text:
How To Plug Detected Light Values into Variables and Still be Usable in Programs in EV3-G
I've seen teams, mostly in the world festival do this, and what they do is they program the robot so that when a brick button is pressed, the robot detects a value (usually RLI) and it is used later in the program. My program looks something like this so far.
Am I on the right track? Is this program correct? Or am I completely wrong?
The program runs OK, but the variable can't be used later in the program.

Hi, the program runs but the variable can't be used later in the program. Thanks!

First guess: the wait for button command is bad practice.  Well, not the whole thing, just the use of the middle button.  The reason is that that button is also used to start the program.  The program may be jumping past the wait for and saving to "Midpoint" before humans notice that the program has started. Try any other brick button.

Your example doesn't read a RLI value.  It reads and stores a color index value (0 through 8).  This wouldn't stop you using the variable, but the value may not be what you expect.
Variables are global.  You can read or write them anywhere in your program.  The value of the variable is the last value written.  Variables are not persistant.  When your program ends the variable goes away.  This means you cannot use variables to set a value and use it in a different program.  To do something like that use a file,


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Modified 3x2 Plate with Rubber Bristle Bottom and snap-on cover?
I've had this odd little part laying around my desk for some time - does anyone know what it is?  There's no Lego logo anywhere, and I've searched BrickLink somewhat comprehensively, so I'm guessing it's from a compatible set.
It's a modified 3x2 plate, but without a hole, and the red bottom part is sort of a rubbery, grippy substance.  The "cover" is softer, non-ABS plastic, and can snap onto the plate either way.
I'm guessing it came from my wife's nephews in a whole pile of stuff they gave us - mostly Lego but there was some MegaBloks stuff mixed in too.  Probably not from after 2000 at the very latest.

Definitely not LEGO. Part with red insert seem to represent a brush. Do both pieces come apart easily?

The two pieces are not difficult to get apart - it's clear the one is supposed to be a "cover" for the red part of the other.  The red stuff is a rubbery substance - like it was supposed to provide traction or something.

Is it not normal to close the newer question as a dup of the older one (granted the quality is about the same)?

So, the curiosity bug bit me again.  The mysterious part appears to be a Kre-O "Motion Brick" which appeared in various sets. In my research I found that there is a variation (hollow vs. solid) in the studs, as shown in the picture.

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

sort: votes


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How I can program a solar panel heliostat?
I want to make a program for an EV3 solar heliostat.
It consists of two motors and a color sensor. I want it to follow the light. The station is fixed.
EV3SolarStation pdf

i want it to follow light .also the station is fixed

Can you provide more details then this, currently it's too vague

Hi @morad ! Could you please provide either a detailed description or a picture of this solar station? Knowing the orientation of the motors and the general idea would allow us to help you better. Thanks!

As far as I see, you have two possible ways of accomplishing this, given that you have already built an Altazimuth mount or any other two-dimension mount from the two motors that can hold the color sensor and point it in any direction.
Calculation
This is the harder way but it grants neater results. It involves taking a precise measurement of the device's location and orientation, setting up a known orientation for both motors as zero, and porting a known solar-tracking algorithm to the EV3 (like this or this). The resulting setup then must not be shut down, moved or rotated since the control of the motors is done by an algorithm which only takes into account the starting conditions (spatial and temporal) and the elapsed time. The accuracy of the EV3 internal clock may also factor into the precision if the project is to be left running for a long time. As an added bonus, you don't need the color sensor at all.
Using iterative methods
This approach requires a lot less intial setup but offers a not-so polished end result. The basic premise is using the color sensor to get an estimation of the amount of the light incoming from the current direction, then comparing it with the measurement(s) from some other direction(s), finally turning toward the higher value.
There are two problems to be solved here: first, the current position of the Sun (or its equivalent if you are indoors) must be found among all possible orientations. This is an example of the mathematical operation known as finding the global maxima of a two-dimensional function on a constrained range, where the two input dimensions are the altitude and the azimuth and the output is the measured amount of light coming from the given direction.
Then, the software must account for the inevitable changes due to the relative movement of the Sun in the sky. Since you have chosen this way and not the first (Calculation), you can not know in advance which direction the Sun will move in. So you can only attempt to find it again after a set amount of time or after the measured brightness drops to (or by) a specified amount.
There are countless ways this approach can be fine-tuned, depending on the precision of the motors, the precision, update rate and measuring range of the sensor, the amount of location and orientation information known beforehand, the required precision of the resulting system, the allowed complexity of the software, etc.
The most basic and a very ineffective system would consist of the following pseudocode:
repeat forever:
    oldBrightness = read(colorSensor)
    movementXAxis = getRandom(-10, 10) // decide on a random direction to turn to
    movementYAxis = getRandom(-10, 10)
    moveXAxis(movementXAxis)           // turn to the new direction
    moveYAxis(movementYAxis)
    newBrightness = read(colorSensor)
    if(newBrightness < oldBrightness)  // if the new direction is worse than the old
        moveXAxis(-movementXAxis)      // then turn back to the old direction
        moveYAxis(-movementYAxis)
    wait(someTime)                     // bask in the sun for a while :)

This of course can be updated with more advanced logic, including but not limited to

paying attention to the amount of difference between the old and new measurements
moving first in larger steps to get a coarse direction and then refine it further with smaller steps
staying pointed in a direction longer if the brightness is higher there
moving continuously in one direction while the brightness is increasing and stopping when it starts to fall
storing directions and corresponding measurements to create a 2D function which can be analysed using mathematical methods to find the best result
storing historical data to predict and account for changes in the long run
(but by now you are practically in the complexity region of the Calculation-way)
etc.

Consult the relevant Wikipedia page for some advanced reading material and as a starting point if you are interested in learning more about the applicable algorithms.

I use mindstorm program for ev3 .I am greatful for you but can you give me a program on mindstorm.i put a link for solar station.thanks very much

https://github.com/diabad/EV3-Solar-Station/blob/master/EV3SolarStation.pdf

@morad sorry, your link seems broken, the browser days the file is too big to display and the PDF reader says it's invalid.

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What was the first Christmas themed Lego set?
For as long as I can remember Lego has been making Special Christmas themed sets every year. Advent calendars, Winter village sets, Christmas trains, and on and on.
What was the first Christmas themed Lego set?

I don't know whether this quite qualifies as a set, but there is a LEGO promotional Christmas box from 1964 listed on bricklink

Nice find! Brickset doesn't list this set so I didn't see it come by in my search.

Are they Lego bricks? As in: can you plug them to other classic bricks? Or are those plain flat dominos that you can't attach to anything?

@Cœur I not quite sure, but the description on bricklink says "outer box have storage wear inner boxes and parts still new" so it sounds like they are LEGO bricks.

There have been Christmas-themed sets for a long time, for example set 246-2 Santa and Sleigh from 1977.

Scrolling through all LEGO sets on Brickset, starting from 1949, shows that this is also the first set in their records that is Christmas themed, together with the (likely unreleased) two Santas set 245-2.


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Please identify the sub assemblies
Can you please identify the sub assemblies from the pictures. Is this part of a set or something someone just build? As you can see there are a lot of missing pieces. Do they ring a bell to anyone?
(A)

(B)

(C)

Please ignore sub assembly (B) as it it not made from Lego parts.

Assembly A comes from 75103-1: First Order Transporter

See instructions 75103-1 page=30

Assembly C is from page 65
(thanks @ LegoSonicBoy)

Which non-Lego parts do you see in assembly C?

@henrik; missing logo on the right plate (could be the lightning of the photo)

@Syberion: It's the lighting. I can just about make out pixels of shadows of the logo on the studs. Assembly C is from the same set - you can see it in page 65 of the instructions.


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How to build a waterproof roof out of LEGO blocks?
How would Lego blocks be tiled to provide a water proof roof against the rain?
The lattes or internal support structure of the roof doesn't have to be also made of Lego. Basically the tiles on a roof would be replaced with lego in such a way to be waterproof where the glue holds them together but isn't the water barrier.

Hi Muze! Just to clarify, do you mean building a roof-like structure out of LEGO bricks that can offer protection against real-world rain? If so, what is the size of the roof or the area to be protected? Does it need to stay dry even in windy or stormy weather as well?

@zovits how is this? Thanks for pointing that out.

I have provided an answer based on my current understading of your expectations and my assumptions on your constraints and goals. If any of these does not fit, please amend the question with the appropriate details.

I'm still wondering how big of a roof you are trying to build.  Is this for a small shed or a house or a dog house or .... ?

Since you are willing to use a non-LEGO frame to hold the roof and glue to fix all together, I would recommend buying baseplates in bulk and gluing them onto a wooden frame as if they were shingles. If the gradient and the overlap (vertical between rows and horizontal between individual plates) are correctly matched, the rain won't get inside.
For more resources on professional shingle roofing see these links:
https://www.iko.com/na/pro/building-professional-tools/roofing-101/how-to-install-shingles/
https://www.wikihow.com/Lay-Shingles


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Is this non-disassemblable LEGO instruction step real?
I've seen this image shared a few times around the internet as an example of a LEGO instruction step that assembles pieces in such a way that they cannot be disassembled (at-least not without some serious strain on the parts).

If one were to insert that Technic axle into that hole, it would sit flush inside holding the other red piece in place, and since the black piece wraps around the back, it would not be possible to slide it off the axle without some substantial bending.
Trying to find the source of the image has proven difficult, and those who share it don't ever seem to include the source of the image.
Is this from a real LEGO set's instruction, or is it faked?

Last time I remember looking at one of those axle-joiners, there was a hole of a small diameter that a toothpick might be able to poke the axle out through. Is that the case?

@Eric In the red piece yes, but it would be covered over by the solid black piece. You would have to bend it some to do that (which is probably the best way to try to remove it).

Oh wow, I missed that the left end is solid, and assumed it was an axle hole.

It turns out it is real, just not from a single set itself, but from the official instructions for a combo-model between Exo-Force models 7700-1: Stealth Hunter and
7701-1: Grand Titan to make Mountain Warrior.

You can find the pictured step on page 26 of the instructions.


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What's the Difference Between an Open or Hollow Stud, and Solid Stud Brick?
What's the difference between an open stud brick, and solid stud brick? Should I watch out on which one I use?

