Splat

I would like to present my motorized and remote controlled (IR) version of this year's Monster Truck set (42005). My first goal was to keep the overall look and dimensions the same as the official model: The wheels, chassis and body are in the same positions, Only the axles, inner workings, and battery box have changed. My second goal was to somehow get the vehicle to have both steering and 4WD: As you can see above, I achieved the steering by making the entire front and rear axles turn via the use of gear racks and 6L links, while the drive goes through the ball joints, differentials, and portal hubs. Steering is handled by a PF Servo Motor, while drive is handled by a PF L motor. It is powered by a PF Rechargeable Battery, and a PF IR Receiver V2. My third goal was to increase the vehicles clearance as much as possible: And my last goal was to maintain a good amount of articulation: I had to modify the suspension attachment to allow an extra degree of movement to allow the suspension to operate smoothly. It runs quite well over small obstacles, however it is very top-heavy, so it does roll over quite easily. This isn't helped by the fact that as it turns, it leans outwards (opposite to how a skateboard works). Here are the parts (guts) that I had to remove from the original model: All pictures can be clicked on for larger versions at Brickshelf (once moderated). Here are some more pics: And last but not least, here is a link to the LDraw file: 42005_motorized_monster_truck.mpd Overall I am pleased that I was able to get this motorized given that there was only a small space to work with, and the model is very sturdy. I hope you like my motorized and RC 42005 Monster Truck. Any and all feedback/constructive criticism welcome. Edit: I have submitted this MOC to Rebrickable. Edit: I have created a quick video: Sorry about the audio quality - it was a very windy day!

Nice work again Sheepo I have to agree that the wheels do look just a little bit small at this scale though.

Nice work! The track ended up looking great, and it looks like everyone involved had a great time. I think anytime that there is something interactive at a Lego expo, it is going to drew quite a big crowd and keep the kids (and you) busy. I visited BrickWorld Indy earlier this year, where they also had a crawler track set up, however they had theirs at ground level so it was a bit hard to see with the crowd surrounding them. You can see some of the track in this video, but I like your track better. Congrats!

A similar design has already been shown on this forum by Zblj here. It is still an interesting design though, and nice and compact.

This looks great. Nice work I like that you have used the battery box as a counter-weight, and the way you have reinforced the wheel attachment (seen in the bottom pic). The only concern that I have is that the axles that drive the LAs also act as the pivot points for the bucket arms. If there was a lot of weight in the bucket, there would be a lot of sideways pressure on the axles, causing a lot of friction and possibly causing the drive-train to stall. However, it looks like it is working fine with the small amount of weight (pins) that you have in the bucket.

I've started making parts of a course too, but trying to make it out of Lego as much as possible (I have quite a few Technic frames 64179 and 64178, but probably still not enough). How about some more dynamic features so that timing becomes important: rolling road made out of tank treads going to opposite way, so your crawler has to be fast enough to pass wrecking balls (made out of something soft) so that you have to get your crawler out of the way before it gets hit sections of road that move up and down, such as ramps, or even just flat sections that move up and down a seesaw that you have to drive up and over - perhaps dampened with some of these 32181c02 a rotating platform, where you have to get onto it quick enough, but also get off it at the right time to make it to the next part of the track For something more static, how about a section where one side (left or right) goes up a ramp, but the other stays flat, to test how far over the crawler can go sideways before tipping over.

Hi Piterx, thanks for the LDraw file - I've saved this away so that I can build this model when I have access to my Lego pieces again (currently working overseas). Just some tips for MLCad: The colour number for Light Bluish Grey is 71, and Dark Bluish Grey is 72 - this will make your greys look a little bit more consistent. The use of 'Multiparts' can make it easier to get things lined up nicely, especially when they are on weird angles. It is sort of like grouping, but I find it a lot easier to work with as it means that you work with smaller sub-models and keep things in the sub-model 'square', and can then align the entire sub-model within the main model. When you save a file with multiparts, it will be an MPD file instead of an LDR file. Great work so far

I also saw 'Rubber Attachment for Track Element Parts' available on the US Lego Education site recently. That site seems to be having issues right now, but they came in a pack of 30 and cost US$20 + tax + shipping. Once the site is back up, go to www.legoeducation.us/eng/categories/products/middle-school/lego-mindstorms-education-ev3 (scroll down and click View All)

If you want to see all the different prices around the world (from Lego S@H), TechnicBricks has table showing them all here. I just ordered my copy of 41999 from US Lego S@H, as well as a few other small sets that are hard to find in shops.

Can I reuse my entry from last year...?

This YouTube video also does a great job of explaining how a differential works. It is in B&W, and might appear old, but the principles still apply:

Great work piterx The Polaris looks great at this scale. I like the rear suspension, and all the angles that you have incorporated into the body work. I also like that you played with different colour schemes.

