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Found 66 results

  1. Hey everyone, I stripped down my Dodge Demon MOC to the chassis and I want to modify it in a way that will make it look more rugged and potentially even have some RC components added! Do you all have any suggestions that you could please give to support the build?????? Here is a before and after of the chassis as of today: The Changes I have made are the following: - Improved central ground clearance - Components of the chassis have been removed to allow the fitment of bigger tyres - Larger Tires - Some reinforcement of the suspension struts and how they connect to the chassis I have a workbench post on rebrickable with a video! https://rebrickable.com/users/CrazyKreations/workbench/6109/ What should I add or change next?????
  2. I started this project because I wanted to share my experiences building various offroad models over the last decade. This topic is meant to guide the builders with comparisments, suggestion and best building practices, It is however not a place to find already finished and perfected designs - that's up to you. Various aspects of the design of the vehicles will be split into several subgroups and explained in details. 1. Number of wheels First thing we need to know is how many wheels our design will have. Most common setups are as following: 4x4 Setup Advantages: 1. The simplest and most widely setup 2. Having only 4 wheels means lower weight and higher performance 3. Higher manoeuverability 4. Simple suspension and driveline design Disadvantages: 1. With only 4 wheels the suspension has to be designed to be as flexible as possible to get the most out of the wheels 2. In a case of a mechanical failure of a single wheel, the whole model's performance is greatly affected 6x6 Setup with double rear axles Advantages: 1. Two rear axle provide more traction area, especially when going uphill 2. Usually 6x6 vehicles are longer than 4x4 and therefore less likely to tip over 3. Since the front and second axle are usually closer than in 4x4 setup, there is less ground clearance needed between them 4. Greater redundancy in a case of a mechanical failure Disadvantages: 1. Lower manoeuverability due to a longer wheelbase even with rear wheel steering 2. More complex driveline and suspension design is required 8x8 or more wheels setup Advantages: 1. Having 8 or more allows for much greater traction area 2. Ability to drive over ditches 3. Because wheels are usually much closer there is much less chances of getting stuck on top of an obstacle 4. Excellent redundancy in a case of a mechanical failure 5. Better weight distribution 6. Less suspension travel required per each wheel as with 4x4 or 6x6 and hence better stability Disadvantages: 1. Lower manoeuverability even with rear wheel steering 2. Powering 8 or more requires a very complex driveline 3. Depending on a driveline, combined torque required for powering all 8 wheels can destroy gears if a single wheel gets stuck 2. Type of wheels and tyres Now that we decided on how many wheels we want for our offroad beast, we have to look into what type of tyres and wheels we want to use. I will hereby cover only the bigger types of tyres and wheels. 1. 94.8x44R Advantages: 1. Low weight 2. Good thread design 3. Low rolling resistance Disadvantages: 1. Low traction, these tyres are prone to slip on the rim at high loads 2. Due to its rounded shape the tyres tend to slide off obstacles when crawling over them 2. 94.3x38R Advantages: 1. Low weight 2. Medium traction 3. Low rolling resistance 4. Realistic design and proportions Disadvantages: 1. Shallow thread pattern 2. These tyres are very hard and don't adjust to the terrain 3. 107x44R Advantages: 1. Low weight 2. Medium traction 3. Very deep thread 4. Currently largest tyres by diameter Disadvantages: 1. High rolling restistance and vibrations due to the thread pattern 2. These tyres are a bit hard and don't adjust to the terrain 4. Power Puller tyres Advantages: 1. High traction 2. Good thread 3. Largest Lego tyres ever produced 4. Deep wheel offset Disadvantages: 1. High weight 2. Hard to use, they require complex hub assemblies 3. Very rare and expensive 5. Outdoor challenger wheels Advantages: 1. Very high traction 2. Very good thread pattern 3. Deep wheel offset 4. Over 7 studs of space inside the wheel Disadvantages: 1. High weight 2. Hard to attach to the standard axles 3. They require a lot of torque to use them at their full potential. 6. Tumbler wheels Advantages: 1. Low weight 2. High traction 3. Very flexible Disadvantages: 1. Low thread pattern 2. Small size 3. Expensive For the 94.8x44R. 94.3x38R and 107x44R tyres we have a choice of two wheels: 1. Racing wheel large Advantages: 1. Good mounting option with axlehole and pinhole 2. Available in multiple colours 3. Cheap Disadvantages: 1. No inside wheel offset means steering pivot point can't be placed inside the wheel. 1. Futuristic wheel Advantages: 1. Deep wheel offset allows us to place steering pivot point inside or closer to the wheel than racing wheel large 2. Slightly larger wheel size stops the 94.8x44R tyre from slipping on the rim Disadvantages: 1. Limited mounting options, with only one axlehole 2. Hard to find 3. Hubs Now that we have our wheels and tyres we need a way to mount and power them. Here are the most common currently available options: 1. New standard ungeared CV hubs These hubs are usually driven by the CV joint counterpart which pops inside Advantages: 1. Low steering pivot offset - usually at the edge of the tyre: 2. Firm wheel mounting 3. Readily available, easy to use and to build on. Disadvantages: 1. Low operating angle - the CV joint can operate to a maximum of about 30 degrees, which limits steering angle. 2. Very low torque transfer - the CV joints are prone to deforming and popping out even with low torque applies to them 3. Low ground clearance 2. Old ungeared CV hubs Advantages: 1. Low steering pivot offset - usually at the edge of the tyre 2. Firm wheel mounting 3. Better ground clearance than newer hubs Disadvantages: 1. Very low operating angle - the CV joint can operate to a maximum of about 25 degrees, which limits steering angle. 2. Very low torque transfer - the CV joints are prone to deforming and popping out even with low torque applies to them 3. Hard to find and expensive 4. No other mounting points than 4 ball joints 3. Built cardan ungeared hubs Example of a hub using a cardan joint to directly transfer the power to the wheel Advantages: 1. Low steering pivot offset - usually at the edge of the tyre 2. Easy to build 3. Can transfer higher torque than a CV joint 4. Higher steering angle Disadvantages: 1. Mounting relies only on the axle and is not as firm as standard hubs 2. Not capable of transferring high torque to the wheels 3. Low ground clearance 4. Standard portal hubs Advantages: 1. Easy to use and to build on. 2. Can transfer very high torque to the wheels when using 8z and 24Z gear combination 3. High steering angle 4. High ground clearance 5. Firm wheel mounting Disadvantages: 1. Very high steering pivot offset - requires stronger steering mechanisms and more fender space for wheel to swing 5. Built portal hubs Advantages: 1. Easy to build. 