Moz

Wall thickness will be the issue I think. You will need to glue/weld stuff to the sides anyway which quickly leads to "I wouldn't start from there". I've made values for Lego before but out of brass tube using solder. But the circularity of the tubing wasn't great, so I ended up machining them from solid and paying a bit of attention to rotational symmetry in order to get better circularity. It was still a PITA and I never got the solenoid part working very well (think 9V/1A to switch). These days I know way more about machining but I still think you'd want to ream your main hole to get it as round as possible, then use a lathe to get similar roundness out of your spool. And the even better news is that you can buy cheap desktop sized machine tools off AliExpress that work way better than anything I had access to in the 1990's. I am resisting the temptation to look at them :)

Would you be better off 3D printing a jig or guide so you can drill the necessary holes more accurately?

I'm inclined to wait until those hit pick a brick and just buy them in bulk for a more properer build. If the reading above is correct even Control+ fans aren't going to be thrilled at needing to buy and fit 2-3 more motors and at least one more winch before they can really play with the model.

For those of us without a supported smartphone the Control+ stuff is just another PITA that has to be built around as well. At least that junk is relatively easy to sell but it adds to the cost and hassle of the set. Hopefully there's a decent supply of new truss/BUTPs* to offset that irritation. And ideally they will ship it without the drivetrain issues that made the Volvo dump truck such a disappointment. IMO that's likely to be driving the shift towards a less exaggeratedly oversize model as much as anything else. While AFOLs can get away with "it kind of moves, leaving behind a trail of shredded plastic" TLG should not be doing the same thing. Size-wise I can just throw it in the middle of my train layout because I don't even try to pretend that that's a Lego City build. I have a slightly over-scale container crane that bridges 4 parallel tracks now and is 500mm high, adding a metre-high construction crane might actually fit the theme. (* what's the unofficially official term for big single-purpose technic parts? "Yet Another Technic Mudguard"...)

If the tyre is removable they would make great pulleys for small cranes. With the usual problem that you can't ever let them lose tension, but it's still a heap better than the alternatives.

Yep. I remember having a C64 and being the only kid I knew who coded at all. None of the Spectrum or Apple kids did more than school assignments. So I ended up with a couple of adult fronds from the electronics community as my mentors/teachers... but they were more into the C64 as a cool thing to hack. So I had a C64 with variable clock that ran up to about 2.5MHz (from the base 1MHz) and had 4 16kB banks of RAM that I could soft-switch in using spare register bits. Which was handy for copying games once I added a debounced switch to one of those registers :) These days you buy a kit from one of the Arduino companies if you're a "real geek", or just use a Pi or one of the 200 other sorts of little hardware. I gave one to a 12yo a while ago so they could set up a MineCraft server that ran 24/7, and then we had to plug it in at my work because their parental units like to turn the internet modem off when they're not using it. So now kid uses SSH and a YubiKey to access their server... "back in my day" indeed. My experience of MindStorms is very untypical - I got the first kits, played with NQC, used an IR dongle on my PC to fiddle with them, then decided that writing code all day then coming home to write more code wasn't making me happy. Unless there was something I couldn't do otherwise I never really got into MindStorms. I sold one unit with a MOC and the other two just sat there until I sold most of my Technic when I was in a nomadic phase of life. Then I deleted the virtual machine that I used to talk to those Mindstorms once I no longer had them. But it was hairy... the official MindStorms serial device plugged into a USB-serial adapter forwarded to the VM. I think something like PyBricks is the way to go, just because kids are learning that or similar languages already so the whole visual programming stuff isn't necessary. Even the C-like stuff for Arduino seems pretty accessible to the kids I deal with (there's a strong selection effect there, though). And I keep thinking that there might be a place for an equally modular controller. Make a set of joystick, slider, knob control elements that plug together into a compute/comms/battery module. That would get around the problem of future phones not being backward compatible with the original Control+ Hub. I don't like my chances of using an Android emulator talking to a USB-C BlueTooth 5.1 adapter to run the Control+/Lego Control+/Technic Control+ app (pick a name, Lego, pick one name for the darn app).

FWIW at work we build a couple of devices that include touch screens. It's ridiculous how cheap a complete Android touchscreen is compared to the exact same screen with no Android device built in. We're talking $30 for the bare screen, $40 for the Android version. Some don't even bother with the bare version, it's Android or nothing. So Lego could make a cheap-ish physical controller based on that if they wanted to, the main issue would be that we'd expect them to support it for the life of the sets it came with... 20+ years. My fear is that in 4-5 years we're going to find that the Control+ hubs we have now won't talk to the Android/iPhone devices we have then. They won't run the app, or they won't use the right APIs, or some other trivial thing. I have a couple of kilos of power functions bits and they all work just as well now as they did when I bought them. Except for a couple of motors that have worn out after a couple of hundred hours of operation. The business where I need to grind around the internet looking for Android devices that are compatible with Control+, compare prices and available in Australia, then buy one just so I can play with a Lego set I bought seems silly to me. I'm going to try PyBricks and "Remote Bla Bla" as a workaround, but it annoys me. OTOH, there are so many bugs in Technic flagships these days that it's probably not much harder just to rebuild the models to use Power Functions. The issue UnBrickMe points out where some models require synchronised movement of multiple channels doesn't seem like a real issue for me, I already build MOCs that have limits like that.