While the difference is most often cosmetic, an open stud can serve as a connection point for bar elements:

This type of connection is less common than simply using the stud as a stud, but if you are looking to buy elements to build a particular model, you might want to check to see if you need the open stud variety.
In addition to the obvious direct bar connection, open studs can also facilitate connections with the tubes on the underside of 1xn elements. Here's a nice picture showing the bar connection I'm referring to from New Elementary:

This can be used in combination with an open stud to allow elements to connect at a half stud offset. This technique isn't used frequently in sets, but it does sometimes come into play. For example, it is used to fix the top windows in place on the Parisian Restaurant:

The combination of bars on the underside of the 1x6 plates and open studs on the windows allow the windows to be held in place firmly despite the fact that their top stud is offset by half from the regular grid.

jncraton gave lots of great information about connections. Open studs allow for lots of great building techniques. But not all open studs are open simply to facilitate building. Sometimes the studs are molded open for reasons to do with how ABS plastic cools. If the plastic is too thick, it will deform (shrink) as it cools. This is why lots of pieces have open studs, so that they can be formed properly. Not all open studs are open for this reason, but there are lots that are.


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LEGO remote control 8879 for 2016 Winter Train not working
I purchased parts 8879+8884+88000+88002 to power the new Winter Holiday Train.  Fresh out of the package the remote controller 8879 does not make contact with the positive end of the battery.
Thanks to this post, I was able to make an adjustment to the controller so that contact could be made saving me a lot of time and headache. Is there an easy way to get the positive contacts to stick out further?

I had the same problem, so I looked at the forums, but I couldn't solve it.
In fact it is a problem with the contact, so I put some aluminium foil (the same one from the kitchen) in the positive contacts, and it worked!!! Yeah, I used DuraCell...

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


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Bridge from just basic bricks?
I teach an after-school engineering class using LEGO bricks, one of our classes has the students build a bridge.  Each student gets a custom set of about 150 2x4 bricks, about 300 2x2 bricks, and, if I'm feeling generous, about 15 2x8 plates.  Although I've seen many fancy bridges made with technic parts, I've never seen an awesome bridge made with just basic bricks.  I'm looking for a reference bridge to show the kids, after the build their own, what is possible.  So, show me the best bridge (either a link to someone else's bridge , or a photo of your own) that can be made with just basic bricks!
Scope note: Most people don't have this custom set of bricks, so links or pictures of any bridge that uses almost no rare parts and use almost no technics would be cool.
Background:
LEGO Bridge Page: http://lego.sparre-andersen.dk//Transport/Broer/
Arch from archive

Cantilever from archive

Big:  from archive

Sort of basic arch: from flickr

From the FAQ:
You should only ask practical, answerable questions based on actual problems that you face. Chatty, open-ended questions diminish the usefulness of our site and push other questions off the front page.
Your questions should be reasonably scoped. If you can imagine an entire book that answers your question, you’re asking too much.
If your motivation for asking the question is “I would like to participate in a discussion about __”, then you should not be asking here.

I don't think "off-topic" is the right close vote here...

I think a better question would have been: How do we make [this bridge - with picture] more robust? With a picture of the bridge in question, or something like "How would you go about about building a functional Cantilever bridge using the following components?" and then tag it [tag:technique] or similar

I disagree that this is off topic.  I think Joubarc's answer is perfect.  The question is practical - I face this problem.  And although it is open ended, it is not inherently open ended, any more than any 'what is the best'  type of question, which are often asked and answer, for example, on stack overflow.  I do like Zhaph - Ben Duguid's suggestion as being significantly more constructive and less discouraging than simply closing this.

Pubby8 asked this http://bricks.stackexchange.com/questions/273/what-is-a-good-ratio-to-buy-bricks-in I feel that either these should both be closed, or neither should be.

I think Lee DeLapp was just plain wrong. This question should not have been closed.

@ErikOlson and AscendlyJJ: At this stage (private beta), both of you should be able to vote to reopen this (I have done), or vote to close the others. Oezi's question as originally asked was even more off topic, being related specifically to programming mindstorms. Just commenting doesn't really help ;)

I've added this as a meta topic for discussion http://meta.bricks.stackexchange.com/questions/59/will-all-open-ended-questions-be-closed-i-certainly-hope-not

Ok, I never saw a reopen on stackexcange before!

If you also want them to be aware of the solidity of their bridge, you may want to have a look at this contest.
Note that bridges made of stacked plates are much more solid than Technic ones.

To prevent the stack-of-plate loophole, most Lego bridge contest now have a weight limit.

Since you mention an engineering class, I assume you probably mean a functional bridge that can be tested for capacity.
This bridge may not withstand a great deal of weight, but it appears in a 1964 LEGO Idea Book and is created only from basic bricks available at that time. (LEGO did issue a more detailed Tower Bridge set a few years ago)

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


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How do I build a sloped roof with a 60° rake?
I've seen the sloped roof on the "Winter Village Post Office" and similar using plates, and I want to build a roof with a similar angle:

What should I use to ensure they are well attached?

See the instruction for that set on pages 56-59, 65 and 68/69 for the 3 different roofs of it.
they're using a different technique and different pieces for all of them, so this perfectly shows up some alternatives (technic-like parts for the big roof to the right, blocks with studs on the sides for the small 90°-roofs and 1x1 with clips for the roof to the left).

In the past, LEGO produced a perfect element for this:

It's probably hard to find in big quantities now, so I give it more for reference than anything. I wish LEGO would still produce it though (not to mention its educative value).

That's an interesting piece I've never seen (nor have in my collection).  I wonder what made Lego abandon it?

I imagine they stopped producing it because you can create the same slope with other available elements (like hinges), and those other elements provide a much wider range of building possibilities.

Maybe they didn't like the fact that the angles are not integer (53,13° at the bottom); but then again they have Technic beams with the same angles. I'm quite curious too as to why they stopped it..

To keep it simple I would use hinges placed on top of the wall, connect the roof plates and angle them to fit.
 <-- or -->
Edit: You could even add a small plate hinge at the roof ridge, under the roof plates.  This would keep them from separating.


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What piece is this ARC-170 Starfighter cockpit?
I got these with the ARC-170 LEGO Starfighter (archived):

I'd like to get more if possible. They are a part of the cockpit.

Is this from the cockpit?

@BoltClock Yes it is. Sorry, should have mentioned that in the question. edits

It's common for the pieces to have numbers printed on them. Try to see if the numbers are visible.

That looks like 30384 Windscreen 7 x 4 x 2 Round. In general, BrickLink is a pretty decent place to browse around for parts identification. Peeron is also pretty good.
BrickLink provides a comprehensive list of windscreens both plain and decorated.

Ahh, experienced researcher found the brick where I just found the set

+1 for Peeron. If you know the set, you should be able to find the piece there.

This is the Trans-Black Windscreen 7 x 4 x 2 Round

(7259) ARC-170 or (8088) ARC-170 Starfighter.
The part can be found in these sets on Bricklink and a cool alternative list.

I believe the question is asking for the specific piece, not the set.

@Rebecca - I expected that first identifying the set would help find the brick... See the last links


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How can I combine multiple PF XL Motors
I have built an enormous and heavy Lego RC tank, driven by 2 XL Motors, connected to a subtractor, one motor is for steering, the other is for propulsion. Despite having already geared down the motors to provide more torque for the vehicle, the sheer weight of the machine is too much for a single XL motor, even geared down, so the gears tend to grind a bit,  but I do not want to gear the motors down any more since the vehicle already travels incredibly slowly. I am wondering if combining two XL motors for propulsion and steering (resulting in 4 XL motors in total) will give me more torque whilst retaining the same RPM.
Thanks,
Nick

This question likely already has answers in the form of https://bricks.stackexchange.com/questions/8867/how-to-get-double-the-speed-from-2-regulated-ev3-motors/8868#8868 and https://bricks.stackexchange.com/questions/1327/whats-the-best-way-to-link-two-or-more-lego-power-functions-pf-train-motors?rq=1, even though those questions have slightly different scope.

Maybe you could provide some pictures. Then we may help in your particular build. At the moment, the question is rather generic and a possible duplicate of other questions.

The XL motor is already pretty powerful so you do have to consider the ultimate strength of any plastic gears involved in the drive train particularly when it is well geared down. Using two motors will tend to compound the gear strength issue. As others have said some pictures of your tank and its drive system would be very helpful.


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What was the first Lego tie-in film or television production?
Nowadays, it's pretty common for TV shows and films to be released by film studios in agreement with The LEGO Group and tying in to current LEGO set themes - famous examples include the recent films (The LEGO Movie and The LEGO Movie 2: The Second Part), LEGO Star Wars: The Yoda Chronicles, the Legends of Chima TV series, and Ninjago: Masters of Spinjitsu, all of which were released after 2010.
What is the earliest television or film production that was officially tied in with a LEGO set or theme or with LEGO bricks in general? The earliest that I was able to find was Edward and Friends from 1987 that showcased the Fabuland theme, but LEGO was already decades old by then. Was there anything before that?

I think you already answered your own question: The earliest Lego television production is Edward and Friends from 1987 that showcased the Fabuland theme.
From the Wikipedia page:

It was Lego's first foray into animation and television in general.


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Is there a hobbyist standard for Trains track modules?
Many non-LEGO model railroaders have standardized track module standards allowing for interchangeability of (often highly-decorated) track sections (due to availability, damage, scheduling, etc.) as well as quick set up and breakdown of layouts at meetings and conventions. For example, most of the N-scale model railroad clubs in my area adhere to the NTRAK standard. One can make their own custom 4'x2' module at home and "just show up" at a meeting and expect to connect to the organization's layout that day. Similarly, if someone drops the club's Police Station module and damages it, a spare Quarry module that someone happened to have in their trunk can be swapped in as a substitute with only very minor assembly work (mostly plugging things in).
Is there anything resembling a standard module size or configuration among serious or organized LEGO railroad hobbyists?

Yes there is, and the standard is not unique to trains, but rather applicable to all LEGO construction. It is called MILS (Modular Integrated Landscaping System). You can find its specification in many places, but a good resource is at L-Gauge.org, where they have many more resources and standards for the LEGO train hobby.


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What was the shortest-lived color?
I've been reading about the history of the LEGO palette, most notably the transitions in gray and pink that have happened over the years where older shades were more or less completely replaced with newer ones.
What is the shortest-lived official LEGO color or shade? To be clear, I'm asking about shades that were officially released for public purchase as a set or individually (so no prototypes, test runs, employee swag, or third-party retints). I'm also not concerned about what parts were specifically made in that color, just the history of the color itself. If a particular color appeared in a 1x2 plate for two years, that part was retired, but the color was then used for a 2x4 brick for a year, that counts as three years for the color.
For example, have there been any colors that were released in only one set or theme and were fully retired when that set or theme was retired, never to be revived again?

