Robert Cailliau

Absolutely fantastic... Do you have a parts list & building instructions? I would like to make a copy...

Maybe you can fly a TARDIS back to when you can order from Alien Motors. Never mind. It's probably much more useful four your child to get some more straight rails. But I found a motor here: https://www.banggood.com/fr/20MM-3V-DC-Miniature-Electric-Brushed-Motor-For-Smart-Robot-p-1017125.html?akmClientCountry=FR&cur_warehouse=CN and here https://www.ebay.fr/itm/3x-miniature-moteur-DC-DIY-Toy-130-petit-moteur-electrique-3-a-6V-basse-tens-F1/363204090655?hash=item5490a69b1f:g:eBwAAOSwKBRaz3k7 and here https://www.amazon.fr/Moteur-SODIAL-electriques-12000RPM-vitesse/dp/B01E9TDBGW I don't know but they sort of look like they might work. I could order & send if you wish.

That's better! In your first post you mentioned 60198 (or did I read it wrong?) which is definitely not Duplo. 10875 is duplo and cute. As usual, it has only 4 straight rails against 18 curved ones. When my wife & I started buying Duplo trains for our granddaughter we noticed the lack of straight rails. We then bought lots of them second hand, which has been very successful. However, the Lego marketeers have cleverly changed the colours over time so that the older ones don't look very good when mixed with new ones. There are at least four different colours. Fortunately little kids are not (yet) influenced by fashion and don't care. (ah, the curse of science training… and maybe the alien motor guys watched too much Doctor Who)

:-) Yes, I have fixed some of them, since I'm also in the group of people who simply cannot throw anything away if it can be repaired. There is a worshop in the basement complete with 3D printer and metal working miniature lathe + milling machine, and with a lot of "materials" that "might come in handy", and they often do. But I have none of these motors. My pages about opening Lego locomotives are of no use to you, as we have nothing as recent. And by the way, that set looks like it is not DUPLO, but normal. Correct?

Alternatively you could perhaps buy a whole thing: https://www.bricklink.com/v2/search.page?q=28743&tab=A#T=A It might not be more expensive.

Hi Jan! I had not understood the thing about the generalised track layout program! Fantastic. That is NOT an easy thing to write. I played a bit with the free version, looks great. You have taken everything into account… I did in my younger days (60 years ago) play with some Märklin and remember the tool they had: a plexiglass cut-out drawing tool. With all those different circle radii. All the best with that!

It is a funny piece in more ways than one. It follows the old style, where they could not be put on top of bricks or plates because the coupling bits went down too far, getting in the way of the studs of the plates or bricks. Therefore they cannot be used to build on supported slopes or bridges, only laid out flat. You may wish to explore /L/Lego/Duplo/Train/Rails/Dimensions/ (on first visit you may have to click the "Englsih" button and then reload the link; I'll change that asap) So who wrote the track planning app? Can I get it? BTW, also note this: /M/Mathematics/APR/Description/

Goede middag Edge_nl, For some reason I did not see your thank-you (thanks!) nor your very interesting 3D printing suggestions for more rail formats. Sorry for that, I just saw them this morning. And yes, a topic for 3D printing of compatible parts is a very good idea. I have a printer (Ultimaker-2), but the grandchildren have outgrown Duplo… Does a 3D group of topics not already exist? I have not looked. In any case, Duplo rails do not require the same precision in 3D printing as standard Lego pieces do. Unless parhaps for sticking to Duplo bricks. Thanks! (I've got OpenSCAD too)

There you go: So it's three studs by four. These bits are useful to close some layouts with tracks at angles other than 90º. However, they do not stick to plates or blocks and there is quite a lot of play. The answer then is: 3x8=24, so 8 small ones will have the same length as 3 standard ones. Nothing in between.

Yes, "someday" is also on many of my lists… ;-) Anyway, perhaps I should research techniques for getting 0.5 unit distances with the studless beams. Another "someday": publish a list of parts that would be useful but do not exist. Many of them are connectors.