For me it's knowing that if I want the flagship crane I'm going to have to buy a compatible phone and none of those are cheap. The Control+ and Buwizz apps don't work on my Fairphone even though Brickcontroller does (I could buy an actual controller to use with BrickController but that seems like spending half the money money to get half a solution). I'm part way converting the Volvo truck back to Power Functions and I really don't like my chances of doing that with the crane. I think TLG really need to bring out some kind of physical controller for the Control+ stuff, because the whole Lego idea of "buy it now, your grandkids play with it in 20 years time" is completely incompatible with "buy a new phone every second year".

Sadly they refuse to use black for connectors or axles as part of their colour vomit, annoying those who want things in the "odd colour" of black. Sort of the anti-Ford "any colour you like as long as it's NOT black". I'm just happy we finally got "Technic, Axle 2L with Pin with Friction Ridges" in black, so I can cut down the axle side and get "Technic, Axle 1L with Pin with Friction Ridges" in black that way, rather than trying to buy all 500 of the available ones off Bricklink. 200 of the 2-long axle version for ~5c each and some time with the saw beats 20c or more and each seller has 1 or 2 of them so it's 20c plus $10 postage each. Now if we can just get a long axle-with-stop in black so I can cut those down too (8L for Euro0.80/$AU1.30 each does not count, give me 12L for even ~30c so I can buy 500 of them).

I got some more parts yesterday, including some old Lego metal axles and some really old red wheels with metal stub axles that go into the black 2x4 bricks. I made my test track a bit steeper but the really old wheels still only just barely managed to roll on straight track. So I didn't include them in my tests. Likewise I now have 8 wheels that take cross axles, so I put those on a test wagon and was equally disappointed (as expected). Those are really only good for fitting to motors, since I don't have ball bearing races that fit them. The older metal Lego axles appear to be very slightly larger diameter, only one of them fitted through the BrickTracks ball bearings so I haven't managed to test them at all. I did a bunch more tests and by repeating some I've established that the variation between tests is larger than the variation between some setups. Specifically, adding graphite to the metal axles doesn't do anything useful (either in the wheels or the holders). With R40 curves I struggled to get consistent results, so I gave up after about 20 trials. Conclusion: even on R40 curves the ball bearing races are significantly better for rolling resistance. They're a huge PITA to work with as the wheels fall off very easily (by design, they're supposed to have Lego wheel holders). Pic below shows the abomination I used for testing just so I didn't have to go chasing M2 washers out of the carpet after every run. The next best option is the old metal axles, with graphite, IMO.

The weirdest thing was several small collectable dolls. I looked up the brand online and found a few collector websites. If I'd got them 10 years before then they would have been worth a few hundred dollars... but I suspect the reason they were in with $100 worth of Duplo is that the owner knew they were worthless. But mostly what I find is mysterious goo stuck to the Lego. Toothpaste? Chewing gum? Glue? Excrement? Who knows... I just work through my collection of solvents and cleaning agents until one works or I run out of options. Most vanish in a bucket of warm soapy water, some resist caustic soda, vinegar and isopropyl alcohol (one at a time!) I don't think I've ever found money. The worst was some "non-smoking household" Lego that stank of cannabis smoke. I ended up assembling a couple of sets and selling them with the warning "stink of cannabis smoke" because I couldn't wash the smell off. The extra parts I just dumped, I'm not wishing that problem on anyone (cannabis is illegal in Australia).

So the solution is to buy the BrickTracks wheels and axles, rather than using Lego ones. I will have to order some and wait. For me HABricks postage is half what BrickTracks charge (USA postage is more than the cost of whatever I'm ordering).

I ordered their ball bearings in Technic bricks and one arrived disintegrated. The balls are tiny (as expected). Definitely not roller bearings. Tiny ball races like that are relatively fragile, I expected that, and when I was shoving axles through them I was appropriately careful. But still applied axial loads, especially because the tolerances on Lego axles and the bearings themselves meant that some combinations were too tight to fit together. Which makes it all the more surprising that one bearing fell apart in transit. I have emailed them but not heard back et (it's the middle of the night in Europe) https://ibb.co/JygMbpV the black blob is a Technic 1x2 brick with two holes, and part of the bearing race in it. Note 2mm hole through washer and tiny ball next to it.

I got the HDBricks ball bearing bricks, and I'm a bit unimpressed. One bearing arrived in pieces, and just generally the Lego axles+wheels I have don't stick together very well so picking up a model generally means half the wheels fall off. I suspect I need to 3D print some holders that have an exterior section like the Lego wheel holders do. It makes testing rolling resistance very tedious as I have to find all the wheels and washers then reassemble the test vehicle after every test. Does anyone have advice? Upside is that the BrickTracks R104 points are very nice. Injection moulding really does give a better finish than even the decent 3D printers that TrixBrix use. In Australia it's cheaper to buy BrickTracks stuff from Europe because postage from the US is extremely expensive (more than the cost of the tracks in any combination I can find). Now if only they offered more than simple points :)

Thanks for the link. Although given the limited advantage of the metal axles in tests so far I think I'll hold off until the HDBricks sample pack arrives and I can test those. Same seller lists in Australia, but only 10 sets of bearings... for 1/4 the price of 100. A different seller has 50 for ~$US18. If I want some I think I'll contact the seller you linked and ask for 100 :)