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How much torque can a lego axle handle?
from to this question, it seems that the gears are stronger than the axles, which begs the question of how strong are the axles? if you connect one of the stronger motors, such as say the buggy motor:

which according to philohome can produce 14N*cm of torque with an adequate power supply, is this enough as-is to break axles? what if it's geared down 1:2? 1:4? (such that it turns slower with more force), at what point do you risk breaking axles? (or more likely, at which point will they start to bend and lose strength)

now I wonder how much torque can go through a universal joint

In this forum thread I have found the following tidbits:

"We all know that XL motors can twist axles to their breaking point" This means 40 Ncm, according to Philo.
"If you're looking to get max torsional stiffness, then stacked 2L axles + connectors would definitely be much stiffer in torsion than a single long axle."
Axles can twist without breaking in two

Besides these, I couldn't find an exact number.

I have never broken an axle. That's despite dealing with some rather hefty forces that dwarf any LEGO motor. I made a flywheel (around 800g and 8cm radius) and spun it by hand up to 1,000 RPM (through a gearing system and a monstrous handle). That's 28 joules of kinetic energy there. I then released it all into a single wheel (with more gearing up), with the drive passing through A SINGLE axle. The axle was only slightly bent, and could easily be twisted back.
On another note, I often use torsion bars as shock absorbers in my vehicles when I need a compact double-wishbone suspension. A 1.5kg vehicle provides enough weight to twist eight 7-stud axles by around 5-10 degrees.


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How can I extract part id or design id from a photo?
Is there any software/site that tells me which LEGO parts exist in a photo? I would love to get a csv of parts from a photo.

As far as I'm aware, there isn't such a service. Akiyuki designed a LEGO part sorter that sorts bricks by identifying the shape and weight of the brick. If you can get an accurate reading of a pieces weight in milligrams that should help you get a more accurate identification.

LDraw distribute a library of most LEGO parts in 3D. You may also be interested in the Signal Processing Stack Exchange site.

As far as I know, no such project or software or site exists. The closest one I could find is (was?) a thread in the Eurobircks forum, where exactly this topic came up. The members there tossed about various ideas, mentioning Akiyuki's brick sorter device (with the factors that made its job easier than the one you propose: uniformly lit background with known color, precision scale, only one piece at a time, a few hundred possible parts), some proof-of-concept code was written to test the capabilities of the OpenCV library, but then the interest faded and the topic was abandoned.
There are several problems in this proposition that are highly difficult (if not straight impossible) to overcome:

Lighting conditions

The optical recognition process depends heavily on sensing the difference in the brightness and color of adjacent points. If the lighting conditions are allowed to vary (that is, not requiring the use of a light box) then the differences between each color and the background can't be set in the program. One could still overcome this limitation if the image contains a piece of a known color, but then the calibration must be done for each image.

Overlap

If pieces are allowed to overlap then they can be easily mistaken for similar pieces, or if sufficient parts are overlapping then clear identification can become impossible. If you can only see a part of a Technic axle, you can't tell how much of it is under the 6x6 plate, so the lenght of the axle can't be determined. The same analogy works for many kinds of pieces (bricks, tiles, plates).

One point of view

If this system can work using only a single image (taken with an ordinary camera) then some pieces can become too similar to tell apart. For example, from straight up, a 2x2 brick and a 2x2 plate look exactly the same, just like a 2x2 brick and a 3x2 brick if both are standing on their end. Shadow analysis could help with this matter, but only if there are clear shadows cast from a known point in space related to the camera and the surface on which the pieces are laid out. So we have essentially arrived at the "very precisely controlled and known lighting and photographing setup", called light box, but also added a ton of processing logic and advanced mathematics. Not to mention the problem of dealing with shadows cast on other pieces, which can render shadow analysis moot or even obscure some pieces so they won't be recognized correctly or in extreme scenarios maybe not even seen.

Differences only visible from one side

This might not concern you, but in some cases pieces only differ from each other in a very small detail that can only be seen from a certain point of view. For example, if a minifig head was laying on its side, it is optically impossible to tell if it has a hole on the top or not.

source: Stack Exchange

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Large trap door - alternative to door with frame 4595708
I need to build a large trap door, the trap door 4x5 with frame 6x8 is too small for my model. Other doors/hinges seem to have too much resistance and the door doesn't fall by itself, it must be rotated. Do you have any ideas as to which parts I could use? I thought I could use 3 of these doors together, the problem is finding the right counterpart.