According to the BrickLink Colour Guide, there have been three solid colours that were used for at most one year:

Fabuland Orange (1983; half barrel from Peter Panda Takes a Bath)
Very Light Orange (2000; only example being the aforementioned crouching cat)
Clikits Lavender (2005; four examples)

In addition, there has been one "chrome" colour (solid with metallic detailing) with a single-year run:

Chrome Black (2009; Darth Vader torso)

And finally two "speckled" colours, both from 2006:

Speckle Black-Copper (2006; Karzon Visor)
Speckle DBGrey-Silver (2006; three examples, all helmets)

As noted in one of the other answers, there are additionally some new colours for 2020. In my opinion it is too early to say whether these will have a single-year run.

While brikclink doesn't have an image of an item in Fabuland Orange it has the Fabuland Orange bathtub listed in its catalogue. "zero examples in Bricklink" is a bit misleading here.

@jk-ReinstateMonica: Bricklink does have an entry and even an image of the Container, Barrel Half Large, Fabuland Orange, but there seems to be something wonky with their database. In particular, on the Peter Panda Takes a Bath set page the part is marked with "Part Color Code Missing".

@jk-ReinstateMonica Thanks for spotting that. Will amend my answer.

Further to Alex's answer, from that source I found eleven colours that only lasted a year:

Fabuland Orange 1983
Very Light Orange 2000
Clikits Lavender 2005
Chrome Black 2009
Chrome Green 1999
Satin White 2020
Satin Trans-Light Blue 2020
Satin Trans-Dark Pink 2020
Glitter Trns-Orange 2020
Speckle Black-Copper 2006
Speckle DBGray-Silver 2006

Of course the four 2020 colours may continue next year!
Fabuland Orange was only used for one item in one set for one year, so could be considered the rarest colour.  The set was "Peter Panda Takes a Bath", and the part was Peter Panda's tub, a part barrel affair.

Kudos for spotting more colors.

According to Bricklink, Very Light Orange was only used by single part for one year only - in 2000. It was used in 2 sets (Scala and Belville) and 1 "gear".
That part is this cat:

Another color is Clikits Lavender used by a number of parts (9, to be precise) for Clikits theme and these were produced in 2005.
Here's a picture by Ryan Howerter


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Lego Duplo Train Track Switcher washable? / Best way to clean them?
I've found some pretty old Lego Duplo train track parts, that I'm looking to sell on Ebay.
As these are pretty old and caked with dust, I wanted to used my usual method I usually use to clean all kinds of Lego parts: Put them in a duvet cover with a zipper so they don't go everywhere, and put them in the washing machine, and wash without any detergent and no spin cycle.
Afterwards I take them out of the machine (thanks to the duvet cover I can take them out just like a bag) and spread them on my terrace to leave them in the sun to dry.
As these track switchers have metal springs in them (at least I think so, judging based on the sound when moving the red thing) I was not sure, if they were just normal steel or stainless. Does anyone of you know about this, or know a way to open them without destroying them?

According to this page it is glued together and can not be opened without damaging the part
You are correct about it containing a metal spring

I would just wipe it with a slighty wet towel


text:
Do Thomas the Tank Engine Duplo trains seat figures?
Lego made Thomas the Tank Engine licensed Duplo sets in the 2000's decade at the same scale as current Duplo trains. Do the Thomas trains seat Duplo figures like current trains do? I've seen some pictures of disassembled Thomas trains (e.g. in this video) that seem to indicate that there is space under the roof of the train, but all of the Thomas trains seem to have opaque windows, possibly implying that adding figures was not a priority.

The train bodies do indeed consist of a stack of 4x4 "blocks" that were fully enclosed when assembled - and as I recall, we could fit a seated Duplo character within most of the cab sections.
Toby and the coaches had the most room, but most engines just about had room.


text:
Can someone indentify this clone brand?
Just bought some 12 kilos of unsorted Lego.
As usual there is some other stuff mixed up as well.
Among other things around 60 bricks of some clone brand that I have never seen before.
Mostly 4x2 and 2x2 roof-slopes in red with a couple of roof-cap pieces and some 4x2 and 2x2 bricks. Some roof pieces are dark purplish-blue.
(Edit: Later I also found some white 2x2 bricks and a black 3x2.)
The pieces are fractionally smaller (about 0.2-0.25 mm) than the corresponding Lego pieces.
You can force the bricks on top of a Lego brick, but not the other way around (at least not without risking the Lego brick to break).
The slopes have no tubes or baffles at the bottom and have very narrow studs as you can see in the picture.
The normal bricks do have baffles. 1 baffle across the 2x2 and 2 in the 4x2 (between stud 1-2 and 3-4, no baffle between 2-3).
Probably a European brand as I got these in the Netherlands.
According to the seller all the Lego is from the 80's and early 90's, which matches the included booklets and what I see from the Lego, so the clone stuff is probably from the same era.
Can anyone identify these?

Kinda a duplicate of https://bricks.stackexchange.com/questions/16885/i-got-a-vintage-roof-brick-that-is-very-nice-but-can-t-find-what-it-is

@IvanSanchez You are right. It is a  duplicate, but since my picture also shows the blue ones and the 4x2 and 2x2 bricks I leave my question up. The only extra information I get from that Etsi listing (if that can be trusted) is that these may actually be a lot older (1950's) than I thought.


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Utility pole and angles
I am using the following MOC from the Internet:
http://www.moc-pages.com/moc.php/8435
This model is fine if the sets of power lines are all in a straight row. But what about at an angle? How does the model need to be adjusted if the lines meet at, for instance, a 90 degree angle? 45 degrees? Thanks.

The pole itself can be rotated on almost every level, so that’s nothing you need to worry about.
Additionally, you may want your cables to be parallel. To achieve this, you need to increase the width of your bars, or more specifically, the distance between the cable supporters.
If your distance between the supporters for a straight line is d and you want an angle of θ, you need a distance of d/cos(θ/2) at the angle, which can be obtained using trigonometry:

So, for an angle of θ=45°, you need to increase your distance by a factor of 1.08. For θ=90°, it’s a factor of √2 = 1.41.
The obvious items to adjust the distance are 1×1 round bricks and plates. Also, you obviously can only approximate the perfect distance with bricks in most cases, but the inaccuracy will be negligible.

And you definitely won't be able to able to increase the distance by a factor of √2 – See my edit. Also, you could technically switch to moving some pieces along Technic axles, where the only limit to your accuracy is your motor abilities. Finally, assuming ideally shaped and connected pieces, √2 is actually possible by zig-zagging – it doesn’t look good though.

Is it important that there are four lines on the pole? Is each line on a separate circuit, or are they in pairs?

Also, are brown axles common?

@posfan12: Is it important that there are four lines on the pole? Is each line on a separate circuit, or are they in pairs? – I am really not sure what you are aiming at, but I see no reason to treat the second level of lines differently than the first one.

@posfan12: are brown axles common? – Brown is one of the more common colours for axles. That being said, I really would’t go for such a solution as you won’t be able too tell the difference in accuracy.

My question was more with regard to how power lines work in real life. Is each cable a separate source of power? Or do the cables work in pairs, where one is negative and the other is positive?

@posfan12: You usually have three phases for power and one neutral. Either way, this is beyond the scope of this site.


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Connecting "out of system" roads?
I've been trying to figure out how to connect SNOT road models that are at varying angles to one another. You can see my efforts in this thread.
Are there any interesting methods of connecting roads like these that most people might not be aware of? I read up on integer triangles, but there are none for 45 degree angles, and probably none for 30 and 60 degree angles as well.
Are there any special parts that make this possible?
See also: https://math.stackexchange.com/questions/2607147/is-there-a-pythagorean-triple-whose-angles-are-90-45-and-45-degrees
Here is an example that is fairly close, except that the road pieces are not connected to one another.

It'd be nice to include the images over here in case the other page goes away.  It is an amazing and lovely project.

See also. https://math.stackexchange.com/questions/2607147/is-there-a-pythagorean-triple-whose-angles-are-90-45-and-45-degrees

There ARE integer sided triangles that have angles of 60 or 120 degrees, see here : https://en.wikipedia.org/wiki/Eisenstein_triple but I'm not sure how this helps you for building roads.
45 degrees there indeed aren't any.
A progress of going one stud forward one stud left will get you 45 degrees if working studs on top. In case of SNOT 2 studs forward, 5 plates will also progress in an angle of 45 degrees.
There are elements that let you progress half a plate, so 1 stud to 2.5 plates works also.
For 60 or 30 degrees, the tangent is irrational so no 'precise' or exact progression exists, but it can probably fairly well be approximated.
There are technic pieces called angular connectors that make angles that are multiples of 22.5 degrees. Also several connectors that make multiples of 60 degrees.
Also hinges that "click" in angles of 22.5 degrees...
Update: picture of angular connectors
you would additionally need technic axles and bricks having axle holes:

But there are lots of other ways to connect the connectors, e.g. bricks with pin holes and a half-axle pin, half pins with stud, axles with stud,...

Which technic pieces are these? I do not use technic much, especially Bionicle.

Edited the answer to add pictures of them from bricklink

How would I fasten them between the SNOT road and baseplate underneath?

If its permissible to have the SNOT road one brick higher, I would say bricks with axle holes or pin holes to the baseplate. The connectors with axles or pins to the bricks and the road on the bricks like you would have attached them to the baseplate. More compact solutions probably possible if I would have more details on how the road is now attached to the baseplate.

