Battery Acid Dust Issue I was recently digging through some old boxes looking for old LEGO bricks I had as a kid.  In two of the boxes I found old double A batteries that had busted (the boxes were in a building that has got hot during the summer).  Well in the corners of the plastic boxes I found brown dust.  I'm thinking this might be lead dioxide from the exploded batteries.  I also burnt my hand accidentally touching one of the exploded batteries.  Am I right in this assumption?  Is there a way to clean the bricks by soaking them in water with a chemical (baking soda)?

Any advice would be appreciated I just don't won't to lose these LEGO bricks.

It's very unlikely to be lead, smaller batteries don't use it. If the batteries were old rechargables they might contain cadmium (NiCd batteries). Most likely what you had was a disposable AA battery which will be an alkaline cell. As you'd guess, you can neutralise that with acid. But not a strong acid - you don't want to dissolve away the metal parts of the Lego battery box!

There are a few how-to guides on the web that I found, like this one and this one They all suggest either lemon juice or vinegar as the acid, and focus mostly on

don't touch the battery gunk with your hands (or eyes!)
wash it before scrubbing it as well as after
use something disposable to scrub it with
and don't touch it with your hands

Personally I'd put on rubber gloves, dump it into a plastic bucket full of water (always put chemicals into water, never water onto chemicals), swish it around and see whether the mess washes off. That's easy and you'll end up doing it anyway, so starting there might save you even having to find the vinegar bottle.


Accessing ARM Processor Memory Registers through NXC Specific to the NXC (Not eXactly C) programming language. Is it possible to access the memory registers on the ARM AT91SAM7S256 processor? I'm trying to investigate the use of Timer Interrupts to schedule a sampling routine.

I do know it's possible with nxt-gcc, but I don't know enough about NXC to understand if it would work. Would it not be possible to run with interrupts since the firmware uses the blocking I2C to communicate with sensors?

NXC creates bytecode for the standard (or NXC upgraded) NXT virtual machine. The idea of this virtual machine is to create an abstraction layer to prevent malicious low level calls such as accessing memory registers on the processor.

So, without a low level compiler, such access would not be possible.


Why is there no set with much RC Straight tracks? after visiting many Lego events (brickmania, antwerpen, BE), I wish to expend my train layout much more than adding a box or two of 7499 ...

Why does Lego didn't released a set with, for example 24 straight track ( #53401 )

Even if 7499 contains flex rails, I don't like these, they are noisy.

Any tips for finding some ??

I can't imagine peoples who exposes layout in 5 meters by 8 meters with 4 tracks have bought a palet of 7499 !

According to Brickset there are 8-8 straight track pieces in both of these sets:

7896
7499

This seems to be the maximum amount, even the large complete train sets do not contain more than 8 straight tracks.

You might have more luck purchasing them piece by piece from other AFOLs, or see if there is a Pick-a-brick shop in your area.


Identify these windows/doors I have these old windows. I am unsure if they are even official lego.

LEGO logo is visible inside hollow studs on genuine parts. While it is hard to identify if pictured items are genuine LEGO parts, such elements have been produced as LEGO:

Window 1 x 6 x 3 Panorama with Glass

Window 1 x 3 x 2 could be either one of these.

Door 1 x 2 x 3 Hinge on Left

Window 1 x 1 x 2 could be in two versions: with integrated glass (single piece) or with glass that can be attached (two pieces together).


What are good DUPLO projects for around 2 year olds? It is always good to have a bunch of (short) building projects to suggest to our toddlers.  Here I would like to collect some easy ones for DUPLO.

I'm not particularly interesting in creating duplicates of real world objects, like building animals, houses, etc.  The projects can be abstract, focus on something unexpected, or whatever.

Please share your experiences.

And here is my first project: Color towers:

Building towers is probably the first directed building effort that toddlers undertake.  In this project I gave our son (20m) many bricks and built 4x4 monochromatic socles for towers.  I told him that we are building a 'green', 'red', and so on tower.  At first he only got that we are building towers, but I directed him toward using only the color that is already in the socle and after two or three wrongly placed colors he got it.  After a few layers he even asked for specific colors to continue a specific tower.  After the towers were high enough, together we inserted some nooks for figures to stand in.  He did most of the building, and I only occasionally changed the orientation of some 2x4 bricks to make the towers more stable by interlocking.  The visual impression of the result surprised me:


Prepare for Wedo WRO My son is 5 years old and completely hooked on to Wedo. I would like to unlock the possibilities for him to explore his area of interest. One such avenue can be to prepare for competitions like WRO. Please advise on any information about the competitions - what are the things that need to be learnt. Also any open resources available for preparing can help.

LEGO has this page which mentions World Robot Olympiad (WRO) and FIRST® LEGO® League (FLL).  There's a tag for FLL (fll) on Bricks.SE so you can see what other folks have asked about it.


What are the dimensions of a technic axle? I'm working on a LEGO compatible motor system that will be largely 3D printed.  I want the connectors to fit standard LEGO axles, but I haven't been able to find the dimensions online, and I don't have any on me to measure.
What are the dimensions of the cross-section of a LEGO axle. Is there a difference in size between the plus-shaped hole for and axle and the axle itself?

I found CAD files for LEGO technic axles here: https://grabcad.com/library/lego-technic-axles-1
and some gears which have holes for technic axles here: https://grabcad.com/library/lego-technic-gears-1
Using their online viewer I found the following dimensions (Which are a little inaccurate due to the limits of their online viewers tools. For more accurate and detailed dimensions download a copy of the CAD files)

This would seem to indicate (if accurate) an interference fit between the outsides of the axles and the holes (i.e. the hole is slightly smaller) which could be accurate as axles are usually tight.
Someone should also probably measure actual LEGO parts with some calipers for confirmation on these dimensions.


Minifig wrist attachements? I'm looking to attach a weapon to a minifig's wrist ala an Assassin's Creed hidden dagger (https://www.brickwarriors.com/hidden-blade/) or a wrist-mounted crossbow. What are my options to do this?

Minifig hands, officially, are not to be removed. Lego doesn't make many accessories that fit the arms of the minifigs. The arm is slightly larger than the standard bar piece and so normal claw-shaped attachments don't fit. The minifig handcuff piece, which does fit over the wrist, is larger than the standard claw pieces.

You'll need to look to third-party solutions like the brickwarriors piece you linked in your question, or make your own pieces.


Database of parts with alternate numbers I am ordering parts for some MOC I found online. As I compare the parts needed against my inventory, I find that I already have some of them but under different part numbers. For example, I have part 30526 under 53540 in my inventory from the sets we have collected. It gets even more complicated for some parts like this one here and here, under five different numbers.
Is there anyway to retrieve  all the parts with alternate numbers?

What you are asking here is to have all possible part numbers for similarly looking elements. However, while both elements could look to be the same for you they may have significantly different properties.
Both Bricklink and Rebrickable have alternative numbers for the same mould, which is the case with the element in first URL. However, last two items are different elements - one has Thin support and the other comes with Thick support - which is why they are separated. It may be negligible for you, but someone else may find such difference essential.
Another approach would be to lookup by name - searching for "Arm Mechanical, Exo-Force" results in finding both elements, no matter if it is thin or thick version. Looking up by main properties (mainly size) can give you other, alternative elements as well. A good example here would be "Brick 2 x 4" - there is a classic 2x4 brick as well as some modified ones, that would all work fine when building, say a wall. But classic brick may not work if model utilize special properties of that particular modified version of 2x4 brick.
If your issue is with building MOCs that you found on Rebricklable you can adjust your building options. You can apply this permanently across the website in your setting page: Account > Settings > Building Sets/MOCs > Ignore mold variations in parts.

Or you can apply this setting for particular Set/MOC: Build this MOC > Change Build Options > Ignore mold variations in parts


LEGO Digital Designer Part Numbers When I go through these LEGO kit instructions (as an example)

https://shop.lego.com/en-CA/Telehandler-42061

I get the list of all parts and part numbers at the end of the PDF pages:

None of the part numbers in the above list are recognised by the LDD. LDD had different part numbers. Why is that?

Is there any easy way to convert part numbers mentioned in the instruction PDFs to the LDD part numbers? Or is there any easy way to have LDD recognize the part numbers in the instruction PDFs?

Update 1:

All of the parts in the 42061 kit are available in LDD, with different part#. You can see for yourself by taking a look at its LXF file available for download here:

https://www.eurobricks.com/forum/index.php?/forums/topic/41226-key-topic-official-lego-sets-made-in-ldd/&page=189

The two different number systems are:

Element ID: 6-7 digits, uniquely identifies a piece by shape and color
Part number: usually 4-5 digits, uniquely identifies a piece shape, stamped on many bricks

(Unfortunately an element ID is not simply a few numbers added onto a part number)

In LDD regular mode (not extended mode), you can search by both numbers. I was able to find the 3L blue pins by searching both element ID 4514553 and part number 6558. When in extended mode however you can only search by part number (many of those pieces listed are only in extended mode).

Generally, you can also search for an element ID on BrickLink and find the part number. Not sure about going the other way.


Is there a tool that can consistently remove hundreds of 2x2 Tiles? I have hundreds of 2x2 Tiles that I use to create LEGO City scale footpaths and floors. They are arranged in a grid on baseplates in a similar way as shown below:

Recently I had decided to rebuild the entire city and I've struggled to find a way to easily remove all the tiles. For some of the larger baseplates, I can make it easier to remove tiles by slightly bending the plate so that they pop out.

I have been using the chiseled end of the orange brick separators to remove the pieces. They work perfectly when new, unfortunately the chiselled edge is quite soft and it bends quite easily, becoming almost useless over time.

The other end of the brick separator is even harder to use and I have tried the old grey brick separator also.

Do you have any recommendations for tools (LEGO, 3rd part or non-brick based) for removing these pieces?

I would prefer not to use anything metal or that may damage the bricks.

The tool should also be comfortable to use for removing many pieces.

Try using the orange brick separator upside down. This is a trick I learned from someone who professionally works with LEGO. The lower angle makes it easier to go under the lip of the tiles and it is much less damaging on the brick separator, as you are more pushing and sliding rather than digging and prying.

