2GodBDGlory

Well, electronics are ok, but I think he elsewhere said that no third party stuff was allowed. Either way, though, do go ahead with the model!

Looks like a fun little model! You mentioned that you wanted to use a CADA battery box, and while it's hard to tell, I think you've got CADA micromotors in there as well. Overall that should allow it to be very nice and compact, but I'd recommend that you get more confirmation from Jim that those are ok to use. I saw that you asked a couple times in the discussion thread, but never got an official answer as far as I can tell. I think it would be pretty cool if that stuff were allowed, but I would personally assume that they're not, especially since TLG supplies the prizes. Just thinking you might want to make sure about that before you put too much more effort in, though even if it would turn out to be ineligible, it'd still be a nice MOC.

Yeah, it definitely is hard. That dumper looks pretty nice too! I really like the way you integrated the portal axle housings with the bevel gear brackets, and the rotation of the bed is really neat too. Is that what you mean by the "vat"? I wouldn't call it that myself; I'd probably just call it a bed, or a dump bed, but maybe vat is a technical term I'm unaware of.

Congratulations on putting an automatic gearbox in there! It's such an interesting concept, and this design is actually pretty practical, but so seldom used! The rest of it looks thoughtfully engineered as well.

Yeah, I think the size of the boom is somewhat overkill, and will cause the model to be very cramped in other areas, but I think I can get it all to fit in the limit. It kind of doesn't feel like I'm building a mini vehicle, though, it feels more like a full-size model in a smaller space.

I've seen these on the side of the road, but never really figured out how they work, so I'll look forward to seeing your version!

So, for this update I've added the rest of the functional parts of the superstructure (A cab and paneling can come later), as well as the connection to the chassis, and the manual control gearing for the winch, rotation, boom lifting, and boom extension have been added. Here is the "hook." Because of a rather inefficient cable system, considerable weight was needed to keep it pulled all the way down. I started off with a simpler setup using just the magnets, which I figured would add weight without taking much space, and would give me a cool, unique way to operate it, by picking up metal things. That wasn't heavy enough, though, so I had to work in a weight brick, but I kept the magnets because while I may not need them for weight anymore, I still thought they were a fun idea. Here is the bottom view of the carrier part under the superstructure. The middle rear knob runs boom lift and extension through the gearbox, while the left and right ones control superstructure slewing and the winch. Here is the boom raised. The linear actuator positioning was a bit odd, but I didn't think I could route drive to have rear-mounted actuators like on most mobile crane models I've seen. This seems to work fine, though. Note the boom mounted on small turntables, and the winch in the middle. I would have liked to do a more typical winch, but space was super tight--the boom rests directly on top of the spool. The small spool seems to be working fine, though, because I'm using compact dental floss instead of regular string that would fill the spool too fast. This works nicely, especially since I don't have any normal string long enough anyways. I also got in the function I think most interesting, the two-output distribution gearbox with both outputs above the turntable, and the shifting control below it. Occasionally I'm getting skipping from one of my bevel-gear connections when trying to extend the boom, but overall everything is working pretty well, so I'll be able to venture into some other stuff on the chassis for my next update.

Is the universal joint going into the actuator working well at that extreme angle?

Yeah, I've got two weight bricks, and I'm hoping to put them in. I'm sure they'll help, but unsure if it'll be enough.

I don't think fitting it will be too hard, though I'll have to watch the height limit. It is more or less in scale, so the other stuff will hopefully work out, but I think the biggest problem is going to be stability.

I like the thinking there! I don't know if you have any old 14T gears, but I think those run more smoothly with the 20T single bevel gears.