2. Can transfer very high torque to the wheels when using 8z and 24Z gear combination 3. High steering angle 4. Higher ground clearance than standard portal hubs 5. Low steering pivot offset when using futuristic wheels Disadvantages: 1. Wheels are mounted and held only by one axle, not as firm as standard hubs 2. Hub relies on friction of the components to keep it together, which can slide apart after prolonged use 6. Built planetary hub Advantages: 1. Highest gear ratio of all other hubs, 1:4 2. Firm wheel mounting when using futuristic of power puller wheels 3. High steering angle 4. Lower steering offset than standard portal hubs Disadvantages: 1. Requires old turntable, futuristic or power puller wheels for best results - all are hard to find 2. High number of moving gears 3. Least efficient due to the high friction caused by the large surface contact area and number of moving gears 4. Suspension Suspension is the mechanism that will keep our model's wheels in contact to the ground and will be supporting most of its weight. Most of the designs cover 4x4's Following factors determine the type of suspension system we will use: 1. Weight of the model - The heavier the model, the stronger the suspension components have to be 2. Speed - Faster models require more responsive suspension systems with low unsprung weight 3. Flexibility - The higher the obstacles you want to climb over the more flex and/or wheel travel suspension has to provide 1. No suspension I have yet to see and offroad vehicle without any type of suspension (except for maybe 42070, 42081 and 42082), but I will list my opinion regardless: Advantages: 1. Simple design - having no suspension simplifies our design...and that's about it Disadvantages: 1. No flex over terrain means, there are only 3 wheels at once touching the ground 2. Low stability 3. Poor weight distribution 4. No shock absorption at high speeds 2. Pendular suspension This is the simplest suspension you can put on your vehicle. It basically means one or more of your axles are free to swing about. When using this suspension I suggest using the small turntable where drive axle enters the axle. This will keep the drive axle from carrying the weight of the model, which causes unnecessary friction. 42030 is a typical example of this suspension system. Advantages: 1. Simple, robust design 2. Using this suspension on both axles can give the model very high flexibility 3. If there are no springs used, the model can have perfect weight distribution on left and right wheel Disadvantages: 1. Large unsprung weight, poor responsivness at high speeds 2. No shock absorption means this suspension is not suitable for high speeds 2. When using on one axle, the stability of the whole model relies on the unsuspended axle. 3. When using pendular suspension on both axles springs or a transfer mechanism are required to keep the model upright 3. Single torque tube suspension This suspension became available with the release of the 8110 Unimog. Best examples of this suspension are 8110, 9398 and 41999. It is the simplest suspension which also allows for vertical suspension movement. Advantages: 1. Simple, robust design 2. Universal joints can be placed inside the ball joint, allowing power to be transferred to the axle 3. Easy to implement Disadvantages: 1. Large unsprung weight, poor responsivness at high speeds 2. Axle requires a some kind of a linkage system to keep it cenetred (panhard or parallel links as seen above). 3. Using this suspension on the front axle usually results in negative caster angle which causes higher rolling resistance 4. When used on rear drive axle, the suspension has the tendency to cause oscillate, especially with soft suspension and high power 4. Hard to connect springs to the chassis 4. Double torque tube suspension This is an evolution of the single torque tube suspension, which uses two ball joints to drive each wheel side respectively. It is my own original idea. Advantages: 1. Simple, robust design 2. Universal joints can be placed inside the ball joint, allowing power to be transferred to the axle 3. Easy to implement 4. Self-cenetring, since axles are connected in the center there is no need for linkages to center it 5. Can carry power to each wheel side independently 6. Drive torque compensation Disadvantages: 1. Large unsprung weight, poor responsivness at high speeds 2. Using this suspension on the front axle usually results in negative caster angle which causes higher rolling resistance 3. When used on rear drive axle, the suspension has the tendency to cause oscillate, especially with soft suspension and high power 4. Hard to connect springs to the chassis 5. Parallel floating axle This suspension uses linkages which keep the axle parallel to the chassis of the model. For best functionality and reliability the lengths of all links and that of the double cardan joint should be equal. Also all the linkages and drive axles should be parallel. Advantages: 1. Keeping the axle parallel to the chassis reduces the oscillations effect 2. Better responsivness compared to the torque tubes 3. Neutral caster angle when used on front axles. 4. Self cenetring when using A arm as upper link or 4 link setup 5. Can be configured to carry power to each wheel side independently 6. If configured to carry power to each wheel side independently the drive torque can be compensated. 7. Easy to connect spring to the chassis Disadvantages: 1. High unsprung weight, less responsive at high speeds 2. Increased mechanical complexity, double cardan joints required to carry the power to the axle 6. Half axle independent suspension This is the simplest independent suspension you can build. Best example of such suspension are Tatra and Pinzgauer trucks. Advantages: 1. Independent suspension with low unspring weight, suitable for high speed 2. Robust design with low number of moving parts 3. Easy to connect spring to the chassis Disadvantages: 1. Changes of the caster angle as the wheels travel up and down 2. Hard to implement a drive system that does not carry the weight of the vehicle 3. Hard to implement steering system 4. Wheels tend to drag sideways on the ground when suspension travels up and down, reducing efficiency 7. Trailing arm parallel independent suspension Personally I have not used this suspension yet, but I did use a normal trailing arm suspension which does not keep the hubs parallel. Normal trailing arm suspension which does not keep the hubs parallel acts similarly to torque tube suspension. For the prallel version of the trailing suspension I imagine the following: Advantages: 1. Independent suspension with low unspring weight, suitable for high speed 2. Robust design with low number of moving parts 3. Long links allow for high suspension travel 4. Very easy to connect spring to the chassis 5. Can be configured to carry power to each wheel side independently Disadvantages: 1. Hard to keep the wheels from sagging under the weight of the model. 