To be clear, instead of holding the brick separator with the LEGO logo and the Technic pin on top, turn the brick separator upside down. You will notice that this transforms the angle of the tip into a little ramp that you can slide under the lip of the tiles.

For flat tiled surfaces, like the one on your picture, the upside down brick separator works very well, with very little (if any) damage to the brick separator. However, notice that this method also requires more space, as the brick separator needs to lie more flatly against the surface. For tighter spaces, like when you have a wall around the tiled surface, you would still use the brick separator right side up, as the different angle of the tip requires less space for removing tiles. Once you freed up enough space to lie the brick separator more flat, you may turn it upside down to work on the rest of the tiles.

The brick separator really is a well thought out tool that works for almost all scenarios when you need to separate LEGO elements. If you find it not performing so well one way, try from another angle, or upside down, or two brick separators together, and you will likely find it working much more efficiently.

EXTRA TIP: For very tight spaces, the LEGO minifigure accessory crow bar works very well for removing tiles. The tips on the two ends are different, and can be used at different angles. The only issue is that the tool is quite small, and for people with large hands it can be a bit difficult to maneuver.


Does soaking Lego pieces in isopropyl alcohol discolor or otherwise damage them? I need to clean my Lego including minifigures, printed pieces and cloth pieces from smoke (apartment fire). I have found that soaking the pieces in isopropyl alcohol removes the smell, but am I damaging the pieces by soaking them for 1 or 2 days?

First of all, sorry for your loss and we all wish you good luck recovering your bricks!

As for cleaning LEGO bricks, if you need to remove physically visible dirt, here you can find lots of tips on doing just this, or you can go over to the official LEGO website and heed their recommendations.

If the only problem is the smell of smoke, there is another question about getting rid of foreign scents, maybe you could find valuable information there. If I were in your shoes, I'd try the less aggressive, less risky methods first, and only gradually progressing towards the inorganic solvents if all the previous steps have failed.

There is a similar question over at Chemistry.SE, they might be more knowledgeable than us. But even if the ABS material of the LEGO bricks prove to be immune to the deleterious effects of alcohol, the minute amounts of other ingredients, coloring pigments or printed details might fare worse. LEGO however, recommends cleaning electric parts and pieces using alcohol though, but they specifically mention wiping, not soaking, and especially not for prolonged periods.

But if you really intend to use the alcohol bath, I'd recommend that you pick a few "volunteers" who will test the method before you apply it to the general populace, therefore only risking your less precious, more easily replaceable pieces.


Do old LEGO bricks contain lead, cadmium, or other hazardous elements? I have a set of LEGO bricks from Denmark and they were made in the late 1960's; should I be concerned about my son playing with them because of any danger of lead, cadmium, or other substances in the product?

No, you should not be concerned about lead.  LEGO has always used lead-free colors in their elements, even back in the beginning.

However, not all LEGO-compatible bricks are lead free.  For example, Mega Bloks, which are made in China, suffered from the poor quality control that led to massive recalls over lead-tainted products a few years ago.

  David Clerk, the magazine's publisher and the executive director of
  Les Editions Protégez-Vous, said that after consulting with Health
  Canada, the magazine hired an independent lab in Quebec to perform
  what he called a "total lead test" on 32 toys, including the Maxi
  blocks.

  Essentially, the process involves scraping off a sample of the toy's
  plastic, dissolving it in acid and then analyzing the solution.

  When the results were returned by a lab, which Clerk said he could not
  identify because of a confidentiality agreement, a yellow Maxi block
  was the only toy that exceeded the 600-parts-per-million limit for
  lead set by Canada and the United States. Blue and red Maxi blocks
  showed no lead at all.

  For confirmation, the magazine tested a second yellow block. It
  contained 1,180 parts per million of lead, nearly double the initial
  result.


Arranging claws radially and horizontally I would like to arrange 3 claws in a horizontal circle (parallel to the ground ), pointing outward from the circle with roughly equal radial distance (120 degrees) between them.  Any ideas on how I can do that?

Your claws will fit in this Technic element:

https://www.bricklink.com/v2/catalog/catalogitem.page?P=10288


Unidentified LEGO 6 bag set dated 2007, sand, dark grey, and dark red pieces with small dinosaur statues There's six bags here dated 2007:

Any help would be greatly appreciated.

Most parts are from 7627-1: Temple of the Crystal Skull, based on Wall Element 1X6X5, Abs and Limb Element,

There are also some parts from 3315-1: Olivia's House is the photo's, like: Wall Element 1X6X5, Abs, Fence 1X4X2 W. 4 Knobs & Flat Tile 1X4.


NXT light sensor homework help Read value from NXT kit using light sensor and show it in the middle of NXT screen.
If measured lightness value is less than or equal to 50, right motor will stop and left motor will move with the power of 35.
If measured lightness value is greater than 50, left motor will stop and right motor will move with the power of 35.

How can I do this?

Without solving your homework, you will need at least the following blocks:

for bullet 1

Light Sensor
Data to Text
LCD Panel Display

for bullets 2 and 3

Loop (forever)
Switch (based on light sensor readings)
Motor Block (4 of these, 2 for > 50% + 2 for <= 50%)

And it probably makes sense to put bullet 1 inside the loop of bullets 2 and 3.


Mindstorms EV3 education 1.4.2 for Windows crashes when opening second project The EV3 software opens the first project with no problems, but when I open a second project it crashes and terminates.
I tried to install the EV3 software on Windows 10 (MS Surface laptop i7,16GB RAM), or on Windows 7 (Thinkpad i5, 16GB RAM), but problems
remain the same.
Please guide me on how to fix it.
Thank you very much.

If the same project crashes your software on multiple installations, the problem is the project file itself. Sometimes files get corrupted. Unfortunately the only real solution is to recreate your project.


My EV3 program will not run despite clicking on the program from the brick This is a new EV3 Education Core Set. I have made a simple move forward command using the Lego Mindstorm EV3 Students Edition and downloaded it into the EV3 brick.  However when I press the program in the brick, nothing happens, not even a loading screen. When connected to the computer and the program is there, I just can't run it. How do I troubleshoot this?

I don't own the EV3, so unfortunately I can't help you with first-hand experience.  Here is a link to the LEGO site containing videos with everything you should need to know to get started.
Getting Started with LEGO® MINDSTORMS® Education EV3
Based on my experience with Mindstorms NXT, if you are sure the program is done correctly then make sure you chose the correct ports that your motors are plugged into.


Why are there no faces drawn on the black heads? There were two black heads in the Star Wars 2011 advent calendar and neither had a face drawn. Is that because there was no face necessary since it was going to be covered with a mask anyway or is there a rule that the faces only go on the yellow heads?

They made them solid black so there are no alignment issues when veiwing the masked minifigures. By leaving them blank LEGO ensured the eye slots always appear black. Side note: The only Stormtroopers seen without helmets in the StarWars Movies were Han and Luke in disguise, therefore Stormtroopers are faceless.


Can you identify this LEGO space set? I've just purchased a random box of Star Wars LEGO at a car boot sale and there's a few bits in there that I'd like to identify the set for.

It's not a Star Wars set, it's most of the main part from "70704 Vermin Vaporizer" from the Galaxy Squad theme.

The word "pressure" on the green tile hints that it's not Star Wars, as that would normally be in Aurebesh - the written script you see in the films.

It turns out the curved white roof tile (Circle 90G 6X6 Roof Tile) at the front was only used in three sets, which helps identify it.


Dan I open/repair this Duplo pullback motor? My son has a Duplo pullback motor.

This motor does not work well. After pull back it moves forwards 2 and a half wheel turns and stops. There is a small resistance forcing it forward two millimeters it makes a louder click and then the wheels rotate again 2 and a half turns to stop again. After forcing 2 mm it continues again and again until the spring is loose.

As there are no screws to open it and fix the mechanism I don't know how to open and fix it.

Can anyone give a tutorial to open it non destructive and fix it?

Some Lego assemblies like this are welded together or otherwise permanently assembled. Usually the best you can do is cut them where there are seams, then glue them back together. Or, if that seems like too much work, buy a replacement on Bricklink


Power Function Converter Cable for LEGO MINDSTORMS This is a follow up to this question:
How to use Power Functions with Mindstorms EV3?

The question was asked in 2013 (5 years ago). Fast forward to 2018, the product that was suggested in the answer is retired:
https://shop.lego.com/en-US/Converter-Cables-for-LEGO-MINDSTORMS-NXT-8528

Is there a replacement for the retired product?

Is there any better option, other than what is shown in this video?

https://www.youtube.com/watch?v=Ns3TODgRlCE

No, there is no replacement yet except soldering your own cable or using third party products. Basically the answers in that question of 5 years ago are all still valid.
Mind that LEGO is transitioning to a new power functions system (with motors and sensors as in the boost and WeDo 2.0 products), perhaps we'll see solutions for that quite soon.


How can I make an EV3 vehicle follow an elliptic equation? Has anyone succeeded in having the EV3 driving base moving following an ellipse? I would like the kids to think about how would we program a satellite orbiting around earth.

They would input the equation for the ellipse and then they will have the robot driving around it. Any thoughts?

I think it would be more realistic to have the robot drive in a straight line but have a linkage to the foci of the ellipse that "pulls" the robot towards the center of the ellipse just as orbiting objects are pulled toward Earth by gravity.

For example, you could use two nails in a board as the foci. Tie a string in a loop to use as the linkage. Place the string loop around the nails and attach to the side of the robot. Drive the robot forwards (no steering). It will travel in an ellipse. You could even attach a pen to the robot to draw the ellipse.


Capture video stream from LEGO Studio Camera (Logitech USB webcam) in ev3dev? Once upon a time, LEGO made a digital camera for the LEGO Studios and Mindstorms line. Internally it's an old USB Logitech camera repackaged in a LEGO housing.

It could also be used with the old LEGO Mindstorms software, to do some very weak video recognition when connected to a PC.

Fast forward some years, and Mindstorms are much more powerful, and even have a USB port, which this camera can be attached to, as some people have done.

