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jam8280
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Everything posted by jam8280
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This spinning LEGO blacklight show is really meant to be seen in person. Video hardly does it justice, and phone camera stills aren't much better. But what you do see here is entertaining enough that I'm sharing it anyway. In person, the tree colors change with spin rate, which here reaches 550 RPM in 7 steps. Around 300 RPM, the orange and green start mixing to yellow. By 550 RPM, you see a completely yellow tree encircled by blue and white rings -- the white coming from mixing the yellow with the blue. (Additive color-mixing rules apply.) The small 3-bladed propellers are worthless for boat propulsion, but they really shine for their size under blacklight. Minifig heads emit the blue. The tree holds its shape and balance reasonably well at top speed. The tolerable wobble peaks at intermediate speeds. I'd love to report that the inverted tree works as a spinning top. But centrifugal force would surely rip it apart long before it reached operating speed. Besides, air resistance would quickly bring it down.
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Just superb.
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Simple, elegant lines -- gorgeous! I want one -- not as a fighter, but as a solar system Gran Turismo coupe (think space Ferrari). Imagine laps around Saturn, weaving your way through moons. Just some sight-seeing on a Tuesday afternoon. Hard on the fuel, but what a ride!
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dye or paint to make lego parts fluoresce
jam8280 replied to Juxtapoisson's topic in Minifig Customisation Workshop
Did you ever find a fluorescent coating both thin enough and bright enough? Guessing that you haven't based on my own experience with blacklight builds using the 4 brightly fluorescent LEGO colors (trans medium blue, and trans neon yellow, green, and orange). The perceived brightness of a given spot seems to vary directly with the number of emitting molecules -- say, of trans medium blue pigment -- along the line of sight. To get comparable brightness, your very thin coating would therefore need an emitter concentration many, many times that of fluorescent LEGO plastic. Seems unrealistic. -
[MOC] My kind of Sneakers.
jam8280 replied to 0937 superfan's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
Love the design, love the laces! -
Superyacht explorer ship in scale 1:40
jam8280 replied to Edwin Korstanje's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
Stunnung in every way! -
[MOC] M.G. Bryan "PERCHERON" - TATRA T815-7 10x10
jam8280 replied to Paliason's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
One word: Spectacular! Impressive write-up, too. Fracking is rightly controversial, but the technology is indisputably cool. -
Elegant design! Amazing how much turning the saucer shape on edge sets this apart from the many other ships incorporating saucer-like sections in the usual orientation (think Enterprise). Glad you clarified the need for wings. So many LEGO space ships are just reworked jet fighters. Makes about as much sense as engine and weapon sounds in space.
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Visually, tops and winter holiday ornaments have a lot in common. The ornament can then be the toy, and the toy the ornament. Made these simple working tops with that in mind. Poinsettias at rest and at speed... Top at upper left at speed... Dreidel marked for the traditional Hanukkah put-and-take game... Various tops with holiday color schemes... Octagonal 10x10 plates are a great starting point... Same top at speed...
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Looking for fellow LEGO top-makers here on Eurobricks. Very little posted on this building genre so far, but I'd very much like to change that. Special Themes seems to be the best fit. Over the last 2-3 years, I've designed and built at least 1,000 working tops and still have well over 700 in my collection. As you can see from my MOCpages top folder and the videos below, the visual and mechanical design possibilities with this simple kinetic art form are truly endless -- especially in the LEGO realm. Since tops are mostly about motion, I'll embed a few of my less conventional spintop videos as an introduction. No need to watch any of them all the way through. Yuri Fassio held annual top-making contests for several years on MOCpages, ending ca. 2012, but there was never much activity between contests, and all but a handful of the tops posted there in recent years have been mine. It'd be nice to have some company.