2. Difficult to transfer power to the wheels 8. Double wishbone suspension This suspension uses two A-shaped arms to keep the wheel hubs in place. As of late it's my favourite suspension system due to: Advantages: 1. Independent suspension with low unspring weight, suitable for high speed 2. Very customizable design with lots of adjustable characteristics (suspension arm lengths, caster angle, camber angle, steering geometries) 3. When build correctly it is far more robust than live axle suspension 4. Increased ground clearance compared to live axle suspension, especially when used with portal hubs 5. Can be configured to carry power to each wheel side independently 6. Extremely easy mounting of springs 7. Very stable compared to live axles 8. Frame holding the suspension can be part of the chassis, therebye lowering the center of gravity Disadvantages: 1. More moving parts as live axle suspension, increased mechanical complexity 2. Limited wheel travel - Lego wishbones allow a max. of around 25 degrees of suspension angle 9. Multi-link suspension To be updated when I build my first multi-link offroad suspension. I can assume the following characteristics: 1. Independent suspension with low unspuing weight, suitable for high speed 2. Extremely customizable design with lots of adjustable charactersitics (suspension arm lengths, caster angle, camber angle, steering geometries, virtual pivot point) 3. Large steering pivot point compensation 4. Increased ground clearance compared to live axle suspension, especially when used with portal hubs 5. Can be configured to carry power to each wheel side independently 6. Very stable compared to live axles 7. Frame holding the suspension can be part of the chassis, thereby lowering the center of gravity Disadvantages: 1. Very high amount of moving parts, increased mechanical complexity 2. Limited wheel travel - Lego wishbones allow a max. of around 25 degrees of suspension angle 3. Hard to connect springs to the chassis 10. Spring types Listed below are the most common types of springs available: 6.5L Soft shock absorber Advantages: 1. Small, easy to implement Disadvantages: 1. One stud of suspension travel 2. Low spring rate, can't support heavy models 6.5L Hard shock absorber 1. Small, easy to implement 2. High spring rate, can support heavy models Disadvantages: 1. One stud of suspension travel 9L soft shock absorber When using 9L shock absorbers I suggest you do not use the default offset upper attachment point, but use an in-line attachment point instead. This will reduce the friction and allow for better high speed performance Example: Advantages: 1. Two studs of suspension travel 2. More attachment possibilities than 6.5 L shock absorber Disadvantages: 1. Default attachment points create friction 2. Low spring rate, can't support heavy models 9L hard shock absorber Advantages: 1. Two studs of suspension travel 2. More attachment possibilities than 6.5 L shock absorber 3. High spring rate, can support heavy models Disadvantages: 1. Default attachment points create friction 2. Rare and expensive 11. Attaching springs to live axles If we start with basics, the first things we have to check is how position of springs affects suspension of live axles. The closer you place the springs together, the more flex the suspension will have, but it will also be less stable: I suggest you to keep springs at a distance of around 1/2 of the total model width. When placing springs you should keep them in-line with the wheel bearing in order to reduce friction. First example of bad spring placements: And example of good spring placement: When using multiple springs make sure to place them symmetrically centrred to the wheel hub: When attaching springs to torque tube suspension, you have to allow springs to tilt in two planes: You can also attach the springs to the suspension links to increase suspension travel. This technique is especially common on Trophy Trucks: 12. Attaching springs to independent suspension Independent suspension allows for much more flexible spring placement. Generally the closer you attach the spring to the main suspension arm pivot, the higher spring travel you get, but lower suspension force. Examples going from the hardest suspension with low travel to the softest with high travel: You can also attach springs inside the suspension arms: Or horizontally: As with the live axles make sure springs are in the center of the wishbones. Example of good placements: And an example of bad spring placement, which causes excessive friction and suspension binding: 5. Steering Steering is the system which allows our model to change direction. Generally there are two types of steering system used: 1. Skid steering Advantages: 1. Very simple to implement and control with two separate motors for left and right sided wheels. 2. Does not require a dedicated steering motor Disadvantages: 1. Not efficient, since wheels have to skid to steer 2. Power had to be reduced or even reversed in order to steer. 3. Not very accurate 4. Not very effective offroad 2. Classical steering with steerable wheels Advantages: 1. Efficient, with minimum loss of speed 2. Accurate 3. Does not reduce the power of the drive motors 4. Can be used in front, rear or all axles for tight steering radius or crab steering 5. Effective offroad Disadvantages: 1. Requires more complex hub assemblies 2. For best steering accuracy you need a dedicated servo motor. Examples of a simple classical steering system for live axles 1. Parallel steering system for live axles Here both hubs are always parallel. Position of the steering in the front or rear rack has no affect on the steering. Advantages: 1. Very simple and robust 2. Easy to build Disadvantages: 1. No Ackermann steering geometry 2. Steering rack moves inwards as it steers, requiring more space. 2. Ackermann steering system for live axles This system allows the hubs to steer at different rates. The steering arms are offset inside so they form a virtual steering point where at the point where lines meet. Advantages: 1. Better steering performance Disadvantages: 1. More complex assembly 2. Steering rack moves inwards as it steers, requiring more space. 