howitzer

Same here. My entry is still well in progress but I really hope to get it into at least mostly functional and presentable form, though the time is running short...

Swappable attachments for an excavator would be a very welcome function upgrade, as practically every real construction excavator has this feature and no Lego excavator has yet demonstrated it.

Haven't updated for a while but there's been some progress nevertheless. I've tinkered with the transmission line from motors to the gearbox and from there to the lead screw. I built a mockup of the downgearing needed to drive the gearbox, which I simplified by ditching half of the speeds and added a direction switch. The previous design had a high friction connection which is bad because there's a lots of gears and thus lots of friction already. Beside tinkering with the gears I've been attempting to build the chuck. This has been quite a challenge with the requirements of having three jaws and self-centering clamping. My solution is to drive the jaws with a worm gear+rack gear combo which in turn is driven by a ring of banana gears (yellow) sandwiched between more banana gears (black). There's quite a bit of friction but at least in principle it works. There's also some slack which requires idler gears to keep the ring gear in place so it connects properly with the gears which drive the jaws. I also built a stand to raise the thing higher, though it's not yet connected in any way and just sits on the stand. Here's a photo: (Sorry about the mess, I couldn't be arsed to clean the table for photos as I'm going to continue building anyway.)

I missed this when originally posted, but it's obviously quite an ambitious project. I hope you'll get something out of it even if it doesn't work out for the contest. In the meantime, this might give some inspiration:

Wow, there's a dark mode! I didn't even notice before you pointed it out, this is great! Other than that, I guess it'll take a while to adjust to the new theme but there doesn't seem to be any serious problems with it for me at least. The forum appears to be much faster than before the update which is also good.

Another update: I realised that having the spindle driven by both, variable speed motor (using 9V train controller) and multi-speed gearbox is a bit unrealistic, so I decided to drive the spindle straight from the motors with appropriate downgearing. On the other hand, the thread cutting feed requires a gearbox with several speeds so I decided to reuse the gearbox I had already built. The lead screw would also require a significant downgearing relative to the spindle and for friction reasons I decided that the downgearing must happen before power is fed to the gearbox (and from there to the lead screw) so I built a distribution gearbox on top of the spindle. There's also a half-stud offset with the ring gear that's coupled to the spindle and that require some half-stud magic to get everything properly aligned with the distribution gearbox. The bearing frame and various gears also impose some serious restrictions on building so the frame of the distribution gearbox is a dense mess of connectors but it feels strong and secure. Here's a couple of photos: Here's also a computer render of the distribution gearbox design to show the gearing (note that the 16T gear that drives the 40T gear is missing from the photos above):

A quick video to see if there's any obvious problem with the drivetrain. Apparently it works at least with slow speeds even with the current quite wobbly support structure. I'm powering it with the 9V train power supply which I intend to integrate into the build.

A little bit of progress. I built the gearbox (8 speeds for now, I'm thinking of adding a hi/low selector to double the speeds but we'll see) and positioned it so that it can connect to the spindle. The black banana gears are where the connection happens and they're driven by a pair of 20T gears. I wanted to use 32T gears as that would be more efficient but there's no space between the banana gears and the spindle shaft. The gear shifters are the two DBG 24T gears at the top left, which I'll eventually route to proper shifting knobs somewhere in the front of the machine. The whole thing is still very wobbly due to the lack of supporting structure and I don't dare to try running it motorized but turning by hand it works fine. Next I'll get the support up and attach the motors and then we'll see how it works.

The limit of 32L axle indeed is the reason why I opted not to even try it with the old worm gears. It's true also that you could have the worm gear in the carriage and pair it with stationary rack gears but not being realistic I didn't consider it either. Yeah, the spacing is 2L. I haven't yet built a solid support structure for the bearings so I haven't tested them properly but we'll see when the project goes forward.