I did not find this set so very good. The pneumatics don't really work as well as I would expect, probably due to the not so very good compressor, but also due to the hoses to the pistons. The gearbox that drives it all is complex and has a lot of friction. The geometry of the steering is good though. But I would certainly not rate it as the best Technics set ever. There are some excellent sets, and some that are rather disappointing. Admittedly, it's very difficult to make Technics sets that work well and in the end are also good-looking. The Arocs gets 5 out of 10 from me. The bucket wheel excavator (42055) is the best one I have built: everything works well and all dimensioning is correct (*) Then there is the whole issue of creativity: building a mechanism with the new-fashion beams that have no studs is sometimes frustrating, as there is no easy way of getting a half-unit offset. (**) But that has nothing to do with this particular set, it's a general remark. Robert. (*) the ferris wheel, 10247, has Pythagorean triangles that are wrong, one of them has a side that is off by 2.77mm (implemented: 132mm, Pythagoras: 129.2308mm); there are several Pythagorean triangles in the bucket wheel excavator but every one of them is correct! (If you need elucidation: a Pythagorean triangle is a right-angled triangle in which all sides have integer lengths, such as 3-4-5 (because 3x3+4x4=5x5), which is needed in the case of Lego where everything has to fit a discrete grid). (**) For example: making a 40 tooth wheel mesh with a 16 tooth is difficult: the axles need to be (40+16)/16 = 3.5 units apart. 3.5 is easy with the bricks with studs but not with the studless beams. I'm trying to design an astronomical clock that's as good as John Stouffer's (https://www.buildsteam.com/home/introduction-to-the-lego-astronomical-clock) but will sit on a table top instead of needing a large drop. Using only the "new" Technics "religion" of studless beams is very difficult, and I have actually given up and reverted to the beams with studs.

I never see a reason why an old thread would necessarily mean it's inferior. As to your observations, I may have posted the url https://www.cailliau.org/Alphabetical/L/Lego/Duplo/Train/Rails/Dimensions/ before, or not. And yes, my (my granddaughter's) locomotives can also pull many carriages. The locomotives have changed. It also depends on the wear on the rubber tyres, the state of the batteries etc. Many parameters. Have fun, Robert.

Jim, you wrote: In the thoughts below I used the part numbers as they appear on pages 481 and following of the construction manual. (1) In the construction manual on page 163, on the frame, the rubber liftarms (4198367 rubber liftarm length 2) lie horizontally. They connect to vertical black beams (4142822 beam length 3) that can rotate around fixed blue pins that go through their centre hole. (2) On page 200 the bottom holes of these black vertical beams each get a suspension arm (6055628 steering arm with ball socket) connected to them (the picture on page 200 shows the assembly downside-up, so the bottom holes are at the top in that image). Note that these arms are shown at an angle in all illustrations. Geometrically the sockets for the ball heads are therefore closer together than they would be if the arms were horizontal. They need to be pulled apart slightly if they are to adjust to the Lego grid. (3) On page 218 these arms get the ball heads of the four pegs (4184169 pin with ball head) of the double differential. (4) On page 219 the "shock absorbers" (they are only suspension springs really) are attached and they push the differential away from the frame. That distance puts the steering arms at the angle they were already depicted at, which pulls outwards on the vertical beams. The necessary flexibility can only be achieved by the stretching of the rubber liftarms. If you replace the rubber ones with normal, stiff ones (4211741 for example) then it all feels very different. There is an image at http://www.cailliau.org/Alphabetical/L/Lego/Models/42043-Arocs/RubberLiftarms.jpeg The distance between the black ball heads indicated by the red line with arrows is a fixed distance (on the differential assembly)

OK. Sorry, I did not know there was more about this specific thing elsewhere. The only reason I wrote anything at all was to point out that the different angles Jim mentioned in his review are indeed desired and not a design mishap in the Arocs. Off for now, R.

Well, I did have a go at Ackerman steering in Lego. Competion: anyone can do it nicer, more robust, more compact? See this page: http://www.cailliau.org/Alphabetical/L/Lego/Models/42043-Arocs/AckermanSteering/'>http://www.cailliau.org/Alphabetical/L/Lego/Models/42043-Arocs/AckermanSteering/ There is a link to an .lfx file so those who want to try it may use buiding guide mode in LDD to see how I did it. I'll put some real photos up too, and will make it into a remote-controlled car. (you can also watch http://www.cailliau.org/Alphabetical/L/Lego/Models/42043-Arocs/ and http://www.cailliau.org/Alphabetical/L/Lego/Models/42043-Arocs/Steering/ ) to Starmort: it's all a matter of local taxes, people getting money off you just for postage, and other weird things, nothing to do with an open market. That needs a lot more hammering from the European Commission.