Adam Badura

After spending lots of time playing LEGO Duplo (mostly trains) with my kids and also building some larger layouts myself I got few questions regarding (mostly) design of Duplo tracks. I asked them at Polish LUGPol forum but some were not answered (it seems LEGO Duplo is not popular enough) so I’m reposting them here hoping for larger audience and thus better answers. I believe that LEGO parts (which includes Duplo tracks...) are done carefully and decisions are unlikely taken without evaluating many issues. So the radius used for curved tracks must have some reasons behind it. I don’t know which and I would very much like to know. Since I already know much of troubles caused by that choice. Read further. (1) Curved Tracks Radius A single Duplo curved track spans on a 30° angle. Three such tracks make a right angle. But the simple staff ends here. Ever tried to connect the ends of such right angle with Duplo bricks? It failed, didn’t it? You could actually make it but that would require to strain those tracks a bit (they are significantly flexible so it doesn’t require any strength nor does it seem to make any breaking risks). If you would do that with a hole circle of 12 curved tracks you would not get a circle but an ellipse with short radius of 17 Duplo studs and long radius of 18 Duplo studs. The actual radius of a circle is somewhere around 17.5 Duplo studs. It might be aligned with LEGO studs, I haven’t checked that but I doubt it. This might seem insignificant especially that the tracks are strained so little that it is not visible to someone who “doesn’t know”. But still this is some disadvantage that shows when you try to build something bigger or mount everything on a single solid base (possibly done with plates). Since the strains add up and things start to fall apart easily. (2) Curved Tracks Alignment to Straight Tracks So I looked further wondering to what the curved tracks align well. Sadly without success. Another failed example is when you connect two curved tracks in opposite direction. That way the lines entering and leaving the two tracks are parallel. Its tempting to see if you can mount it on a plate. But as it shows again it is not possible. Such a connection of tracks does not align well with Duplo studs (and thus also straight tracks...). (3) Long Trains In my experience a train having two or three railcars significantly slows down on longer curves. The cars are long and wheels don’t turn around in no way which means that the do no align well with curved track and cause some friction. With more railcars you can see how the train slows down and sometimes even hear that. With four or more railcars its nearly sure the train will stop on a longer curve. Would the curve track have a larger radius this issue would be (somewhat) smaller. Now knowing the drawbacks of current curved track design we might wonder what are its advantages so that the trade off goes well. Anyone? And this is still not end to the questions. (4) Move Direction Why current locomotives do move in only one direction? Would changing the button to a three state switch (forward, stop, backward) make it much more expensive? Or would it be much more difficult for kids? Current sets with locomotives are from 2 years. How it was with the old “smart locomotive”? As I think it was far more “difficult” and “complex”. (5) Locomotive Anchors I find it rather odd that (current) Duplo locomotives don’t have anchors on both sides as all railcars do. This way making the locomotive push the train rather than pull is rather difficult and likely to cause derailment when using more complex layouts (like ups and downs or junctions). (6) Corrugation (I’m not sure if this is the correct word for it) Tracks and the engine wheels of the locomotive are corrugated. Why is this needed? As it seems LEGO trains don’t use it. So why Duplo trains need it? Any “rational” for those? And as a final question. (7) Does LEGO provide precise specification of their “bricks”? Like exact dimensions and sizes or power of motors and so on?

Definitly! At least one autmatic train and some more tracks with switches will make the fun even better. Although do mind the space. I'm not sure how much flat space do you have available. Also from my experience it is good to add some amounts of simple bricks and plates so that something more can be build. From the movie he builds by his own already from the book. Mine started that much later. But if so then the extra bricks can easly change to more variation in track layout by allowing to build elevated tracks or Bridges between pices of furniture.

Recently we bought not so new anymore (2013) but still current large train set, the 10508: Deluxe Train Set. To my surprise the locomotive works differently. Not only it makes a different sound and the on/off button seems more like rubber than plastic but also it rides differently. Now there is no auto-stop on difficulties. Only on timer (2 minutes if I recall correctly). Instruction describes this as a new feature to make it easier to play with the train. From my point of view this is better for older children. The train can now do more work without risk of stopping. For example it is capable of dragging more carts. But for younger children it might be somewhat worse as the often not care for the train running against the wall (or similar). While now it will not stop automatically anymore.

I'm storing my LEGOs separated on sets. This way it is somewhat easier to play with kids (and to cleanup afterward!) which are still a bit too young to comprehend entire collection (even if sorter by type or color). I decided to store instructions separately because experience so far shows that storing them along bricks in bags leads to various small damages. I’m afraid that with time they will accumulate. But if I will remove instructions from bags with bricks I have to have a good solution to easily identify a bag with a set. That could be easily done by just printing set picture. Since I print it myself any damages do not matter – if they get worn too much I will just print a new one. Another issue that is left is to be able to inventory a bag quickly. For that I would need a list o bricks in a set. For new sets those are at the end of instruction (very good idea!). For old sets (and I do have many of them) the issue is even worse since the instruction doesn’t have list anyway. My idea was to print lists and store it in bags as well. Again since I would print them myself any damages are unimportant. The issue here is however that lists based on popular sites (like Peeron for example) are far too large after printing and don’t feet well with small bags of small sets. Finally I can reach the question here. Where to get a list of bricks that would be significantly smaller and still useful and readable. Like the ones that are printed with instructions? I could make some scripts to parse publicly available brick lists and generate print page that fit my needs. But that is likely some work to do which possibly was already done by someone somewhere. Any help or advice?

Sure. Robert, will you start the new thread with the sim up? Could you then post here a link to it?