This hinge combined with a technic pin lets you easily make large trap doors. You can see a train-track-sized trap door in this model using two of these parts. In this model the trap door falls down when you retract an axle that normally holds it up. Other arrangements are possible.
The beauty of this particular hinge is that it is symmetrical, so there aren't two different halves to keep track of, and you can use any kind of technic pin you want. The relatively long plate on it makes it sturdier than some of the older variants like this one.

@Ana You're welcome. There are, of course, infinitely many other ways to do it. But this is using one of the newer, available-in-stores techniques. And using different pins to hold the plates together allows you to have looser or stiffer trap doors.

You can build your own trap door from System and Technic pieces. Use plates for the surface and frame (maybre reinforced by bricks if necessary), and attach one or more (depending on the weight and size) Technic joints underneath. I have no pieces with me at the moment, so I can't show you, but if you need clarifications, I'll look up images of the pieces I'd use.

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How to read the EV3 display
Is there a users guide or something similar that describes in detail all the images that one sees on the display? There seems to be a lot of stuff there, but no explanation.

For most of the screens, you can find detailed descriptions in the Users Guide found on LEGO MINDSTORMS download page. Additionally, there is some information in the help file of the EV3 programming software.
The best resource I have come across that shows "everything", though, is the Apps > General Information: Userinterface section of the documentation from the lms2012 source code. The source code is officially available from the "Advanced..." section of the LEGO MINDSTORMS download page.
You can also find the compiled documentation hosted at http://ev3.fantastic.computer/doxygen/uiapp.html.
I've included the relevant images below as well in case links break.
Although this shows "everything" it does no have much in the way of detailed descriptions. On the other hand, it does provide some hints to some obscure things that are not documented anywhere else.


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Would LEGO use recycled plastic?
I have been studying the application of new recycling technologies because I am concerned with plastic pollution. I have thought of a way to apply new technology differently but the missing piece of the picture was how to find  a company that would be willing to work with our city to apply this technology.
With 9% percent or less of plastics being recycled in America because of sourcing and down-cycle challenges, LEGO is positioned to positively transform the way plastics are used and galvanize support for their brand. It would really just take a single industrial leader, operating at scale to make it happen. Others would follow.
If LEGO could transform the way that plastics were produced, and create living wage jobs, would they?
In other words, do they have any motivation to use recycled plastics, or hire American workers, and if so, what motivations?

We here at bricks.stackexchange.com don't represent the Lego company. We cannot answer this question for you.

I'm voting to close this question as off-topic because it can only be answered by the Lego company.

LEGO do already have a sustainability report (see my answer here) and LEGO's environmental pages here: http://www.lego.com/en-us/aboutus/responsibility/environment/goals

The LEGO Group has already created clear sustainability goals.
TLG is currently investing money to try to find sustainable and non-petroleum based ways to design LEGO bricks. Here's some info about the new Sustainable Materials Center that TLG is working on:
http://www.lego.com/en-us/aboutus/news-room/2015/june/sustainable-materials-centre
It sounds like they are investing significant money (1 billion DKK, ~150 million USD) and manpower (100 new employees) into solving this problem. They have also made it clear that they want to keep their focus on product quality while exploring sustainable technologies, so it sounds like whatever new plastics they develop will need to be at least as high quality as ABS.
If you are interested in collaborating with them on this, you'll need to get in touch with TLG directly. This is a fan-moderated FAQ site, so you are unlikely to get a response from a LEGO employee. I'd recommend using the "Contact Us" page on LEGO.com.

Unlikely, since TLG prides themselves on high quality, which somewhat contradicts the notion of reused materials. But there are more practical concerns too:
I'm far from an expert in plastic manufacturing, but I guess it wouldn't be trivial to gather the trash, clean it from any foreign materials, sort by color, remelt and recast into bricks.
Also, recycling would be much better suited to high volume items, like packaging materials, where allowed tolerances are an order of magnitude larger.
LEGO bricks have a very high life expectancy, apart from breaking due to excessive forces or discoloration caused by chemical reactions (which in itself makes recycling quite complicated - who would like their "new" white bricks already yellowed?), there aren't any ways that would transform usable bricks into recyclable trash, so even if implemented, the scale and therefore the environmental impact of this operation would surely be negligible compared to plastic bottle caps for example.


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Where can I learn how to program an NXT using C#?
I've been toying around with my NXT 2.0 set for a few years now and I would like to learn how to program it using C# language. I have no experience in coding and I am definitely not a computer geek. Are there any tutorials that can give me a headstart in this thing?

If you have no experience in coding, why are you set on programming the NXT in C#? There are other options, such as using LeJOS NXJ which helps you program the NXT using Java, arguably the language C# was largely modeled after .....