When used with ev3dev, it's even possible to take some low-res pictures with it using a CLI tool like fswebcam.

However, I'd like to use it as a webcam, and capture a constant video stream from it, so I can use it in competitions where only official LEGO parts are allowed. Seems easy enough, but I've so far been unsuccessful.

It seems that OpenCV doesn't support the camera, because it uses an unusual pixel format encoding. Has anyone found a good solution for capturing a constant video stream? Something better than repeatedly calling fswebcam and parsing the output file (which would be unnecessarily slow).

Since I'm no software engineer my solution would be to retrofit the insides with known compatible hardware. Cheating? Maybe... but it isn't like the original hardware inside was actually Lego to begin with.  The mention of potentially using "compatible software" would seem to be already stepping out of bounds with "only official Lego parts", since it didn't come packaged with it. So...


Please help identify this set & figures Please help identify this set, and which sets these figures are from. Thanks!!

Set #8049 - Tractor with Log Loader.

???
Part # NBA005 - NBA Ray Allen, Milwaukee Bucks #34.

???
Part# NBA006 - NBA Pau Gasol, Memphis Grizzlies #16.


Identify LEGO set with "5T33R" sticker Tiny orange truck with license plate "5T33R". Also has "Steer Well" sticker, flames on the sides. Have searched and can’t find online.

That stickered tile seems to only appear in set 8186 from 2009.


Why can't I reproduce this SD card box in LDD? I've built an SD card box a few years ago. Now I am trying to reproduce it in Lego Digital Designer.

However when I tried to reproduce the closed version, LDD refuses to snap it in place.

In real-life, my box just snap very nicely. Why am I not allowed to do that in LDD?

Here is the WIP .lxf file

The issue here is that the hole in a Technic brick isn't at exactly the same height as the stud on the side of a System brick. Here's a slide from a great presentation which explains the details:

This difference is barely noticable when building, especially in your scenario because the hinge adds some additional play, but I believe that LDD won't allow these to connect because they are actually off by .12mm.

I tried to take a few pictures to demonstrate what I mean, but they didn't turn out very well. Here's a System brick (tan) connected to a Technic brick (blue). You can just barely see the .12mm difference at the top:

The difference becomes more obvious when more bricks are added so that the error is allowed to compound:


How can I get a direct hyperlink to a result on LEGO shop? When I visit the what's new page on lego.com, I'd like to be able to share a result list including the filter I set in the left column (in my case limit to Duplo). At the moment when I set Duplo I get an updated URL ending with productListing.jsp?_requestid=XXXX

Unfortunately, this URL is just relevant for my session and can not be shared. Is there any way that you know of to get a direct link to a result list on lego.com shop?

Unfortunately the shop.LEGO.com website has a number of issues, and the fact that all transactions are handled server-side and not bookmarkable on the client is one of them (this might be intentional on behalf of LEGO but I don't know why). Other issues are that from time to time the website will refuse to display search results (it will just show you the home page of the shop if you do), or that the navigation buttons at the bottom of a category listing ("View: 25 | 1 | 2 | 3 >") take you back to the home page. For those the best solution is to either close your browser and open a fresh browser, or to use the Private Browsing/Incognito Browsing options of your browser to simulate creating a new session.

For background, the shop.LEGO.com uses Java Server Pages (jsp) which store their status in a cookie and in server-side maintained information. So when you navigate, your browser does not know where you've gone to - only LEGO's server knows.  This all works fine as long as you have an active session with LEGO, but as soon as your session expires (e.g. when you bookmark a specific place on the site and revisit that bookmark a few days/hours later) all that information is lost.

TL;DR: No you cannot save a direct link to a page on shop.LEGO.com as that site is programmed to store link information on the server, not in the client (as a browser URL).


Bag 3 identification help! I have bag #3 with 539R7 underneath it. The plastic bag has 135149 which indicates it’s from 2011. The bag has red, black, and dark grey pieces along with 6 wheels.
Any help would be appreciated.

According to BrickLink, 60183 Heavy Cargo Transport seems to be the only set that has all of

Red 4 x 6 plate
White Tile, Round 2 x 2 with Open Stud
Tile, Round 2 x 2 with Open Stud


Useful machines built with LEGO I am looking for examples of useful machines built with LEGO (probably Technics, NXT etc.). There are many fun project examples and proofs of concept, such as a Rubik cube solver and a Turing machine.

Do you know any examples of LEGO machines that simplify some actual task or where should I look for examples?

Here are some examples that caught my attention in the last years:

Cambridge scientists are using LEGO Mindstorms in their lab instead of a professional robot, saving them large amounts of money.
The Kno tablet development team is using a LEGO rig to perform automated stress tests on their devices.
University of Southhampton is using LEGO bricks as the structural frame for a cheaper supercomputer (warning: they use the word legos).
Building custom encasing for electronics like this monster three-motherboard PC.
For automatic milling and sculpting, there are also plenty of examples of LEGO CNC machines. They can be used to prototype parts, make molds, etc. Here's one.
A loom machine to produce usable weaved cloths — pictures, video.
Pheromone Labs is using LEGO Mindstorms 2.0 to perform automated tests of a tablet app — link, video.
Low-cost nanoscope at UCL (news, main page)
Handling insect specimens (link)
UV-Vis spectrometer (Link)
Braille Printer (Link)


Resources to learn useful common Mindstorms mechanical construction patterns I'm currently working on building a small scale CNC-like (X-Z, no Y axis) machine to cut glass mosaic tiles.
I decided to give it a go using my EV3 set and I'm having some trouble with the Z-axis movement.

I find I'm loosing too much time figuring out by myself how to build what I'd expect are known elementary construction units, or what I'd call "patterns" (get my SW Eng bg? :-)). For example: a circular-to-linear movement using the medium servo (push vs pull), commonly used gear assemblies, duplexing servo movement axis, etc.

I'm looking for resources where to learn some basic construction patterns that would help me speed up building more complex structures.  For example, a while ago I saw a book that seemed to contain some construction patterns -> combining gears, how to build strong structures, ... I can't find it anymore.

Any available online/offline resource that could help is welcome.

I've had trouble finding good examples as well. One of the most interesting one is, sadly, in Spanish, but the images (and some help from Google Translate) helped me some. Hopefully it can be a start.

http://www.hispalug.com/foro/index.php?topic=11730.0


Is it possible to use a LEGO NXT ultrasonic sensor for a LEGO train crossing? I was looking at LEGO NXT components, and I found the ultrasonic sensor. I was wondering that if I put off to the side of the track, the nose of my train would activate the sensor, thus operating the servo and closing the gate?... I have already prepared my crossing with a gate attached to a 12 stud axle. At the end of the axle pointing away from the track, a servo would  move the axle at about 45 degrees. Is this possible or are there any alternatives that would work better? I'm not sure if my idea has been attempted before with Power Functions tracks. Also note that I am using a 32x32 base plate. I am hoping that I won't have to use a Mindstorms control panel (I'm not entirely sure what they're called) because they are so expensive.

As you suspected, you cannot use the Ultrasonic sensor without an "Intelligent Brick" (EV3 or NXT). MINDSTROMS would be a great way to automate your train if you are willing to make the investment.

For more ideas on how to use LEGO MINDSTORMS with LEGO trains, check out Sioux.NET.


Is there difference between different colors of LEGO axles? There are a few different colors of LEGO Technic axles, but not enough to really use for artistic variation - black, grey, some beige, and recently I have started seeing blue.

The particular color used in different Technic sets seems arbitrary to me. Is there a difference between the different colors aside from just the color, like a slightly different size or tensile strength?

The first LEGO axles were milky white and were probably made in a different plastic than they are now.

Later on, LEGO started making all-black axles when they started doing more serious technic sets. However, the tendancy is now to make sure all difficult technic pieces are "color-coded" so that children can pick them out more easily. As such, nowadays, the following axle lengths and colors are standard:

2: red, notched
3, 5, 7, 9: (new) grey - no 11 yet as far as I know but I suppose it's just a matter of time
4, 6, 8, 10, 12: black
3 with stud: dark tan
4 with stop, 5.5 with stop, 8 with stop: (new) dark grey

Similarly, 2L friction pins are black, non-friction grey, 3L friction pins are blue and non-friction tan, and so on. All that to make sure they're easy to pick. Even gears are being changed now, for example the classic 24T is now dark grey.

That said, there have been other colors used for axles, when the color itself was important. I've seen tan, red, green, brown, but possibly others exists. The long ones (32 and 16) have also been produced in black, white, and yellow (32 only).

As far as I know the plastic used is always the same, so they should all have the same mechanical properties.


Lego Pneumatic Engine: Possible Damage from Baking Soda and Vinegar? I have a question on Chemistry.SE about secondary reactions producing something other than CO2, and from a bit of discussion there, the answer seems to be that there aren't any, but some of the original ingredients can get splashed up into the LPE.

So, has anyone tried doing that?  If so:

What was your setup?
How did you clean the LPE afterwards, if at all?
Was there any damage after a few days?

I'm thinking about a 3-step process, but I'm also wondering if it's even necessary:

Run it on Baking Soda and Vinegar as planned.
Run it on Water to rinse out whatever raw ingredients might have gotten into it.
Run it on Air to dry out the water.

The water is probably from a garden hose, with the unsolved problem of how to hook it up to a Lego hose.

The air is probably from a shop compressor with the regulator turned down.  I have a bicycle pump for testing, and a sports inflator needle to make the connection, but I don't think I want to pump it that much!

The reason to use Baking Soda and Vinegar at all, instead of just using Air in the first place, is to have a compact, self-contained system that can run itself around a track for a while, and be able to start and stop on command without over-pressurizing for lack of use or running out from constant use.

So, I've rigged up a pressure-regulated, motorized air pump to displace vinegar out of one small plastic water bottle, and into another that has the baking soda, which then creates the working gas.

I've seen a big bank of pre-pressurized soda bottles on an LPE-powered car, but that's just too bulky for what I'm doing.

Some pictures may help:

The water bottle sits horizontally, under the black "hold-down bridge", with the bottom against the RCX.

