janssnet Posted January 12 Posted January 12 On 1/7/2026 at 4:22 PM, vergogneless said: Have you considered moving to an oil-filled suspension setup? I did, but haven't found the right product yet. Mostly they are too stiff for the LEGO wishbones, especially when you can only mount them on 1 side of the wishbone, the force gets unequally divided and things brake apart. Any suggestions regarding oil filled shocks for LEGO models, let me know! This is the latest status of the build. First outdoor tests were nice. However, as most of you might have noticed, the weakest part for faster LEGO cars is mostly the steering link and the 'pin with ball'-connector (6628). When it gets bumpy it disconnects. Took some non-LEGO measures and ready for a stress test now. Quote
janssnet Posted January 14 Posted January 14 This thing runs super! Great torque, great speed, good cornering, no parts falling off I'm pleasantly surprised. Not only the performance is great, the costs are minimal: €20 ESC, 4 x €12 motors and a €13 battery. The combination of these light weight motors together with the planetary gear hub (46490) is doing the trick. Will do more footage soon. Here a first preview .... https://drive.google.com/file/d/10PWXrrdkgM4LEOsqPBHX2jvJd-DXuTh9/view?usp=sharing Quote
gyenesvi Posted January 14 Posted January 14 7 hours ago, janssnet said: This thing runs super! Great torque, great speed, good cornering, no parts falling off That runs pretty smooth even on the dense grass! And indeed, the cost sounds good too! What are those motors exactly? They seem pretty flat! And how did you fix the U-joint to the output shaft? With a thin plate inserted? Quote
janssnet Posted January 15 Posted January 15 (edited) 18 hours ago, gyenesvi said: What are those motors exactly? And how did you fix the U-joint to the output shaft? With a thin plate inserted? Motors: Samguk Series Wu 2206 2400kv U-joint: Metal 5mm to 4mm. Cut the 5mm axle of the motor down to 5mm length (careful, put some paper around the axle to protect the motor otherwise the metal fragments get onto your magnets ) Then drilled the 4mm hole into a 4.8mm hole using this 'holder'. And then put an axle (59426) into the u-joint, fixed with a 3mm headless screw. Edited January 15 by janssnet Quote
keepbricking Posted February 23 Posted February 23 Found some videos of the car while it was still up and running https://drive.google.com/drive/folders/1d8dyh4JQTdbmoK5pFK_T-POxt6vZc5cr?usp=sharing Drifting it is very fun, also had to put tape on tyres to try to stop them from EXPLODING but didnt work The throttle in the videos is about 20-25% Quote
DadScientist Posted March 19 Posted March 19 "I haven't been away that long, there's probably only a new page or two..." (4 pages of new builds and servo ideas later...) Wow... So many things I want to comment on... @janssnet: That new buggy is AMAZING. I used the planetary hubs on my build of your brushles buggy build that I started writing up months ago... They work really well, and cut down on the axle twist. I've heard they start to overheat after a while, but haven't hit that issue yet... Probably because I was busily melting everything else. Also: I noticed your recent new in-wheel RC car video on Youtube... It was cool to see the tech make the jump.. Side note: You did mention something in the write up about people offering feedback in the comments. Not sure if you noticed or not, your comments are turned off on that video. Re: Oil shocks: I've seen some in 1/18 scale and 1/10 scale for crawlers that have internal springs, which might help for clearance. The 1/18 mounting points had sleeves, not ball joints, though. The 1/10 do have ball joints at the mounts, and use 3mm screws, I think. I need to double-check, but I'm pretty sure I'd used M3 with an M2.5 washer before to mount a servo: The M2.5 washer had a 6mm OD that perfectly fits the recess around the holes in a technic beam, which keeps the bolt centered. So, that might actually pass through your A-arms, if they were a bit longer. @vergogneless: I love that little car! I hadn't thought much about using an SG90, but the tiny form factor is hard to ignore. I'd been so excited to see that a standard size RC servo drops in so smoothly (~40mm length is 5 lego units) and bolted on so simply. I have ideas for a mounting bracket that are going to eat at my brain for a bit. --- I don't have anything new just yet. I had to detour into actual RC cars, because it was clear that I really didn't know enough about the electronics, and I'm hoping that sensored motors solve some of my meltdown problems. But now that things are slowly settling out, I'm looking forward to finishing the write-up on my experiments with janssnet's brushless buggy. Quote