You could start here for example: LEGO MINDSTORMS NXT Tutorials Overview
For a generic C# introduction see here: C# Tutorials or The complete C# Tutorial or C# Tutorial or just do a Google search for "C# tutorial".

Thanks a lot for the suggestion, i really appreciate that .

You are welcome! If any answer proved useful to you, you can upvote it with the upward pointing arrow on the left side. Or if you think an answer is the correct one for your problem, you can also mark it with the check mark as accepted, signaling the future readers which solution works.


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EV3 turning in circles
New programmer feeling my way around. I set the most simple "steering block" to 25, the power to 50, and the number of motor rotations to 40 or 50.
Then I let it run expecting the bot to go in a circle. Instead it circled around somewhat erratically with roughly the right radius, but without coming anywhere close to following the same track.
Hard to tell exactly what it was doing but maybe the outside wheel on the turn was moving steadily forward and the inside wheel (the slower one) was progressing unevenly.
What do I need to do to get nice clean circles?

It is quite common for the tires to slip and cause this type of behavior. For example, here is a similar question. The answer here is the same.

Make sure your center of gravity puts most of the weight of your bot on the drive wheels.
Make sure the tires and the surface your are driving on are free of dirt/dust.
Use sensors to help compensate for any slippage of the wheels.

If you only want your robot to go in a perfect circle and nothing else, you could fix a beam to the floor on one end an your robot on the other so that it cannot deviate from the circle.

Thanks again David.A little weight on the wheels did the job. Like magic.. Motivation was to be able to program exact courses using arcs and line segments.

What is the best solution? would a fabric surface like a pool table work better? What about using sandpaper or a wire brush on the wheels?

I have heard second hand that using sandpaper to rough up the wheels does increase traction. It should be noted though that for anyone participating in FIRST LEGO League or another competition that prohibits the modification of LEGO parts, this is against the rules. "Best" is a subjective term, so you will have to experiment and come to your own conclusion.


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Is there a standard distribution of minifigs when you purchase an entire case?
The last couple of times I purchased a case of collectable minifigures, each one had three complete sets (16 x 3), plus an extra 12 remainder of random minifigs. My last case I ordered only had two complete sets, and the remainder of minifigs had a much wider variance (five of one minifig, none extra of others).
Should each case contain three sets, or is it truly random?

Every box contains the same distribtion of minifigs. For example see this review on www.eurobricks.com of series 13 has the same distribution as my box. (links to his other CMF reviews are on the bottom of the first post)
For most series boxes contains 3 full sets and 12 remaining ones.
Series 9, 10 & 11 contain only 2 complete sets, with 2, 4 or 6 bags of the same minifigs. These boxes where also available as 'half' with only 30 bags. This way these boxes contains 1 complete serie.

Ok so basically with a box of 60, there should be at least two complete sets, but not guaranteed to be three?

Based on the current released boxes yes. At the moment its 3 sets again. Both Simpsons series and series 12 & 13 have 3 complete sets.


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What is the difference between these two Technic half bushings?
While randomly browsing some LEGO sites, I came across a weird (to me anyway) looking bushing. Its part 4265c. Below is one of the images describing it and the left one I recognize, but the right one I have never seen. It looks like there is some built-in play to the axis.
So my questions:

Are the two bushings on the image interchangeable?
Are they both really referred to by the same id (4265c)?
Is there any practical difference between the two?
Are there any specific use cases where the second would be preferred over the first one?

Related to: What's the difference between these hole shapes?

They both appear to have the same part ID despite being quite different.
Sariel answers most of your questions in The Unofficial LEGO Technic Builder's Guide.

toothed half bush with a cutout
The second variant, the toothed half bush with a cutout, is exactly
  what its name implies: a copy of the previous version with part of the
  axle hole cut out, which makes the axle hole large (see Figure 4-13).
This modification was introduced to make it easier for children to
  take half bushes on and off the axles, and that's exactly what makes
  it much less popular with builders: These bushes are more likely to
  shift when stressed than the first variant.
Other than that, it has every quality of the original toothed half
  bush except that, having been introduced a few years later, it's newer
  and thus made of strong material.
(Chapter 4. Page 36.)

Pawel "Sariel" Kmiec, 2012. The Unofficial LEGO Technic Builder's Guide. 1 Edition. No Starch Press.

Interesting... brickowl lists the right picture for 4265c while peeron lists the left picture.
This leads me to think that both are interchangeable and that the one in the right picture is a more cost-efficient version of 4265c (using slightly less ABS). Lego Pick-a-Brick also shows the version in the picture on the right.