"Steam" locomotive with Walschaerts valve gear.  And yes, it runs.  :-)  Both directions.

(Wires and sensors are in false color to show the connections.)

There's also a tender car with the other water bottle and the air pump to displace something out of it.

I see two main problems that need to be adressed here.

Intrusion of liquids into the pneumatic system
Intrusion of solid particles into the pneumatic system

To filter out solid particles, namely baking soda, a fine mesh could be used, either alone or in multiple layers.

To get rid of droplets, some absorbing material such as cotton could be inserted before, after or rather between the layers of mesh.

So if we can suppose that the bottle will have an exit point that is always clear from the liquid-solid phase (based on your comment "with hose connections in the cap"), we can imagine the following filter system built inside a small diameter tube (like a plastic straw), where # denotes layers of fine mesh fixed inside the pipe, capable of holding back both baking soda dust and the loose cotton swabs:

 ________________________________________
/                                        \
|                                         \
|                                          \
|                                           \___
|                                               |
|            #cotton#cotton#cotton#cotton#======+
|                                            ___|
|------------------------------------------ /
|    o     8      O   Ö    *     0    .    /
|  °    vinegar + baking soda   :    ö    /
\________________________________________/

Or if you need to fill the bottle more than halfway, but can ensure that the sloshing will not reach the top of the laying bottle, then you might be able to use a doubly-bent straw:

 ________________________________________
/                                        \
|        #cotton#cotton#cotton#cotton#=\  \
|                                      \\  \
|                                       \\  \___
|----------------------------------------\\-----|
|  :         *           ö                \=====+
|       o      Ö    0        8     O    .    ___|
|   °                 Ö                     /
|    o     8      O        *     0    .    /
|  °    vinegar + baking soda   :    ö    /
\________________________________________/

But as MaxW has noted on your question over at Chemistry.SE:

  You won't get pure CO2 out of an aqueous solution. There will be water vapor in the CO2.

So your metal parts will definitely be exposed to a (probably highly diluted) carbonic acid, that "can corrode, rust or pit steel but the extent of those effects depends upon the chemical composition of the steel. Stainless steel, in contrast, resists general corrosion caused by carbonic acid." (Source)

How fast of how much will the parts be corroded? I can't find a definitive answer for that, but in the end, it all comes down to three, highly variable factors:

The exact composition of the steel used in your pistons (pretty much unknowable, especially since the particular pistons are about 20 years old)
The concentration of carbonic acid in the generated stream of CO2 (depends on the filter, the water content of the vinegar used and probably other factors as well)
The duration of exposure (that can be minimized by applying the cleaning steps outlined in your question, but consider that rinsing with water brings another set of problems, like limescale or rusting - so if I were you, I'd skip step 2 and only run it on warm, dry air to remove any moisture from the system)

Looking forward to read your experience!


What 1x8 ski part is this? I looked through the usual places BrickLink/Rebrickable. I can't seem to find what part this is. It has no markings other then Lego and LEGO Group. I seem to remember it going to a set where this singular ski part goes in the front.

This seems to be item No. 2823

Technic Forklift Fork (white)

It was part of four sets:

6342-1 Beach Rescue Chopper

6545-1 Search N' Rescue

6401-1 Seaside Cabana

6663-1 Wave Rebel

All images bricklink


Is there a way to plan and organize your LEGO project like a GitHub hosted software? I have the idea to host, plan and maintain a LEGO project (building a MOC in several steps with different functionalities) like a software in GitHub. The project should have forks, pull requests and version tracking.

Is there a possibility to do this with existing software? LDD, Leocad, Stud.io in combination with GitHub or similar?
How to realize a crowd/community project that builds on a LEGO model? What functionality might be needed?

While you could indeed manage the project with a tool like GitHub (using the Issues feature), you might be better off initially managing the tasks through a tool like Trello which allows you to create tasks and move them through various status (i.e. Planned, In Progress, Review, Complete) in a fairly simple, intuitive user interface.

An issue with managing the actual project files within source control is around the format of them - some file types work better than others when it comes to source control, and some formats of those types work better than others as well.

Git is a "Distributed Version Control System", which means that anyone can work on any file in the repository on their local machine - this is usually fine when working with text based files, but is not so good when you have binary files, because understanding the differences between two versions is often not easy. If the tool you choose stores projects in binary files, Git is probably not the best option.

I would strongly recommend that you consider a Centralised Version Control System such as Subversion (SVN) or Team Foundation Version Control (TFVC or TFS) as this allows your collaborators to "checkout" or "lock" a specific file to say they are working on it, and then when they've updated it, "check-in" their changes - this will (hopefully) get around the main pain points of trying to merge changes in these files, albeit with the caveat that you might still have people check-out a file and then "go dark" and forget to check it back in for a long time.

Sadly for you, most developers have moved to Git based source control, as it's very good at dealing with code files, and generally much quicker when working locally, allows for "offline" working, etc. and solves the problem of people working on different parts of the same file or project simultaneously, so most of the free options (GitHub, GitLab, etc.) focus on that. You might be able to use the free options within Azure DevOps to create a TFS based project, or find another SVN host for your project. Most of these also offer "Work Item" tracking for task planning and management.

In terms of the current software for building your MoC, the likely contenders are:

Stud.io - uses a binary (.zip) format. This doesn't play well in Git. Furthermore it's a password protected archive, so you can't easily extract the underlying .ldr files.
LDraw - uses a text based format. Potentially a better fit for Git, however the format itself would be very easy to mess up in merges if two people work on the same model files at the same time.
LEGO Digital Designer - uses a text (XML) based format. Potentially a good fit for Git. While XML can get messed up in merges, it's usually easier to see in merge tools where the changes should belong, and so easier to correct/adjust if two people work on the same model file. However, this is likely end-of-life now, especially with the announced purchase of BrickLink by The LEGO Group.

  What about Studio and LEGO Digital Designer – what will happen with the
  two digital building experiences since they’re quite similar?
  The LEGO Group is planning to support and evolve Studio and will review opportunities
  for both services following the closing of the deal.


Sloped pieces in winter scene I'm trying to build a winter scene similar to this scene.  Can anyone identify the large sloped/curved white pieces on the rivers edge, near the bottom of the picture?

Looks like Windscreen 6 x 4 x 1 Curved. This piece doesn't come in any of opaque colors yet.


Problem with running two XL motors motors We are trying to run our Grand Prix racing car on remote control and would like to use two XL motors for the wheels. One motor on its own works fine, but when connected together the motors stop running. Could it be that the battery power isn't strong enough for both?

As others have said, it's difficult know what is going without seeing your design. I would expect what you have described to work, but it is possible that your design is overloading the over current protection in the battery box.

PF battery boxes are designed to provide 800mA. Any more than this, and they have protection built in to cut power and prevent damage.

LEGO indicated that the XL motors draw 300mA under normal conditions, and Philo has the stalled current listed at 1800mA. A single stalled XL motor can overload the battery box, and two of them working hard can easily as well. See this answer for more information.

As a quick check, if you disconnect the motors from your car so that they can just run free, are they able to both run as expected? This should work fine and draw only 160mA if everything is connected and working properly. If not, one of your components must be performing abnormally or not be connected properly. As others have said, a photo would help us diagnose connection or build issues.


Help identifying which set this bag is from? White plates and Technic panels and transparent red circle plates? Can anyone help to identify the set that is shown in the photos?
They were in a bulk lot of LEGO - so no manuals, no box.

Thanks!
Dale

Given the transparent red Plate, Round 4 x 4 with 2 x 2 Hole, white plates, and trans-blue Windscreen this is set# 76028 Darkseid Invasion from the Justice League series.


Is this red axel bushing an original Lego part? Is this an original Lego part? Technic maybe?

This is

Part# x1299 : Technic Bush Old 1


EV3 with NiMH batteries Could I use 6 NiMH 1.2V batteries and keep pressed the small black circle in the battery compartment in order to adjust the battery gauge and low battery alarm?

EDIT:

Yes, pressing the button will affect the indicator and low battery alarm/shutdown.

From the official LEGO firmware:

#define   BATT_INDICATOR_HIGH           7500          //!< Battery indicator high [mV]
#define   BATT_INDICATOR_LOW            6200          //!< Battery indicator low [mV]

#define   ACCU_INDICATOR_HIGH           7500          //!< Rechargeable battery indicator high [mV]
#define   ACCU_INDICATOR_LOW            7100          //!< Rechargeable battery indicator low [mV]

...

#define   LOW_VOLTAGE_SHUTDOWN_TIME     10000         //!< Time from shutdown lower limit to shutdown [mS]

#define   BATT_WARNING_HIGH             6.2           //!< Battery voltage warning upper limit [V]
#define   BATT_WARNING_LOW              5.5           //!< Battery voltage warning lower limit [V]
#define   BATT_SHUTDOWN_HIGH            5.5           //!< Battery voltage shutdown upper limit [V]
#define   BATT_SHUTDOWN_LOW             4.5           //!< Battery voltage shutdown lower limit [V]

#define   ACCU_WARNING_HIGH             7.1           //!< Rechargeable battery voltage warning upper limit [V]
#define   ACCU_WARNING_LOW              6.5           //!< Rechargeable battery voltage warning lower limit [V]
#define   ACCU_SHUTDOWN_HIGH            6.5           //!< Rechargeable battery voltage shutdown upper limit [V]
#define   ACCU_SHUTDOWN_LOW             6.0           //!< Rechargeable battery voltage shutdown lower limit [V]

The BATT_* are used when the button is not pressed and the the ACCU_* values are used when the button is pressed.

ORIGINAL ANSWER:

The small black circle is used by the Li-ion battery pack from LEGO. This battery pack actually operates at a higher voltage that Alkaline batteries. On the other hand, NiMH batteries operate at a lower voltage than Alkaline, so pressing the small black circle would have the opposite effect of what you are hoping that it will do.


I can’t run the NXT 1.0 program software on my Mac version 10.6 How do I fix this? I run the install program, restart my computer, go to the “Applications” folder and there is a folder named “LEGO MINDSTORMS NXT”. I open the folder and there are three “options”: a folder named “engine”, a ".ini" file, and a “uninstall” file. I’ve browsed the “engine” folder and it’s full of ".ini” files. The “uninstall” file is a text file.

