Stereo

All the differentials should be about the same for wheels going opposite directions, since they use the same 12t bevels. The gears might not be slid into place properly inside it. I think when assembling it you want to drop all 5 in, have the one on the open side be floating loosely and centered, and then put the cap on. It has enough friction that a wheel won't spin indefinitely like it would if it was just an axle connected to nothing, but usually easier to turn the other wheel than to move the drivetrain.

8 small sets in the same colour is interesting, would have thought they would make them look a bit more different. I guess it's good for people designing 8x combination MOCs. To me it looks like dump truck, cement mixer truck, bulldozer, wrecking ball crane, excavator, front loader, truck crane. I can't see the 8th one, maybe another truck like the dump truck.

I think it's because of the red gears that float on the driveshaft, if you hold maximum steering, those are pressed against the axles and increase friction a lot. (both within the gear and the beams it passes through in front/behind) Zero Ackermann also contributes though, the front tires are scrubbing quite a bit if it's on a smooth floor.

Ah, but what if it's the modern Dodge Chargers from Fast 5, that they used to move the bank vault? (I know, it's going to be Dom's from 1st movie)

Well, if it was car transporter scale, it should be wider than the car transporter, not transported on it. Since it's bigger than most cars. The previous minifig Tumbler was about 14 studs wide with 4 of the 3-stud wide truck tires (which I hadn't realized have a truck tire tread until the GT40 got car tread ones).

The Technic subforum's light theme broke for me today, a lot of white-on-white text. The Dark theme's text is too dark for me to comfortably read in a lot of spots, but I don't normally use it so I can't say whether it changed.

I don't know, I'm guessing people call ~2010-2011 the peak of consistently having trucks in the lineup? 2010: 2 car/motorcycle, 3 heavy duty trucks, 4 off-road equipment (excavator/tractor), 1 helicopter 2011: 3 car/SUV, 5 heavy duty trucks, 1 off-road equipment (backhoe), 1 helicopter 2012: 2 car/quadcycle, 3 heavy duty trucks, 2 off-road equipment (tractor/crane), 2 aircraft 2013: 7 car/truck/motorcycle, 2 heavy duty trucks, 2 off-road equipment (excavator/backhoe), 1 hovercraft It's not really that favorable compared to modern era 2024: 12 car/truck/motorcycle, 2 heavy duty trucks, 6 off-road equipment (incl. space rovers), 1 aircraft, 1 boat, 1 orrery 2025: 13 car/truck/motorcycle, 1 heavy duty truck, 5 off-road equipment (excavator/loader), 1 aircraft, 1 submarine Categories aren't necessarily super well defined, I put anything that's people-transport in the first group (monster trucks, pickup trucks), anything that has functionality and can drive highway speeds in the second (mobile cranes, flatbed trucks, semi trucks), other wheeled/tracked vehicles with functions in the third (so sort of 'anything else') This year's heavy duty truck does let down the category a bit compared to 15 years ago, but last year had 42175 which I'd say is a decent member of that category... For me the wheel loader is the only 'must buy' of the year but I haven't actually picked it up yet - got a good deal on an 8865 which seemed more urgent than stuff that's still at retail sale.

Good progress on the switch, it's now feature-complete for a version that will not let you run backwards the wrong way. I designed it to use BrickTracks switch stands primarily cause I have a couple so I can measure them, but also I think they have a good feature set (works on either side of the switch as needed, low profile, simpler track piece). 6-gauge R85 switch to demonstrate something new, not just a copy of existing sizes. I was a bit conservative removing studs, so round tiles should stick to all of them, and square tiles to most. The switch mechanism's designed to assemble from the top with no tools. First you slide the tie bar (light grey) in through its slot, first through the diverging rail, then back through the straight rail to lock it in. Then use the underside features of the points to connect it: 1) Knob fits into a groove and can be slid into its place. 2) The other end of the switch has a slot for the tiebar to move it. 3) Then rotate the point into place and this ledge prevents the knob from popping out. Once the switch stand is attached to the tiebar, the range the tiebar can move is limited to where ledge #3 is always engaged, so nothing can come apart. I also have one feature that only makes sense for a 3d printed part - the straight rail is hollowed out so the point piece can slide underneath it. This stops the end of the point from lifting up, without needing a little latch around the end of the point. The groove #1 is curved away from the rail because of this - the point drops in at the loose end, but then slides under the rail. One thing I'm not really happy with is that the point piece is lower at the knob end, so it has no ideal orientation to prevent supports. The mechanism only has 1.9mm of vertical space to fit in otherwise, and I didn't want to go to <1mm thickness, so having it descend halfway into the tie keeps everything 1.6mm around there. (the tiebar ends are 0.8mm thin around the hole, but it's the easiest part to replace if broken) I have some limitations on what I can generate because of the ties - they're only coded to work as multiples of 4 - but I can still use some odd numbers. Here's a 5-gauge switch on 14 stud track spacing, making it R227.5 and 56 studs long. I'm still stress testing it by trying odd values, but I think it's pretty close to ready to share/print now. One flaw I'm aware of is that in 4-stud narrowgauge, there's no way to insert the tiebar without bending it. The simple solution is cut off the end loop on the point side - it needs to be 1 stud shorter for the insertion method to work. I'd also like to make a click-detent version of the tiebar so it's more functional without the BrickTracks switch stand, I just need to decide where along the tie to position it. Once I'm fully happy with it, I'll set up a version of the file for diverging routes that just has you pick radius and track length. Mostly a matter of going through and redoing some of the tie generation logic so it doesn't assume the two routes have near-equal track length.