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NASA's 6x6 rover mobility system
jam8280 posted a topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
Robust working 1:12 RC model of the 6x6 rocker-bogie mobility system used in Mars rovers Perseverance and Curiosity... Tons of play value. Works well over most neighborhood surfaces and terrains, but sometimes gets stuck in loose sand. What you put on top is up to you. NB: The NASA rovers are 6x6x4 platforms, with 6 wheels, all 6 driven, and the 4 corner wheels steered. At 1:12 scale, steering individual wheels with LEGO motors is out of the question. So this model is necessarily a 6x6x0 platform — but one with reasonably effective skid steering. Several years ago, made a pretty faithful working 1:12 model of Curiosity with more emphasis on visual realism than on mobility system performance. The current model vastly outperforms the old one... Purist alert: SBrick RC receiver, non-LEGO elastics used to suppress wheel spread. -
NASA's 6x6 rover mobility system
jam8280 replied to jam8280's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
You're welcome. Good luck! Make sure the front and rear motors can't hit the hull when negotiating rough terrain. Thanks! Short answer: Not enough to affect performance if you phase the gears properly. The differential inside the hull ensures that if one rocker is at angle A from the horizontal, and the other is at angle B, the hull is always at angle (A+B)/2. Among other things, this helps the rover stay right-side up in rough terrain. The differential bar above the hull helps to keep all 6 wheels firmly on the ground. And that reduces the chance of getting stuck -- especially in soft soil, any rover's greatest nemesis. -
NASA's 6x6 rover mobility system
jam8280 replied to jam8280's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
Thanks, @howitzer! Some images here show a PF receiver, but the final version in the video uses an SBrick. Upper deck removed. The differential connecting rocker axles inside the hull (see my last post) is built up from parts and anchored to hull bottom... Suspension arms on port side without motors. Note black differential bar above upper yellow hull cover and empty wheel motor mounts. The hull levels out once the receiver and battery are installed. Front geared wheel hubs. The 3:5 reduction shown is the best general-purpose gearing. You'll need some undercarriage elastics to keep the port and starboard wheelsets from spreading apart. The centaur-like biomechanical reptilians inhabiting Mars also use this mobility system to get around... -
NASA's 6x6 rover mobility system
jam8280 replied to jam8280's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
Sorry, having a hard time uploading even one 320x240 photo due to a ridiculous 0.02 MB file size limit. So anyone interested in building this rover chassis should go to NASA's web site and study suspension arm geometry in the many rover photos there, as I did. Use Technic liftarms (not axles as I did previously) for the suspension arms and stay as close as you can to the angles and proportions you see in the NASA images. Critically, note that the rockers (the suspension arms carrying the front wheels only) connect through a differential gearbox inside the hull and also through the pivoting black "differential bar" crossing horizontally above the hull, as in the real thing. These essential connections maintain hull attitude. The hull does NOT balance on the rocker axles going into the hull. -
Excellent build and presentation! Will be studying the structural solution carefully.
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@ExetriusThe only thing better than LEGO is LEGO with bling! Many great designs here. Keep up the good work. BTW, I think an SBrick + Power Functions teleporter bracelet might just be possible with long sleeves for cable management. ;^}
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NASA's 6x6 rover mobility system
jam8280 replied to jam8280's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
Thanks for all the kind words! Sorry, no instructions. Photos are very tedious for me to prep for upload here, but I'll see what I can do. Meanwhile, take a close look at the stills and turntable segment in the video after 9:04 for construction clues. The key part is the recently released 3x3 Technic connector, here used for front and rear motor mounts. -
Yes, it's all about angular momentum transfer through the pivot bearing friction between carrier and rider. If you started the carrier in one direction and then the rider in the opposite direction, the rider would slow and fall before reversing speed, as it needs a certain critical spin rate to stand against gravity, regardless of spin direction. That critical speed is the same whether the rider's on the carrier or on the ground. Doubt a 2nd rider would stay seated long. A rider with even half the carrier's mass would probably be too heavy to carry, but this is a complicated question involving moments of inertia and launch speeds.
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The only thing better than one long-spinning LEGO top to play with is another stacked on top of it... Both tops are based on Spike wheels with dish fairings to reduce air resistance, the main cause of spin decay. The lower "carrier" must have a large axial moment of inertia and a high launch speed to make the upper "rider" this easy to launch by hand and this tolerant of knocks and manipulation. After video above, fitted the carrier with a permanent rider mount greatly improving ease of use and therefore play value. The starter (below left) and detaching stem (right) for finger play now engage the carrier through a 2-pronged drop-out dog clutch. Many other rider designs work, but rider weight can be neither too heavy nor too light. Purist alert: Fine black carrier tip cut from 4L antenna.