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What are the differences between NiMH and Alkaline batteries for the EV3?
Currently I am using six rechargeable batteries for my Lego Mindstorms EV3.
A few seconds after I start a motor the EV3 gives a notification that that the battery is low.
I know that good batteries are alkaline ones. However, personally I want to avoid using them because I will need to throw them away after use.

We need more details - what motor are you running, which rechargeable batteries are you using? I have been running an EV3 on rechargeables (Duracell) for a while and get at least 2+ hours out of them - continuously powering 2 medium motors. So what you describe is not normal for standard Lego motors.

"Best" is a subjective term that we try to avoid. See http://bricks.stackexchange.com/help/dont-ask. It would be better if your reworded your question as something like "What are the differences between using Alkaline and NiMH batteries with the EV3? (And are there other types of batteries that work with the EV3?)"

@DavidLechner sorry for that. I edited the question.

NiMH batteries only provide 1.2V per cell whereas Alkaline batteries provide 1.5V (nominal values). This means that new/fully charged batteries will provide a total of 9V for Alkaline and 7.2V for NiMH. The EV3 is programmed to show low battery somewhere around 6.2V and turn itself off around 5.5V. There is no option a available to tell the EV3 the difference between these two types of batteries. The EV3 was designed for Alkaline batteries. You won't get good performance from NiMH with the EV3.
LEGO also makes a rechargeable Li-ion battery pack. Being designed for the EV3, this battery is properly sized for comparable performance to Alkaline batteries. Be aware though, that this battery pack makes the EV3 one LEGO beam width taller, which could require some models to need to be adjusted to accommodate the extra size. Also, when you remove the batteries from the EV3, you will notice a small black circle in the battery compartment. This is actually a button that lets the EV3 know that the battery pack is installed rather than regular Alkaline batteries. This lets it adjust the battery gauge and low battery alarm for the slightly different voltages of the rechargeable battery pack.

The difference between alkaline and NiMH is not so clear: Good NiMH have a discharge curve flatter than alkaline so they may actually last longer (even if initial performance is lower than alkaline). See http://www.philohome.com/batteries/bat.htm.

Another possible choice of batteries are lithium-metal batteries like Energizer Lithium Ultimate batteries.
The performance to price ratio is better than premium alkaline batteries but worse than discount alkaline batteries (which often perform quite as good as the premium brands).
I use them mainly because I can't be bothered by replacing batteries too often. Also their voltage level stays nearly constant until their charge is depleted, which is definitely not the case for alkaline batteries. For alkaline batteries the EV3 starts complaining while there is quite a bit of charge in the batteries left.


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What is this 2x4 brick with a clear bottom, a small hole at each end and a 6 brick high pole?

It is a 2x4 with a clear bottom a small hole at each end and it is smooth on top with a 6 high pole coming out.
The brick has no numbers on it so I'm not sure what it is I have tried searching for it however I can't find it if anyone knows what set this is from that would be great.

Are you sure it's LEGO? The green bricks in the background don't look like they are LEGO.

@Ambo100 Yes I am sorting a big box and separating the Lego from the non Lego the stuff in the background is some non lego

You mentioned you couldn't find a number, can you find the LEGO logo on the piece anywhere?

& other picture wrong, item of 2 part.

It looks like it's 799c800:

This part was used to implement a simple "hand of god" steering system on a bunch of sets in the 70s.

Image is up-side-down.

@AndrewHodson No, it's not: http://www.peeron.com/scans/336-1/5

Also wrong way up on peeron, was also on 1 other website which I've told the error. If you look at image Nos. you see 6 instead of 9.

@AndrewHodson Oh, sorry - you're indeed right: the previous image has steps 7-8 and the following one 10. Thanks for the heads-up! (Corrected it here)

Steering column complete, fire engine, tipping lorry, low loader that came with crane, also on its own 'Lego spares' at Wrexham. Look for 4 & 5 wide plate with a hole, plate with part 2 studs wide with hole, 4-stud wheels (or 1 stud & spokes) & a 1×2 with the word 'LEGO' on side.
1 of mine broken, = on fire engine. So I'm after 1.


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LEGO Set 10188 Help on Step 160
I have the LEGO Star Wars Death Star set 10188. I am stuck on step 160 because when I try to clip the parts into a circle, parts snap off and I can't seem to bend it down. Thank You.