I don’t have any idea of what to do next. Please help!

You can get the Mindstroms NXT 2.0 software from here. It will run on newer versions of OS X.


Programming on a chromebook with EV3 How do I install the new Lego block programming software on a chromebook? We have the standard version, but want the new one that looks like Scratch.

Can you just install Scratch? MIT supports EV3 directly


Does Enlighten Brick mainly produce copies of old LEGO sets? I have recently purchased the Enlighten Brick Black Pearl set. It seems to me though that the set is not an original, and is mainly a copy of a prior LEGO set (6285).

Is it true? And does it apply to all Enlighten Brick products?

Enlighten Brick is a Chinese LEGO knock-off brand.

A lot of, if-not most of, the sets the produce are basically copies of existing LEGO sets, either current ones or popular retired ones.

From their website though, they do appear to have some of their own designs.

Edit by Phil B: Word of Warning: By buying counterfeited sets (such as these Enlighten Bricks copies of LEGO sets) you are sponsoring illegal activities, which if not stopped might ultimately cause irreversible damage to the LEGO brand and the high quality, original sets it provides. Enlighten can offer sets for less than what the equivalent LEGO set would cost purely because instead of investing in R&D they have stolen LEGO's Intellectual Property.


EV3 T-Rex we build keeps toppling over on step I'm building the standard T-Rex project from Benedettelli's book.

We double checked construction and also step my block - all looks correct.

Any pointers appreciated.

I built a walking machine when I was a kid several (cough) decades ago, and it had a similar problem. We finally figured out that what I had built was very front-heavy. Weight has to be balanced equally, forward and backward, over the "hips" of the creation. Pick up the creature by the top of the hips and see which way it swings. I solved the problem by adding a longer tail. You might also try putting the head up in a higher position or moving a battery case rearward.


How do you make a triggered counted ball drop? Is there any solution on making a drop of a counted number of balls when one ball passes through the system?

For example: One ball falls into a hole on the top and ten balls (plus/minus (not important) the ball that fell in) come out.

I have thought about letting one ball drop into the system and activating a lever which pushes open a tunnel with a lot of balls in it and the lever then self-closing afterwards. To limit the number of balls dropped there should be a closing mechanism on the upper side of said tunnel that closes when the tunnel itself opens, so only the balls in that section would get dropped...

But how would you do that without jamming?

If someone cares about the ball-size and weight, that should not really matter because the basic construction can always be a little bit reconfigured if the ball size is between 12 and 15 mm. Same for the weight.

EDIT: There has been some misunderstanding apparently, I am sorry for that. It should be noted that this mechanism should be repeatable for as long as you have a supply of balls coming in from a second source (auto-refilling of the reservoir). While this itself is not an issue because you can simply make a big pressure-based ball reservoir that gets triggered everytime the small reservoir empties, it is an important aspect because it means the whole mechanism should not only be able to run one time.

I've seen this done in a GBC module that counts the balls that pass by. It worked with scales that eventually tipped over, each scale representing a decimal of the total number of balls that passed by.

Can't exactly find the GBC module but found this clock from jkbrickworks that uses the same principle.


Are transparent neon Lego bricks made from a different plastic than usual? There are several colors of transparent, fluorescent Lego bricks. In particular, "trans neon yellow" and "trans neon orange", introduced in the early 1990s, exist in a variety of specialized shapes like skis, satellite dishes and visors.

A Eurobricks discussion on why minifigs are not made from transparent colors suggests that the transparent colors require a different plastic resin than the normal bricks:

  I think some of the issue is that (according to Jamie Berard [Lego designer]), the transparent bricks are made from polycarbonate plastic (PC) rather than ABS. And that's fine most of the time, when you've got opaque ABS and transparent PC, it works just fine. ... But when PC and PC parts get next to each other, they bond VERY TIGHTLY.

I've never really noticed this issue with transparent bricks, but perhaps it's only an issue for certain blocks or with the flexibility needed in minifigs. Still, it's good to know the characteristics of what you're working with!

I can find plenty of information about the normal ABS bricks, but little specifically about how  the transparent neon Lego bricks are made. Are these bricks made from PC rather than ABS?

All of this is correct, ABS can't be transparent and thus transparent parts are made of PC.
PC against PC bonds way too tighly and designers are actually forbidden to do that in their models. (I've a 4L lightsaber blade stuck in the crossend of a Technic beam, both trans-red, and I can't get it out.)

I'm fairly sure there's a designer (possibly Jamie Berard indeed) presentation on things forbidden to designers but I can't find it back.

Edit: @Grandpappy found it back: http://bramlambrecht.com/tmp/jamieberard-brickstress-bf06.pdf and it's indeed by Jamie Berard. Worth reading again and again.


My Blocks with return parameter I have the retail EV3 kit and have created a function with in and out numeric parameters.

While using the [in] params seem quite straight forward, it seems that I can only set the [out] param once. Dragging a second wire from a constant or variable will not connect when I place them.

Can I only set an [out] param once?

Does setting the [out] param act like the "return" keyword?

I have had a look around, but there is very little help on the EV3 My Blocks at present.

Bad, but simple example:

Please note that this is a simplification of the problem, and in this case I could set x to -1 or have another case in the sensor switch to set x to -1. I am trying to explorer the limitations of EV3 My Blocks out parameters.

Can I only set an [out] param once?

Yes. You cannot tell it to be 2 different values at the same time. This applies to any block, not just the output block.

  Does setting the [out] param act like the "return" keyword?

Not really. The return keyword in most (if not all) programming languages causes the function to exit, which is not the case here. It just allows you to assign the output value (or values - you can have more than one output parameter).


Towards a different sort of set-identification I thought it might be fun for the holidays to try a different sort of set-identification.  Even though I know which set this is, it seemed like a pretty random set of bricks so I thought it might provide a brief challenge to the community.  Here it is:

If this proves to be an actual challenge I'm happy to add hints later.

40205 LEGO Holiday Little Elf Helpers. :)


What sets are these vintage figures and wheels from? Where do these belong to? (their head/body/hair/hat might be mixed up).

Here are the parts you're looking for:
wheel
wheel
2x4 wheel
wheel base 2x4 and so on
arm holder
hand
arm part
also arm part
female hair
head with freckles
cap
Based on the collected links, this might be one of the sets you own. It is too challenging for me to identify any others, sorry for the inconvenience: https://www.bricklink.com/v2/catalog/catalogitem.page?S=200-1#T=S&O={%22iconly%22:0}


ERROR CODE 7- Cannot download needed file for the program I am kind of new in LEGO MINDSTORMS, I tried to download a program to the NXT robot and got the Error code 7- "Cannot download needed file for the program" - can someone tell me what should i do?

This is most probably an accessory file (sound or image) not present on your machine. Verify all the sound or display blocks that might use such non-standard contents.


Monorail Switch Internals I'm trying to figure out how monorail left and right switches work internally. Tearing one apart risks permanently damaging it so I was hoping to find schematics or images of someone else's teardown. Does anyone have a good picture or description?
Note that I've found a Eurobricks thread with broken links to a Flickr album and a fan written PDF. I was unable to track either down online so perhaps copies of these could help.

I have found the linked .doc file by using the Wayback Machine, consider making a donation to their awesome service if this has saved you time and/or money :)
But in order to reduce load on their servers and provide a backup, I have reproduced the contents of the document below:

Anatomy of a Monorail Switch
Introduction
This document describes the features and components, both internal and external, of a LEGO monorail switch (or point). Suggestions on how to disassemble and reassemble the switch are also given.
For those few reading this that are unaware of the operational features of a monorail switch, the switch rails (point blades) can be changed both manually, from a slider at the side of the switch, and also semi-automatically, by trip levers set into the running rails of the branches. These trip levers change the switch rails to the correct branch if a train comes down the branch with the switch set against it.
DISCLAIMER: The content of this document is provided “as is” for information only. Neither the author of this document nor the hosting web site will be held responsible for any damage sustained while attempting to follow the content of this document.
External Features
The following annotated photos show the key external parts of a monorail switch

General top view of the switch

General bottom view of the switch
Internal Features
The following annotated photos show the key internal parts of a monorail switch

Underside view of the track bed

Top view of baseplate
Sub-parts
Track bed
Part numbers 2880 (right) and 2885 (left)

Part 2880 – Right trackbed external (top) and internal (bottom) view
The left trackbed (part 2885) is a mirror image.
Baseplate
Part numbers 2881 (right) and 2886 (left)

Part 2881 – Right baseplate external (top) and internal (bottom) view
The left baseplate (part 2886) is a mirror image.
Switch rails (point blades)
Part numbers 2882 (right) and 2887 (left)

Part 2882 – Right switch rails.
The left switch rails (part 2887) are a mirror image.
Switch
Part number 2883

Trip lever
Part number 2890

Each monorail switch contains two of these parts
Lever rod
Part number 2911

Each monorail switch contains two of these parts
Switch wheel
Part number 2884

Spring

Operation
Set to straight branch

External view showing position of switch, “unused” switch rail and raised trip lever on the curved branch.

Internal view showing “at rest” position of the internal mechanism
Set to curved branch

External view showing position of switch, “unused” switch rail and raised trip lever on the straight branch.