3. Steering system with diagonal linkages This system acts similar as Ackermann steering system by using diagonal steering links. Advantages: 1. Better steering performance 2. Steering rack only has to move in one direction without sideways movements 3. Can be configured to be used in front or the rear of the axle. Disadvantages: 1. More complex assembly 4. Simple steering system for independent suspension 1. Very simple and robust 2. Easy to build 3. Can be even more robust when using double steering racks and links 4. Steering rack only has to move in one direction without sideways movements Disadvantages: 1. No Ackermann steering geometry 5. Ackermann steering system for independent suspension Advantages: 1. Better steering performance 2. Steering rack only has to move in one direction without sideways movements Disadvantages: 1. More complex assembly, less robust. 3. General steering tips 1. When using independent suspension always make sure your links are paralel to the suspension arms, otherwise you may end up with wheels which are not parallel and are causing excessive friction: 2. When using standard portal hubs make sure your steering system is robust enough to deal with the forces generated by wheel driving into obstacles. 3. If possible use servo motors which allow for high steering precision and return to center. They are especially useful at high speed models. 4. Most efficient way to steer the wheels is using the steering racks. 5. Build axles in such way they have positive caster angle, example for direction of travel from right to left. This will self-center your wheels and reduce rolling resistance. 6. Drivelines Drivelines are the responsible for transferring the power from the motors to the wheels. There are various drivelines you can build, here I listed few with their characteristics: Driveline types 1. Permanent 4x4 Advantages: 1. Simple, centralized, low mechanical complexity 2. Wheels are always powered, great offroad performance 3. Light weight Disadvantages: 1. Poor steering radius 2. Tyres have to skid when steering, lowering efficiency of the model 2. 4x4 with open differentials Typical example of this driveline is 42070 Advantages: 1. Differentials allow the wheels to so spin at different rates when steering 2. Very efficient since wheels don't have to skid when steering Disadvantages: 1. If one wheel loses traction, all the power is transfereed to it, poor offroad performance 3. 4x4 with lockable differentials Advantages: 1. Differentials allow the wheels to so spin at different rates when steering 2. Very efficient since wheels don't have to skid when steering 3. All differentials can be locked, so wheels are powered for great offroad performance Disadvantages: 1. Higher mechanical complexity 2. Dedicated motor is required to actuate differential locks, higher weight 4. Axle mounted motors Typical example of this driveline are 9398 and 41999. Advantages: 1. Differentials allow the wheels to so spin at different rates when steering 2. Very efficient since wheels don't have to skid when steering 3. If one wheel gets off the ground the second axle can still pull/push the model. Disadvantages: 1. Higher mechanical complexity 2. Usually the rear axle motor is more loaded than the front, especially when climbing uphill, the motors can't "help" each other. 3. Worse offroad performance than permanent 4x4 5. H drive: This is my favourite driveline due to the following reasons: Advantages: 1. Motors allow the wheels to so spin at different rates when steering 2. Model can skid steer 3. Very efficient since wheels don't have to skid when steering normally 4. Having 2 drivelines allows you to carry more torque to the wheels 5. Redundancy, even if one drive fails the model can still move 6. Wheels are always powered, great offroad performance Disadvantages: 1. Higher mechanical complexity 2. Slightly higher weight 6. Wheel motor drive Each motor powers a wheel independently. Advantages: 1. Motors allow the wheels to so spin at different rates when steering 2. Model can skid steer 3. Very efficient since wheels don't have to skid when steering normally 4. Redundancy, even if one or more motors fails the model can still move 6. Lower mechanical complexity Disadvantages: 1. Motors can't "help" each other 2. Higher weight due to a higher motor count Transferring power axially When transferring power via axles, you can reduce the flex by using connectors instead of simple "bare" axle: Use axles with stops to prevent them from sliding out of gears: Where possible always brace tooth gears from both sides: Transferring power at an angle Where pairs of U joints are used, make sure to align them to eliminate vibrations: Brick built CV joint which can transfer high torque at over 30 degrees angle Brick built cardan joint which can transfer extremely high torque up to 15 degrees angle Brick built flexible drive which can transfer medium high torque, extract and retract, suitable for low angles Transferring power perpendicularly The following perpendicular gearboxes are the best suitable for transferring high torque Avoid knob and worm gears, because they waste energy Gearboxes In my models I generally use the following gearboxes: 1:3 differential gearbox Advantages: 1. Very high gear ratio between low and high gear, 1:3 2. Capable of transferring high torque 3. Very efficient since only 2 gears are used at any time Disadvantages: 1. Takes a lot of space 2. This gearbox requires a good housing to brace the gears properly Compact two speed gearbox Advantages: 1. High gear ratio between low and high gear, 1:2,77 2. Capable of transferring high torque 3. Very efficient since only 2 gears are used at any time 4. Very compact design Disadvantages: 1. Requires two of the rare 20 tooth clutch gears 2. More complex shifter assembly. Diagonal gearbox Advantages: 1. High number of gears 2. High gear ratio possible, over 4:1 2. Capable of transferring high torque 3. Very efficient since only 2 gears are used at any time Disadvantages: 1. Takes a lot of space 2. Input and output axles are not parallel. 3. A complex shifting assembly is required for sequential operation. Driveline effect on suspension Transferring torque on the wheels can affect the suspension, especially when live axles are used. The following photo shows how the torque causes one side of the axle to push down and the other to lift up: In order to minimize this effect I suggest the following: 1. Make sure to have most if not all the downgearing inside the axles, so you do not need high torque going to the axles. 2. Make sure your models have a low center of gravity 3. You can eliminate this effect by using two counte rotating axles which cancel each other's torque, example below: 7. Motors and control Following are the most common types of motors used for Lego models. You can find more info here: http://www.philohome.com/motors/motorcomp.htm My personal favourites are L and RC motors due to the balanced output speed to torque ration and great mounting options. 