If you're able to share an image of what you've managed to build of that step, we might be able to diagnose the problem :)

I'd double check that you've got all 16 links in the chain - if you're trying to squeeze it into a circle with less than that it won't fit. Also double check the placement of the pieces from sub-steps 7 and 8.
Finally, when forming the circle, try carefully working your way around from one end, moving completing each bracket before moving on to the next - possible starting with just one click each, and then going back and adding another as needed.

This gets my vote as possibly the most fiddly construct in an official LEGO set, but it sure is worth it once you manage to get it together.


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A custom LEGO velociraptor
I would like to make a custom paint job on a LEGO velociraptor (to look more like the one in the LEGO Jurassic World game), but I don't want to paint it myself because I can't paint for the life of me so it would look bad and it probably wouldn't move. So I looked for a website to see if I could have one printed but I can't seem to find anything. Could someone help?

In my understanding of the question, you want to take an existing LEGO velociraptor and repaint it, but you are afraid that doing a custom paint job will rub off quickly.
There is no easy solution for this, but here are a few tips:

You could send an email to the guys at minifigs.me and see if they would be willing to help you with this, either as a one-off job (but it will cost you) or as an offering they wish to add to their collection. Their contact form is [here].(http://minifigs.me/make-me-a-minifig/contact/)
You could try and do this yourself. Removing the existing print from
a raptor fig should be relatively easy (this article at
Eurobricks
recommends Brasso and a paper towel/rag/cotton ball) even though
that is very mildly abrasive and hence might leave some minor
scratches. Brickjournal ran a series
of articles back in 2008 about minifig customization - I found this
online
copy that explains how to give LEGO pieces a new paint color - they
recommend acrylic paint. I also found this link describing how to prime & paint LEGO minifigures. They recommend priming and sealing on top of an acrylic paint job.
To get the finer details, consider using a Sharpie pen.

Net - Customizing your velociraptor is definitely possible, but there is no "ready-to-go" customization service for this yet. Doing it yourself can be done, but it is not easy nor quick to do this, especially not if you're doing it the first time. Definitely not a job for kids.

You wer a great help sorry if the question didn't make sens I was half asleep wen I wrote it

If I understood your question correctly, you wish to build a velociraptor yourself, from basic bricks (as opposed to the single functional unit that LEGO introduced as part of the Jurassic World line). In this case I have no idea what search did you do, but just doing a Google search for "lego velociraptor" results in several models of varying proportions and looks:

1
2
3
4
5
6

As for the painting and printing, could you please clarify your question? Why do you wish to paint or print and exactly what?


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My building is developing gaps and spaces
I am building a large project, and there are spaces developing between bricks and plates. I've been working on it for almost a year, and some places are 20+ bricks high. What can cause this over time? Can plates get soft and warp? If the weather is warm, can this affect it? Has anyone else had this problem? Also... As many times as I've undone and re-done sections, some places won't level out and can be less than one plate off in height.I would love some advice. Thanks!

I'd say it depends on the brand and quality of the bricks.  I've seen this happen with Megabloks, but LEGO seems to be higher quality than most other bricks.  What brand of bricks are you using?

I am only using official Lego blocks and plates. It's just so strange how these gaps/spaces are showing up about 15 brick heights down, so it's really too hard to un-do everything to reach these spots. And I really can't figure out why I can't even things out in other places. It starts out level & then suddenly it's no longer level. My fingers are raw from tearing out and re-building. Anyway... Thanks for answering! I'd include a picture if I could.

Are the bricks old? I've seen older bricks and plates getting warped, but newer (say, roughly 1985 and forward) generally holds up well. If we had an image we might be able to see if you're putting stress on some of the bricks, since that can also be a cause of disfigurement.

Are you building on a hard surface, or soft?

A photo might help us diagnose the issue.

Lego bricks are built to certain tolerances. Maybe your structure is large enough that rounding errors are creeping in?

@LegoPatient Let me know if there is anything I can help you with in order to get a picture posted, since it would make the question much clearer (Are there vertical or horizontal spaces? How big or regular they are? Are the parts otherwise lined up?) and we could help you more efficiently.