Internal view showing “at rest” position of the internal mechanism
From straight to curved

This annotated photograph shows the motion of the internal parts when moving the switch rails from the straight branch to the curved branch. All joints (due to the angles they make), and hence the parts, have a “preferred” direction of travel and these all coincide with the direction they must travel for the mechanism to work smoothly.
From curved to straight

When moving the switch rails from the curved branch back to the straight branch, the reverse of the motion shown in the annotated photograph above should happen. However, the joint highlighted has a problem. This joint is very close to a “point of singularity”, that is, where the joint is in such a state that it can move one way or the other without preference. If it moves in the direction of the red arrow, the mechanism will effectively lock the switch rails, if in the direction of the green arrow, the switch rails will change to the correct position. Due to the slight wear on the parts in this particular switch, the joint has actually gone past the point of singularity “in the wrong direction” and its preferred direction is now upwards! (This also explains why you can sometimes get a stuck switch to work by placing on its long straight edge and gently tapping it, as gravity will pull the joint back the correct way.)
Disassembly Procedure
It would appear from external inspection that the baseplate can be removed from the track bed by simply turning the switch upside down, releasing the five retaining clips (see underside image above) and prising the baseplate up and out. If you attempt this it will not work (even if you manage to release all five clips at the same time) as the baseplate is also glued to the trackbed at various places.
Baseplate retaining clips
Whether the five retaining clips were originally intended to fully hold the baseplate to the track bed or whether they were only intended to hold the two parts together while the glue dried is unclear. Whatever their original purpose all they successfully do while trying to part the baseplate from the trackbed is to get in the way.
Given that it is almost impossible to hold them in the unclipped position while freeing the glued parts and that they are likely to fracture due to stress while freeing the glue, it is easiest to carefully cut the lip from each clip thereby releasing the baseplate from their grasp.
Glued supports
With the retaining clips removed it is now necessary to part the glued supports. Using a blunt thin wedge (such as a jewellers screwdriver), carefully insert it between the baseplate and the trackbed at the end of the straight branch and lever the baseplate upwards. Take care not to cause stress marks. If the baseplate won’t lift, don’t force it, try the end of the curved branch, don’t force it, try a different place on the end, try slightly down one side, don’t force it, try the other side, try further down a side, and don’t force it. Eventually the glued joint between the trackbed and the top of the support at the end of a branch will fail and the baseplate will lift sufficiently to get a long bladed craft knife in. Carefully using the craft knife separate the trackbed from the glued supports at the end of each branch and around the area where the frog would be on a standard two-rail switch. Don’t try to cut through the supports with the craft knife, use the blade to apply pressure where the top of the support has been glued to the trackbed – as if you were trying to cut through the glue.

Photo of the removed baseplate, highlighted to indicate the position of the glued supports.
Once sufficient supports have been release it is possible to start removing the trip levers, lever rods, switch wheel and switch. Doing this provides more room to work inside the switch and also reduces the chance of damage to an internal part should the craft knife slip.
The glued long supports by the straight edge of the switch should be attempted last. Take extra care over these as you have to prise the trackbed and baseplate quite a long way apart to reach the knife all the way from the other side and this will cause a large amount of stress on the curved side wall of the trackbed. This is not made any easier by the fact that this is the wall with the three switch rail access slots in it which weaken the wall.
It took me a good hour and a half to fully separate the baseplate from the trackbed.
Assembly Procedure
Before re-inserting the internal sub-parts, using a sharp craft knife, carefully de-burr the supports, underside of the trackbed and any place where the blade slipped. Then remove all swarf from the parts, either with a lint free cloth or by blowing.
Insert parts
Replace the switch rails (point blades) if you removed them. Turn the trackbed upside down and insert the sub-parts starting with the switch wheel. Make sure that the switch wheel fully engages with both the spring and the switch rails. Insert the trip levers into their slots. Insert the switch onto its runner and connect to the straight branch trip lever. Insert the trip levers into their slots and join the curved branch trip lever to the switch wheel and the straight branch trip lever to the manual switch with the lever rods. Finally replace the baseplate.
Test operation
Before re-gluing the baseplate check the operation of the switch. The only real mistake you can make is to use the wrong slot in the switch wheel to engage the switch rails. If you do this the switch rails will not fully travel to the straight position but stop about 3/8ths of an inch short.
Glue baseplate
Important note: Observe all usage instructions and hazard warnings while using liquid glue.
To complete assembly it is necessary to glue the baseplate back to the trackbed. One option would be to apply a tiny blob of plastic model glue to the top of the supports released during disassembly. However, this runs the risk that the glue will spread where it is not wanted and seize an internal part or that an internal part will be dislocated from its correct position while the baseplate is inserted.
It is therefore preferable to “dry assemble” the switch and use liquid glue (also known as MEK) to secure the baseplate to the trackbed. Check the internal parts one final time (for burrs and swarf) and assemble the switch. Test the operation and then use some temporary means to hold the switch together. I use copper wire, metal paper clips (the big ones with arms that fold over to open them) and modellers G-clamps with soft metal faces (and not elastic bands, sticky tape or masking tape as I’ve managed to glue all of these to the plastic models in my youth!) Once the switch is held temporarily, turn it over and make sure it still works (and doesn’t rattle!), then, when satisfied that all is correct, turn it back over and using sparing amounts of liquid glue (and being aware of where any excess will run) glue the baseplate to the trackbed.
Thoughts
Lubrication
As all the internal moving parts are plastic there seems little to be gained from attempting to lubricate a “sticking” switch. The “sticking” is most likely to be cause by wear on the bearings/sliders or from foreign matter causing an obstruction. If the former, there is very little that can be done. If the latter, a strong blast of air (from one of those cans of air for cleaning computer keyboards) is probably a better bet as most lubricants (being sticky themselves) will only cause the foreign matter to combine into larger obstructions or aggravate the situation by attracting dust, etc into the internal mechanism. Also, the most obvious places to apply lubrication (in the switch running groove, on the lever rod bearings, on the switch wheel bearing and slot and under the trip levers) are almost impossible to reach without disassembling the switch.
Design – Brilliant or Flawed?
On initial inspection the design of the internal mechanism seems brilliant – economy of parts, reuse of parts between left and right switches and simplicity of function. However, I believe that there is a major design flaw in the design that failed to allow for normal wear over the life of the switch. The position of bearing for the lever rod on the switch wheel is very close to a point of singularity. This means that as the bearings wear the mechanism (when activated from the trip lever on the curved branch running rail) can either change the switch rails to straight or lock them in position.
Do you need to replace everything?
The only internal parts needed are the switch wheel and spring. With just these two parts the switch rails can be moved from straight to curved to straight by “the big hand” and will lock in position. Adding the manual switch enables the switch rails to be changed from the side and adds the possibility for motorised/pneumatic operation. The curved branch trip mechanism seems to cause the most problems (and was totally jammed on the switch I disassembled that gave rise to this document) and is beginning to fail on a number of other monorail switches I have. I therefore omitted the trip lever and connecting rod when I reassembled my switch. This is not a problem for me as the curved branch of this switch enters a siding, so a train should never be set to run through it when set to the wrong direction.


Help identifying piece with slide handles on both ends I'm trying to build a custom build from YouTube and it contains a piece that I've never seen before. I'm completely stumped. Can anyone identify the brick and part number?
I've attached the image. It's from this video @ 2:17
Any ideas??


Any substitute / schematic for Mindstorms 2.0 IR tower? I came across a used Robotics Invention System 2.0 set, but in addition to a few missing bricks, it is missing the IR tower. Is there any generic replacement that I can use to program the RCX or does anyone know where I can find a schematic to build my own? Thanks...

There is no non-LEGO product that can substitute the infrared tower used for communicating with the RCX, as the USB and Serial towers use a very specific protocol that does not match that of other Infrared devices. Nonetheless, it does appear that there are schematics available for the IR Tower, courtesy of Mark Bellis:

I'm no expert on low-level electronics, but it looks like this site has a lot of additional information that could be useful if you want to replicate/manipulate the IR tower.


Minifig with multiple arms? Is there a minifig that has multiple arms that all have the ability to hold weapons or tools? My 4 year old is asking for one. I thought maybe Doctor Octopus, but can't tell by the pictures if his octopus arms can hold things.

There are already quite a few multi-armed minifigures. I usually won't count Doctor Octopus as one, though. But I'll count it this time.
The very first minifigure to be able to hold more than 2 tools is Doctor Octopus, from the "Spider-Man" theme from 2004. This was achieved by building a harness that goes on the neck. This version appeared in 4 sets, all in different variants.

It should also be noted he received a 4+ figure version, which is aimed to kids 4 and above. This version is not exactly a "minifigure". His tentacle harness is built into the figure, and is not removable. This one was released in 2 sets.

2012 brings another Doc Ock, based on the Ultimate Spiderman TV show, using a similar trick as the 2003 version. This minifigure only appears in one limited edition set.
The 2019 version includes a simplified harness with droid arms, significantly restricting movement, which was reverted in 2020 to a design closer to the original.

The next multi-armed minifigure is General Grievous from the "Star Wars" theme, hailing from the 2005 "Revenge of the Sith" subtheme. He was made out of a specialized head and torso; however, his legs and arms are common droid parts, with 4 of these arms attached to the special torso. This version appears in 2 sets, though one is more highly sought after due to Grievous having an exclusive cape in that one. Both versions came with his iconic lightsabers, but his arm posability are rather limited; they only move sideways, and their wrists don't hinge.

Grievous gets a re-release in 2010 as part of the Clone Wars subtheme. This was, accuracy wise, a major leap. He was composed completely out of exclusive pieces. Now his arms hinge up and down, but like a lot of other LEGO robots, his wrists still don't turn. Also, his second pair of arms attach to the first pair, giving a rather awkward looking angle and less posability. This version appears in 4 sets: 8095, 9515, 75040 and 75199.

Next, we have Frenzy. Frenzy is a Space Police Minifigure released in 2009. He was a large step forward to the original Grievous. He had a special molded head that goes over his regular, albeit uniquely printed, Minifigure torso. This extra head has a twist: it has room to accommodate a pair of droid arms, giving him 4 arms, although the upper two has little use, since their grip is permanently sideways. Still, it's a step up. Frenzy only appears in one set.

2011 brings about Samukai, the former king of the underworld of the Ninjago theme. Samukai is similar to the other skeleton soldiers, but with a massive head that, like Frenzy, fits over his torso and has room for arms. As an addition though, his upper jaw and lower jaw is separate, so he can open his mouth. His head is designed so it can snugly accommodate a second row of skeleton arms. Samukai's top-heavy stature caused by his head prevents him from getting his own spinner, thus making Samukai only appear in 2, very large Ninjago sets from 2011.