Nice! Be sure to check it with switches, crossings (both rail-rail and rail-street), and bridge. Those are places where other Duplo bases fail. For example 10558: Number Train doesn't fit on that type of track and that is sad. Yours looks like it would have no issue but it is always good to keep that in mind.

Looking forward for new results! In the mean time having a third kid put me out of theoretical work. :(

Wow! Not only I got a thriving (as far as it gets with Duplo!) thread on Duplo Trains but also it includes giants standing on the shoulders of other giants. Fantastic! I have to tell someone in real life, that will be a great story! :)

Excellent! I'm so happy that I have started this topic! Really interesting things got said/published here!

Until few days ago I was using Lego Digital Designer to build some models from time to time or to play around with some ideas. But since I hit an obstacle of missing parts more often than I would like to I decided to try something else. By the way I don’t quite understand where is the problem in adding all Lego pieces to LDD. I guess it is lack of “human resources” to do that job. But if so then why not open data format and allow fans to add the parts they miss, post them for a review or something so that on the Lego side of the task it would be much less work. Or maybe there is some programming needed around new pieces and thus the work cannot be released to public without actually releasing entire project. Anyway I’m dragging here myself from the topic so lets get back to the issue. I started with MLCad as from a quick “look around” it seemed a good starting point and quite popular. I gave a short try to LeoCAD but didn’t see any significant difference here. Then also SR 3D Builder which seemed to have advantage of auto-alignment of pieces like axles. But since it is under development (the one that installs with LDraw All-In-One-Installer doesn’t even work due to some integration issues – what is the point to include it that way?) and non-free I stopped exploring it (for now). But trying to do a model from instructions I had on paper I really struggled with MLCad. It is FAR more difficult to work with it than with LDD (at least for me – lets state here that I don’t have any CAD experience). And the most difficult part is to align pieces. As it comes to standard bricks the “Coarse Grid” seems to be good enough (but still alignment has to be done manually). But since I chose a Technic model obviously soon I came across pins, axles, bushes and holes. Aligning that still seems to me more of an art than science. (That is why I decided to give a short try to LeoCAD and SR 3D Builder.) I think that somehow I made it. Or at least it looks good enough on the 3D view. But I’m not entirely sure. Is there a way to verify model? If it is physically proper? That I haven’t move a pin one step to far for example? Can it be done automatically? Are there any tools to verify if model honors various building rules (like not stressing pieces too much)? And since I’m already writing then some side questions: Is it possible to move the camera rather than the model in the 3D view? That way it might be easier to see some details within the model? Is it possible (maybe in some external application) to animate MLCad model? Are there any open source editors for LDraw?

I meant LEGO System Trains theme. When it comes to trains in LEGO the System ones get all the love while you will rarely find anything on Duplo ones. At least such is my experience.

Thanks for your notes and time! Also the layout page: that is excellent (still have to read it to the end thou). I was thinking about those issues myself some time. But I was going into representing the layout as graph and then see how things look and maybe find some rules. Anyway I really admire your effort and work. It is nice to know that somewhere out there is someone playing with Duplo rails more than just "randomly". This topic seems to be unpopular, people use System rails instead. Likely I would have done so myself if not having too small children. And since I already invested in much Duplo (mostly rail) it will stay for some time at least. But is there a way to browse through the topics of the http://www.cailliau.org page othrwise than alphabetic? As it has very wide selection of topics while I'm interested in Duplo and LEGO only (for now! ;)). For example I wasn't aware of the very interesting entry in Mathematics... And I do have SVG editor. Anyway if you would like some help with those entries I could try to contribute whatever I can (likely not much sadly).

That is interesting! But it seems tha page states the same (or close enough) questions and doubts that I had without providing much answers.

I cannot find it. Sure there are some comparisons but they don't include Duplo trains (or it is hidden under code/type name which I don't recognize). Can you please share the link? (Either here or in PM.)

"Annoyed" isn't a good word here. I'm more "curious". Maybe a bit "disappointed". Young kids maybe don't. Their parents (for example me ;)) sometimes do. zephyr1934 gave you an example. On YouTube you can find many more (including few of my own). Yes, but that works if and only if you place the track directly on the floor. Once you start placing it on other structures so that they connect to other bricks the flexibility is gone. And now all the non-aligned issues come back to haunt you forever more... I don't think that it "isn't designed for long trains". I'm starting to think that instead designed against long trains. Railcars have fixed wheels (unlike LEGO trains...). This could be explained with lowering costs and making things stronger and harder to break. Sure. But why they are so long? While at the same time curves radius is rather small. And you noticed yourself (and I did see that myself too) that kids like to make long trains. The Duplo train can as well. But not on curves. Even bridge doesn't put that much limitation as do (longer) curves. Now if train pushes rather than pulls it is not connected with railcars. And this leads often to derailments on bridges, curves or switches. Adding a front connector would add a nice opportunity at least partially covering for missing backward move. Note also that (manual) Thomas line locomotives had connectors on both sides of the locomotive. What is odd however is that they were opposite to what is now so if you would like to connect Thomas line engine to current locomotive it needs to go backwards. Well, the funny part is that they... don't! To see that yourself you have to mount the tracks on 4x2 bricks (or plates) so that they are not "flexible". Then you will notice that the two curved tracks are slightly longer than two straight tracks. I had a chance to play with it only once but it was already very old and used. Didn't work well anymore. Buying one now is very expensive and somewhat risky if you buy a used one. But I'm still hunting for one! I have heard rumors that the tracks are going to be sold in packs containing all types (curves, straight, ...). But nothing I can link to here so I don't know really. We will see when it comes. ;)