Right now, the roads are not (yet) connected to a baseplate. They are sitting on a virtual flat table surface (the model is digital). If you have MLCAD installed, you can take a look at these files: http://www.mediafire.com/file/qgt1zrq8v514t93/ldr_diagonal_snot_roads_20161104.zip


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Help with my Ev3 printer
I'm building an image printer using my ev3 set and several more pieces, as a project to keep me occupied while I'm stuck at home.
Here's how it looks:

I've done the build part, the way I've chosen to do this is by converting my image to binary (B/W) and reading each number in my binary array, then drawing a dot if there's a 1 or skipping the dot if there's a 0.
I'm using Ev3 Python, as that's the language I know and I found it easiest to program in, but after I created my program my brick doesn't seem to process it properly and my brick weirdly starts to draw dots in the same spot, then instantly starts to move its top arm in the same direction for much longer than its programmed to, then sort of just stops its paper-moving wheels and starts doing more weird movements.
I tested my program's values before I wrote the program, it can draw 2 dots in a line correctly spaced out, but it starts doing weird things when I give it a whole line of data to draw.
Here's my code:
#!/usr/bin/env pybricks-micropython
from pybricks.hubs import EV3Brick
from pybricks.ev3devices import Motor
from pybricks.parameters import Port
import time

ev3 = EV3Brick()

LR = Motor(Port.C)
UD = Motor(Port.D)
FB = Motor(Port.B)

def pendown():
    UD.run_target(40, 40)
def penup():
    UD.run_target(40, -40)
def nextline():
    LR.run_target(40, 300)
    FB.run_target(40, 30)
def nextdot():
    LR.run_target(40, -30)

byteval = '''
0000000000100100001001000000000000100100001111000000000000000000
'''

bytevalues = list(byteval)

# wait a bit
time.sleep(5)

# define grid limit

x_limit = 8
y_limit = 8
number_of_cells = x_limit * y_limit;
x = 0
# scan grid and perform action depending on cell value

while x < (number_of_cells):
    z = bytevalues[x]
    if z == '1': #draw a dot
        pendown()
        penup()
        nextdot()
    elif z == '0': #go to next cell value
        nextdot()
    x+=1
    if (x % x_limit) == 0: #go to next line
        nextline()

[I'm using an 8-Bit happy face as my image]
I don't know why this weird movement is happening, I don't think it should, please help me with this issue.

Have you tried putting a sleep in your while loop ?

I did, still isn't working

Changed more values, now it drew 4 dots in a column? I'm very confused

I think this question should be on Stack Overflow.

It could be, but you need people familiar with EV3 and ev3python.

You accepted my answer (green checkmark), does this mean it fixed your problem?

Yeah, it solved my problem, thanks!

You are using the function run_target... which tells the motor to run to a specific angle.
So it turns to an absolute position...
This might be correct for the pen_up and pen_down cases, but I think that for the movement, you want relative movement, i.e. relative from your current position, hence I think the instruction you need is run_angle instead of run_target.


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How to pause, and restart (without resetting), a timer block - ev3
We're trying to pause the timer block, and then have it restart at the same time where it left off.
By using the touch sensor in a loop before our timer code we were able to get the text output to stop and restart, however on restart the text output just jumps to the current timer output, so it's clear we're not actually pausing the timer output.
Any ideas on how to pause and restart the timer block using the touch sensor?
Here's our code:

I don't think there is a shortcut.  The timer sensors record how much time has elapsed since they were reset.  The starting of the program gives you the first reset for free.  So the psuedocode ends up something like this.  The button touched vs released is a personal preference.  I think of the interval as starting when the button is released and extending until it is pressed.

Set a variable "totalTime" to zero
Loop start
wait for button touched
Set a variable "intervalTime" = timer sensor value
Set "totalTime" = "intervalTime" + "totalTime"
Set intervalTime = 0
wait for button to be released
write to the LCD display "ready for next interval"
wait for button to be touched
wait for button to be released
reset the timer sensor
Loop end (forever)


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When did LEGO stop using perforated plastic bags and switched to simple ones?
I'm talking about those sophisticated bags used to pack the contents of the sets in 90's.
Here is an illustration of such bag:

Could anyone tell when LEGO started to pack the majority of their sets into simple bags instead of perforated ones?

AFAIK TLG still uses these bags, and they are not unique to the 90ies. They are used for accessory bags, such as the one in your picture, or other various accessories such as these that came in the 2013 Friends Advent Calendar:
https://store.bricklink.com/v2/catalog/catalogitem.page?S=41016-11

Thank you for your reply! I didn't know that. However, I shall probably update my question because I implied usual sets, vast majority of which used to be packed in those perforated bags.

Now they are about to get rid of plastic bags altogether in favor of paper. https://www.bbc.com/news/business-54169686


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LEGO family identification
I found this little guy here, I remember I already had it in my childhood (~30 years ago).

Could somebody tell me what LEGO family it is?
The grid size is 2x2 LEGO studs, it just fits right onto one Duplo stud.
On the inside I see the LEGO logo and the following indication "4 01".

The most common term for the "cams" you refer to is studs.

Seems to be 4224c01: Basic Figure Finger Puppet Female (bfp001)

It appeared in two sets:
1050-1 Basic Pack (1986) and 1089-1 Lego Basic Figures (1985)
Edit (thanks to @Mark comment):
While Brickset list only 2 sets with this figurine, BrickLink lists 25.

BrickLink lists 28 sets:https://www.bricklink.com/catalogItemIn.asp?M=4224c01&in=S

@Mark Nicely found, I edited my answer.


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How to protect my LEGO city from the dust?
I have a LEGO city with all the modular LEGO in my bedroom. But the dust is killing me at nights. How can I protect them? Where can I get those display domes?

How big of a city are we talking about?  Adding a picture of your set-up might help people come up with more ideas for you.

Where I'm from it's called Plexiglas. Other tradenames are Crylux, Acrylite, Lucite or Perspex...
Anyway, you can get sheets of it cut to size in D.I.Y-shops or hardware stores to build your own domes.
If you are less handy, you can find lots of shops offering standard or custom solutions.
If I google "plexiglas", I find dozens of solutions near where I live.
I know of one person who had a custom pyramid shaped Plexiglas dome made for the 10181 set (Eiffel tower)

I know it is a bit simplistic, but you might try just using a light sheet.  If it is a light, tight fabric, it probably will go on and off pretty easily.
If you have lots of delicate parts on your buildings, you could get some small stilts of some sort to hold the sheet up over those areas.  That will give you the circus tent look, I imagine.


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EV3 color sensor strangeness
I've run across something very strange with my color sensor when using multiple sensors and multiple nested loops for a sumobot. I have 4 separate loops continuously monitoring the "optical", "ultrasonic" and two touch sensors ("touch1" and "touch4"). The main program of nested loops controls the motors in response to the sensors breaking different nested loops. I have attached a simple version that I removed the motor blocks from so you can follow it easier.  When the program starts, it defaults to the "search" loop (innermost loop in main program). The optical sensor is looking for reflected light greater than 20 (white color). The first time I put a white paper over the optical sensor, it breaks the "search" and "charge" loops and proceeds to the "color" loop, as it should. However, it only works the first time! All the other sensors work as they should, all the time. Sometimes after multiple attempts, the color sensor will work again. Mostly it doesn't.
Here is where things get strange. If I remove any of the other 3 sensor loops, the optical sensor works perfectly. Another thing- If I change the color sensor in the "optical" loop from "compare reflected" to "change reflected-either direction" (keeping the value it is looking for the same), it works perfectly with all of the other sensor loops running. Also, using "change reflected- increase" or "decrease" doesn't fix it, only the "both directions" setting fixes the problem. Does anyone have an explanation of why this is happening? My only thought is that the multiple instances of the "wait for-color sensor" blocks are conflicting... but that should happen no matter how many other sensor loops I have running. It's driving me crazy helping kids troubleshoot why the optical sensor craps out. Any input greatly appreciated.

Perhaps you need to add some hysteresis in your sensor loops. Each loop waits for a condition to be met, but then repeats infinity as long as that condition is met. Hysteresis means waiting for another condition to indicate that the sensor has returned to the original state and usually includes a deadband (meaning the positive trigger is not the same as the negative trigger) to filter out noise.
For example, wait for the color sensor to detect black again before repeating the loop with a deadband of 10%:


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Adding Power Functions to LEGO Mack Anthem Truck (42078)
Does anyone have experience adding Power Functions to set #42078 LEGO Mack Anthem truck?
It’s a Technic set, but only features manually actuated functions.
I have seen it motorized on YouTube, even though a Power Function option is not mentioned on the box. Any details on how to do it would be very much appreciated.

I modified the unit. It's quite intense. If you have built the unit you have to take a lot of it apart but it dose look cool running along. I’m about to buy a motor for the trailer. I’m going to get a independent motor with battery and switch and hold it on the back only because it a lot of turning on the cogs.

There is this thread on Eurobricks:
42078 Mack Anthem Mods and improvements
Also this youtube video
KlikBriks Lego Technic MACK Anthem (RC MOD) l Instructions

There is an instruction on Rebrickable on how to motorize the truck. Please be aware that instructions are not free (I'm not affiliated with model designer).
This gives you list of parts you need to have to complete the motorization.
You can also check Rebrickable for other 42078 set and Mack related modifications, alternate and unique models with instructions (free or paid) available for each of them.


text:
Ninjago set identification
I’m trying to identify a set to search for instructions. However all I know it is a Ninjago but cannot find the set on Google. It looks like a helicopter with out the blades on top. I am hoping someone might know what this is.

The pieces you have are from Ronin R.E.X. (70735) set.

Instructions can be downloaded from LEGO Customer Service webpage.

Thank you Alex!!!


text:
What is this extra bag from 11019 set for?
This came in the classic 11019 Lego set. No additional instructions. I looked on Lego website and nothing showed up. There was an online locomotive to make? Looks like there’s sets of wheels and gears. Any help is appreciated! The bag that came has the number 135149 copyrighted in 2017

i found 2 of them: https://www.lego.com/cdn/product-assets/product.bi.core.pdf/6394760.pdf and https://www.lego.com/cdn/product-assets/product.bi.core.pdf/6394891.pdf

Does this answer your question? How can I identify a set based on one or more original sealed bags?

Nope. I have instructions, but it came with this spare unlabeled bag with lots of extra pieces

I'm sorry but what is the question? You've already determined that this is from set 11019, and according to the part list of that set, it matches up. Classic sets like this one don't really have instructions because you're meant to make stuff up yourself.

As you've mentioned in your question, the bag is from set 11019.
It seems that the confusion arises from the fact that most Lego sets do not have so many "spare" parts as is the case here.
However, with the Lego Classic line you will often find that there are more parts in the set than building instructions. If you look at the box you can note that it says "Ideas included". I've found that when that text is there, the instructions have several smaller individual builds for most of the pieces, but there is an "extra" bag or two with additional pieces which fits the theme - in this case exemplified by the gears.