In 2012, Garmadon, Ninjago's antagonist, becomes four-armed through less-than-known means. He is the one I truly consider the "first" four armed minifigure. He had a specialized body extension piece that goes over his torso, which is the same as the one in 2011, and a head that goes on that torso extension. He appears in 2 sets, both following suit as Samukai, in the sense that it appears in 2 very large sets. 2013 has a very similar Garmadon, except for a different helmet and staff. This variant appears in 1 set.

Another Minifigure is four armed in 2013, and once again it is from Ninjago. He is General Kozu, general of the stone army. He also utilizes a torso extension like Garmadon, but a different mold. Like a lot of characters in the 2013 Ninjago wave, he is exclusive to 1 set.

Last, but certainly not least, is another Star Wars minifigure named Pong Krell. He uses a similar torso extension as Garmadon or Kozu, but his alien head was incorporated to the extension. He carries his iconic twin double sided lightsabers, and, like many Star Wars figures, is exclusive to one set.

I know this answer is pretty long, but it's very comprehensive. Please edit it if I miss something, or I wrote something wrongly. Bear in mind that all these minifigures can hold conventional minifigure tools.


How to repair leaky pneumatics? Some of my pneumatics parts, mostly pistons, have seals which no longer prevent the air from escaping completely. On some parts they are unreliable and on others they are not working at all.

Why do those parts become leaky, how can I minimize the risk of it happening with maintenance and/or proper storage, and is there any way to repair already leaky parts?

Zhaph suggested disassembling the piston and replacing the seal with an o-ring, however the seal in question was not a simple o-ring and getting a replacement is properly difficult:

From the left:

Top piece locking everything together
Top rubber seal, with a bit particular shape
Bottom rubber seal, which is just a wide rubber ring
A plastic spacer between the two rubber seals

While the top piece appears to be safe to remove, the bottom rubber seal easily gets damaged when you try to force it off the piston. The amount of pressure it could retain after forcing if off a couple a times became limited.

The parts become leaky due to the seals inside the pistons deteriorating.

Typically, the seal is made with an "o-ring" - a circular rubber band (cross section as well as the shape) - if this is the case in the LEGO pistons, and then it's possible the o-rings are made with similar rubber to the LEGO rubber bands, and then they will deteriorate over time in the same way the rubber bands do.

I've not tried dismantling any of my pistons, so I couldn't say how easy they are to repair - they look like you should be able to unclip the black part and access the piston that way (there's a YouTube clip of someone doing so here, you can just see the piston head too, but I can't confirm the o-ring).

A good car spares or similar type of shop should be able to sell a selection of replacements.

From my time spent diving, there's not much you can do to stop this happening over time, other than keeping an eye on them and checking them regularly for replacement.


How can I build an (automatic) Mindstorms charging-station? I'm thinking about buying LEGO Mindstorms and start programming robots. I'm a software engineer and LEGO fan since I was a child so this sounds like the perfect combination of my dearest hobbies.

But some questions come into my mind that I simply can't find out on the LEGO website:

Is is possible to programmatically check the battery charge status?
How is the NXT 2.0 block, where the power for all those motors and sensors come from, charged
Is there a possibility to build some kind of charging station where my robot can drive in to get recharged?

The point of this is, I would love to have a robot that's driving around doing stuff, and when the batteries are almost empty (let's say < 10%). it would drive to the recharging station on its own — and when it's full again (> 95%), get out of the station again and continue doing other stuff.

As a software engineer, you would probably be more at home in NXC, a C-like language compatible with the standard firmware. You can then use BatteryLevel().

If you want to use the standard programming environment, use this custom block.


Is it possible to edit a MyBlock input parameter value? I have created MyBlocks but want to change the input parameter to negative. Is this possible or must all the MyBlocks be re-written?

It is possible now (since version 1.3.0) by pressing the button at the upper left corner of the block:


What are the thick red cylinders in 80104? What are the thick red cylinders with handles (not the drumsticks) that two minifigs are holding in set 80104 supposed to represent?

Michael has answered what pieces it is, but you ask what they represent, so I'm going to offer a guess at that: Fireworks.


Can anyone help me identify this Fabuland figure? I found 2 of them in a box of LEGO I had as a kid, it fits the LEGO baseboards/bricks but I don't have a clue what it is or where it is from!

My daughter is now the proud owner of my Lego (along with a ton more!) and wants to know more about this piece before we release it into a Geocache (keeping the second one at home)

Any help would be much appreciated!

This is Boris Bulldog a.k.a.

fab2c: Fabuland Figure Bulldog 3 with Police Hat

it appears in the following sets

3603: Boris Bulldog and Mailbox

3786: Boris Bulldog

3793: Boris Bulldog and Mailbox


What is the appropriate way to request a creator to add more of their designs to MOCHUB? There are some brilliant LEGO creators with many designs on YouTube out there who choose to remain anonymous- who put some of their designs on MOCHUB but not others. (In particular ones relating to pneumatic engines.)

There might be a reason for this I’m missing.

I could comment on YouTube but then my comment would be against my name for all to see forever, and I’d prefer a communication method more discreet.

What is the appropriate way to request a creator to add more of their designs to MOCHUB?

Some creators may not want to share building instructions as there is a fear of knock-off companies releasing them as sets. Especially if MOC's are of top quality.

It is also possible there a personal choice to limit (control) their work results via fewer platforms. Or simply may not like some platforms at all.

Edit: Thinking from my point of view (someone who has created and shared instructions for LEGO MOC) I would consider alternative web redources if there would be obvious benefits. So it might be worth finding such reasons, like audience growth, unique features, something else. Then contact the author via one of the ways he is available and suggest him to contribute to your choice of web portal listing the possible reasons. It could be the easiest way of letting this person know and understand if he has anything against it.


How can I use the Flex Tool easily on LDD? On LEGO Digital Designer, I find it very hard to move the piece being flexed to the correct position.

Are there any tips or musts that I should try to help me flex it into clips etc.?

This eurobricks thread has several LDD tricks, some of which use the flex tool.

Please be aware however that LDD can easily crash from using the flex tool or the hinge/hinge align tool.

There are other tools to flex parts but they are not as simple to use as LDD's flex tool.


Why are some of the supports on bottom of a lego piece hollow, and other are solid? I've added an image of me holding two 1x3 bricks, one has solid supports (not sure the technical name...) and the other has hollow supports.

Does anyone know the reason why they are different? Other than that, they are identical and from what I know they were purchased at the same time (I didn't buy them).

Almost assuredly it is a move to reduce the amount of plastic used. It may seem inconsequential, but adding up hundreds of millions of these makes for a ton of savings. The same thing goes for the brick walls, but not in the case of the ones you show here. I haven't seen it in any 1x bricks, but in most 2x bricks these days, the walls are a tiny bit thinner (perhaps the cause of many complaints of translucency) but with little ridges there the studs touch to keep clutch at appropriate levels. One might guess that this new wall would reduce the number of times a brick will accept a stud before losing reasonable clutch power.


How to get a random value in the LEGO Mindstorms Robot Inventor software I am making a Python program with the LEGO Robot Inventor software which will, among other things, turn the robot a random amount periodically, which of course requires a random number. However, I could not find any way to do so. Is there any Python function which I could use to get a random number?

Under operators, there is a block "Pick Random" where you can specify to pick an integral number between x to y... x and y you can type... So for a random direction, set it between 0 and 359 degrees ...


Compatibility between vintage (80s/90s) Technic and current parts (motors etc) I've recently got my old Technic out for my daughter (who's a little young for her own, but her Friends now drive around in a tank).

If I start to acquire more, and more sophisticated, motors and controls, are the old ones (e.g. 6216m) still usable? Are there adaptor cables? Do modern motors even use the same voltage?

The motor you have linked is indeed quite old and as far as I know, not compatible with anything newer. Seeing that it works with simple DC current, it wouldn't be hard to construct a converter cable, but it is still some work (especially reducing the voltage from 9V to the 4.5V required by this motor).

The next generation (9V system: large motor, micromotor, mini-motor, buggy motor) has much better prospects regarding compatibility, as they can be used with the voltage regulator, the control center with the recording function, dumb battery boxes, first generation RCX controllers, cybermaster and code pilot units and there are even converter cables for the PF system. There are even light and sound elements for this system and the cables are nice and simple 2-wire ones with brick-compatible connectors, carrying anywhere between -9 and 9 volts.

The PF system has been in use for the last several years and is widely compatible even with 3rd party accessories like SBrick or BuWizz. The cables here have additional wires for controlling servo motors and the connectors are stackable, but proprietary and only partially compatible with LEGO bricks.

It is not yet clear if the even newer Control+ system will at any rate be backwards compatible at all, but knowing the LEGO community, it is only a matter of time.


Two separate functions of 5282 RC remote? Given the RC set of 5282 and 6272c01 below:

Is there a solution to use the two paddles that command the auxiliary output of the receiver for different functions?

For reference, see this at 1:45.

I'm trying to light two different 8870 led lights, one with the left paddle, the other with the right paddle.

With only using existing non-modified LEGO parts a mechanical solution with a servo motor, two polarization switches and cluch gears is thinkable, but this is all really cumbersome...

It's a bit ironic really, there's a bit of (trivial) circuitry in the 2x2 black brick before the wires of the LED lights split that causes the LEDs to work no-matter the polarization, because LEDs by their nature only work when the correct polarization is applied...

One solution would be to modify the circuitry in the 2x2 plate.

Schematics are here:
http://www.philohome.com/pf/pflights.htm

What basically needs to happen is that the diode bridge is removed and the C1 wire is soldered through to the + side of the leds (to the resistors) and the C2 wire to - side ...

Same for the other pair of leds but switching C1 and C2...


Is it possible to dismantle and refurbish an original 870 Technic motor? I have a couple of ancient 870 motors (the 4.5v ones) that run but don't sound great. I've looked for, but can't find, a guide on how to dismantle them. I'd like to either get in there and clean/lubricate them selectively, or perhaps even replace the motor element.

The end cap where power is supplied is clearly where they went together, but some gentle wiggling and pulling suggests there's probably some internal one-time assembly clips.

Is there a trick to get them apart?