On the actual car they're pistons mounted to the underside of the car that lift all 4 wheels off the ground when air is applied, then retract when air pressure is removed, it's to make pit stops quicker. For Lego it's probably linkages. "Accurate firing order" is doubtful to me, 6 cylinder boxers use 120 degree angle crank offsets and every single piston is on its own offset section of the crank, since each pair of opposed cylinders hits TDC at the same time. Would need new parts designs.

The usual construction to power it from outside the tower would be a turntable - for example Large 60 tooth is the current production piece, they've had about 5 minor variants over the last 40 years - so one motor meshes with the teeth on its perimeter, and the other runs an axle up through the center to drive functions inside the spinning pole. It depends how large you want the build to be, but 36 tooth gears could provide the linkage of the 4 arms on top - which are external to the pole on the actual one. 3 of them would be mounted exterior only, 1 would have an axle run through to the interior of the tower and connect to the axle coming up the middle.

I briefly mentioned the Pythagorean triples before but I was thinking about them again, and used them to derive the curve radius for switches, so I'll demonstrate that: The base unit "1" is how far the switch has to diverge so that a symmetric piece will meet it from a parallel track. Here it's 8 studs. Switch "size 3" is thus 24 studs long, 3*8. It creates the green triangle, whose hypotenuse is the radius of the curve, and 'base' is 3. The other edge is 1 less than the radius by geometry. So we have the Pythagorean triple r² = (r-1)² + 3². In this case it's easy to observe that it's 3-4-5, but more generally, replace 3 with x and expand: r² = r² - 2r + 1 + x² 2r = 1 + x² r = (1+x²)/2 So for 'size 5', r = (1+5²)/2 = 13. Multiply by studs per base unit 13*8 = R104. Anyway, burying the lede, I've got parameterized rail, and most of the ties sized how they should be (in this case, long enough that the 2 end studs are usable on every tie unless they overlap the one diagonal tie). The remaining gap is where the switch is operated, so it's going to be 3*8 studs with a slot in the middle. I still need to remove a bunch of studs, add a switch mechanism, and add guards for the frog area. All seems feasible with the tools I already understand though. Took a while to find a process that would let me generate variable-length ties with correct integer lengths but it appears to be operational.

I didn't take it apart myself, just got it this way (without the brick) but it should just pull out. I don't know how much force it takes. I guess the ridge clips into something. (modern wheel/tire for scale - it sticks nearly 2 studs into the brick) It slides freely through the wheel, I just put it in to show size.

Bit of a throwback question, but I've noticed that my vintage Technic has 2 sizes of part 2825 1x4 thin beam. The bigger size is 1 stud wide, the smaller one is a bit smaller, which seems to be the same size as other studless beams. Does anyone know when this changed? I would guess it's around 1995-97 when the other thin beams (1x3, 1x5) got added. The Light Bluish Gray one is from Surface Space Loader; other two are Light Gray: Also interesting to me that it's (c) 1992 on the new one, as the part was introduced in 1989 sets.

More of a test piece than broadly applicable, this is for changing which side of a larger gauge the narrower gauge rides on: In this example, it moves 4-stud narrow gauge inside 6-stud standard gauge over the course of 32 studs. It let me test several features of switch tracks - rails merging, guardrails, flat area for the flange to ride on - while being a smaller project. It's designed as a half-piece that you print 2 copies of, to cut down on the size of the printed piece. As before, it's parameterized, in this case you have 2 gauges (larger one as #Gauge, smaller as #DualGauge) and #TrackLen. There are practical problems with designing a dual-gauge switch, that are solved by having the moving point be on the shared rail, so that's one situation where you might use this. Unfortunately I don't see a good option in Onshape for creating the mirrored version of this part, so I'll probably end up creating two files, one where the narrow gauge shifts left, one where it shifts right. For now I only have this "leftward" one. I'll keep looking though, creating 2 versions of the actual switch file will be more tedious than managing it in this smaller design. The reason it's a problem is the rail end clips - if you simply mirror the whole design, they'll end up backwards. So parts have to be mirrored selectively. Another example to demonstrate parameterization - this is 5 gauge with 4 gauge inside, over 16 studs (which makes it R64 curves - don't worry, the CAD does the math for you). Sort of ends up being oddly shaped, in that the rails end right at the split between the pieces, so maybe it's worth designing a version that doesn't split there. And a 3-rail curve - the extra parameter #DualInset says how many studs from the inner curve rail the third track is. So for 4+6 stud gauges, you set it to 3 or 2, depending whether you want the narrow gauge to run on the inside or outside of the curve. Though the real point is things like this example, with 5.3 and 7 stud gauge, where there's no off the shelf piece available that does this. Less than 1 stud gap may cause collisions, and likely doesn't work with Lego train wheels anyway.

I have some Classic theme 'googly eyes' that I might swap into the Anglia, if I see it for a good deal (assuming it'll be $80+US msrp). Not sure about the mouths, maybe there's a classic 1x2 tile with smiling/frowning mouth (11031 monkey fun, but only medium nougat)? I don't actually hate the printed tiles it comes with, I just think googly eyes are funnier.