Without more information, it's hard to know what can be causing the gaps. My theory is that the structure has gotten large enough that the spacing in the bricks is adding up such that your structure is no longer "square".
According to this page, there is a 0.1mm gap between two bricks attached to a common base. This gap makes it possible to remove the bricks once they've been placed. Also, Lego claims their manufacturing process has a tolerance of 0.01mm (10 microns). With a long enough structure, those mm add up.
Here is an example of the gap in play

There are the same number of plates on the left and on the right. The left ones are all pushed together, the right ones are attached to a baseplate (or some other 16-stud plate or brick). Because each plate has a 0.1mm gap, multiplied by 16 plates gives 1.6mm difference. Even if the 0.1mm isn't the right value, you can see that there IS a gap and it is large enough to be significant over a small distance.
When you are building a very large creation, inevitably some things won't want to fit properly. I am building a multi-story building using 1xN bricks for the walls (mostly 1x2 and 1x4 bricks). Each story is the same size as the previous one, and each one is re-inforced by the flooring and internal walls, but it's painfully obvious that the different stories don't fit well together. When I take one story off another, it doesn't want to snap back into position later.
It's even possible to take advantage of the gaps to make curves. If you make a long enough wall out of 2x1 bricks, you can physically bend it into a circle.
As far as advice on how to avoid this problem, I don't really have anything concrete. One thing you could try to do is to space things uniformly, using the same kinds of pieces all the time. If you build a long strip using 2x4 bricks on one side, and 2x2 bricks on the other, you may find that they are not the same length even though they have the same number of studs. Or, design your creation in modular sections, counting on the fact that it will not quite meet at section boundaries. This is how people build bridges: they are frequently designed to allow for expansion and contraction of the bridge sections by placing seams that allow for the change in size as the bridge temperature changes.


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What tool can get the Technic pin out from a connection closed in the other end?
I'm having trouble removing these LEGO Technic pins apart from their connectors and I don't want to use carpenter tools like pliers which may damage the bricks.

What tool can get the pieces separated without force that damages the pieces or my fingers?

always used muh teef in such conditions ;)

Finger nails typically work for me lol!

I would have said...uh...your bare hands. But I suppose you tried that already. ;-)

Push the Technic pin in a beam hole, then insert a rod (antenna or minifig tool handle) into the hole in the pin from the other side. The rod will prevent the "lips" of the pin from closing in, therefore preventing the pin from leaving the beam. Then you can pull on anything attached to the other end of the pin.
This example below shows the removal of a pin from a beam:

Heh, beat you by that much.. probably the time it took you to type a fuller explanation. :)

Oh now look at you with your fancy pictures! :)

Thank you for your fast tip! I found a solution and posted it below.

I figured out a solution while waiting for answers. The tool I used for it was a universal T20 bit which most people have or can easily get access to. I took some documenting pictures of it which I would like to share here.
EDIT: Use a plastic LEGO rod as zovits and others recommend. If you don't have that, use metal tools as a last resort. And if using a metal tool, use Allen a.k.a. Hex key instead of Torx. as PlasmaHH commented.

Hard to argue with results, but I'm reluctant to apply metal tools when plastic will do. :)

The results were good. I tried to take a photo of the inside but it was too blurry and dark. I don't have the laser beam but would for sure use it before the metal tool which is not round. SO my tip might help out those without the full lego brick set up.

Please use allen wrenches, not torx.

Stick the pin end into a Technic hole (like in the middle of those two red bits), then stick a light saber rod into the pin, and pull the red bit.
BOOM.

Thank you for your fast tip! I found a solution and posted it below.

I recently noticed that LEGO included guidance on this exact issue in their instructions in the late 80s and early 90s. Here's an example from the 1989 Universal Building Set (8034):

Here's the bit referring to disassembling these sorts of elements:

Nice! This was actually my first Lego Technic set, forgot it until I saw the images. Nostalgia!

@Tim That's great! It's a fun set. My son and I just dug it out of my collection to rebuild.


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Is it possible to use DUPLO bricks in LDD?
Is there a way to import DUPLO bricks to Lego Digital Designer? Or is there another way to make DUPLO build instructions?

LDD is a closed world where people can't add its own parts. If you want to create Duplo building instructions you should use LDraw that has many Duplo parts in its library, and allows you to create the missing ones if needed.

Short answer is no. Maybe they will add it in the future, though.


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What will LEGO do when all the crude oil on earth is used?
When crude is no longer available (which is in 53.3 years) what will LEGO do, since oil is needed in order to make plastic? Is there a plastic alternative, or another type of material that is strong and durable like ABS plastic?

Somehow I think that what Lego bricks will be made out of will be low on the list of concerns. Of greater concern: how will The Lego Group ship anything anywhere? How will food be transported anywhere? How will humans move about on the earth without gasoline-powered cars, trucks, airplanes, ships? Will the global economy crash? What will we eat? Etc...

They're working on it! Should be ready in 15 years.
http://www.nbcnews.com/science/environment/no-more-plastic-legos-company-searches-sustainable-material-n379976

Hmmm... would have to be something relatively light, slightly flexible but also mostly rigid, preferably waterproof/buoyant, easy to mold, and cheap... perhaps some future form of carbon fiber? Or perhaps some organic material that comes from animals, and so is infinitely sustainable...