1. PF-M Advantages: 1. High speed output 2. Smallest available motor 3. Cheap and available Disadvantages: 1. Low torque 2. Poor mounting options 2. PF-L Advantages: 1. High speed output 2. High torque 3. Cheap and available 4. Great mounting options Disadvantages: 1. Odd shape 3. PF-XL Advantages: 1. Very high torque 3. Cheap and available 4. Good mounting options Disadvantages: 1. Slow speed output 2. Large form factor 4. PF-Servo Advantages: 1. Very high torque 2. Very precise output with 15 positions 3. Good mounting options Disadvantages: 1. Slow speed output 2. Output axle can move a max of 180 degrees 3. Large form factor 4. Hard to find 5. 9V-RC motor Advantages: 1. Most oowerful Lego motor 2. Very high speed output 3. Good mounting options 4. Two output axles with different gearing ratios 5. Drive axles can pass through the motor Disadvantages: 1. Low output torque 2. Low efficiency 3. Power hungry 4. Odd form factor 5. Hard to find and expensive Power options 1. PF - AA battery box Advantages: 1. High capacity 2. Good mounting options 3. Works with rechargeable batteries, but with lower performance 4. Cheap and easy to find Disadvantages: 1. 750mA current limit - not enough to fully power RC motor 2. Heavy 3. Has to be removed and opened to replace batteries 4. Wasteful 5. Odd form factor 2. PF - LiPo battery box Advantages: 1. Small form factor 2. Light weight 3. Easy to recharge Disadvantages: 1. 750mA current limit - not enough to fully power RC motor 2. Low capacity 3. Studded design 4. Expensive and hard to find 3. RC control unit Advantages: 1. No current limit - can power 2RC motors at once 2. 3 Power levels 3. Has integrated steering output with 7 positions 4. Good mounting options 5. Easy battery replacement 6. Radio based control Disadvantages: 1. Poor quality, prone to breaking 2. Limited angle (45 degrees) and torque from the steering output 3. Has to be removed and opened to replace batteries 4. Very large form factor 5. Expensive and hard to find 6. Heavy 7. Required dedicated antennas and remote Control options 1. PF receiver and controller Advantages: 1. Receiver is easy to integrate into the model 2. Controllers have physical feedback 3. Cheap and easy to find Disadvantages: 1. IR based, low range, useless outside 2. Lack of PWM motor control, unless using train controller which is awkward to use 3. Odd form factor for use with steering 2. RC control unit See above 3. Third party options such as BuWizz and Sbrick Advantages: 1. Smaller form factors, easy to integrate into model 2. More outputs than PF system 3. Smooth control of motors 4. High range thanks to Bluetooth control 5. Higher power available with BuWizz 6. Customizable profiles Disadvantages: 1. Smart device is required 2. No physical feedback 3. Sbrick is limited by PF battery box 4. Price 8. Chassis Chasis is the backbone of your model which olds everything together. For chassis I suggest you to use the following components in order to make it strong and robust enough to deal with the stresses involved when crawling or driving at high speed: Some flex in the chassis might be a good thing to improve offroad capability, but only if id does not affect the driveline and cause friction on the drive axles. Remeember to use diagonal support, since triangles are the strongest shapes. You can also use panels and motors as structural support. Interlocking your chassis will keep it from slipping apart. For good examples of chassis designs I suggest you check the instructions for 9398 and 42083.
  3. Finally finished a first version of a LEGO RC Car with 2 in-wheel, brushless motors. While I know some of you hate the combination of RC electronics and LEGO, others enjoy these hybrid models (hence this post). If you are more the purist type and in favour of LEGO only, please skip this. If you like stretching the envelope using (RC) electronics please have look and let me hear your thoughts. While searching for brushless in-wheel motors I ran into the ideal product: Turnigy Multistar 4225-610Kv. It mounts easily onto LEGO (same measurements) and fits almost any 56-rim. The result is spectacular. Great speed, no wear-out, all traction goes to the wheels, no gears necessary. Sadly, it turns out this motor is no longer available (working on an alternative). Car also includes an (adjustable) software differential running on an Arduino Nano, works surprisingly well. When fully applied the car has serious oversteer, when turned to 0 the car has understeer. The body of the car is a 54100 modified boat hull . It took some cutting but ended up nicely. Please have a look at the video here:
  4. In an attempt to create an RC LEGO motorbike, I had to figure out a steering method. Moving a weight from left to right was (successfully) done before, but I couldn't find LEGO bikes with counter-steering. Inspired by the videos of many real RC bike lovers, I came up with this LEGO-ish implementation. It's not for LEGO purists, it contains modified parts. But it demonstrates pretty nice how counter-steering works and how it can be implemented on a LEGO bike (using a servo). I therefore thought it might be of interest to some of you. If modifying LEGO parts makes you sick, please skip this video. If you enjoy creating new parts (out of other LEGO parts), great! Let me hear your thoughts. On this matter, I personally start to enjoy the use of custom springs more and more (will do a separate video on this subject) and ... I'd love to make a case for an axle with one ball socket. Together with a (custom) spring, can be used in almost any vehicle for suspension or anything else. Have a look at the video and you'll see what I mean. Was an essential element to create this steering. Enjoy watching, looking forward to hear your comments. https://youtu.be/AZQkJCd0VKg
  5. I guess you could say I couldn't make up my mind about the kind of Unimog I wanted to make next. So I decided to make a platform that would support multiple versions. Features: Interchangeable platform Long and short wheelbase options Standard and Doka cabs, removable Manual control PF control (drop in) Front and rear suspension Steering 4x4 with I-4 fake motor Opening doors and hood Tipper bed options Feel free to check out thirdwigg.com to learn more about the build. Manual SWB with tipper bed. Manual LWB Doka with tipper bed. Power Functions (XL drive, Servo steering) LWB with cover. Manual LWB with canvas bed showing the suspension travel. You can find more pictures on my flickr. I have been adding instructions for the various versions here, and more will be added over the coming weeks. Someday I'll make a camper, because, everyone needs a camper. This was a fun project, and I loved the way it turned out. I have the LWB on my desk right now, and I keep getting distracted from work. I hope to add additional options for the system at some point, and will take other suggestions for versions to add. Hope you enjoy.