This set doesn't have an intention to use all the bricks to build a defined set of models. As seen from description below (emphasis is mine) included instructions is a way for young builders to learn using LEGO bricks in new way and more of an inspiration for own builds. Extra bag is just a bag of more bricks to play with.
Description for Bricks and Functions (11019) set:
LEGO® Classic creations with fun functions
The LEGO® Classic Bricks and Functions (11019) building set comes with a colorful selection of LEGO pieces and instructions to make 7 fun buildable toys with gear-driven functions. Kids get to construct models with moving parts, from a pirouetting ballerina to a helicopter with spinning rotors, before diving into the bags of extra bricks to build their very own LEGO creations.
Perfect for children aged 5 and up
Kids will love building and playing with these functional models. And because each one comes with a step-by-step, pictorial building guide, even first-time builders can experience the pride and joy of constructing their own LEGO toys.
Kids develop key life skills
LEGO Classic playsets inspire children to get creative with exciting themes and building ideas that stimulate open-ended play. Learning has never been so much fun!
Create LEGO® models with different functions – The LEGO Classic Bricks and Functions (11019) playset comes with colorful LEGO pieces and 7 mini builds with gear-driven functions to kick-start the fun

What’s in the box? – All kids need to build a pirouetting ballerina, a push-along helicopter with spinning rotors, an apple with a pop-up worm and more, plus lots of LEGO® bricks for creative building
Open-ended creativity – Kids get to build and play with the 7 included model ideas, then innovate and discover as they find imaginative ways to create their very own LEGO® toys
A gift for any occasion – The LEGO® Classic Bricks and Functions (11019) toy playset is a gift for any occasion. Suitable for kids aged 5 and up
Includes 500 LEGO® pieces – Kids can build whatever they imagine with this original LEGO playset and can combine it with other LEGO sets for even more creativity
More sets to collect and combine – Kids can combine this playset with others from the LEGO® Classic range
Step-by-step, pictorial building guides – Every model comes with easy-to-follow building instructions, so even first-time builders can experience the fun of constructing their own LEGO® toys
Playful learning – Kids develop important creative skills as they build and play
High-quality creative building toys – All LEGO® Classic components meet strict industry standards to ensure they’re consistent and compatible
Safety first – All LEGO® building toys are thoroughly tested to ensure every playset meets strict safety standards

Is it this set? The parts appear to match and it has the same set number.
If so, there should be an instructions booklet in the box (not the bag itself) and possibly a QR code somewhere. Otherwise, you can look at the pictures of completed models (7 in all) that appear on the website. If you've already made them, it could just be spare parts! Legos are for creating your own thing. You can experiment with the parts and make your own contraptions :)


text:
Can anyone identify this set for me? It's a mech with white, grey and gold elements
What LEGO set is this? I am trying to find its manual/instruction.

This is from Titan Mech Battle (70737). Identified by unique tile with sticker. Instructions can be downloaded directly from LEGO Service.


text:
Found bags of LEGO bricks at a thrift store. What sets they belong to?
I am wondering if anyone can try and help me identify these bags. I picked them up a thrift store and all my googling has come up empty handed
This is the first bag

Second one

Third one

Then there was this small one with no identifications on it

And finally these loose pieces

Those all look like parts from set 31109 Pirate Ship released in 2020 :

Note this assumes the colors aren't accurately represented in your pictures. Eg. the 10 loose pieces appear to be reddish brown from your picture, but would be medium nougat in the set. Additionally, dark azure parts look like regular blue, yellow like pearl gold, pearl gold like brown, dark bluish gray like black, etc. in your pictures. Ie. all colors appear darker in your pictures than they'd be in real life.


text:
Trying to find the name of a LEGO set from a sealed bag
I have got a couple of bags which I think are for the same set.

Hi Terry and welcome to Bricks.SE! Please note that we already have guides on how to identify sets, like for example here: How can I identify a set based on one or more original sealed bags?. After trying the steps described there, edit your question with the details of what you have done and where you got stuck and we'll be able to help you.

This is from The Skeleton Dungeon (21189) set.

Identified by unique combination of:

Orange Plate, Round 1 x 1 with Flower Edge (5 Petals)
Dark Bluish Gray Plate, Round Half 4 x 8
Trans-Dark Blue Brick 2 x 2


text:
Electronic inside Spike Ultrasonic Sensor 45604
What is inside the Spike Ultrasonic Sensor 45604?

Pictures of Top&Bottom PCB-Assembly would be helpful.
PoweredUp Cable and Connector use 6-Pin, but why is there used 8-Pin connector inside "black-and-white" Module connection? Are these 2 additional pins in use? What is their function?

The back of this sensor unscrews. The back breaks out the 6-pin cable into an 8-pin connector:

The order of the connections for the pins in that picture from left to right are:
 6    5    4    3    x    x    2    1
ID2  ID1  VCC  GND   x    x   M2   M1

The primary sensor can be pulled out of the front of the part:

We can then remove the shroud around the sensor to reveal the front side of the PCB:

The largest chip on the front side is an STM8S105K6.
Here's the PCB from the back:

The largest chip on the back is a HEF4049BT hex inverting buffer.
I don't have any insight into why an 8-pin connector is used internally when there are only 6 conductors in the wire, but I did confirm electrically that 6 of the 8 pins are connected to the 6 conductors in the wire.
There are 3rd-party breakout boards that can make the connections from the back of the ultrasonic sensor available for advanced usage:

A header (or individual wires) of appropriate size can also be inserted directly into the back of the sensor without a specialized board, but the pitch is smaller (0.050" or 1.27mm) than what is typically used by hobbyists.

I'm confused/intrigued by https://community.legoeducation.com/blogs/31/220 , about "the back of the [distance] sensor can be removed and the cable detached, effectively becoming a LEGO Power Functions 2.0 (LPF2) breakout cable"

@IvanSanchez Thanks for sharing that! I've added info about that breakout board to the answer.

My guess for the 8-pin mystery is that it's a fail-safe mechanism. AFAICS, pins 3 and 4 are +VCC and GND, whereas 5 and 6 are not connected to anything. Since the connector is symmetrical, one could plug a connector rotated 180° - when doing so, +VCC and GND are connected to nothing, i.e. a fail-safe state. If this fail-safe was not in place, it could be possible to connect +VCC to GND and GND to +VCC (or some other weird combination) and potentially damage the circuits.

Thanks for your quick answer Can you confirm uC : STM8S105K6 in QFP on Top-Side ?
What is the SO16 Chip on Bottom Side ?
An Hex-CMOS Inverter as 9V Driver would be in SO14, so would not fit ... Jo

@user22626 I've added the info for those chips.

Pins 5 and 6 can also be multiplexed as UART. Pin 5 is TX and pin 6 is RX from the point of view of the hub.


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Help identify Mega Bloks set with red, blue and metallic gold elements
I found this set in my garage. It belongs to my son but we don't have the instructions and since we don't know the name or theme of the set we can't find it online. I don't even know if everything is supposed to be together!
Some parts broke sadly.


text:
No instructions for sealed Lego bags
I have 4 sealed bags of lego with no instructions. Each bag has a QR code which provides a number (one is 6172062) but nothing comes up online.
Please see photo below of bags.
Any help would be greatly appreciated.
KR
Mark

These bags appear to be from "90 Years of Play" (11021) set released in 2022. You can download instructions directly from LEGO. Identified by Technic, Brick 1 x 4 with Holes in Yellow.


text:
Connections for windup key holes?
I recently bought a set with a Windup Key (piece 29979/79812) and took note of its holes since they're slightly smaller than the standard rod / minifig accessory diameter.

After an (admittedly brief) look through my own pieces, I couldn't find anything that fit perfectly in them. The closest I could find are minifig hands, though the holes are slightly too large for them.
This made me curious: are there any legal connections for the windup key's holes?

I don't have the part to check, but if the hole is slightly smaller than a bar, it might fit the smaller clips used in some wheels, such as on this part:

EDIT: No, it wont fit, see this image below here (in BL studio):


text:
Found 2 random bags in my son's set any idea what they are?

Help finding what these pieces are would be appreciated. Colors are brown, tan, gray and black there are wheels and eyes if any of this info helps

Was expecting something a bit more, um, "unique" in the bags after being lured here by "Hot Network Questions".

Based on 6 parts that I identified:

4x4 plate (3031) in Tan
2 2x2 round plates (4032) in DBG
2x8 plate (3034) in White
Slope 3x2 (3298) in Reddish Brown
1x6 brick (3009) in Tan
4 rims (8mm d. x 6mm w/ slot) (34337) in White

All these parts are in Creative Ocean Fun (11018) set

Comparring the round 2x2 with the "Tile, Round 1 x 1 with Bar and Pin Holder (20482)" and the 2x2 in the bottom of the picture, I would guess those to be LBG.

Since this is one of those "Creative" sets I'd probably add a comment that elements included within the box are for creative building, rather specific model(s). Instructions include some inspiration models, which result in a number of elements being unused, thus may confuse as to why some extra elements being included.

@Henriksupportsthecommunity The round 2 x 2 is definitely DBG, You can see some LBG parts; plate 1 x 2 [w/ wheel bearing], brick 1 x 2 w/ hole, and plate 2 x 8. All clearly lighter than round 2 x 2 and not white

I only see one 2x8 plate, and @LKBricks determined that to be white. According to the inventories (I checked but brickset and bricklink) of the set he points to, it doesn't contain a 2x8 plate in white though, it does contain two in LBG, and it has a different color from the white elements, so I think I agree, it is LBG. That in turn makes the round 2x2 plates DBG, as I also agree there's a clear difference in color, and then the difference to the 2x2 at the bottom of the picture must be due to the lighting. I also struggled to find a set matching.


text:
Trouble connecting NXT 2.0 block to Mindstorms Home EV3 software on Mac
My son has finally shown an interest in Mindstorms and we are trying to use an NXT block with my 2015 Macbook Pro (latest OS) running the EV3 Mindstorms home edition software.
I have read in many posts and Youtube videos that it is possible to program in the EV3 software and upload to the NXT 2.0 brick - with a few caveats for updated sensors not being included and etc.
However my problem is I just cant see to connect the NXT by either Bluetooth or USB using the 'connect' icon at the top left of the program window. The NXT is connected Bluetooth as shows in the connected devices list. The Wizard goes through the steps to connect but just wont find it under Bluetooth or USB and just sits there.
When I try and connect in reverse from the NXT block itself to my Mac - it can then see Mac but when I click on it - it says 'failed!' on the NXT LCD.
The NXT version is showing as 1.31
The software I downloaded is 'Mindstorms home' 1.5.0
Any ideas?

