sacm93

I think the idea of a conveyor belt for surface interaction testing "a la wind tunnel for aero testing" is a brilliant idea, however because the forces aren't acting in the same way/ on the same surfaces as they would be if the vehicles were driven, it can't be used as an accurate way of testing. If the vehicles were powered through driven wheels and we're not held in place by a point in a position other than the axles, this would be brilliant. If, however, this is exactly as you wished this clever contraption to operate, the only advice I can give is perhaps to lock the vehicles with HOG steering straight as they have no caster angle to keep the steering centred on its own. I personally love this idea though as it might help to adjust suspension designs if made bigger for RC technic mocs, perhaps.

I also have the Galaxy S5 and can confirm perfect function with SBrick. In fact, here is my first MOC. It shows SBrick and Galaxy S5 working perfectly together... https://www.youtube.com/watch?v=uXQ99vxzW_8&t=3s

Hey aminnich, "how many gears is too many?" is a very open question which is impossible to answer outright due to the number of gears not being the only contributing factor to loss of torque and rpm due to friction. Other things which MUST be considered are; type of gears used (spiral, bevel, spur etc), placement and housing design (if the housing is not rigid and flexes this can add friction due to the structure that the gears are built into being twisted when torque is applied through the input shaft(s), length of shafts (a drive train may not be able to withstand the torque being supplied if any one shaft is too long and can flex), the drive motor (different motors have different rpm/torque outputs and the performance drop for each motor will be different depending on the given number of gears between motor and final drive. Hope this helps!

I feel like if you changed the front end slightly and one or two other things, it would be a Lancia Delta Integrale. Great MOC!

Thanks JJ2, but I'm afraid that's one thing SevenStuds shared with me before he published his crawler. We actually corresponded together for a while regarding various building techniques, he was a great help to me. It actually has quite a lot of torque. The AA battery box can supply up to 9 volts rather than the 7.4 volts supplied by the Li-Po battery box which enhances motor performance while the added weight of the AA box assists traction. The major limiting factor is really just the flexibility of the lower arms. Knob wheels were used to transmit torque from motors to along the axles, so teeth skipping was not an issue. I did. It looked ugly in my opinion and added certain other suspension-related limitations. I really wanted to set and achieve the goal of having some kind of shaft working properly alongside the suspension links. Backlash is moderate but actually surprisingly workable. I found having drive on the front axle helps the wheels the "claw" their way over obstacles instead of being "pushed aside" (if that makes sense).

G'day from Australia everyone! This is my first topic created on Eurobricks and my first serious MOC since the end of my "dark age". I'm seriously super glad to be here and keen to share my Technic creations with you all from now onward. With this in mind, if there's any way I can improve how/what I post, by all means let me know so I can keep everyone (including staff) content. I am committed to giving this site the full respect it deserves. :) As a few of you have suggested, it's a good idea when coming out of your dark age to develop designing/building skill by drawing on other people's MOCs for inspiration and guidance for different building techniques... Partially inspired by SevenStuds' recreation of Tim Cameron's rock bouncer "Showtime", I present my own 4x4 Rock Bouncer. Features.. Drive: 2 PF XL motors (1 per axle). Final ratio is 3:1. Steering: 1 PF Servo motor with rack and pinion Suspension/axles: Full-time locked solid live axles with portal hubs (geared 3:1), suspended by 9.5L shock absorber (soft) (2 per axle) and stabilized by a double triangulated four-link setup. Tires: Third party scale RC tires similar to the "Rock Crusher" by RC4WD. Battery: 1 x PF AA battery box Receiver: 1 x PF V2 I initially began designing some kind of rock crawler which was to include PF XL motors, third party tires of some description and (after quite a while researching suspension design) double triangulated four-link suspension. This kind of suspension is ideal as it provides maximum articulation and strength of the axle while eliminating the requirement for a Panhard Bar or Watts Linkage because the triangular positioning of the upper and lower control arms oppose each other, eliminating sway and allowing all desirable movement. By far the most difficult part of designing was the requirement for a steering shaft which moved harmoniously with the suspension cycle of the front axle. Because the upper control arms are shorter than the lower ones, the angle of the axle relative to the chassis changes through it's cycle and this means that when positioning the steering shaft, it must be such that the radius of it's motion doesn't change (due to angle change) as TLG doesn't offer any part which works purposely as a slip joint to negotiate the effect of plunge. After many, many, many... many attempts, a sweet spot was discovered which offered a negligible discrepancy. (This was a happy moment). It's biggest performance drawback would have to be that when the angle of climb and drive torque applied is too great, the rear lower control arms buckle and the rear axle begins to walk under the chassis. Trust me, it's cringe-worthy. With 15L beams instead of 16L links and consequently different suspension geometry, however, this could be resolved. The turning circle also suffers due to the wheel base. Overall, I am reasonably happy with the final product as it is capable of most of the things I intended it to be and in my opinion, the body could look worse. ;) I unfortunately don't have video footage, but I do have photos (see below). Enjoy! All comments welcome. :D

Mbmc, this creation is most definitely one for the record books. The technical and creative ability you have expressed here is without doubt that of a legendary builder. Congratulations from Australia on a truely astounding build! THIS deserves the win.