  6. Please suport my project on Lego Ideas. https://ideas.lego.com/projects/bc17ae38-b3e7-4cb2-b804-401e0bcc7aef Power functions: 3x L-motor 1x IR Receiver 1x IR Remote Control 1x AAA Battery Box 1x Control Switch 1x Extension Wire Description All openable doors. Model have fake motor V6. Color: Black and Yellow Number of Pieces: 800-100 Thank you very much for your support! Military version: Hägglunds BV 206s
  7. Always wanted steering in the Caterham Ideas set, so yesterday i did it. It if fully connected to the steering wheel. Fenders do steer as well, but they sit a bit high at the moment Wheels are temporary and will be replaced with the new 49.5x14 soon. Also the dashboard, nose and trunk lid are now more securely attached. Video -> -> https://imgur.com/M38hvCU
  8. Finished 01.01.2021 A couple of years ago I started a modular Unimog project with the hopes of having a build that would be flexible enough to support a number of different versions and options. It certainly was. However, the Unimog 437 project was intended to provide a U500 cab option, but for a couple of reasons (namely those tires), it was not a great fit for the project. So in the back of my mind I figured I would do a proper U500 version at some point. The 437 was pretty popular, and it fits within my current design language; mid-sized, manual, truck/car, feature packed. Then when I saw the first reviews of the 76139 Batmobile set, and saw the new 68.7mm tires, and I knew it was time to resurrect the project. I would keep the scale at 1:17.6 as I did with the 437, and those tires would equate roughly to a 445//65/R22.5. Off to the races! I am partial to the 1st generation (2000-2013) U500, plus @I_Igor did a great 423 series already (Eurobricks). Also, I like the 500 more than the 300 or 400. The 300 looks tiny, and the 500 SWB gives me two extra studs on the wheelbase (24st) over the 400 (22st). I guess if I have enough space I'll switch to a 400, but I (generally) never need less space. I pulled a PDF for the scaling, and I started to set my build parameters. I build my MOCs by making a first draft with all the constraints: wheelbase, length, height, width, and general bodywork ideas. I try to keep the colors correct, but if the part is not in front of me, I move on to replace later. Then I start working in features, and rebuild as needed. The first draft came together pretty quickly. While I managed to buy the first tires available on Bricklink, I was not willing to wait for their arrival before I started building. At this point, I determined the features of the truck: Front and Rear Live Axle Suspension (sans portal axles) (With dual leading/trailing links and Panhard rods) Front Steering Fake Motor Tipper Bed Tipping Cab Front PTO Rear PTO Rear Bodywork PTO Front Mounting Plate Modular Rear Bed Attachment Points Realistic Bodywork The tires arrived in time for the second night of building, and they look perfect. By now, all the functions were in place. Loosely. Below you can see the general Front Mounting Plate, and the front PTO. Currently in front of the bed is a Gear that will power features on a mounted body (al la TC9 Entry) Below you can see the rear bed system. I have found this three way tipper option to work great on my 437 and the MAN TGS truck. The control input is currently on the left side, but it will need to move. The orientation of the lift is backwards, which does not allow for good tilting leverage. Turning the mechanism around will need to move the input to the rear. This compounds the issue with the rear PTO. It is currently in place just above the hitch, but will need to move when the tipper input is placed in the rear. Few U500s have a rear PTO, so I'll have to decide if this is a feature I want to retain. More to follow... Until the next post, hope you enjoy the next Thirdwigg Motors project.
  9. 10220 is my favorite Lego model of all time (yes - it wins with every Technic set ;) ) - but it definitely needs some love to be something more than just a beautiful sculpture. I would like to add suspension and steering - but I do not have any bulletproof solution for such a small space (picture of bare "base" - http://3.bp.blogspot.com/-c2sdXPLjFxw/TpfWQGZQUmI/AAAAAAAACO8/ARmir6mTTow/s1600/H88-Lego-10220-T1-Chassis.jpg - thanks to The Car Blog) Has anyone ever made a Lego car in similar space with working suspension? I need some inspiration :)
  10. This is a type of steering for a tracked vehicle that uses so-called subtractor which means input from motor used for steering is subtracted from the main drive input
  11. Hi all, I'm experimenting with a 6x6 chassis design (3 motors, one powering each axle independently) and I want it to have steering on two axles. Not an engineer but I've Googled a lot of 6x6 designs, but it's not clear to me which arrangement provides a tighter turn radius - front/rear or front/ middle. The front/middle seems most common in military designs (like the Stalwart). But I find my prototype turns pretty well.
  12. Hello everyone! This time the challenge was to create a steering mechanism with suspension as small and compact as possible. Together with some other techniques and the usage of a technic chassis, this humvee was born! And i will share the concept of the mechanism: More photos https://www.flickr.com/photos/27805688@N05/ If anyone wants, ill upload an LDD file later.
