jtlan

Why the flex rails?

So it's really a passenger car, right? Nicely done! It's great to see a more whimsical car for a change. Will we see cars for more monster-folk in the future?

If he's at the limit of traction (where the train slides downhill when the wheels are locked and no power is being applied), then increasing the weight won't help -- unless not all the weight is on powered wheels. @cardinal808, does your locomotive have one PF motor under it, or two? If there's only one, redistributing the weight to put more of it above the motor will help. You could also add a second motor. You can also try to improve the traction of the PF wheels by replacing the rubber tires on them with tires that have more grip -- try checking your local hardware store for O-rings of the right size and see if they have better traction than the existing wheels. You can also improve traction by roughing up the track, whether it's through sanding the track gently or using the old 12V rails. (1.) and (2.) would increase the available torque, but since he's slipping down the ramp friction is his limiting factor and I don't think additional torque would help. (3.) would actually reduce the available torque, so that doesn't seem like a good idea at all -- consider real-life freight engines, which tended to have smaller drivers for improved pulling power. Unless you use the large wheels to build up speed and then charge up the hill…?

Originally I was concerned about mixing old/new grey -- my collection is mostly from before the color change. However, it produces an odd mottled look here which I think looks okay on an industrial engine, Thanks! The worst of the SNOT construction is in the nose of the loco and the 1/2 plate vertical offset in the hump -- I should really post some internal images. There's another 1/2 plate vertical offset in the tender to recess the central boss of the Big Ben wheels I used for fans. The core body of the loco is just ordinary studs-up construction, albeit an odd width (3-wide frame --> 7-wide running boards --> 4-wide body). There's some great SNOT tutorials out there on the web (such as the ones linked here) if you're interested in learning about this stuff. Sometimes the best way to build intuition for this stuff is just to pick up some bricks and experiment, though. I had considered putting "streamlined" in quotes. It's sort of a token attempt? Not sure how to describe the shape, as it's somewhat unconventional.

What kind of batteries did you buy? You can get a rough sense from the battery's capacity and the expected current draw of the motor. Let's say the motor draws 200 milliamps (mA) at load. A typical 9V alkaline battery might have a capacity of 550 milliamp-hours (mAh). From this, you can expect to run the monorail for: 550mAh/200mA = 2.75 hours = 2 hours 45 minutes on a single battery. Of course, I'm not sure what the current draw of the motor is; you might try measuring this with a multimeter if there's a wire you can splice in to. The 9V batteries you bought might have more or less battery too. To circumvent the problem, you might consider buying a few rechargeable 9V batteries, which might be a good plan if you expect to run monorails a lot in the future.

Hello everyone, Years ago, I saw a 3D rendered image of a streamlined locomotive online. I built a model of it then, but I didn't do a very good job of modeling it. Complicating the matter is the fact that the locomotive seems to be fictional, so I only had one render of it to go on. After coming back from college I decided to see if I could do a better job of it. Here is the result: and here's the image I based it off of: Some details wound up being cartooned away. The fictional locomotive appears to be based in part on H45 024, a high-pressure variant of the DRG Class 45. Since there was only this one rendered image for reference, I had to extract out the proportions of the model by "reversing" the perspective of the image to figure out what the locomotive looks like from the side. The side view suggested an oddly short condensing tender; I may change that on a later revision. There are two things I enjoy a lot about this model. The first is the three linked flanged drivers, which prompts a lot of head-scratching when I point it out. The model does in fact drive through all switches and curves -- I'm using a variant of Ben's sprung wheel trick shown here. Essentially, the middle drivers are on sprung half-axles and retract inwards a little on curves. The second feature is the use of technic piston heads for buffers -- they're just the right size! It turns out that if you jam them over a 1x1 plate with horizontal clip they stick. Full gallery here. Thanks for looking -- let me know what you think.

Nicely done! The photos are a little blurry though ... have you considered shooting them outside or with more light? It'd be great to see more details. Is this the normal lego green or the "bright green" used in some of the newer city sets?

Hmm. Were the connecting rods quartered properly? Were there other small wheels attached rigidly to the same frame somewhere else?

I don't see why that wouldn't work, plenty of models have the wheels set that close together. @garethjellis: There's a distinction between maximum distance and distance at which scraping becomes unacceptable. I probably wouldn't do more than 10 or 11 studs axle-to-axle (i.e. measured between the centers of the axles).

There's no room between the rear wheels for the differential, so it's mounted in the middle of the body and drives the two wheels through two separate driveshafts. I could have gone without, and that would have let me get more details in, but the idea that the wheels could be scrubbing bugs me. In practice, I suspect it wouldn't make much of a difference if I didn't have one. The actual W108 seems to have the differential mounted on one of the swing arms, but there wasn't room to try that here either. The Lego differential is just too large at this scale!

I've run the engine for quite some time and I haven't had anything bad happen. Those vertical clips hold quite tightly, and there's no force trying to slide them axially along the bar (unless you consistently crash the car into objects at high speed). There's not much force twisting them around the bar either, since they're only lifting a 2L axle and a half-bush. The other nice thing about the engine design is that it's possible to adjust the phase of the "cranks" so engines of different configurations can be modeled.

Hello! If you're not adverse to using third-party software, I highly recommend using Bricx Command Center and developing using NQC. It uses the same original firmware, but it's a lot easier to write more complex programs using an actual programming language. If you're on Windows 7, I'm not sure if a VM is necessary, since it should be backwards-compatible. As an aside, I'm a fan of the RCX -- sure it's a lot less powerful, but i'm a lot more used to building with beams and plates than the new studless pieces. The other nice thing, if you've actually got one of the original 1.0 versions, is the power jack on the back, allowing you to make robots that run for weeks at a time -- I once created one to water some plants while I was away on a trip. Best of luck!

Hello everyone! First-time poster here. Here's a model I built of a Mercedes-Benz W108. I built this with the goal of putting as much mechanical functionality in as small a space as possible. The resulting model is 14 studs wide (not counting rear-view mirror) and features: 4-wheel independent suspension Moving inline-6 engine connected to the rear wheels Hand-of-god steering which also turns the steering wheel inside The scale is roughly 1:15. It's kind of chunky partly because I was going for an "old-style" technic feel, and also because the actual W108 is rather boxy. As on the actual vehicle, the front wheels feature double wishbone suspension and the rear wheels use swing arms. Because the model is so narrow the differential isn't located between the rear wheels, but rather connects to them through a pair of shafts: You'll notice that the universal joints don't seem to correspond to any hinged parts; they're there to accommodate misalignment between Technic beams! There are a few locations in this model which feature sub-millimeter precision; if people are interested I can write a post later about alignment and why it's bad to pass an axle through more than a pair of beams. Speaking of sub-millimeter precision, the front steering depends on the fact that a lift arm is slightly narrower than a stud. Here's a view into the steering mechanism with the engine removed: The dark grey and black lift arms in the center of the image form a parallelogram linkage, so the dark grey steering links get actuated in sync. You can also see where I put the differential... Speaking of the engine, here it is: It's based off the excellent "fake engine" by laixEngineering. I highly recommend this engine for smaller models; not only is it better scaled than the massive engines built with the actual piston parts, it also makes a pleasant diesel rumbling sound when spun. Due to the relatively small size of the model I didn't have room to model some features, such as a gear shift or the rear seats. It's actually possible to motorize this model, although the steering/drive motors take up all of the interior space and the battery box looks rather silly sticking out of the trunk... Full gallery here. Thanks for stopping to take a look! I'm happy to answer any questions about the construction, precision alignment, etc.