aeh5040

Awesome work! It looks so simple, but of course getting it to work so well is not simple at all. It's also great to see several people's great ideas combined. I would like to see a version that can be switched by a motor (M or servo). It doesn't seem so easy to adapt this particular design, because the shift lever is not fixed to an axle - am I right?

Er, no - a dragster. Although that's a good idea...

Thanks! Actually it only took a few hours. E.g. 1950 plates at 1 per second would only be 32 minutes. The hard part was getting the six rings aligned correctly - when only a few are present they do not hold together on their own...

Sorry folks....

Here is a little MOC for your enjoyment. It is a sphere (more precisely, a spherical icosidodecahedron), made entirely from one part, the trans 1x2 plate (1950 of them). It was very hard to put together, but it is very sturdy!

Wow - just wow! It's a mechanical marvel, and it looks beautiful as well! It reminds me a little of Jennifer Clark's work (from many years ago). I think it is the way you manage to make things that ought to be impossible work...

Thank you everyone for the kind comments! I did think quite alot about different colors, but it is very hard to find enough of them... Here are a few pictures of the "gear box". It's really very simple... More here when moderated.

Perhaps it is in effect an adverising tactic. The seller does seem to sell bulk lego by weight in more conventional quantities. A listing like this gets peoples's attention, then they look at the seller's other listings, I guess.

Very strange. Can it be real? Hard to believe, but it does appear to bear the signs of being legit. Would anyone really buy this, I wonder? If so, for what price? http://www.ebay.com/itm/LEGO-10-000-LB-4-535-9-KG-of-TECHNIC-MINDSTORMS-Bulk-Lot-Pound-Brick-Piece-Part-/262495928546 Please note: I have no connection with this seller - I am not advertising. I just thought it would be an interesting topic for discussion.

The emoji would be the clue that it was a joke...

Ironically, I had not thought of that! I'm surprised that the Hobson coupling is not being adopted for motorcycles and dragsters everywhere...

I see. Maybe a gear in contact with the side of the tire?

I'm not sure if I understand what you are asking. The newer 12t bevels can be used instead of the 14t ones pictured. Also, there are knob wheels: Or self-contained gearboxes: Do you count those as being "not crown or bevel gears"? But what is your objection to crown or bevel gears?

A wonderful piece of work (again)! I'm impressed at how you managed to make your own geared turntable before the advent of the new Bucket wheel parts! Looking forward to instructions coming together...

Here is my latest kinetic sculpture. It won the award for "Maddest" MOC at BrickCon this weekend! (The theme of the convention was "Madness"). Enjoy!

Wow, that's an amazing mechanism, and a very original subject as well! Could we see a video of the internals?

I took some photos, but I was not very satisfied with them so I made an LDraw file! Getting the angles right was an interesting challenge. I would be interested if someone can make a better version - the inventor claims that the coupling can transfer rotation through angles up to 60 degrees with proper shaped parts, but I had to make compromises in the Lego version, so the angle is much smaller. http://www.brickshelf.com/gallery/aeh/coupling/patdan.mpd

That's a detent mechanism, and a very nice compact one!

No, it definitely wouldn't be useful for actual Lego vehicles. It is much too large and weak for that. The purpose of the model is to show how it works. If it were made from real metal parts, there seems no reason why it couldn't handle high torque. So far as I know this has not been done.

For those wishing to take a break from Porsche-mania, I offer this little MOC. Some explanation: The standard way of transmitting rotation through a variable angle is the trusty universal joint. However, as has been discussed here before, the universal joints do not have the constant-velocity property. If the input rotation is uniform then the output will be slightly jerky - faster and slower at different parts of the rotation. In some applications this can cause problems including vibration. One possible solution is the double Cardan joint, which consists of two U-joints in series, aligned to be reflections of each other. (In Lego that means lining up the two slots on the middle axle). If the two angles are equal then this will cancel out the irregularity. (If they are aligned the wrong way then the irregularity will be magnified!) I made these models a while ago to illustrate the difference: However, the double Cardan does not completely solve the problem, for several reasons. The middle shaft still rotates irregularly, which means that it is accelerating, causing vibration. Also, to work properly, the two angles have to be equal. In a movable coupling this requires an extra linkage, which ends up being complicated and bulky. Some other types of coupling ARE constant-velocity, such as the Rzeppa joint. However, until recently, all such used sliding surfaces of some kind. This changed with the invention of the Thomson coupling, which is effectively two universal joints combined into one, with an internal "spherical pantograph" that bisects the angle. As you can see, it is pretty complicated, and the pantograph part is quite small and fiddly. I did not manage to implement this in Lego yet. Remarkably, a new coupling has recently been invented. The inventor calls it the "PatDan" coupling. This is constant velocity, and has no sliding surfaces. It is much more symmetrical, and arguably simpler than the Thompson coupling. For more information see http://www.pattakon....takonPatDan.htm It took a while, but I finally worked out the geometry, and the above is the result! A key property is that the central axle (yellow in my Lego version) bisects the angle between the main axles.

And more...

I have used quite a few... And this one doesn't actually use different meshing angles, but it is pretty cool...

That's right. The point is that, for a _fixed_ voltage, torque is determined by load, which can be varied. (This is Newton's third law - the torque provided by the motor is equal to the load applied to it.) Applying a higher load (torque) will result in a lower (angular) speed, up to the point when the motor can no longer turn (i.e. the speed reaches zero), which happens at the _stall torque_. The _stall torque_ does indeed depend on the applied voltage, and in fact should be approximately proportional to it. You can test this very easily. Hook up an M motor to (e.g.) only two batteries (providing 3V), by short circuiting the battery box, and see how easy it is to stop the axle rotating by hand. Compare that to the full 9V. The amount of force you need to stop it corresponds to the stall torque. The stall torque is also what you care about if you want to know "can my vehicle get up this slope, or get over this obstacle". Philo's data about varying the voltage is obtained using the _same_ load for each voltage. You can see his picture of the set up - he has a weight on a string wrapped around a drum. So of course the torque is always the same - that is as intended. He does not report measuring the stall torque at different voltages, although that might be an interesting thing to do. So, I don't think there is anything that needs explaining...

That's insane! Both performance and the body work. Nice job. If there is a better use for a sausage I have not seen it!!!

Wow, that's outstanding! Ingenious and beautiful! I like the simple programming "language". I guess in principle it could be all done mechanically, without the need for Mindstorms. E.g. a bit like . (I'd like to see that!)I have seen yet another other machine of this type, at BrickCon a few years ago. That one used the large (3.5 in) red and blue Lego Education balls. They were arranged in the right order, and then fed through several "mega-GBC" type modules and finally to the printer. But in any case, yours is a wonderful work of art.