  13. About two black ages ago I came up with a mechanism to add steering to very small models, and I worked on two models based on it. I have never been able to finish them to my satisfaction, and I'm realizing the current black age I'm in will probably last until retirement, or at least until I get a bigger living space, so I'm posting what I have now. I should probably have posted about the mechanisms years ago, but I wanted to have some neat models to show off with it too so I never did. Last time I searched around the web for anyone else who had shown the mechanism off I didn't find anything, so I don't think it's a well known thing. Here's an album with pictures it this post: https://imgur.com/a/ixZOK0s Overview of the two mechanisms. Vertical and horizontal variants of the small mechanism on the left and bigger one on the right: Small mechanism with vertical axle: Same mechanism with horizontal axle: Here's the bigger mechanism with vertical axle: Here's a WIP wheeled excavator based on the smaller mechanism. The bottom right picture is another control scheme I was exploring. I'm mostly satisfied with the model, it's only the arm and bucket I don't like. Here's a bigger WIP model. This one uses very tightly packed pneumatics. It's missing the cab and arm, but I'm otherwise pretty happy with what I've got. I was never satisfied with the arms I managed to build. They were either too bulky or too fragile. This model feels very nice to roll around on the desk, it has some a weight and grounding that the smaller one lacks, and the turning is pretty satisfying too, even though it can't exactly turn on a dime. Lastly, here's a half scale model of the 8049. Lacking fenders, seat, lights and the trailer. I would like to get the two excavators finished one day so I can have them hanging out under my monitor, but my hobbies have shifted to electronics and plants, and I'm lacking in desk space anyway. Maybe one day though :-) Hopefully these mechanisms can help you in your builds! As a bonus, here's my collection of all technic excavators, except for the Liebherr, which I'm hoping to find used for cheap. Note the blue excavator from the 8888 idea book! If imgur decides to stop hosting the pictures, contact me on BL where I have the same username and I'll get them hosted somewhere else.
  14. Well overdue for a Delorean MOC, to make it stick out from the bunch I've packed some Technic into it as with all my builds. Full independant suspention with working steering. The Doors open up the steering wheel works, all the fun stuff. There is about 1 beam width of suspention travel And a engine under the cover. 33% bigger than the real one, It might make it to 88mph now. I'm quite proud of the front end, It's probably one of the most complex ive made. I remeber seeing the concept of a virtual Pivot steering,Sariel's I belive, and though it could be expanded on to include suspention, just never got around to trying it. So thanks Sariel. Underside Steering and suspention there is a chanel on the underside runing the entire length of the car that would be perfect for a HOG steering shaft to come out under the rear bumper, I just can't figure out a way to connect it up to the steering gears without fauling the mechanism. If you have an idea on how to, I'd love to hear it. I've now realised the poster is missing part of the car, The rear wheel should be between Marty's legs By some amazing stroke of luck all of it can be build in LDD, just need to connect one 5beam to the 1.5 pin in the steering and to bend the hood down ~2degrees
  15. Hello everyone, I have built a model of one of Britains classic race cars, the Bentley 4.5l ‘Blower’, a project that was never actually approved by W.O Bentley (company founder) but nonetheless took part in the 1930 Le Mans 24hr race and French Grand Prix where it finished second behind a much more agile Bugatti type 35. Its claim to fame was not through racing victory but through its racing stories. The model has working ‘worm and wheel’ steering and a removable bonnet to expose the 4.5 litre, 4-cylinder supercharged engine. Accuracy and realism was key right from the chassis frame and the parts were spray painted to give two new green colours. For more info and images please Click here to take a look at the project on Lego Ideas. Many thanks...
  16. One of the questions that pops up here on a fairly regular basis concerns the maximum distance between axles without binding or derailment becoming an issue. On a couple of occasions I have mentioned the Castering Effect and it's possible application to the LEGO railway world. Having raised the possibility I thought I should find out for myself what use it might be and to see whether I could harness this effect and see what it might be made to do. And so I set about building myself some prototype vehicles and a test track and got to work. This is the test vehicle I designed. It's a bit of a "parts bin special" but it does the trick. In the light of the lessons learned the test vehicle design was changed slightly and then retested. There is still much more work to be done with more prototypes and testing, but I'm hoping to come out with some sort of working MOC at the end of this process. I appreciate that there is rarely anything new under the sun and that I'm probably just replicating someone else's work. Comments welcomed as always. **EDIT** By the way, those black boxes are video links.
  17. Hi All! Often a "reader", now a "poster", i´ve got a problem i cant fully wrap my head around. I try to keep a steering axle straight while going through a pivoting point or turntable. The axle should rotate with the pivot (eg in the picture below the yellow bricks should always align with the grey liftarms even if the liftarms are at 90 degrees of each other) but i want to rotate it manually on one side, with the rotation + offset of the pivot on the other side. Like the axle itself would have been twisted. The furthest ive got with this is pictured below and works as long there is no friction on the left output. I want both sides to rotate at the same time, but if you rotate the pivot/turntable then it should add just an offset "within" the axle. I dont know if this is actually possible or how to split the axle in two, add the pivot rotation to one part and then add both rotation together.
  18. I think anyone who ever used the portal hubs came to this issue. The hubs simply have the steering pivot point so far from the center of the wheel, that you need to either reduce the steering angle, or have a model with large fenders. Today I came up with this simple mechanism to compensate for that by simply turning the whole front axle in the opposite direction. The two tilted 6L links are usually used to keep the axle from moving forwards/backwards. In my case they are attached to the steering rack at a high angle. Moving the steering rack will cause the geometry of the axle to change - rotating it to (mostly) compensate for the large pivot point: Of course this is just an idea for now, but it should be easy to implement on a real model. The wider the axle, the better the compensation. Of course the axle has to be designed in such way, that suspension, drive and steering system will be able to work with this degree of movement.
