2GodBDGlory

Well, my analysis is that in order to avoid hitting the firewall, the biggest possible driver gear is a 24T, if you can find a way to make the stud where its teeth rub something else, like a bush. If you want a differential in there, the smallest ring gear you can have is also going to be 24T, since I don't see how you can reverse the 24/16T one in that space without the 24T side rubbing the motor. Therefore, the fastest gearing you can get using a differential is 1:1, with a 24T gear meshing with another 24T gear on the differential. If you get rid of the differential, though, you have the option of moving the motor closer to the axle and gearing up with either 20:12 or 24:8. Either way, you could potentially put a second L motor on the front of the axle, though you may need the space for something else, and the torque may not be necessary with the low 1:1 ratio, at least.

I got tired of waiting to acquire the AT-AT ring gears, and now that the B&P interface has changed and they're no longer on there, I decided to take matters into my own hands and 3D-print some of my own. That led to experiments to determine which gearing options worked with it, and in the end I found four options: 24:12:24, 20:20:20, 16:28:16, and 12:36:12, plus a bonus of 14:32:14 using a 3D-printed 32T gear: That got me wanting to try out options with the old 48T option from the Power Miners wheel, and in addition to the three options commonly known (20:8:20, 16:16:16, and 12:24:12), I noticed that by using retro 14T gears one can get 14:20:14 as well. This is also another area where the new non-beveled 12T and 20T gears will be handy, because my existing designs with beveled ones require the carrier to be set back half a stud, which would not be necessary with those. Finally, I decided to make a spreadsheet of all the possible combinations of gears for all possible ring gear sizes in multiples of 4 from 24 up to 60, using the formula that the sun and two planet gear tooth counts must add up to the ring gear tooth count. The takeaway here is that the 40T ring gear is likely the most practical for Technic MOCs, though it doesn't exist, because of its compromise of many ratios and small size, while the 60T we did just get is rather disappointing in that it doesn't even have five possibilities like 52 and 56 because two of its ratios happen to land on gears we're missing, with the 32T and the 44T both working theoretically. 56 would also have an extra possibility with a 32T gear. With this in mind, I'll think about designing and printing a 40T ring gear housing and designing a more realistic automatic-style planetary transmission, though I've got plenty of other projects I'm interested in.

I don't think it's going to be legal, but I know I've done it with the similar 64589 connector!

Thanks! It's not really suitable for Rebrickable, though, because not only would the complexity deter all but a few people, but the unreliability and need for constant troubleshooting by someone with a deep understanding of the machine would make it extremely frustrating for the few who might build it. Perhaps one day I'll come up with something practical enough for that, though!

Thanks! You're referring to my post from a few days ago? I did actually program that calculator shown in the video there, but the idea was for it to just be funny that I did such a useless thing without the appeal of it's being mechanical. Thank you! It did take a lot of parts, but surprisingly little math. The tricky part was just in covering simple math operations into workable mechanims. Yeah, the backlash was disappointing. The nice thing here was that any backlash before the spirals didn't affect accuracy, but even with that it ended up being too much. Yeah, this is totally overkill for the basic math it can go, but I at least haven't been able to think of any way to simplify the design, though as I mentioned I've got vague ideas for one using linear motion instead, which could change a lot, and get rid of a lot of backlash. I've even got hopes that the working principle will allow me to add multiplication and division for the first time, but that'd be pretty hard.

Yeah, Wranglers do default to RWD, and some generations (JK at least) were sold in a solely RWD version. The live axles are a worthwhile feature!

Do you mean updating it each year? Yes, I've been doing that since 2017 (though I hadn't shared it yet), and I plan to keep doing it for the foreseeable future.