legomen Posted March 26 Posted March 26 L Motor with brushless motor and integrated ESC. The motor uses existing L Motor housing and PF connector. It can be connected and controlled with existing batteries, like Buwizz or even Lego. Quote
everybrickasculpture Posted March 26 Posted March 26 2 hours ago, legomen said: L Motor with brushless motor and integrated ESC. The motor uses existing L Motor housing and PF connector. It can be connected and controlled with existing batteries, like Buwizz or even Lego. Are you working on this? Or is this just an idea? Quote
HorcikDesigns Posted March 26 Posted March 26 (edited) @legomen@legomen sounds like very small motor and compact custom ESC with probably integrated signal conversion. Do you have more technical details and working photo? It also sounds like welding the connector contacts and plastic, original wires are not designed for such load. Edited March 26 by HorcikDesigns Quote
legomen Posted March 26 Posted March 26 36 minutes ago, everybrickasculpture said: Are you working on this? Or is this just an idea? It is in prototype stage. I am testing it with two different motors. 3500KV and 4100KV. 19 minutes ago, HorcikDesigns said: @legomen@legomen sounds like very small motor and compact custom ESC with probably integrated signal conversion. Do you have more technical details and working photo? It also sounds like welding the connector contacts and plastic, original wires are not designed for such load. Motor can draw up to 5A, but this are short spikes. Normally, it draws far less current. I do not think the wires are a problem. Also did not notice connector troubles. Motor with an ESC. Quote
everybrickasculpture Posted March 26 Posted March 26 Very interesting. So it's using the voltage as the signal? And the voltage is not constant across the RPM range? I'm interested in how this works at low RPM. Quote
legomen Posted March 26 Posted March 26 3 hours ago, everybrickasculpture said: Very interesting. So it's using the voltage as the signal? And the voltage is not constant across the RPM range? I'm interested in how this works at low RPM. It is using standard PF PWM signal to define desired RPM (in both directions). 100% duty cycle means highest rpm and 0% is stop. PF has two signals, one for each direction. The ESC is using FOC algorithm in order to maximize efficency at every RPM. From theory of FOC, the most problematic is startup, because the motor is sensorless and FOC can not estimate the proper rotor angle. For that ESC is using different technique to start the motor and once it is started it switches to FOC. Motor assembly with Kyosho XSpeed41. Expensive, but very high quality motor. and fresh ESCs. Quote
legomen Posted March 26 Posted March 26 And here is the test rig for the first prototype. I have used this rig to test Lego L motor and compare the speed with Brushless L motor. Later is more then twice the speed. The bottleneck here is the battery. Because of the voltage drop, the motor has only 6V to work with. Need to try it with Buwizz at 11V. That will most surely speed things up. I have decided to design a NEW battery system to be used with my brushless motors. It is in the working:) Quote
2GodBDGlory Posted March 26 Posted March 26 That is some very cool stuff you're working on! The power supply is going to be the challenge, though, as you said. Quote
legomen Posted March 26 Posted March 26 1 minute ago, 2GodBDGlory said: That is some very cool stuff you're working on! The power supply is going to be the challenge, though, as you said. Thanks. Yeah, this why I am now working also on my own battery, although Buwizz should have enough power to drive it. Quote
msk6003 Posted March 27 Posted March 27 That's really cool! I think XL motor has bigger inner space so maybe it can be more powerful than L version? Quote
BrickTronic Posted March 31 Posted March 31 On 3/26/2026 at 3:32 PM, legomen said: It is in prototype stage. I am testing it with two different motors. 3500KV and 4100KV. Motor can draw up to 5A, but this are short spikes. Normally, it draws far less current. I do not think the wires are a problem. Also did not notice connector troubles. Motor with an ESC. Hello, Are you willing to share the schematic diagram ? What uC and what H-Bridge Driver is used ? Jo Quote
legomen Posted March 31 Posted March 31 1 hour ago, BrickTronic said: Are you willing to share the schematic diagram ? What uC and what H-Bridge Driver is used ? Sorry. It is not an open source design, yet. I am using DRV8317 driver. Quote
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