  19. Dear folks, Don't know if this forum is in need of 'yet another AWD front steering', but decided to post it anyway since it may have some interesting features to share: - Compact 5 stud high modular design - Strong, double suspension per arm - Embedded cross block, to prevent bending axles - Adjustable steering arms to enable toe-in and toe-out (and as a side effect, prevents damage when crashing) - Ready for (2.4 GHz RC) servo steering ;) I needed a flat front module to fit my chassis, but didn't want to use the 'old' 3 stud high Wheel Hub (50301). It simply has too much friction in the turns and breaks too easily. Furthermore I wanted to use the universal joint (61903) in stead of the cardan cup (92906). Since I'm putting significant torque on these joints, and it turns out the universal joint is much stronger. However, this does requires the wheel arms to pivot 1 stud wider than using the standard config. Using the 5 stud high 11949 front wheel bearing and bound to a maximum height, I needed a way to fit suspension within this height. Very happy with the result. Anyway, have a look if you're interested. Happy to hear if anything can be improved. https://www.flickr.com/photos/153697698@N03/sets/72157695812709340
  20. I have been working on this project for what seems like forever. I'm happy to have it done. The full gallery can be found here. Much more at thirdwigg.com. Full Lift With TLG Balloon Tires Chassis
  21. Hi, I'm getting the parts together for the Avtoros Shaman 8x8 MOC https://rebrickable.com/mocs/MOC-5360/Madoca1977/avtoros-shaman-8x8/#info It requires 8 of the 11949 Technic, Steering Wheel Hub Holder with 2 Pin Holes and 2 Ball Joint Arms. https://www.bricklink.com/v2/catalog/catalogitem.page?P=11949#T=P&C=86 The current price of these on BrickLink is around €12 each, and has risen sharply in the past few months. I was wondering if it would be possible to use the 23801 Technic, Steering Wheel Hub Holder with 2 Pin Holes and 2 Axle Holes and two Axle Towballs. It looks like it would work based on the models in LDD. Has anyone tried this on a model? Here is an example of how they are used in the Shaman build:
  22. This is ASSAULT3R, a Lego Mindstorms EV3 Assault Vehicle. After getting a second Lego EV3 set, I knew that I had to build something awesome. Features RWD and Steering Ultrasonic Sensor Infrared Sensor Two Color Sensors Dual Ball Shooters Gullwing Doors Detailed Interior and Exterior The ASSAULT3R's front sports red lights that will strike fear in enemies and their machines. Its dual ball shooters will shoot a total of six Lego balls, three for each side, high or low. That's twice the weaponry used by EV3RSTORM. The gullwing doors allow easy access for operators and it makes the ASSAULT3R look futuristic yet sinister. I had a lot of fun building this, and I'm very happy with the result. And of course, here are some photos as always.
  23. Hi folks, This is not for purists. Contains modified and non-LEGO parts. My urge to build a super fast LEGO RC Car often stopped at the stage where the body needed to be build. Seeing all the great designs on forums like this, it somewhat discouraged me building my own. Besides the fact that these bodies come with some weight and will not hold a crash a higher speeds, I had to come up with something else. As a result of an earlier project (building a fast LEGO boat) a had some damaged LEGO Hulls (54779). Since a car body works basically the same as boat hull (but 180 degrees rotated), I thought I'd give it a try. Have a look at the result in the YT video. It works fine. Gives strength to the car, the aerodynamics work well for good driving stability and it is not that ugly :) Called it The LBOW (Lego Boat On Wheels). Included standard RC components: ESC, brushless motor, 3s Lipo battery, digital steering servo and .... a Gyro. Resulted in a very fast RC Car. Theoretically this should be able to reach 100 km/h. Speed test will follow (need to find a good track first). For those trying to do similar things, I'd strongly recommend to add the Gyroscope to your car. It prevents the car from breaking out at higher speeds. Very useful.
  24. So most everyone i've seen likes to add drive to their front axles. I'm having trouble building a dead front axle for my truck. I'm no good at steering geometry either. Here's what i've come up with so far. Right now it works for what it is, but could use improvement. If anyone has any ideas or links, please share. I'll try to add some pics.
  25. Camellia Café presents a special designed SERVO JEEP model being controlled by Camellia Café Servo motor controller with ARM technology. ' This JEEP is a Full time or Part time four wheel drive car with shrink function and Servo running model. Front wheels and rear wheels are driven by two individual LEGO motors. When both motors are active, it is a full time four wheel drive car. When either is active, it is a part time four wheel drive car. The speed can be adjusted in a large range and with good accuracy via our motor controller. With an addition motor, the car body is able to shrink for easy parking, and extend to get spacious inner space. When using a mobile phone and Camellia JEEP APP, your children could control SERVO JEEP remotely. No matter turning, running back or running uphill, SERVO JEEP is mobile and powerful. In the SERVO mode, SERVO JEEP can run in a precise distance at a preset value. This plays a key role in autopilot and auto parking. The steering motor can be controlled with 5 degrees at minimum. Front differential and rear differential are used. Front wheels driven motor and rear wheels driven motor. Front wheels use double wishbone suspension. Steering system With an addition motor, the car body is able to shrink for easy parking, and extend to get spacious inner space. 40th LEGO Technic nameplate. Without car cover cloth. The car body cover. Open the front cover to see the front engine. Front engine - 6 cylinders V type. Rear engine - 2 cylinders V type. Rear of JEEP. Car lights: Daytime running light, Foglight, High beam and Red lights for break. Please enjoy Camellia Café servo motor controller and drive SERVO JEEP model. And make you own car at home. http://www.camellia.xin/models/servojeep.html