The "new" Scratch-based LEGO MINDSTORMS EV3 software products don't support NXT. This includes "MINDSTORMS Home" and "EV3 Classroom".
The "old" LabView-based EV3 software does support NXT. However, it is 32-bit software and won't run on modern macOS because they require 64-bit software.
If you have access to a Windows computer or can run a Windows VM on your Mac, you can use the "old" EV3 software or even the original NXT software. Both are still available for download on the LEGO Education Retired Products page.

this makes sense now - thanks very much for the response

if you use Mac, a great app for VM is the UTM project.


text:
Identify parts I found in some kind of Star Wars set
I found a ziplock bag with these parts in a drawer. I don’t know if it’s a full set or part of another set, but I see a lightsaber handle and a ship control panel in there.

A search for sets containing both 30387 brick 1 x 4 with hinges at both sides and 2 x 4 tile in yellow quickly yields set 75172 "Y-wing starfighter":

Thank you so much! It looks like it is just the loading trailer from my son’s y-wing kit. Appreciate you figuring it out!


text:
Please help me identify this set
I've got sealed bag №1. Please help me identify this set.

Oh, Man! I spent my whole day trying to identify this damn sealed bag! The set is 76023: The Tumbler


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Should there be a LEGO logo inside SW Clone Trooper helmet?
Should the Clone Trooper (sw0541) helmet  have any LEGO markings inside proving its authenticity?
I have one without any marking inside. Is it original or not?

Normally, both the logo and part number are on the inside of helmets. I don't have that specific one to check where it is. Typically either inside the stud recess, or on the ring around the stud recess. They're often hard to discern, but some direct light shone into the helmet can help.


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Help identifying this blue part

I have scanned through Bricklink and I cannot find this part. I can not determine what to even call it. It has LEGO on the stud tops. I am assuming it's from a old set that has been discontinued. Any help will be highly appreciated.

This is Part 818 - Vehicle, Tipper Bucket 2 x 4
 I used Google Images to identify it.

Please add a link to the relevant bricklink page

Thank you so much !!     I thought of Google image search at one point but then forgot about it.

https://www.bricklink.com/v2/catalog/catalogitem.page?P=818#T=S&O={%22iconly%22:0}


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Set Identification: 2017 set, 4 bags
Can anyone help identify which set these bags come from?

Based on the 60608 window shutter and the 8x8 plate in azure, this is set 11015 "Around the world".

Unfortunetly, the pieces are different

@Denyria Care to elaborate? I gave a cursory look at the parts list for set 11015 and it seems to contain the parts visible in your photograph, at least the two bigger bags.


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How to connect to SPIKE Prime Hub via Bluetooth Web API and send code?
I am trying to go under the hood of the Bluetooth connectivity of the SPIKE Prime Hub as a demo for some kids. I managed to figure out how to use the Bluetooth Web API to connect to a Bluetooth device. However, after this I don't know how I can send Python code to the hub to be run.
Note that I am aware of libraries like Pybricks that do this, and that's an amazing library. I am doing this more for educational purposes. My understanding is that the LEGO Education SPIKE web app does this as well, and was just trying to implement a very basic version.

There is information on the BLE wireless protocol used by LEGO available. It might be overwhelming but maybe it can help you.


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What Lego set do these go to?
I have bags 2,3,5 and 6 the number on the bags is 321R9 from 2017. Any help would be appreciated.

Codes are totally irrelevant for set identification - please post clear photo with contents.


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I need help identifying vintage knock off blocks
This may even be two sets. Vintage, without stamp that I can tell. I’m pretty sure some of them have numbers under them. I have included a picture.

@ashley_johnson Can you please take another picture showing one block next to a ruler? Right now it's a bit hard to judge the size of the blocks.

Possibly related to https://bricks.stackexchange.com/questions/9880/can-someone-identify-this-brick

If you add the picture suggested by @IvanSanchez, please include a close-up of both the top and bottom side of one of the 2x4 bricks. A clear picture of the numbers you mention (or any other markings you can find) might also help.


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D11 42131 caterpillar
I have stared to build the above and I was half way through  point of inserting the connectors to the hub. I have tried all the ports and looking at the schematic plan on on page 169 and have followed the instructions to the letter the diagram and I can only get the blue connections to work in the hub. I have been trying to figure it out for 4 days now

Apologies with bad explanation above I should of said the only connectors  i have working is blue and green but cannot get the red and yellow connectors to show yellow and red as per the schematic plan above

You mean you expect hub make LED's light up in these exact colors? Based on this diagram, colors are used here to help you align each motor with correct location in hub. Are you running a test within the mobile app and it fails?

Hi Alex thanks for reaching out for me, I will take a couple of snap shots which may be easier than me explaining this issue if that’s ok with yourself

Hi Alex I look on my controller app  I have green and blue , ticked but I cannot seem to get yellow  and red ticked as it shows two crosses

Am I doing something fundamentally wrong ?

There have been quite a few questions with regards to 42131 set and LEGO Control+ app. Not sure how many of us here own this particular set to verify the issue. I would suspect the issue is with mobile app, but don't have anything to prove the statement.

Hi Alex is there a way I can send you a screen shot showing the issue i am facing at the moment, I am not sure if could forward this on to you

I have no means of helping with this particular issue, unfortunately. However, you can also try reaching out to LEGO Customer Service to address your issue. If it happens you find the solution this way please make sure to return here and post your solution as an answer to this question.

Hi Alex I contacted Lego regarding the issue was facing and they gave me some trouble shooting options but when I tried to copy these to send to you I cannot add the comments due to how much I can send to you because I have used more characters

If the troubleshooting suggested by LEGO Customer Service proved to be helpful you can post these details not as comment, but as an answer in a field below "comments" section.


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How to compare 2 custom lists of lego details?
I have a .lxf file for MOC. With Bricklink Studio I can create a list of details for it.
In Rebrickable I have a list of all parts that I own. Do we have a way to get somehow a list a details for this MOC that I do not own?
Rebrickable has this feature for sets and MOCs, but I can't find an option for custom lists.

First you need to create a Custom list on Rebrickable with contents of LXF file you got from Stud.io. Then you go to Compare sets where you have an option to compare a MOC vs your Custom List. You can find needed MOC by either its MOC ID or by its name in "Set Num" field. Custom List can be selected from drop-down menu.


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Can I connect technic hub 88012 to remote 88010 directly?
My seven year old has got the Technic hub and remote, and we were expecting them to pair but they won't. Do we have to pair them via the app or can they pair directly?

You can connect them directly using Pybricks (a 3rd-party firmware for the Technic hub).
There are some tutorials at: https://pybricks.com/projects/tutorials/wireless/remote-control
Using official LEGO software, you have to use an app as a relay between the two.


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Lego Control plus doesn't work with Cat D11 Bulldozer (42131)
When I am testing my remote control for the Cat D11 Bulldozer (42131) all features are working except the two motors for the wheels. Also when I am syncing the CONTROL+ app nothing is working. I have tested the motors with BrickController 2 app and the motors are working perfect. I also installed the CONTROL+ app on another device (tablet) with no result. I tested it also with the motors connected directly with the hub, no result. What am I doing wrong?

Same here ! Finally you found a solution !?


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Is there a web resource available to browse LEGO Minifig head designs?
I am curious if there is a minifig browser or gallery that allows you to view and identify LEGO heads created over time? Ideally, this resource would also list the date the minifig head was first available.
Brickset seems to have a minifig browser, but not specifically an option to browse by "head" types.

You can find all the minifigs heads ever made, with the date of release, in the BrickLink catalog: http://www.bricklink.com/catalogList.asp?pg=1&catString=238&catType=P&v=2
Please note that I have already sorted the minifigs heads in the link above by year released, however on the first two pages of the results you will see heads where the year is not applied yet. These are new minifigs heads and the sorting and cataloguing haven't bee finished yet. You will start to see the yearly results on page 3.

You can try firestartoys.com. They sort minifig heads by theme. I hope this helps!


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Which Star Wars set is this?
It is from the Star Wars theme but which one?

Based on the silver jetpack, Jango Fett head, Phase I clone helmet, and orange battle droid parts, I believe it is 75015 Corporate Alliance Tank Droid.


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What are proven methods to sort/categorize a large number of parts?
How would you recommend to sort your Lego parts? Finding a certain part in a box with parts of about 20 models takes ages.
Should I sort by color? Or by size? Another category?

get you brother/sister/cousin to sort them ;)

Worth a read: http://news.lugnet.com/storage/?n=707

Related: Has anyone automated the LEGO hand-sorting process beyond "pawing and piling"?

I think the correct approach to this is to consider the whole process and not just the sorting part, although the short answer "sort by form" will still be valid.
The whole process is not limited to sorting, but in a more general way goes from the moment you decide to store a part away to the moment when you retrieve it to put it in a model.
As such, you have to keep in mind your ultimate goal: find the part you need for the model you're currently building. Most of the time, you'll have a specific part in a specific color in mind, and need to find it as fast as possible. But not always! Sometimes you don't care what color the part is in (invisible support structure), or maybe you can't see it (blind kids). In most cases, the form is at least as important as color, but sometimes it's just color you're after.
So what is sorting? Sorting is a way to do some of the finding work in advance so that when you need that particular part, you don't have to waste too much time. You'll also win serious time on the sorting since you do it for a lot of parts at the same time.
Let's assume you're after a specific part in a specific color, which will be most of the time. So that means your parts have to be sorted both by color and by form. That may prove too impractical for normal people, but keep in mind some serious builders do that.
So the trick is since you have two sorting criteria, you use one at the moment of building, and the other when storing or sorting parts (with discipline1, you'll sort when storing). Usually, you'll want to do as much tedious work when sorting, so you'll keep the color-sorting for when you're building. Color-sorting is the fastest, just think of a tub with all red bricks of all sorts and find 5 1x1 bricks in it, then picture the same task from a tub full of 1x1 bricks of all colors.
Again, this depends on what you'll end up doing with the bricks; if you want to build a lot of 2-studs-wide uniform walls for example, maybe a tub with one color of 2xn bricks makes more sense than separating the 2x2, 2x3 in different color tubs.
In any case, keep in mind the ideal way is to have each part in each color stored separately. If this is impractical, consider mixing parts which have as little in common as possible. If one container holds 1x3 and 1x4 bricks together, it will be more trouble to pick them apart than if you mix 1x1 and 2x3. Or, maybe you can mix 2L Technic axles with 1x2 slopes.
And the last thing to consider is how many of the part you have. If you have 2000 blue 1x1 bricks, and only a few dozens of other colors, don't mix them. Separate the blue ones and the others, or better, separate the blue ones but keep a few mixed with the others, so that the nearly-2000 blue-only 1x1 bricks can go to long-term storage. Similarly, make sure that rare parts for which you only have a few are easy to find, even if that means they have to have their own storage bin (maybe they can be mixed together, though).