Our estimated time to run out of crude oil in roughly 500 years. As timeless of a product as LEGO is, I think that playing with them in 500 years will be like playing with rag dolls. And those were more like 350 years ago. After that, boys had guns instead, and girls were learning more productive uses of their time than running around with rags sewn around a walnut and giving them names.
And besides, we probably won't hit that 500 year official estimate, because when something is becoming scarce, you plug your car into a wall instead, and make your coffee cups out of corn. But if we do just chug along and then all the oil just disappears at the 500-year mark, do you really think that plastic won't have been replaced?
Wood was a big deal. Then it was flint/obsidian. Then copper, tin, bronze, iron, steel, plastic, polymer...
I think we'll have either moved on from LEGO or moved on from ABS plastics in 500 years.

Oil won't run out in 46 years' time, it will just need more energy to extract it than it can be got from it. Lego can still afford the small amount required for each brick even then.
Guess perfected re-cycling by then, all plastic returned to maker to make the same things again, which means Lego won't get much.


text:
Groove dimension of 4216 or 88393?
What is the dimension of the groove of LEGO part #4216 or #88393?

According to LDraw, the slot is 8 LDU wide (1 plate, 3.2mm) and 5 LDU deep (quarter module or stud, 2.0mm). Here's the relevant quads from the LDraw file for reference:

Thanks for answer. I guess you mean 3.2 mm wide and 2.0 mm deep? I don't know LDraw. But I guess these are the correct dimensions.

That's correct. I misplaced my decimal converting to millimeters originally, but the correct dimensions are ~3.2mm wide and ~2.0mm deep.


text:
EV3 IR, ultrasonic senosor datasheets
I want to connect EV3 IR and ultrasonic sensors to my Arduino.
Unfortunately could not find any good documents describing how to use/control them.
Could you please help?
Thank you very much.

LEGO has released the source code for the EV3, so you can see how it works. Look for the "EV3 Firmware Source Code" at http://www.lego.com/en-gb/mindstorms/downloads.
You can also find the documentation generated from this source code at http://ev3.fantastic.computer/doxygen/index.html. In particular, these sensors are documented at http://ev3.fantastic.computer/doxygen/UartProtocol.html. But beware! The documentation on the UART sensors is not 100% correct. When in doubt, trust the actual code and not the comments.
And finally, don't forget to search for existing Arduino libraries for these sensors. Unless you want to implement your own library just for the sake of doing it yourself, you can save yourself some work. For example, you can find a library at https://github.com/lawrie/EV3_Dexter_Industries_Sensors/tree/master/EV3_arduino from one of the leJOS core contributors.


text:
EV3 brick freeze during run big program
EV3 brick sometimes freezes while executing huge programs and do not react on buttons and bluetooth (connect, start/stop program). Only way to continue work is hard reset.
We discovered that freeze depends on medium motor blocking.
Is there any way to fix this?
Program:
http://puu.sh/iQuFg/678d3add5f.ev3

The link is broken.

My kids have this exact same problem when a program reaches a certain size.  Parts of the program that previously worked just fine begin to systematically cause the brick to lock up.  We have found, as ridiculous as this sounds, the simple act of adding a variable read immediately before the motor block which seems to cause the brick to lock up will fix the problem.

Did you set the medium motor block at On For Degrees mode? If you did, the motor would attempt to spin and run until it reaches the degrees set in the block. You could replace the block with wait for X seconds.

No, it is not because of motor block.

lol..............................................................................


text:
Is it possible to change the language in the EV3 Education software?
I have only 1 language in menu "Edit - Change language":

Is it possible to add another language packs to EV3?

I see that you have the Education version of the EV3 software. I would suggest checking with the LEGO Education support. It may be different from the retail version in this regard.
For the retail version:
From the MINDSTORMS Support page:

3.3 What languages are the LEGO® MINDSTORMS® EV3 Home Edition Software available in?
You can download the EV3 Software for free from LEGO.com/mindstorms in the following languages:
Chinese (Simplified)
Danish
Dutch
US English
French
German
Japanese
Korean
Russian
Spanish (ESSA)

These are available via the respective download pages. For example, the US English version is downloaded at http://www.lego.com/en-us/mindstorms/downloads/download-software. However, the installer is for the whole program. There are not "language packs" that contain just the languages.
To test, I installed the German version in addition to the English version and now I have two languages available on the Edit menu.

