation to get it right.