Awesome answer! Maybe you could add a bit about how LEGO themselves sort their bricks?

I wish I knew :-) The only designer workshop I've visited is the one in LEGOland Windsor. There they have huge drawers in their main office with one of each part in the drawer glue on a small baseplate on the front. I didn't see one open, but I suspect they are sorted by element AND color. In their stockroom, about every part is sorted similarly by element AND color; with huge boxes for common parts like bricks or plates while for smaller ones they have a gridlike arrangement of small open hobby boxes. Horizontal is shape, vertical is color (or the opposite, I don't remember for sure).

"mixing parts which have as little in common as possible" is a very good hint. Thank you!

Here also +1 for "mixing parts which have as little in common as possible". Especially makes sense for parts that are rare.

If you have a lot of unsorted lego, it isn't easy to apply a fully-developed categorisation system without a lot of work up-front. One way around this is to develop a sorting system gradually.

Exactly how you sort will depend on the size of your collection, the profile of your pieces, the time you have available and the categories that are convenient for you.

What not to do

As a general rule, don't bother sorting by color until you've already sorted by shape.

General notes

You'll probably have an "everything else" container for a while. Don't worry about it.
This is your collection - sort things in a way that is convenient for you and into categories that are convenient for you.
Think about how you'll use the bricks. Sort for use rather than because the categories are neat. For example, I keep some wheels on axels rather than separating them out because I usually want them that way when I'm building.

Starting off

It is often easier to sort out the big bits first because they're easiest to find.
Some things, like tangled cables and string, can really make things messy.

Get things out of the way:
 - Pull out the big baseboards
 - Pull out any cables, winches or anything else that is prone to tangling
 - Pull out any really big parts
 - Pull out any instructions, catalogues, etc.
Next steps

Develop some broad categories of things that tend to be used together. Whenever you come across anything that belongs in these categories, pull them out into a separate container. You don't have to sort all of the bricks in these categories at once - just pull them out whenever you find them.

Examples of major categories:
  - Technic
  - Electronics
  - Minifigs and their tools

As you go, pull out anything that really isn't lego:

Duplo
"Heretic" bricks (MegaBlocks etc.)
Other toys
Scraps of paper
Fluff, twigs etc.

Sort by shape

Stick similar parts together. Ignore color.

Make stacks of 2x2 bricks
Stick the round things together
Make stacks of plates. Offset the plates so they are easy to separate

Whenever you come across pairs of pieces (e.g. wheels and their tires, right and left-hand wings) stick them together. You'll probably need them as pairs when you're building.

Categorize by general purpose

Stuff for vehicles

Wheels and axels
Windshields
Wheel arches

Stuff for buildings

Doors and windows
Fences

Train stuff
Boat stuff

Categorise by general shape

Big bricks
Slopes
Round bricks
Arches
Plates
1x? bricks
2x? bricks
Hinges and turntables

Sort strictly by shape

1x1 bricks

Finally, sort by color
Where you have a lot of bricks the same shape, sort by color as well.

1x1 yellow bricks

"Heretic" bricks (MegaBlocks etc.)
:)

First group by fit. So you put for example normal bricks on one stack, those technic bricks with holes on another and so on. Then start grouping the different sizes of your bricks like 7 long bars with holes, 9 long bars with holes and so on. I never sorted by color, but after the last step, if you have still to big stacks, you should do that.

A pigeon hole drop panel connected to the rear of a rack of pullout storage trays is a proven way to sort small parts. Just toss your bit into the correct slot and collect the sorted pieces from down below. I haven't seen one built specificly for LEGO elements, but the idea is sound. It would work great in a studio situation where large sorts, frequent model breakdowns, and bulk element storage are part of the routine.

@DVK I'm glad you enjoyed the image. I thought it was fairly spectacular. Now, at SQB's suggestion, I'm contemplating building one. The jury is still out.


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Can you identify this Star Wars LEGO set?
Can anyone identify this Star Wars LEGO set:

Any help gratefully received. I think it's a Star Wars set.

The top and right parts are from the Ninjago Manta Ray Bomber.
The parts on the left are from the Star Wars Magazine Gift Y-Wing.
The panel at the bottom left is from Star Wars Death Star Final Duel (as per Syberion).

The Cylinder Quarter 4 x 4 x 6 with SW Death Star II Reactor Shaft Pattern (Stickers) - Set 75093
comes from 75093 Death Star Final Duel


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Where can I buy DUPLO bulk bricks?
The request seems weird, I'm looking to buy for my 1-year-old some Duplo, but they all come in "dog shapes/windows/humans" etc, with a very small amount of rectangular/square blocks, which is all I want.
The old Basic Blocks (80 pieces) were 80 between rectangular and square pieces, that was all I need.
I can't seem to find a list of pieces of "All-in-One-Box-of-Fun", but the pictures on Lego website don't seem to have many of them.
Any suggestions on how to deal with this? 40 square pieces and 40 rectangular pieces would be a good number, but it seems impossible, unless you go in the 200$ range, which is very excessive!
I'm open to other brands, but the one I bought (36$!) don't stick together, they are completely useless!


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Is there on/off function on the 8879 IR Speed Remote Control?
Just got 8879 IR Speed Remote Control yesterday. Does it have an on/off switch? We don't see one.

No, it doesn't have a specific on-off switch.
But like most remote controls, it uses very little power unless it's actually transmitting. I find that self-discharge in the batteries is more of an issue than the tiny power use testing to see if you're using the controls.
Where this can be a problem is if you throw the controller in with a bunch of loose Lego, and a button ends up pressed. That will drain the batteries quite fast, because the controller is constantly transmitting (just as it would if you used your finger to press the button). So the main thing I worry about is making sure the remotes are all stored with nothing touching the controls.


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What Can I Build With This
I have a set of LEGO pieces that I bought second hand. I know it's a full set, because the bag was unopened, but I have no idea what I'm supposed to build with it.

Just because it's a sealed bag doesn't make it a full set. Most sets have lots of bags in the box.

Based on the occurrence of the 2x2x3 brick in white and the 16 trans-blue garage door panels, I think this is a bag from set 7744: Police Headquarters.

From the picture it looks like your bag builds the bottom right part of the station - the 2 car garages and the platform under the stairs.


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NXT brick not executing programs correctly
I have an issue that I am hoping someone might be able to resolve:
We're using Mindstorms in the classroom as part of a STEM program, and have one NXT brick that won't execute programs correctly. The program is a simple move/turn/move program and the program works on other bricks.
It will move forward and seems to attempt the turn but then just stops.
Working programs from other groups also don't execute correctly on this particular brick so we eliminated a programming error.
We have tried soft reset, hard reset, and updated the firmware all with no effect.
I'm hoping it doesn't mean we have one totally useless robot. Any help is appreciated!

Does it behave in a similar way if you use different ports for the motors?

Without more information, it seems like one of the following is to blame:  bad ports, bad motors/devices, bad wires, bad power, or bad NXT.  The easiest way to test these would be to create simple programs and test things one at a time.

There are a few options for the cause of the error. It could be at the microprocessor level, meaning that the execution of the program is wrong, or it could be at the motor driver port, meaning that the NXT tries to drive the motor attached to the specific port but can't due to some electrical failure.
The first option can be eliminated by using other forms of output (e.g. screen) instead or along with the motors, the second can be analyzed by swapping motor ports and testing them individually.
However, in any case you probably won't be able to repair it yourself, so you should contact Lego instead if the existence of the error is certain.


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NXT Programming not working
I recently got back into NXT stuff (keep in mind I have a NXT 1.0). My screen was broken, but I got it fixed. The software works, but I think the programming doesn't. I tried to make the motor move when I push a button. I downloaded it, and then all it did was jiggle the motor. I tried making a text block, but it didn't work - it just said "Run,Done" in a matter of a split second.
Help me! I really want to program stuff on my computer, and not just a 5 move thing on the NXT itself!

Could you please give us a picture of the program you tried? If you can't embed it in your post yet, please provide a link, we'll edit it in.

For a Text Block, which displays text or images on the LCD panel, it is important the add a Wait Block after the Text Block, to give time to view the LCD panel before the program ends.  Wait for 10 seconds should help.

From your description, it seems you use a motor block which just tells the motor to start running. This works, but since your program then comes at an end, all motor activities are stopped immediately.
To solve this, you have to make sure your program doesn't terminate immediately. You could either use a wait block, with a fixed timer after which the program (and motors) will stop, or maybe a block to wait for another condition to happen (button pressed, sensor activated, number of rotations reached,...).
Another solution would be to change your motor block and use a "move" block - which instructs a motor to move for a certain time (the block wait for that time to be completed).
Keep in mind this is all from memory though, I may be wrong on the particulars; but in essence I'm confident your problem is due to your program terminating immediately.

It is the terminating which causes the problem. The easiest solution, which is not included in your answer, is to check the box "Wait till Completion" in the motor block.

Right, I didn't have access to the program so I forgot about that possibility

Glad to be of assistance :)


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Lego Duplo 10508 train does not pull up the bridge
I tried new batteries, disassembled it, and greased it. The engine wheels seemed a bit sticky due to something sticky inside that got there at some point. I put some WD40 to make it work better and was hoping it will work fine. It goes up the bridge easily on its own. Then I tried with one empty platform, pulled up so so. Got stuff on the platform, and that's it - it stops in the middle with no gear sounds or etc.
Originally it is with 2 wagons/platforms and it does seem to reach the same place and gets stuck in the middle of the bridge going up, and does not get stuck elsewhere.
Should there be some kind of clutch, or does it switch off the engine due to Amps raising?
I found this with gear sounds and can't relate. I examined all gears after disassembling similarly like in the video, except I could not pull the wheels off - felt like it will break if I pull harder. I did not want to risk it too much.
I tried looking around for engine pinion issues and stuff, but can't relate anywhere to what I'm experiencing. I bought it used. It's a bit disappointing to pull it/push it uphill, but so far my son doesn't mind too much :)
However, having a DIY soul, I'm a bit sad and insulted with situation...
Update:
It's a pinion issue, after thinking it through, disassembled once more and the engine spins, with wheels and accordingly pinion - blocked so will go for a metal solution, like here.

