Ryokeen

That's one of the reasons why no hobby grade RC car uses glued in bearings. It just won't hold. What is done there is that there is a small notch between the bearings so that the outer one can't slide in and the inner one can't slide out. The outer bearing get's pressed in by the hex adapter and the wheel, the inner bearing get's pulled outwards by the thicker part of the axle(in the metal U-Joint atempt the small splint thought the joint and axle). Sometimes along with the notch, different outer diameters for inner and outer bearings are differend aswell. The inner bearing got the bigger outer diameter to prevent movement. But anyways almost always 2 bearings are used with a notch(small inside "ring" in the wheelhub) to limit movement of the bearings. But fitting that in the space of a lego wheelhub means very thin bearings.

So far i've had good results with some lithium grease. Used that for some gears and small turn tables and so far, after a year, nothing bad happened. Edit: Silicon Oils(low viscosity) for RC shocks work aswell. They are also unlikly to have any effect on plastics or rubber as they else would cause problems with the seals an other parts.

@Krzychups Nice done there, looking forward to it. Side note. I have those HSP parts here, they do fit, but are a bit higher than Lego pins, means the ballcup won't be exactly one stud above like with lego towball pins And they do hold, but not as much as lego parts, so you need to connec the lower and upper arms, which can be a problem as they might be 1/4 stud more apart than they should be

@aFrInaTi0n Nope think just the 8t gear. The 12t half bevel ones might be a different aluminium alloy but on their site it's just aluminium, where as the 8t is declared as stainless steel.

@vergogneless Nice order, have fun :) 2 advices..some locktite for the 2L 3L metal pin replacements can be usefull if you don't want the screw to get loose without having it screw in to much. 2nd..the 8t gears are from stainless steel, which is harder than the aluminium (12t, 24t and so on) so it might erode the aluminium gears(especially without lube). That actually happend when i used an 8t/24t downgearing. Fine aluminum dust everywhere.

Slight correction, discardged is mostly around 3.2-3.4V depending on how low you want to got(should not go below 3.2V). 3.7V is commonly used as a storage voltage as it's neither full nor empty.

@aFrInaTi0n Had that with one 5L liftarm from them aswell and in the process it got slighly bend. So i looked and the bearings they use are most likly "Miniatur Kugellager Zoll / Inch R156 ZZ / 2Z 4.762 x 7.938 x 3.175 mm". A good sorted store for bearings(kugellager-express) should have them. Just in case you need spare ones or want to pack some in printed/modifiered brick parts.

@gyenesvi The u-joints from them are shorter than regular ones. By about 3/4 stud in total. So the hub works well with their u-joint others will have an offset.

Thought the same, i have some RC cars(and lego hybrids) that can drive 50km/h+ and they are waaay faster than shown here. But yea a crashtest is pretty pointless unless one is still designing an RC car and wants to know the weak spots. I doubt that. I had a crash at 20km/h , not even frontal. A lot of pins broke/bent, same for Liftarms and axles. Panels are quite stable though

You do know that Lego themselfs use strings and used to have customers cut pneumatic hoses ? Anyways, great idea on such a small space :)

@NoEXIST so you have 2-3 Motors per PF Output. Keep in mind that Motors draw more current while starting and that with such an amount of motors the voltage could drop quite a lot in the frist few moments. I don't think smaller ESC have that much capacitor storage to compensate for that.

I just meaned that milling a lets say 2mm in diameter and 8mm in depth shape(4 times the corners of the axlehole adapter) can get problematic :) that's all

Most motor shafts are D shaped so 2 maggot screws won't do much, might even make it worse. Think of it that way, the side that got the hole for the screw is also lighter as it got the hole. The tiny imbalance of the weight of the screw vs the material that would be there in the adapter is neglectable. That's why you screw on the motor and why the motos have longer shafts. Also the + shape in the adapter is nice and Zene does it like that, but when i talked to some cnc operators they told me that it's actually not easy to make with the depth of 8mm(1 stud). They suggested either use electrode erosion(expensive) or use another shape. That's why my metal wheelhub adapters have an axle part. The lego axle to axle adapters are actually quite strong, i use them in my main driveshaft to connect metal axles and not one broke so far. All in all nice work so far :)

That's a 3mm fibre optic cable for diy projects. A bit more milky because it's one that has a certain amount of light going out along the cable. Not the tightest fit with lego pins(as they have 3.12 something mm diameter) but worked well in my Delorean. And i assume it's a lot cheaper than anything from lego (around 8€ per meter)

Good thing is, the fibre optics cables look like they can be easily replaced by 3rd party parts. In case one needs other lenghts, or they get damaged.