So, for this contest I decided I would build a Mobile Crane of some sort, because it has similarities to the boxy cars I'm used to building, and also has a fairly convenient shape for the volume constraints. At first I thought I would be building a fairly standard crane, probably with six wheels. I planned on using Corvette wheels, but since I only have four of them, I thought I might have to do something weird, like put Model Team wheels on one of the sides. As I looked for inspiration, though, I found a compact-looking mobile crane with only four wheels, which fit my supplies better, so I decided to take inspiration from the Liebherr LTM 1040-2.1 The planned features are: Two-stage extending boom Lifting boom Winch Outrigger extension Outrigger lowering 4-wheel steering Superstructure rotation and possibly if I have room: 4WD and a micro I-6 piston engine Live axle suspension Another design goal is to have all the controls manually operated from the chassis--I would like to have all the controls for similar functions in a similar location, and I feel like having controls on the superstructure will result in the boom swaying around as the control knobs are twisted. However, I've got three functions in the superstructure, and we all know how impractical it is to get three functions through one, so I thought of an unusual idea that might help here. It would essentially be a distribution gearbox placed inside of the turntable, switching between functions in the upper half, but with the switch being controlled from the bottom. The plan is to base it off of the 24/16T differential. The 16T side will constantly be driven from the bottom, but with provision to allow the differential carrier to slide up and down a stud. The 24T side, though, will engage different gears depending on whether the carrier is in the upper or lower position, causing it to operate different functions. We'll see how that turns out... I started by developing a design for a two-stage boom based on the gear rack housing parts: I really liked the design--stuff just fit nicely, and the grooves on the insides of the panels were perfect to help locate the red part as it extended. However, as I began to look at scaling the crane, I realized that in order to build the largest possible crane that would be within the rules, I'd be using 56mm balloon tires, and that if I did that, I'd need to have a far, far bigger boom. This crane seems to have a disproportionately large boom! My planned dimensions for the crane are 13 studs wide, 16 studs tall, and 48 studs long, and my boom is currently sitting at exactly 48! Boom contracted The boom is extended by that 3L worm gear driving a set of 4L racks It is driven through these gears. I'll have to put some kind of pivot in still. It extends really tall! This is the how the middle segment is constructed And this gives a glimpse of the pulley system needed to extend the smallest segment. So far, I really like the boom, but I think the outriggers are going to have a really hard job keeping the crane upright with such a huge boom on such a small carrier! Next I'll probably work on figuring out the details of the rest of the superstructure.

That's the maximum; I believe Jim jokingly said in the general contest topic that the minimum was 1 cubic stud...

Cool! That's a nice way to make the bare chassis you need for high performance have some interest, and retro appeal.

Ok, thanks for doing the math for me! Sounds like that model just has some protrusions that drive up the volume without making it look much bigger.

Well, in my testing with the differential, the 8T would kind of mesh, but it would have to be pushed back farther than the half stud it should theoretically be, which would make bracing it hard and likely cause it to skip because it wouldn't engage fully. Another idea could be to use the idea I put above, but instead of using the 28T gear, use a 16T gear and a chain to drive the 24T side of the differential. That would leave the firewall intact, but would end up giving you less total gear reduction. (If you happen to have the new non-beveled 20T gear it would help, but I don't think many people do yet)

How did you come to that number? I'm planning a somewhat similar crane with sightly larger tires, and getting just under the limit. I'd be curious to see which dimensions yours exceeds mine in, to check that my numbers make sense.

Hmm, I'd recommend checking if that 8T will actually mesh with the 16T on the differential correctly. The new style of 8T gear won't really work, because of the extra bumps on the side, and the old style still can't mesh completely. Maybe you can get something to work, but I'm a bit worried about that solution. Here's an alternate option, with a few different gearing options. I've got an 8T gear behind the 28T one, but you could go 20:12 or 16:16 there if you wanted. The only issues I can see are that it might be difficult to brace well, and you may not quite have room to fit the 28T gear without infringing on firewall space.

Thanks for linking that article! I'm glad to hear that new parts should hopefully be available without an excessively long wait.

Personally, I think Bricklink is a much better option for buying used sets, and sets that were generally unpopular (so not being collected) can be had very cheap at times, while still containing good parts. Maybe Ebay makes more sense for Americans, though; most sellers seem to charge an awful lot to ship it up to Canada.

The ideal solution would be to use a 36T gear as the driver, because it's very close to being the right size to mesh with the 16T size in that combination. You'll have two problems with that, though. First, it'll make a hole in your firewall, but it looks like it wouldn't be too hard to remove the vertical 5L beam in it, and at least the gear is generally black, so it wouldn't stand out too much. Second, because of its double-bevel profile, it doesn't mesh properly with that side of the differential, though if you can find a way to offset it by somewhere between 1/4 and 1/2 studs it should work. Another issue with the current setup is that you don't have any great ways to brace that side of the differential, since its right next to the CV joint. Moving it back a little would be great, but then I think the 24T side would interfere with the motor, and the firewall would require a more extensive rebuild to fit the 36T gear. Sadly, nothing is looking simple about the process...

This should be cool to see! I don't recall ever seeing this kind of thing built with Technic, which makes it a fair bit cooler.

Has that been done in past contests? I'd be curious to read up more on how it works.

Cool to see a new contest starting! I've got one question about the rules, though. You state that the goal is to: But what do you mean by "Try to make it as official as possible"? Does that mean that we should try to make our entries in a similar style to an official set?

The way I learned what skills I have was from both checking out MOCs online and reading books, but largely just trial and error. I was always pretty ambitious and tried to put too many functions that I didn't know how to build, into a MOC, but I built fast, then ripped it apart and started over. Maybe this wasn't the best way, but for me, doing a lot of building without wasting time worrying about the finished product, collecting parts, or what other people thought. I didn't get any good models out of this, but I got a lot of practice in a short time, allowing me to be able to build stuff that might be worth keeping (If I was willing to spend money to free up parts from my collection!)