technicfanatic

This is fabulous. Well done. Hope you will end up putting it on Rebrickable.

Very nice. I'm still in awe of this project

Marvelous! I especially like the innovation that allows us to skip LEGO bricks altogether and transcend from the physical to the virtual plane of existence. Could you post videos of Technivac I and Technivac II please? My web searches only turned up photos of vacuum cleaners and now Amazon refuses to show me any product except Hoovers.

This looks great. Any videos of operation? I'm guessing the steering does not work from the platform? In real lifts I'm guessing the steering is basically a remote control - electrically transmitted from the platform. Is the black gear at the back for raising the lift?

These are great, thanks!

Those videos look awesome - very dramatic. It's a great use of such a camera.

There is a hypnotic quality to this. I wonder if you could tweak it such that the average rate at which the ball falls is matched to the speed of the track so that you only have the moving track. I just saw your previous post where that's what you had (I think). Very nice!

I use an Olympus OM-D E-M10 (initial version) on a tripod, with the model set on pieces of white paper, in a room that has spot lights. I use iMovie for editing. It's a very minimal setup but it works. It can't do slow-mo or anything like that. I have been impressed with the iPhone's slow mo (and camera in general). For most demo video purposes I suspect a good cell phone camera is sufficient.

The harmonic analyzer is what I want to tackle next. I find it incredibly clever - the result of Michelson understanding Fourier analysis very well. The videos are super detailed, but I did think that one part of the machine relied on amplifying very fine movements, which would be an issue with LEGO, I think. Babbage's difference machine I would love to replicate, but I find it very daunting.

Helicopter cyclic and collective controls, rigging and swashplate model in LEGO Technic. Model based on the Bell 206. Details, including stud.io file and instructions at https://github.com/kghose/technic-models/tree/main/helicopter-controls (The writeup there is still not done ...)

Exactly the solution I used at first. I found it unsatisfactory (ad hoc), but never thought about it until I saw the Bell 407 design and then found actual 206 pivot sleeve photos on ebay. Then I put 2 and 2 together. This is the final model. I'll put this in a new thread with links to videos I have yet to make. And I need to finish the writeup, now that I know what is actually happening. The stud.io file and instructions are already up here.

Aaah! Thanks for this diagram. I encountered this while researching mechanisms for converting circular motion to linear motion. You make clever use of it as a walker. https://en.wikipedia.org/wiki/Straight_line_mechanism https://en.wikipedia.org/wiki/Chebyshev's_Lambda_Mechanism

Very nice. I especially like your diagram showing the geometry, though I would appreciate it if you could add an explanation for why that geometry is important. Very nice walking motion!

Wow, I have to see how that is done. Is the rubber liftarm acting like a spring in that case?

Cool, thank you. In a "real" crane would these be steel cables under tension? Could you have used thread instead of these links? Or might that cause too much wobbling or indeed, do you need these links to work both in tension and compression?

This is very impressive. I'm guessing about $1000 worth of parts? What is the part that you use to make the "wires" that are holding up the boom? The axle like parts that are held together by the 41677s? Thanks.

Nice pointer, I'm guessing these: That's an innovative idea. I dislike rubber bands because they get brittle, but hey, they are cheap.

Ok. Please tell me if some one forces you and I will come to your aid. Not sure if this is clear. My super-structure is built to support the axle from the inside, and I'd have to add a lot of structure to support the circled axle from the outside so that I can use a friction bushing. Thanks.

I've seen that thread. I find it very hard to extract information from it. A FAQ type page would be more accessible than a multi-year thread with digressions. I find it much easier to have separate threads that have clear thread titles that are easily findable, especially if there are tags. Yes, that could work. Even better would be a shift up to increase the opposing torque. This does add more axles and more axle supports. Ideal would be a bushing with through hole, but I guess that doesn't exist?

Hi Everyone, I'm aware of 32054 to attach an axle and give it friction. Is there anything that can be added to the middle of an axle to add friction? I have a structure with an axle I want to add friction to, but in order to use 32054 I would have to modify the structure in a way that annoys me. It would be much more convenient to be able to add something in a pinhole in a link arm the axle is going through. Thanks!

I saw those, but I think, since they have no through axle hole or an axle hole that will not allow the axle to tilt, they would not work.

The ball fits securely in the gap between the 6632s. There is no play. The ball can't be slipped into or out of place: either you have to assemble the ball and the 6632s and slip them in, or you have to turn the ball on its side and then rotate it into the gap. Yes, I imagine the design for actual operation (high RPMs etc.) in LEGO will require different solutions. My aim was to mimic as closely as possible the principle of operation of the Bell 206 rigging.

Heh, trust you to home in on key issues. This is exactly right - I will add some friction pins. I believe that there is no cross-talk between the two channels because the collective moves the center of rotation of the cyclic levers the same amount as it raises the pivot sleeve (as in the Bell 206), but you are correct in that I have to demonstrate this clearly. Again, perceptive point! I made the center of movement the pin holes of the top disk. I did this to simplify the attachment point of the scissor link and the pitch links whose axes have to go through the center of rotation, otherwise unwanted lateral motions are introduced into what should be pure rotations. This is the reason the cyclic control links attach to the end of a bent piece which brings the attachment (almost) to the plane of rotation (it's actually 1/2 a pin hole off, but this is swallowed by the slop in the components, and this is anyway not so critical as it is for the scissor and pitch links which have to deal with rotation of the turntable as well as tilting.) What I missed even on this iteration is the fact that we are not done constraining the motion of the swashplate. If you look at the photo of the pivot sleeve above you will note a vertical cutout. This vertical guide is essential to prevent the swashplate from twisting, which is what happens currently. I don't have room for such a mechanism in my model of the pivot sleeve, but I can use the mechanism used in the Bell 407/412 which is an external scissor link that constrains the stationary swashplate from twisting. (The scissor link in question is on the left in this photo)

That's very nice! Thank you for the kind words! I'm not aiming necessarily for a small model but one where the mechanism is clearly visible. It is also based off the Bell 206, so I replicated the important bits of the mechanisms. I was delighted to see how LEGO parts fit together. I started out, just as an experiment, by caging a LEGO ball with axle hole with 3x1 liftarms and noting that fit perfectly together and made a universal joint. I would hope they come up with a set of specialized parts, such as these from the Bell 206

Ok, this is insane! It looks like a computer simulation, or a stop motion movie, or an actual movie, except it is real. Brilliant!