Hi, if it was indeed a pinion issue, like your update suggests, please move the update to an answer - you are allowed to answer your own question!

Short answer: It's not a good train bridge and results are disappointing.
Longer answer:
We've tried two different Duplo trains (10874 Steam Train and 10875 Cargo Train) on the Duplo train bridge and they barely have enough power/traction to get over it even without any train cars attached. If you run a bare engine (no cover), it goes up fine. If you run the engine with a decorative cover (the "top" of the train), it will struggle. If you run it with train cars attached it seems like it's 50/50 whether it'll make it over.
You also could consider trying different types of batteries. Alkaline (non-rechargeable) batteries usually have higher voltage when they are new (but then drop off quickly), compared to rechargeable, which maintain a steady, but slightly lower voltage (reference).


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Unknown brick/piece information (curved, decorated slope)
Recently, I got a huge box of LEGO sets all mixed together.
I have been slowly identifying the sets that are there.
Some are complete, while others not, but I have been managing so far.
Still, there is one piece that I failed to discover what it is.
I remember seeing it a while back but can't say from where.
Can someone help me out and tell me what brick this is?

Thanks.

It would be a Slope, Curved 2 x 2 Lip, No Studs with Island Xtreme Stunts Logo and Flames Pattern.


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How can I have EV3 Commander App continue running the motor when I release the slider?
I'd like to control a drawing robot that I am building with EV3 Commander App.
The problem is that EV3 Commander App stops the motor as soon as I release the slider.
Is there an option with EV3 Commander App that allows me to set the speed of a motor such that I don't have to keep my finger on the slider - and keep running when I release it?

The commander app is very limited in it's capabilities. Unfortunately it is not possible to control your own program with the commander app.
I have tried all of the built-in EV3 Commander control pads to see if any of them were suitable. The closest thing I could find to a solution would be to use the 'EV3RSTORM' control pad.
The 'Go', 'Back', 'Left' and 'Right' buttons keep all the motors turned on permanently unless you press stop of change directions. Unfortunately you won't be able to change the variable speed of the motors but you could change the fixed speed with gears.


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Technic bits set
There are LEGO sets containing just a selection of bricks, such as 10717.
Are there Technic equivalents with cogs and so-on?
If not, what is the best way to acquire a general selection of cogs/axles/etc?
This is for a little boy who is just starting out in Technic, rather than for an enthusiast who is looking for specific parts.

Something similar was asked before, but this is a different way to ask it and maybe it is time for some updates.
LEGO
LEGO has released sets of Technic parts at various points in time.  Some sets have been available under LEGO's Education line, but these and a couple of others were released in normal retail channels in 2003:

set 10076: Technic Gear Wheels

set
10074: Technic Cross Axles

I don't see any indication that LEGO will still sell you these directly at this point.
For your purposes you probably are better off finding a Technic set that is within your price range and going with that.  Having instructions for building one or two things will help spark the imagination.  If you can't get more Technic for a birthday or other holiday that's coming up, you can always encourage them to take apart the model from instructions and try something else.  Building from a set also means you end up with a nice selection of parts.  You're not going to end up with 10x too many of one thing and none of something else that might be more useful.  Almost any set is going to have a useful selection of parts for building a variety of things.
Amazon
Amazon has a number of similar things:

https://www.amazon.com/LEGO-Technic-Gears-Transmission-Parts/dp/B014C3A0I2/ref=asc_df_B014C3A0I2/?tag=hyprod-20&linkCode=df0&hvadid=312131879690&hvpos=1o1&hvnetw=g&hvrand=18226918666857499465&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9032019&hvtargid=pla-623543211247&psc=1
https://www.amazon.com/dp/B07F1M6PJJ/ref=sspa_dk_detail_1?psc=1&pd_rd_i=B07F1M6PJJ&pf_rd_m=ATVPDKIKX0DER&pf_rd_p=21517efd-b385-405b-a405-9a37af61b5b4&pd_rd_wg=ryNVZ&pf_rd_r=P9CEA0Z1S4SG7SAJR20F&pf_rd_s=desktop-dp-sims&pf_rd_t=40701&pd_rd_w=p0Dm8&pf_rd_i=desktop-dp-sims&pd_rd_r=49423994-eb39-11e8-b188-2fb63616cf11
https://www.amazon.com/New-Technic-Parts-Connectors-Compatible/dp/B07B8BL2HD/ref=pd_sim_328_5?_encoding=UTF8&pd_rd_i=B07B8BL2HD&pd_rd_r=63555f51-eb3a-11e8-a434-bf3dbd9e97d2&pd_rd_w=xNIfr&pd_rd_wg=dO2LD&pf_rd_i=desktop-dp-sims&pf_rd_m=ATVPDKIKX0DER&pf_rd_p=18bb0b78-4200-49b9-ac91-f141d61a1780&pf_rd_r=YN1CYNNRPRE73YPVXB7G&pf_rd_s=desktop-dp-sims&pf_rd_t=40701&psc=1&refRID=YN1CYNNRPRE73YPVXB7G

If you want to get more of specific kinds of parts in "bulk" this is will remain a viable way to do that.
bulk
You can find LEGO by the pound on ebay and at LEGO stores not run by the LEGO group itself.  We have a place here that you can go in and there are tables with parts to pick through.  They have tons of Technics, bricks, plates, minifig parts, Bionicle bits, etc.  You can get a bag of whatever you want for $20-$80 depending on how big the bag is.
Vendors of bulk LEGO tend to set up shop at LEGO shows and conventions.  You might discover that there are some unofficial LEGO shops in your area already.  Since they don't have the advertising dollars of the official stores they might be in your town and you've missed it.
bricklink
bricklink is the ultimate ebay replacement and encyclopedic reference for LEGO sets and parts.  If you want 200 of a part in one color or 1 each of 200 different parts, this is the place to make it happen.
Conclusion
I haven't done any bulk purchases on ebay or Amazon, but otherwise I've had good luck with LEGO sets, bulk from stores, and bricklink.


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Identifying Parts Used For The Escape Hatch of Sariel's Tiger XL Model
I am working on a similar model of Sariel's Tiger XL in prep for my own designs of a few other German WW2 tanks, and need some help identifying a part or two.
Does anyone know what are the two parts on the left image that stand in for the escape hatch? One looks like a spanner, and the other one behind it is circular.

Great question! Welcome to Bricks.SE!

I think Sariel needs his own tag for Bricks:SE!

 First three from what we can see...

Part: 4735 Bar 1 x 3 with Clip and Stud Receptacle (Robot Arm).

Part 2958 Technic, Disk 3 x 3.

Part: 75c03 Hose, Rigid 3mm D. 3L / 2.4cm.

Last two hidden from view...

4 & 5. Part: 4085d Plate, Modified 1 x 1 with Clip Vertical - Type 4
    (thick open O clip).
I can't see, but I can imagine two crossed vertical 1x1 clip plates, pierced by the flex tubing to hold up the robot arm.
Sing! Now, build it out.  Now, build it out.  Now, build it out...

Great answer! That's a good call about likely having the 85861 element behind to secure it in place. It could just be held in place by the antistud on the arm, but I'm sure that Sariel designs with a lot more robustness than the MOCs that I cobble together. :)

True, or possibly a combination of both.  Darn-it!  Now I have to make another animation!:(

This is actually made of three parts as far as I can tell.

Technic Disk 3 x 3 (2723)

Bar 1 x 3 [Clip / Anti-Stud] (4735)

A cut piece of Hose, Rigid 3mm aka Flex System tubing


text:
Third power functions train runs backwards, why?
We have the passenger train and freight train, both run from a single controller - one through the red and one through the blue side. At Christmas we got the holiday train, and with the power functions kit coming back in stock with Lego, we just added power to it.
Having set this train to red on channel 2, its forward is counter clockwise. Both trains on channel 1 go forward when the dial is turned clockwise!
How do I reverse the controls of channel 2 without affecting channel 1?

Have you considered lifting the train off the track and turning it 180°?

Possible duplicate of My 9398 crawler going in reverse way

The power functions motor block is symmetrical except for where the power cable comes out:

So I think it likely you can (partially) rebuild your city train with the motor turned 180 degrees, which will clearly change the direction the train travels...
Since I would expect all trains going in the same direction when exactly built according to the instructions, perhaps you oriented the motor wrong in the city train or the other two trains ?

Looking at it all closer Michael Verschaeve has it. The drive units on the 2 large trains are the rear bogey on the train thus the power cable comes out the front of the bogey. On the Holiday train the power is in the front wheels so the power comes out the back. As such the unit is reversed and the drive. Stupid I didn’t notice it but thinking now I may switch both the big trains onto one channel and reverse the other for the holiday train.

There are little black switches on the train remote control which you can use to invert the direction.

The little black switches change the direction but of all the trains so the 2 trains on the red dial then reverse how they operate. This means the Christmas train and the blue train work turning the dial clockwise and the passenger train anti clockwise. Turning the train round to face the other way obviously makes no difference!

I see, you want the trains controlled by the same remote. Then my answer indeed doesn't help much, I'll post a different one

Any way to do this on the 88010 remote (or the 88009 hub / 88011 train motor)?

For the 88010 remote, you can physically turn the switch... (plus becomes in the minus position and vice versa), there are no additional control switches...


text:
My 9398 crawler going in reverse way
I built 9398 crawler set and everything seemed OK.
However, when I moved the RC tumbler up, the crawler went back, and when I moved it down, the crawler went forward.
On the battery box I saw tumbler and changed its position, but nothing changed.
I also changed the order of connection motors to box, which also didn't help.
P.S. Turns work fine.

From the power functions FAQ:

Why does my Power Functions model drive backward when I want it to run forward? You can change the direction your model runs by flipping
  the small black switches located on each side of the channel selector
  of your IR Remote Control.

From the sounds of it, you've already tried the little black switch on your remote, and that didn't fix things. I've had the same problem with PF remotes in the past, where one of those switches just stops working. Try unplugging the motors connected to the IR receiver, and swapping which port they connect to. Then see if the toggling works on the other side of the remote.
If the remote is at fault, try contacting LEGO customer service.