I have had the idea of a metal lathe bubbling in my mind for a long time, and this is the perfect contest to make it reality. Originally I thought it impossible to do properly as there was no way to make long enough screw for the feed but that changed with the release of 73763 with which can arbitrarily long screws be made. Another significant problem was the need for a suitable main bearing which can take the weight of the spindle and has a large enough hole through for the bore. This was enabled by the hoop parts 3250 and 77107 along with the steel ball 99948. I tried GBC balls but as expected, the rolling was very rough and not what I wanted for this kind of thing. While I'm not attempting to replicate any real product exactly, I'm showing here the lathe I bought years ago to give the general idea of what I'm aiming to make: I intend to replicate most of the important functions such as: Variable speed for the spindle Centering chuck (not sure yet if three or four jaws but we'll see) Manual and automatic feed, manual cross feed and manual top feed Thread cutting with automatic feed Tailstock It's a big project though and I have limited time available for building so there's no telling how many functions I'm able to build, but I hope to get it to some degree of completion. So as the first part of my project I set out to make the main bearing from the aforementioned parts which is shown here: Few more photos at https://imgur.com/a/RwcEqqJ Wish me luck!

It was released back in 1981 to be compatible with 4262 and other similar parts, which have thickness of a normal plate. 3/4 pin only came in 1996 to help connecting liftarms of half-stud thickness to full-thickness pinholes.

It would suck if there won't be any backward compatibility at all with PU motors. Also I can't see them making motorized sets where every motor etc. includes rechargeable batteries, as those require special handling in shipping etc. so I think there'll be some kind of hub that can take AA/AAA-batteries and the usual motors with wires. An integrated battery would also make motors much larger, which would be undesirable regarding set design, especially when there's multiple motors.

The two topmost parts could finally help make ball-socket connections small enough to be useful for structural connections (attaching panels at weird angles and such), though I guess the socket isn't tight fitting as it's probably meant for suspension and such where free movement is required. The bottom left looks also really cool as it allows another way of creating half-stud offsets which is always nice to have to complement the existing ones.

Hey, you stole my idea! I'm also in the process of designing a metal lathe for this contest, but didn't post anything yet because I'm waiting for a few crucial parts to arrive in mail. Anyway, my plan is in larger scale and custom main bearing so it'll be interesting to compare your approach and mine.

- Useless machine (a machine with a switch, which upon pressing activates mechanism that turns the switch back off)

You'll need the XL motors if you're going to use the Liebherr profile in the C+ app, it recognizes which kinds of motors are connected to the hub and won't work if they are of wrong type. I don't know if the L motors are powerful enough to move the thing but if you're using them, then you'll have to create your own program as well. I guess you could test the motors' strength by building the base and then loading it with some weight to simulate the weight of the whole thing and seeing how it moves (or not).

Arocs had part count of a bit below 2800 parts, so at that scale it's entirely possible to make a large, very functional true Technic flagship set. But I'm not holding my breath, if it really is another car it'll be just a huge disappointment as I can't see them making anything interesting or new with cars.

Wtf is it doing in some star wars set anyway, doesn't look like it's absolute necessary for the design to work? Well, I guess they are making use of the new part as much as possible to get it in the market in more sets and we'll see later the set that it was designed for. Anyway, no matter, this will become a very useful part.

WOOOW

That design by Akiyki is indeed great, though unsuitable for my purposes (I need a design where there is an opening in the centre, as large as possible). Also what I need should be fully functional in any orientation. But I have an idea and now I'm waiting for the parts to arrive to test it...

Many turntables in official sets use one wheel or another, so that's indeed a possibility. Also 1x1 round plates have been used with great success, see for example

I agree. Besides, engines can be used in other applications beside vehicles, emergency generators are a well known example but they have been used in things like air raid sirens.

I was thinking of my entry for the most recent contest and realized that I need a large bearing for it and while searching for solutions I realized this isn't much talked topic in the forum so I was wondering if people could share their bearing designs for others to use. All kinds of designs would be interesting, regardless of type and purpose. So here's a one quick and dirty bearing design that would fit my purposes, except it has some slack and the GBC balls aren't perfectly round so they don't roll smoothly.

Seconded. --- As for the studful Technic, it should be allowed as long as the build follows the building principles of the studful era of Technic, meaning there's no tons of non-Technic parts added simply to make it look pretty but only used sparingly when necessary. So no exterior casings from bricks (unless they are Technic bricks) for example.

It originated as a boat weight, for example 4030 Cargo Carrier had I think 6 of those. It's not usable as any sort of connection point.