So, after posting my tongue-in-cheek "Electrical Calculator," I'm back with my third version of an actual mechanical calculator, the affectionately named Technivac III. This one is a development of the ideas I've started in my last two calculators, combing the differential-adder mechanism of my original calculator with the extra digits (four total) and carry mechanism of V2. Overall, I'm still not happy with it, because a late addition I hadn't anticipated needing ended up bringing the levels of backlash past the acceptable level, but it is my best one yet, and I do have a completely different idea for V4, should I ever decide to build it (namely, measuring numbers with linear motion rather than rotary motion.) Anyways, I'll try to explain this thing, but it's very complicated, so I may not succeed. I've also got a video at the bottom, so that's an option too. To try to keep my description in order, I'll propose an outline here: I. Theory A. Power Supply B. Gearboxes C. Spirals/Buttons D. Adders E. Locks F. Carry Mechanism G. Dials H. Reset II. Results So, (gulp) let's start: I. Theory A. Power Supplies The first thing in the mechanism is the power supplies, which provide the power to rotate everything down the line. This calculator differed from my previous ones in being primarily crank-driven, which helped because the user could be intelligent about how much torque was needed at different times. There was also a PF L-motor running the setup through two clutch gears, but it didn't seem possible to tune it to slip the clutches when the buttons were pushed but still have enough torque to work the carry mechanism, so I generally just left it disconnected and ignored it. The motor was reversible, as was the crank. B. Gearboxes There were two main gearboxes before the spirals. The first of these was a simple distribution gearbox operated by the Num 1/Num 2 lever, allowing the user to switch between powering the upper and lower sets of spirals, which resulted in either the first or second number being inputted. The second gearbox only applied to the second number, and was a simple forward/reverse gearbox allowing one to choose between inputting a positive and negative number. I didn't need one of these on the first number, because the calculator doesn't work with negative numbers, so there is no need to input a negative as the first number. It was operated by moving the red axle up and down. Because when the spirals were reversed, the prongs sticking out from the shaft would be pressing against the opposite side of the axle pushed down by the number buttons, they were offset by a fair bit, so to ensure that the correct numbers were still inputted when subtracting, I added a lever that allowed me to change the labels of the numbers when subtracting. Essentially, I had to reverse the order, and offset it by two. C. Spirals/Buttons The basic working principle of this calculator, as in my previous ones, is the "spiral," or axle with protrusions as close to every 10 degrees as I could get. I ran out of the old toothed connectors with this calculator, since eight spirals were needed (Two per digit, since I needed one for both the first and second numbers.), so I have a few 3D-printed stand-ins, which are only "cheating" in that they allowed me to save money, since they have no functional advantage here (they may be stronger, but that wasn't important.) The buttons worked similarly to before, with axles coming down from each button to block the spiral at a specific degree, but I also had them connected to long vertical axles, which pushed rocker arms, which pushed up more axles in the opposite direction, to block the lower spiral from the bottom. Again, as in the past, it is set up so that pressing any button will press down a linkage that engages a driving ring on the spirals corresponding to that digit. D. Adders The adders here are easier to understand (I think) than those in V2, and allow for the reversing to happen before the spirals, cutting backlash, but also introduce some backlash of their own. They are a simple differential mechanism, using the 24/16t differentials to add up the outputs from the top and bottom spirals for each digit. Drive was transferred to them in most cases by a pair of 24T gears on each side of the diff (the units place used a 16:8:16 gearing in order to reduce the direction, because it didn't have secondary reversing in the carry mechanism), and the differential's 24T side then drove a 12T gear, which doubled the speed to correspond for the halving of speed caused by driving one of a differential's traditional outputs. E. Locks The adding mechanism was nice and simple, but after building it, I realized that when one spiral drove an input, it might drive the dial as it should, but it could easily just send the power out through the other input, backdriving the other spiral. To prevent this from happening, I had to add a selectable lock to lock the unused input. This was done by sliding bevel gears (20Ts for the units place, 12Ts for the rest) which