Correction: You can only change any two wires to change direction on a sensorless brushless motor. On sensored ones that will probably blow the esc and damage the motor. The other point is btw valid for any RC model, regardless if it's brushed or brushless, nitro or gas. Today that mostly doesn't happen as receivers/esc have some protection in place in the case that the signal is lost. Old AM transmitters/receivers didn't have such a protection(also they had more interferrence from other signals as there was no encoding) means if you turned of the transmitter the receiver often did random things as it might pick up a very weak signal on the used frequency.

Valid point but even with 3D printed parts you tend to print more and more specialized parts. I wanted to see how close i can get to onroad hobby grade RC-cars with using a minimal amount of aftermarked/custom parts. what i did here is more of a proof of concept and it allows me to make any chassis i want but still having proper driven and steered axles along with all bearings. And with the speeds i can drive that thing it actually shows very well how durable and versatile lego technic is. I only use screws for the shock absorber and wheelhub mount as there is just no other way. Apart from that the whole chassis holds only with pins and interlocking parts. And it holds very well, nothing came loose so far. Btw, that experiment does not contain a single 3D printed part :D

First, on most RC cars the supsension is mounted ontop of the base chassis plate, that sets the overall diffs a bit higher. Then a lot of rc cars actually don't have one straight driveshaft, but 2 driveshafts going to the front and back dif from a center dif and they go down a bit. Next it's about scale, in my current car i use tamiya parts that are for 1:10 scale cars. Even there if the lower suspensionarm is on level with the bottom of the chassis you have the typical 5 stud high double whishbone supspension with the driveshaft in the center. That means even if the center driveshaft is on the same level, you can use a 36 gear meshing with a 12 thooth pinion. What some cars do(and what i did) is acutally having a cutout at that position in the base chassis plate. So far what i've seen is that Rc cars that don't use an enclosed gearbox(motor to driveshaft) have such a cut out or use smaller gears with a different thooth pitch(mod 0.5 or dp68) and manage to stay on level with the diffs that way. Rc cars that have an enclosed gearbox either have little connections going down to the diffs OR they are in another scale, means the ratio of the car to the motor is different, which along with bigger diffs, gives more vertical space.

Yes i do, tried without a last year and even 2 buwizz buggy motors on 3s started to melt axles and holes, so decided to avoid that. More info here: https://www.eurobricks.com/forum/index.php?/forums/topic/198381-rc-bricks-hybrid-car/

@Lixander nice to hear that it works now, so it was just reversed. Weird but well at least it works. With DC motors(2 Wires) and brushless(3wires) as long as the brushless is sensorless, you can just swap the cables for hard wire forward/reverse. The Geekservo died cause you switched the Signal cable with the negative polse cable :D so there was power applied, not good. About the punch setting i use 75% but might go lower as full throttle doesn't have enough grip anyways. Also to my suprise, 2 x 36tooth(at least from cada) sanded down a bit and connected with 2k resin hold up very well. No wear so far, but i tried my best to enclose the motor pinion to main shaft gears and lubed them. And as we use a very similiar motor, that's what i archieved today with full throttle on a parking lot : But i think without ballbearings in the wheelhubs, the parts might melt quickly.

@Krzychups Hmm if the gearbox shaft is D shaped(so with one side more flat) you would just have an adapter that has an 1 stud axle hole on one side and on the other side a 1 stud 6mm hole with a place for a maggot screw. The screw presses on the flat part of the shaft and thus locks it. Problem might be that for 3D printed, it might need to be thicker than 1 Stud or it might break.

Did but want to print some other stuff aswell an i'm not sure yet what will fit, so i might need some more prototypes.

For that type of motor the first 2 digits are the diameter and the 2nd 2 digits is the lenght. Actual brand is a Robitronic Razer Ten Combo The 36xx and brushed 540 motors(not sure about others) got the nice property that their mounting holes are made for m3 screws with a distance almost perfectly matching 4 studs. So i use something like that and anchor the axles with the chassis. But i will switch to a 3D printed adapter once i bought a 3D printer and know how to work with it :D

ONe reminder, as soon as you put metal gears on metal gears, you need to lube them, especially on high rpm. Plastic on metal should be fine, but still some try lube never hurts(or use dry chain lube)

3652 size, about timing, no clue :D i know what it is, but i think the motor i use doesn't have an adjustable timing. The motor cutting down in RPM every few secs is a bad sign. What kind of ESC are you running ? My motor needs at least an 50A ESC