Search the Community
Showing results for tags 'custom electronics'.
Found 2 results
-
Hi Eurobrickers! This time I'm here with my first build that explores non-lego electronics components for maximum off-road performance :) I have always been curious about what proper RC electronics could do with Lego, how far the performance could be pushed without damaging lego parts or using metal parts. So this is the first chapter in this exploration. As usual, I am more interested in off-road stuff as opposed to super fast cars, such as crawling, precision, maneuverability and good suspension. I start on a fairly large scale for two reasons. One is to see what the electronics and the parts can handle, and second is that on this scale I can maximize the performance os suspension / drivetrain. For crawling, live axles are great, planetary hubs are a must to minimize the stress on drivetrain components, and on this scale the axle design of @Attika is superior, especially with deep rims and 95mm RC tires, so I started with adopting that to my needs and building a generic chassis around them and the electronics components. For the bodywork, I choose a truggy because they are designed for crawling and are typically minimalistic, which is good for weight saving. And when I started searching for truggies, most of what I found turned out to be a Toyota Hilux, so I just went with that. The largest wheel arches are a good match for 95mm tires, and dark blue was a color in which they are available and I already had many parts in, so it was an easy choice. Features All wheel drive with about 6.5% front wheel overdrive Triangulated long travel 4-link live axle suspension on both axles Independent 4-wheel steering, servos on the axles Detachable body (single piece), openable doors Custom electronics Buggy motors inside L motor housing for drive GeekServos for steering Injora ESC 3s LiPo RC receiver and transmitter (FlySky) Custom cables with PF connectors Chassis, suspension, drivetrain I started with the design of the axles based on that of @Attika with the planetary hubs, but I made them 4 studs wider wrt the original 17 stud design because of using the deeper rims and also for a wider stance. My main objective was to integrate the GeekServo on top of it. A key simplification factor I used is the lack of open differentials (would be locked for crawling anyway), this way reducing the space requirement of the gearing, and allowing a flatter profile and lowering the servo while fixing it in a simple and solid way. The steering linkage has really small amount of slack, and the 8T gear on the rack allows very powerful steering. In fact the GeekServo is so strong (especially in this configuration), it can steer the wheel under any circumstances on any surface I tested. On the rear axle, I managed to lower the springs for a more compact suspension to leave space for the bed above it. The suspension is a 4-link triangulated one using 9L links that keeps the axles in place even without a panhard rod. In the drivetrain I wanted to experiment with front wheel overdrive. First I built one with 25% overdrive using 16:16 gearing on the back and 20:16 gearing on the front. It worked, however it felt a bit too much and was not flawless; the 20:16 gearing offset the front driveshaft to the side which created an asymmetric load at the point of the driveshaft entering the front axle which generated quite some wear over time. Also, first I used 12:12 gearing inside the axle as a closed differential, which also worn out after some time. After seeing an RC video that tested 5-6% overdrive against 25-30% overdrive, and concluded that significantly more than 5-6% is not really beneficial for climbing, I thought I'd try a more modest one. The current one on the image below uses 20:12 = 5:3 gearing in the front, and 2 stages of 20:16 gearing on the rear, resulting in 25:16 ratio. The ratio of the front/rear is then 16:15 = 1.0666, so roughly 6.5%. Most importantly, this setup is symmetric, keeping both ends of the driveshaft centered. At the same time I used a 12:20 gearing inside the axle as a differential, taking some load off. So far it has not cracked.. Here is the overall chassis. The motors look like L motors, but they have their insides replaced with that of a buggy motor, as that has the same size as the L motor's, so fits perfectly. This modification is not my own, but was done by @Jantayg and he lent me the motors for testing (the pinion gear was replaced and the thermistor was taken off and soldered back in). They are quite amazing. I measured their speed and torque against the Lego L motors, and found that they have about 1.8x speed and 1.65x torque, so almost 3x power overall!! At the same time, their speed is also in a very reasonable range, about 900 RPM on a 3s LiPo, which means good speed control but a good amount of punch at the same time, quite perfect for lego crawlers. All in a very good form factor! I only wish such a motor was available off the shelf. Luckily, the red chinese PF replicas you can find on Aliexpress approach these ones in performance; I ordered some and measured that they have about 2.5x the power of a lego L motor, only a bit worse then these modified ones. I haven't yet tested those in a build though.. Control Electronics For control, I am using this Injora ESC. It's quite small, about 5x3x1 studs in a nice housing that can be easily attached to Lego parts with sticky tacks and has a turn-on button and status LED. It is designed for smaller scale RC crawlers, but for lego motors it is more than enough, and allows for quite precise speed control. In fact, in the video the model often moves slowly not because that is its max speed, but because I wanted to move with precision; its top speed is much faster than that. Apart from that I use a FlySky transmitter and receiver, and a 3s LiPo. I also had to make some custom cables for connecting the motors to the ESC and splitting the output of the ESC for the two motors to avoid stacking them on the same PF port (I made several versions). Unfortunately, currently the cables result in a bit of a mess.. It would be nice to house these electronics in a 3d printed box or something.. Bodywork For the bodywork, I was aiming for something simple but rugged, but at the same time I wanted to test how the whole setup would work with some actual weight, whether I can later try to build a more detailed scale model at this large scale. I really like 95mm tires, both Lego and RC ones (I bought these inexpensive ones from Aliexpress, option TN1003), as they go really well with large 15 stud fender parts, both the Defender ones and the ones from sports cars. So as I mentioned in the intro, a Toyota Hilux truggy seemed like a good choice, and the Bugatti fenders went well with that, along with some long curved slopes for the hood available in dark blue. I wanted to replicate the characteristic front grille, which I managed by using large window pieces and a lot of small grille parts :) The rest of the body is a just a few large panels and beams, and a simple bed to accompany it with some roll-bars, all connected together to a single piece so that it can be mounted in the chassis on a few points, like in a 'real' RC car. Here are some more renders and images of the complete model. More images are available on Bricksafe. I haven't made instructions for this because of the large amount of custom parts, but the Studio model is available on Rebrickable. Altogether, the model has very good handling, both for speed and steering, and I am quite satisfied with the power of the motors. This all shows to me that Lego RC has much more potential, than the official electronics. And out of all these components, the only 'dangerous' one for the plastic parts are the powerful the motors, but even that danger is minimal in this setup; for smaller models it would even be less (even with this heavy model, the wheels rather spin under it than get stalled). It was really fun playing with this model and making all these video footages! Let me know how you like it and what you think about all those possibilities with custom electronics! Cheers, Viktor -
Hello! I'm back with another MOC, most likely the last one for a long time as I'm rapidly approaching a Lego dark-age of my own (college). This time around I'm finishing off my series of high-speed vehicles with a special rally-style chassis. It is my best handling version so far and it actually has bodywork (more of a tubular rollcage). Details: RC - featuring the custom electronics I've been using for previous versions. Link for those who haven't seen my setup yet. 4 Buggy motors for drive (2 driving each rear wheel, disconnected in the middle). Servo steering (normal Lego servo). 4 Wheel independent suspension - rear includes anti-roll bar and shorter top links while the front has caster and active camber due to shorter top link. Both axles have modified pneumatic cylinders acting as springs+dampers together. Extremely sturdy chassis with little to no twist (I tried hard to twist it from end to end, doesn't budge) plus sturdy rollcage that can be used to pick up the MOC. 3D printed wheels by efferman, as well as 3D printed spherical gear counterparts that act as really strong CV joints. The sturdy construction allows the suspension to work as intended, absorbing every bump. Here is the video: And now for a photo dump: Hope you guys like it! Sorry purists