were attached slidably but not rotatably (real words, and awesome ones) by having their drive axle slide through the side axle hole on gear lever parts. These gears would mesh with gears on the input shafts one at a time, locking them up. They were controlled by a lever marked Num 1 and Num 2, which was actually mechanically connected to the lever for the Num 1/Num 2 gearbox, so you could get away by just pushing this lever, though it was best to push both. This lever moved a bunch of linkages to allow for the sliding of these axles. F. Carry Mechanism I thought the carry mechanism would be a fairly simple stepper mechanism using 10T splat gears, so that's what I built. Like a fool, I had started filming before testing the carrying (I'm kind of paranoid about testing, to my own loss), discovered that it took far too much effort, thought about solutions, and realized another problem (namely, that when carrying, it would backdrive the spiral for the next number, which would cause a button press in that digit to add an incorrect amount, essentially negating the carry.) I then had a fun little evening of thinking and came up with a solution that worked in theory. I then built it, and fell in love with its relative elegance--it was really one of the most thrilling "Eureka!" moments of my Technic career. This solution was to retain the basic 10T stepper, but to use the splat gears as a basis for a custom differential, and to set up the gears so that instead of moving a full tooth (1/10 rev), it would only rotate a half tooth (1/20 rev) when triggered. This wasn't repeatable, but it didn't have to be, since this calculator only does one operation before resetting it. The reason I had to halve the rotation is because of the doubling of speed of the output when driving the carrier while holding one output, as was happening here. The output then drove the lever for the stepper for the next digit. Additionally, the differentials were locked in place by two different methods. There was one spring-loaded beam on the bottoms that pressed a flick-missile bar between the teeth, locking it. When the lever that engaged it neared the point where it actually stepped a tooth, the round end of a gear selector part bumped the lock out of its locked position, allowing it to rotate 1/20th of a rotation, at which point the upper spring-loaded beam moved down, locking the gear again with two offset connectors. The whole locking mechanism didn't work as well in theory as I'd hoped, but I thought it was clever nonetheless. Anyways, the reason that this worked while my simple solution didn't is that the output dial could move independently of its spiral when being carried, because of the differential. This part's late addition did add a lot of backlash within the spider gears, as well as wiggling of the carrier. G. Dials The dials were just basic dials based on tires. There's not much to say about them, except that the direction was reversed with each place. H. Reset In order to reset the calculator, each spiral had to be engaged by selecting the correct gearbox settings and engaging its driving ring by either pushing some button that didn't interfere or just pushing the linkage manually. The crank was then rotated backwards until its spiral hit its stop. This was all pretty simple, but the stops themselves are a bit more complex. The ones for the first number weren't too complex, with a 3L half-beam rotating until it hits a T-beam. This T-beam has a slight bit of movement allowed to it, resulting in the stop being engaged when the 3L half-beam is vertical no matter which direction it comes from. The top had a similar working principle, except that the 3L half-beam equivalent (connector, 2L axle, and half-bush) had to be able to rotate backwards past center when subtracting, which was not possible with a "dumb" stop like on the bottom. As it turns out, in order for the stop to work, the T-beam has to be right next to something (1L beam on the first number), so on the top I set up a fancy linkage connected to a lever that moved one of the pinhole/axle connectors one stud, allowing the stop to be disengaged under operation, or for it to be engaged while reversing. It was spring-loaded to unlock by default, but I had an extra little control that let me lock it in the engaged position as well. It was a weird mechanism, but it worked! II. Results In the end, like I said, accuracy was poor, with there generally being a +/-1 inaccuracy per digit, which is enough to render this calculator useless (if it weren't already! ). Also, I am doubtful that more than one carry at the same time would have worked. Otherwise I think everything worked, such as adding and subtracting, carrying a single digit, inputting the numbers, and resetting it. I'm not too disappointed with this result, since it's extremely complicated, though it isn't the end of my calculator mission as I'd hoped... Oh well, V4 will probably also be fun to build! More pictures here: https://bricksafe.com/pages/2GodBDGlory/technivac-iii