I'm liking this MOC a lot. Nice work

@Error404 - thank you for your clarification. I did understand your original intention, I was just adding to it with other possibilities. Either way would be great - having a little bit more community involvement. If someone creates a really great B-Model, they might even be offered a job to work at Lego.

That could work, but it means that you need to allow room for the gear rack to move back and forward. One of my goals was to keep the gearbox as strong as possible, but also as compact as possible. Using a set of worm gears allows the gearbox to be more compact.

To get the full range of gears for the gearbox that Someonenamedjon reworked, the selector needs to travel 6 studs. Mini LA's only have an extension of 3 studs: The larger LA's have an extension of 5 studs: So neither the Mini LA or standard LA have enough travel, unless you start to play around with levers or some other mechanism, which starts to make things bigger and more complex, and introduce more play in the system. As mentioned above, this gearbox was considered a failure for my needs, but Someonenamedjon has been able to rework it to make it stronger and perform better The final solution that I came up with and am happy with is still this one, which does use a linear actuator:

Thank you for this video - I think you did a great job of explaining the functions, and I especially like that you showed the steering mechanism as a separate model so that we could see how it works. :-D PS. I left this same comment on your YouTube video page.

I think that if instructions were available, this would make me buy another copy of this set. Great job with the colours, and the entire design overall. I also like Error404's idea of having a competition to make a B-Model out of a specific set of parts. If we didn't know what the A-Model was yet, it'd be interesting to see if anyone would design something close to the A-Model. Perhaps all the pieces for the A-Model could be found in a larger set from the previous year, or a combination of 2 smaller sets from the previous year, so that everyone could get the parts easily. It'd also be great to have the top 5 (?) B-Models displayed on the back of the box as 'possibilities', like some of the older Lego boxes. Even if no instructions were provided, this would still be pretty cool.

Thanks Doc_Brown Hi Someonenamedjon, I'm glad you could take this gearbox idea and make it work for you I'm not sure about the worm gears fitting between those two beams though

Great work

I created that gearbox/video, and legomuppet9 is correct, it can't handle much torque the way that it is currently set up. I mention in the video description that "there is a little bit too much play in the sliding mechanism, and this causes the gears to jump and grind when the outputs are under load." This might be able to be fixed with different geometry in the sliding mechanism, but I haven't tried. Also, that video was used to demonstrate one of my gearbox "failures" in my attempt to create a robust 3-speed + 1 PTO gearbox, which you can see in this post.

I was also pleasantly surprised by 8109. While 7471 is actually part of the Discovery theme, I still consider it a Technic set. It also features those damped shock absorbers that allow the solar panels to open up, and the sensor mast to pop up. It also had an interesting way of moving the arm at the front in two stages. You can see it in action in this YouTube video by 'fishcontrol'.

Great work Sheepo I really like the steering geometry at the front, and everything else too.

Let's assume that the XL motor spins at 146rpm at 9v (http://www.philohome...s/motorcomp.htm). For the rear wheels, you can ignore the idler gear, and you get 146rpm / 20 * 24 = 175.2rpm (but I don't know how you are getting the 12 tooth bevel to mate with a 24 tooth 2nd gen diff using a 1x5 liftarm...?) For the front wheels, without any extra gearing, you have 146rpm / 20 * 28 = 204.4rpm. Assuming that you have the same size wheels, you need to get 204.4prm back down to 175.2rpm. 175.2 / 204.4 = 0.857 The closest single gear pairing to this is 24 tooth and 28 tooth, but it is difficult to get a 28 tooth gear. You can use another 1st or 3rd gen diff, but then why use the 2nd gen diff at all? You could also use a mini turn-table, but that introduces quite a bit of friction. The next closest is the 20 tooth and 24 tooth, which gives you a reduction of 0.833, so the front wheels would spin at about 170.3prm. If you use a different motor on the front wheels, just find the speed that they run on Philo's page, and then substitute the values accordingly. But... why do you have to use two different types of differentials? Is this a limitation on the number of parts that you have available?

The only proportional switch with PF is the speed adjustment that is on the rechargeable battery box (8878). You could use a servo motor powered from one battery box to turn the speed adjustment on the other rechargeable battery box, and the rechargeable battery box provides power to the XL motors. You are still limited by the 2 XL motors per battery box, so now you need 3 battery boxes - one for the IR receiver and servo motor, one for the first 2 XL motors, and one for the second 2 XL motors. If you are using the proportional remote (train remote - 8879), then there is a chance that the speeds could get out of sync, even if both receivers are placed right next to each other. If you are using the 'bang bang' remote (8885), then there is a better chance that they will stay in sync as they sync up again each time you let go of the remote controls - at least that is what I am hoping for in a MOC that I am working on at the moment.