Looks awesome! I think an improvement might be to raise the front suspension travel. This would obviously give the front end more clearance but also, as the front lifts it would essentially rotate about the rear axle and increase the caster angle of the front wheels because the whole vehicle is rotating backward. I don't know how possible this is, considering you are working with parts from one set only. Edit: Scratch the jargon RE caster angle. I think the relevant point here is suspension travel and clearance. Maybe some liftarms to lengthen the existing wishbones?

I'm right in the motor-fitting stage of building my Ultra-4 Buggy and have two of each of the motors in question here. I only have 8881 Battery boxes though, so weight will be a problem, therefore the more POWER the better. Anyway, I digress, sort of... I think an important question to ask is "Do I want my MOC to be more efficient or more powerful?" because if you don't care about run-time, RC motors might be the answer, for maximum power. However, if you want a longer run-time and can afford to compromise power for it, perhaps XL motors would be more suited. "Better" in this case is defined either by power or efficiency. Thoughts?

Hey Canmorite! This is one seriously rigid and stable looking chassis. The 3rd party tires just add to the toughness factor, I love it! :) I'd love to know whether you persisted with this MOC as I am in fact in the process of building something with a similar front-end at present, using a similar hub design with the same parts for making the wishbones. I am curious as to how your steering performs with the rack being placed right on top of the forward lower "A" arm as it appears as if it would interfere during the cycle of the suspension. Also, did you experience a lack of torque from the steering motor with the use of the 24t clutch gear? (I understand there are three variants of this part, each with different "torque thresholds" before slipping occurs. It may not be 100% accurate or what you're looking to incorporate, and excuse me if I am out of place by suggesting this (I'm new to EB), but I have found a way to gear down a servo motor so that the steering actually has increased torque (1:1.667) but a slightly smaller angle before full lock occurs using a 12t double bevel gear and a 20t double bevel gear. I would be willing to send you a photo, assuming you're interested that is. I use 3rd party tires of similar size and understand that they require some force to be effectively steered over uneven terrain, and that the servo motor offers far more torque than the M motor to begin with. Also, the slightly more shallow full lock angle allows the CV joint at the hub to not bind up at all; one challenge I am currently facing. I appreciate any feedback (however brief) regarding my commenting habits aswell. :)

From personal experience, when building a double triangulated four-link setup, it's a whole lot easier to build using upper and lower links of: -The same length, -The same angles outward from the longitudinal axis of the vehicle, and -The same length as the drive shaft and/or steering shaft running from the chassis to the axle. Having said this, however, one can achieve a more authentic visual and behavioral effect by using shorter upper links than lower (a good ratio is upper=60% of lower length). One would think that doing this would make it impossible to include drive/ steering shafts (because the very characteristic that this design is aimed at achieving requires the use of a plunging drive/steering shaft; one that uses a sleeve to change length through the cycle of the suspension) however I have found that there is a "sweet spot" where you can position the shaft(s) such that they travel along an independent arc where the axle cycles through the suspension so that the distance between the drive/steering output at the chassis and the input at the axle remains the same throughout the entire suspension cycle, or at least enough of the cycle for a reasonably sized shock absorber (9.5L) to be then built into the design. As soon as I have permissions, I will upload my "Rock Bouncer" MOC to illustrate the above concept. I used 16L lower links and 9L uppers. :) I hope this helps anyone looking to build their own crawler/4x4/bouncer type buggy as I know they're a popular concept.

Do you have any preconceived ideas on how to construct the 4WD system? Open diffs, no diffs, or some kind of torsen limited slip setup as in the real world model? I tried to make a torsen differential, it didn't end successfully. :/

Thanks for the front axle design Piterx! I'm guessing you went with two control arms and a panhard bar for both front and rear axles, am I right? Looks like you used the Hard 9L springs looking at the incline test photo too. Good choice. I'm attempting a 4 link setup with the same axle width and have the rear complete but am dreading having to add drive, 4 link suspension AND steering on the front. Going to try and use 9L Soft springs though and see how they cope with some light crawling. ;)

This is perplexing to say the least! There's seriously NO reason either model or instructions wouldnt sell. Perhaps sending them a message may start the ball rolling again. Thanks for the link and quick response! As far as I can tell I have a reasonably suitable chassis design for a similar moc (compact 4x4 of the same scale), but am really intrigued by how you managed to stuff such compact axles under it. I am new to building live axles but have a really pollished idea that I want to do justice. This 4x4 of yours looked like the best thing to learn and adapt from.

Hey Piterx, I saw how long ago this post was last commented on but figured it was worth the (long) shot asking if there had been developments with instruction availability. Is there any way of getting hold of some? This is one hell of a moc, both aesthetically and by the look of the above photos, functionally too. You've done a brilliant job and should be proud. I look forward to your response. Edit: P.S. I checked the store you mentioned (both mangiobricks.it AND the BL store under that name and they have nothing that I could find). Help would be GREATLY appreciated!