I took apart my 42130 BMW yesterday, and got a few pictures to share: First is the large front shocks taken apart, for any curious about what that looks like: Next are two different ideas for using the disc brakes as rims. This first one is the Defender's (actually the old 8880 version, but it doesn't matter) tire on the non-Defender rim as a simple wheel cover for a strange futuristic look: The second is the Porsche/Bugatti/Lamborghini tire mounted on two discs, spaced two studs apart. They're not quite as big as they should be, but they hold the tire pretty nicely and look good. You'll give up the offset, though, so it's not a great idea.

Hmm, my impression had been that this contest was intended to be for really small models, of only a couple hundred pieces or so. My opinion would be that a contest of really small stuff doesn't need a theme, but by the time we reach Corvette scale the entries will be too diverse to compare with each other effectively without some kind of theme. I think my preference would be for smaller stuff, just because it's an area I've never really explored, but I don't feel strongly about it.

Ok, thanks for the thorough answer! I hope someone does a full on comparison video at some point, especially to compare torque outputs.

Can you direct me to any info regarding the difference in power between CADA and Lego buggy motors?

Well, in a way yes. I did actually make what I said I made; the joke was more in why someone wouldmake it.

Glad to hear you like it!

Thank you! I agree that the ability to build this MOC without physical bricks at all is its key feature. Here are my previous two mechanical calculators, should one have archaic preferences in calculation technology: I'd have to learn how one of those works first... Thanks! If I had a tablet I could definitely make use of a larger user interface, but alas my phone is too small. It's also annoying how the only dials available take up a 2x2 space on the screen. A 1x1 one would be really handy! -------------------------- So, in case I didn't make the tongue-in-cheek nature of this post clear enough, this was my idea of an April Fools joke--A MOC that isn't really Lego in any meaningful way. In case you're wondering, I have actually been working on a third take on my Mechanical Calculator, and finished it a few days ago. It's still not as precise as I'd like, but I think it's nonetheless my best one yet. Once I get some more free time, I'll get around to posting it on here, so stay tuned for that.

Nice job! I've never seen the rear suspension angled like that. Is there any advantage to that when the wheels aren't being steered?

So, as you may know, I’ve built a couple mechanical calculators before, my Technivac I and Technivac II. I’m pleased to have completed those, but I recently came up with an idea that should make even state-of-the-art mechanical calculators like those look obsolete: namely, electrical calculators!!! Electronics would allow me to make the calculator far more compact, give me far superior reliability, and even allow me to add the elusive (though arguably irrelevant) multiplication and division operators. Naturally, I jumped into the powerful and innovative Lego Powered UP app as the obvious choice to attempt such a calculator. I had a few difficulties along the way, but no great breakthrough is without them. And a breakthrough it was! After only a few hours of labor, I had successfully created a completely electrical calculator controlled from my phone, which didn’t even require a single Lego brick (they’re overpriced anyways). Beyond that, as projected, the reliability was flawless, allowing me to add, subtract, multiply, and divide single-digit numbers with ease. I think this idea has enormous implications for the world that go far beyond being a simple Lego MOC! People everywhere will be able to trade in their mechanical calculators for a simple, pocket-sized device, freeing up valuable space in their houses that can now be filled with Furbys, or whatever the latest fad is these days! Beyond that, there will no longer be glaring mistakes in complex calculations, which should allow engineers to build bridges that will last longer than a week. My patent is still pending, but before I reveal this breakthrough to the public, I wanted to make it available to the community here on Eurobricks, free of charge! All you have to do to add this digital revolution to your pocket is download the Powered UP app (if you don’t already have it) and then copy the code blocks and widgets from the images provided here. Enjoy! Here’s a video, where you can see this marvel in action:

Again, nice and clean! One thing that could be worth trying is having two HOG knobs; one on the back, and one on the top. The top one would be used with a trailer attached, since there would then be enough weight on the rear for it to work, while the bottom would be used when there is no trailer, because there is then access to it.

It might not be too bad with a backpack, but it still seems annoyingly complicated!

I'd love to see any solutions people come up with for an onboard air compressor, but I can't help you there. I would imagine that by carefully operating the lever on a pneumatic valve, you could perhaps slow down the airflow enough even with a fixed-speed compressor, but I don't know for sure.

It's cool to see in those different colors, but if I'm not mistaken those wheel covers don't exist in black.

Though because the upper pivot is so far up, it is a smaller effect than it would be if it were lower down.

I like it! It's a much more interesting suspension than we usually see, and looks pretty solid.

Maybe this isn't helpful, but even when I bought a brand new one direct from Lego, it did have noticeable bend. It's not an issue in a model because of how easy it is to straighten under constraint, but maybe it's just normal for these parts.

Very nice job and presentation! A trailer like this could easily become an afterthought, but you put a lot of thought and engineering into adding functions and giving them good execution.