Edited to add:

Further wiggling and poking makes me believe that unfortunately any clip is in the curved sides of the motor casing, which are very resistant to flexing. A thin blade passes into the top or bottom straight edges with little to no resistance.

While it is important to keep old and rare Lego pieces in good condition;
looking at the part in LDCAD, it does not look like there are any screws to take it to pieces, so I think it is internally clipped together, where such clips cannot be pulled back apart again after they snap in. Several Lego motors use these clips.

However since you cannot see them it is debatable weather it matters if they are broken/cut because you can probably super glue it back together and since the glue will be on the inside you won't see that either, but I will leave that risk up to you :)


Minifigure arms and legs do not have stamps I have loads of minifigures from the 1980's and have just found out that none of the arms or individual legs are stamped with the LEGO logo.However, torsos, heads, and hips are all stamped. Does this mean they are not genuine parts?

Nope!
Torsos and leg-pieces are special. They are some of the few pieces of their size that are not actually two separate parts of different IDs. Torsos actually include their two arms, which is why they come assembled, with the arms and hands already attached, and only the torso is stamped. Legs are actually a three-piece combo of left, right, and waist. A mini-figure is made of (typically) a hat/hair piece, a head, a torso-combo, and a leg-combo, all of which have only one stamp apiece. So fortunately for you...
All of your pieces are legitimate.


What is currently in the LEGO Store Pick A Brick Wall? The LEGO Stores feature the Pick A Brick Wall, where you can buy a small or large cup of LEGO bricks. The selection changes every now and then.

Where can I find the current bricks that are available at the LEGO Store?

The bricks in the Pick A Brick Wall are subject to change. As soon as the supply of one type of brick is exhausted in a store, they replace it with another type of brick. There is no particular rotation or order, it is just whatever happens to be in the delivery that the store gets from Lego.

From Lego.com:

  Selection varies by store and the elements are always changing

The brickbuildr.com website has a section dedicated to an effort to inventory each Pick A Brick Wall through submissions from the community (not the Lego store itself), but it is often a little out of date.


How many standard 2x4 LEGO elements are produced in a single 2x4 mold injection? Just how many standard 2x4 LEGO elements are produced from a single mold injection? I realize the molds are used over and over again, but how many bricks does a 2x4 element mold produce at a time?

I seem to remember it's 2 rows of 8 bricks, with the plastic flow coming in the middle and being distributed in the mould through a pipe running between the two rows, but I can't find any reference for this.

It could very well be that future moulds are optimised to hold more, though, but that's porbably not going to happen unless there's a good reason. Another example I heard is that when they started producing 5L Technic axles, the new mould contained twice as many axles as the one used for 4L axles - with a net result that the 5L axle costs less to produce than the 4L one, which is reflected in set design. You would think they would also replace the 4L axle mould, but considering the price tag of a such a mould, it's not interesting to do so until the mould is at the end of its life (and even then, it may not be worth it to design a new one rather than to just reuse the previous design).

Edit:

Well, I was wrong on it being 2x8, apparently it's 2x12 (or rather 2x2x6):


Can Lego soccer (football) parts be used for anything other than soccer? I had the Lego soccer field, but took it apart. What else can the parts be used for besides soccer?  I'm specifically wanting to know about the green bases and minifigure stands.

The green parts are great to make a green smooth field, which is kinda obvious. Landscaping is one usage, and if you find it too uniform, don't forget you can cover some areas with additionnal hills or whatever. The Technic hole in there can come handy as you can easily attach something in it. Since it'll rotate freely, your added decoration can even be placed at an angle. Trees come to mind too: you can attach them to the Technic hole too, and maybe fill the green curved area with brown 1x1 round plates to symbolize earth.

The fact that it's green isn't always the most important aspect; sometimes you'll just need a big horizontal flat surface just for its flatness. I've used some of these parts (tan ones) to create a flat layer udner a SNOT river (basically a wall of blue bricks on the side). Doing that with 2x2 tiles would have been cumbersome, and more importantly I could use parts which I usually have no use for. In my specific case, the fact that they can be attached on duplo bricks was a plus.

The minifig stands aren't that much useful, but the spring in them means you can hope to build interesting mechanisms, especially projectile ones. Have a look at the instructions of set 7020 — Army of Vikings with Heavy Artillery Wagon, the designer of that set did an excellent missile launcher with it.

Don't get me started on what to do with the soccer balls.


Identify a non-Lego Santa set Yeah so basically I tried the usual sites, but even putting in “North Pole sign” came up with nothing except one kinda similar. I can’t find anything on this set. Please help.

I could not find anything for 'Santa's letters' and the parts with 'North Pole' where showing different stickers on Bricklink,
Based on the design of the bricks and the strange colour used for the characters I strongly suspect these are not LEGO bricks.
The 2x2 slope for example does not show a visible LEGO logo on the studs and each stud is quite different. The bags they are packaged in are also not standard.

It will be quite difficult to identify this set if you cannot find a box, instructions or some other markings/part numbers. Clone-brands rarely have an online set database where you can find sets or an official website.


Help to identify a small tube part I'd like some help identifying the black parts circled in the photo.

It's a piece of 3mm rigid hose. It looks something like this:

That particular piece must have been cut from a larger piece, as the smallest it has ever come is 3L (3 studs) and never black at that size.

It's debated if cutting tube pieces is a purist thing to do or not.


How to store a matrix of values and pick out certain elements and compute the difference? I at the moment am trying to make an EV3 robot which is capable of following a gradient decent method. The idea was to store a discretized function in a 2D matrix, and make several lookups in that 2D matrix where I compute the difference between its position and its neighbor's position. and then make the robot move in the direction with descending gradient.

To do so...

How do I use the EV3 software to:

Create a Matrix?
Store values in matrix?
Make lookups in matrix?
Subtract those lookups?

This could be way easier in C++, but is there any supported firmware capable of running C or C++ in the same way as with NXC or something like this? Something with some form of documentation?

This application does seem to be pushing the limits of the official software provided by LEGO. If you are interested in C/C++ (or any other programming language), check out http://www.ev3dev.org.

I like to say that ev3dev is not firmware since it runs from a microSD card and is not loaded into the flash memory on the EV3. Nevertheless, it is an alternate operating system for the EV3 with the goal of being able to program in any language that you like. You can find a list of existing programming libraries here.


What set is the safari car in the 2020 catalogue from? On page 2 of the (German version of the) 2020 January-July Lego catalogue, there is a promotional image with various sets or parts thereof1.

Catalogue online version.

In the lower right corner of that image, we can see a nice-looking safari car with a puma and a photographer disguised as a tree and a colourful parrot on top. I could not find this car anywhere in the catalogue.

Is it from a set? Is it something that was planned to be released, but eventually wasn't, maybe when promotional materials had already been prepared? Or is it a teaser image for an upcoming 2020/2 set?

1: For instance, I can recognize the train from 10874, the 31105 toy store, the tent and campfire (glampfire?) from 41392, the police plane from 60210, and the top half of 71712.

That's a new 60267 set to be released this year under City theme:


Is there any way to connect “sideways” to an axle? There are some pieces whose middle part is shaped like a Technic axle, but that have elements on both ends that make it impossible to insert them into a normal axle or Technic hole:

This makes me wonder whether the axle shape here actually allows for a connection or was only chosen for stability, production reasons, or similar.
With other words, is there any piece (or combination of pieces) that connects a Technic axle “sideways”, i.e., without going over the ends?

I don't think there are any pieces LEGO intends for you to attach to the side of these axle shaped pieces. However, I'm pretty sure you could attach piece 32172 to some extent (assuming the piece being attached to is actually the right size for an axle):

It probably would not connect very well, only the clips on the sides of the socket would hold it, so it would probably slide easily, or pop of with little effort, but it could be attached.


What was the first set produced by The LEGO Group? What was the first Lego set produced, and when was it first released?

Some of the earliest "LEGO brick" sets I could find were these three on BrickLink from 1954:

As other answers have noted, there were earlier sets than this, but they were referred to as "Automatic Binding bricks". It wasn't until 1953 that the bricks were officially renamed as "LEGO bricks" (i.e. "LEGO Mursten").

These sets were using precursor designs of the "modern" plastic LEGO brick without the hollow underside tube. It wasn't until 1958 that the brick design we all know and love today was created. It was officially "born" at exactly 1:58 p.m., January 28, 1958, when it was first patented.

So, if you're looking for the earliest official "LEGO bricks" using the modern stud-and-tube design, these are the sets you're looking for:


Help identify these sets/bricks Some of these are sets and some are bricks. Sorry if the quality is bad, I can't get any other pictures.

Please note: 3 and 4 seems to be from the same build, although I cannot fully verify that.

01)  Bionicle piece ???

Part #98141 Minifigure, Weapon Crescent Blade, Serrated with Bar, with an updated and correct answer provided by site member Phil B.

02) Part #4150 Tile, Round 2 x 2.

3 + 4) Hails from Set #76109 Quantum Realm Explorers.

The yellowed outlined pieces in 3 and 4 is Part #17485 Brick, Round 2 x 2 with Pin Holes.

HERE's a Youtube speed build on the piece breakdown/buildup of this design look you're interested in.


LEGO Mindstorms Motor Power I am working on a project with a LEGO Mindstorms (RCX) motor. For this project, all I need is to spin a motor (43362, http://www.philohome.com/motors/motor.htm).

I was wondering how the LEGO Mindstorms brick deals with motors. Does the brick output a constant power to the motors, resulting in different speeds for different loads? Or does the brick adjust power to meet a constant speed? Thank you!

The RCX system provides a certain average voltage level (via PWM) to the motors. This means that speed can vary based on load, and may even vary slightly from motor to motor. Power will also vary based on load, as a motor with more load will draw more current if voltage is held constant.

If you're interested in specifics, you can measure the voltage and current on the motor lines with a voltmeter, or view it on an oscilloscope if you have one available. From there, you can calculate the power (P=IV) for your setup.

The RCX system does have a rotation sensor if you need to be able to make specific speed and/or distance adjustments. In later systems, additional data lines were added to the communication protocol to allow motors to have embedded rotation sensors and allow precise speed control, but this is not possible with the RCX system.