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NASA's 6x6 rover mobility system
jam8280 replied to jam8280's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
Thanks! BTW, the video contains an error. The best overall wheel+tire combo is not the one shown at 4:40 but the combo seen at 9:45 instead. Makes a surprisingly big difference on some surfaces. -
Purism
jam8280 replied to Erik Leppen's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
As mentioned previously, I'm a selective impurist. I build my working LEGO gizmos as purely as possible but don't hesitate to stray (as little as possible) when a certain functional goal demands it. As I read through all these long and thoughtful posts, I keep coming back to a very practical question: Who else cares about purism? I certainly don't. What others do with their LEGO is up to them. Build and let build. Set whatever challenges you like for yourself. Nor do the thousands of visitors who've seen my stuff in action at regional LEGO shows. All they care about is what I can get LEGO to do with at most minor infractions. Nor do the folks on the non-LEGO forums where I occasionally share my work. Nor do my fellow LUG members. Well, one of them used to fear for my soul, but now he sees why some of my builds can't be totally purist. Build and let build. Nor have the vast majority of commenters on my many YouTube videos and former MOCpages cared. I always gave specs on my MOCpages, explicitly listing any non-LEGO or modified parts used. Protests were few and far between. Granted, LEGO contest participants should care if the rules demand a certain degree of purism. From this thread, we see that the purism called for would clearly have to be spelled out very carefully to avoid misinterpretation. But most builds never see a contest. Am I missing some important constituency or stakeholder? -
42054 - Claas Xerion 5000 - MODs, Improvements, Attachments, etc
jam8280 replied to BrickWild's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
Today I start building my 42054 per efferman's impressive mods. Very exciting! Once I get a feel for its capabilities, I plan to apply it -- with the proper custom attachments -- to a growing problem in Washington, DC: Some of the manure spewing forth from the White House falls short of its intended target -- the Trump base in the red states -- and falls back onto Washington. If only politicians lived there, I'd be OK with that, but hundreds of thousands of ordinary citizens are also getting buried, and the streets are quickly becoming impassible. Being new to manure handling on this scale, I'd appreciate suggestions as to how the Xerion might be used move thick accumulations of manure from DC streets to the halls of Congress and the offices of cabinet members, where it all belongs. I'd be willing to drive over parked cars with Congressional license plates if necessary. -
[MOD] Dinotrack from 42065
jam8280 posted a topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
The only thing worse than a hungry meat-eating dinosaur on your tail is one with a tank! (Well, getting caught is pretty bad, too.) Battery: 7.4V PF LiPo rechargeable in place (was AA box) RC receiver/controller : SBrick/custom joystick on Android phone (was PF with bang-bang handset) Motors: L front and rear (were Ms) Drive train: Direct drive (no change) Steering: Differential power to the tracks (no change) Tracks: Lugs every link for traction (new) Overall dimensions: 206x170x146 mm (LxWxH) Mass: 546 g (down from 599 g) Installed power: 4.3 W (was 1.5) Power to mass ratio: 7.9 W/kg (was 2.5) Stalled torque: 0.52 N m (was 0.18) The biggest and most important advance over 42065 was in outdoor play value -- by far my best yet in any MOC or MOD. The biggest contributors there were the L motors and the red rubber track lugs. Dinotrack performance was generally traction-limited without the lugs. Photos and write-up at http://www.moc-pages.com/moc.php/441699 -
[HELP] Buggy Motor Price
jam8280 replied to Aventador2004's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
If everything really works, that's a fantastic bargain! Heck, if only one motor works, it's still a good deal. -
[WIP] Super Fast Speedcar - current top speed: 32.4km/h
jam8280 replied to mocbuild101's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
One more practical point about Buggy motor thermistors: Current flow is determined only by the voltage applied and the temperature of the thermistor itself. How that temperature is reached doesn't matter. On a hot day last summer, I absent-mindedly put the yellow car (2 Buggy motors) in the trunk of my car to show off its speed to a friend. When I got there 10 minutes later, the yellow car wouldn't budge. Both motors had shut down just from being in the hot trunk! Once the car had cooled off at home, it ran just fine. Since a thermistor throttles current somewhat gradually as its temperature rises, a car with warm Buggy motors for any reason could appear to work when it's actually running at reduced current despite being at full voltage.