Thank you for detailed answer and testing! When you installed the 2nd instance of retail EV3 - does it take the same amount of disk space as the 1st one? If so, it doesn't look quite efficiently.

No, it installed it in the same place on top of the existing install, so essentially, it just added another language. The other files are not duplicated.


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How can the new LEGO pneumatics be used for trains?
LEGO came out with new pneumatics. Since I'm a train guy (my wife is more into technic and already saving money for the Mercedes ;)) I was wondering, how could we apply the new things for Trains?!

The "obvious" way would be using pneumatic cylinders in steam engines, but they would be probably way too large and out of colour. The air supply would also not be trivial, hoses would look and work awfully, and integrated compressors would take up a lot of space in addition to the usually installed electrical components. This could be eased by building a separate wagon (or more) for them and routing the electrical current and air hoses between the wagons and the engine.
For some examples watch these two videos.
Another way would be building tipper wagons that use pneumatics, then you'd probably have less color clash, the same with using pneumatics to open and close the doors on passenger carriages (maybe linking more doors to a single cylinder).
A pneumatically powered rail crane would also look and work great, provided that you can fit all the control valves into the structure.
For stationary applications track switches are mentioned in the other answer, but you can also power boom gates at level crossings and cranes at cargo terminals. In these cases you would have a much easier time fitting all the components, but the hoses could become way too long.

The first thing that came up in my mind when reading your question is: operate switches on your track using pneumatics. You'll require a lot of hose, and would need to experiment a bit with how long the tubes can be without losing too much pressure, but the actuators could operate the switch handles easily, and you can route the hoses under buildings or even under your train table.


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What can I use to glue LEGO bricks to Metal?
So I have no roof lining in my car and instead of replacing it with another carpet I thought covering it in Lego would look pretty cool
What would be the best way to glue the LEGO to the metal of my roof?
I've got a hot glue gun but not to sure it'll work.

This sounds like a job for "Amazing Goop."  It's available at Home Depot and other big stores, at least in the US.  There are a few varieties, including one for automotive use.  It pretty much sticks anything to anything, and once cured, it's on for good.  I've used it for gluing LEGO pieces onto a curved metal surface, and was very happy with the results.  It's a little tricky to work with because it's such sticky stuff, but once you get the hang of it, it's not too bad.  What's great about it is you have a fairly long working time to get the glue on your pieces and get them into place before it dries out. Also it is very strong, and stays flexible, which will be essential to hold up to the vibrations of a car.  One trick will be holding things in place while the glue cures.  Maybe try doing small sections at a time, and using tape to hold the pieces in place.  Also consider gluing pieces onto baseplates, and then gluing the baseplates to your car roof.  It has a strong odor, not terribly unpleasant, but you might not want to drive your car for a few days after gluing.  Good luck!

Try using double sided tape. But I recommend using the soft stuff so if you hit your head it's not as bad.

What's wrong with this?


text:
What will happen if I submerge LEGO in water?
I'm thinking of using real water in my LEGO City and putting the Atlantis and deep sea exploration sets at the bottom of the tub of water, but I don't know what will happen to LEGO when put in water. And maybe having goldfish at the bottom

The Atlantis Submarine Voyage ride at LEGOLAND Windsor has almost 100 models (albeit glued together) submerged in a 1,000,000 litre tank with 'upto 50 species of rare sharks, rays and tropical fish'. If LEGO bricks can withstand those conditions, I think you'll be fine.

Most of these models are quite large (and heavy), so you may need to weigh down or attach some of your models to the bottom of the tub to stop them floating.
Unlike LEGOLAND, you won't have to worry about the upkeep of plants and fishes. I would suggest you replace the water every week or whenever you see it is getting too stagnant.

Exceptions
Apart from the traditional plastic LEGO brick, electronics and batteries should never be submerged in water. Other 'non-traditional' parts including Cloth, Foam, String, Paper and Rubber Bands may deteriorate more rapidly when submerged (depending on the water contents) and stickers will very likely lose their adhesive and peel off.

Basic LEGO elements won't get damaged by water, however depending on the condition of your water source, some residue may build up on the elements after prolonged immersion. So if you are thinking about keeping them immersed for a longer time, I would suggest using distilled water.

The LEGO bricks themselves will be fine, but if you're adding fish and turning this into an aquarium setting you may need to perform some periodic maintenance on them to keep them looking nice... but lots of people have used LEGOs for aquarium decor with great results.

Not much. LEGO specifically designs some models to float, using a solid hull piece. Unless you build a water-tight boat, the pieces will sink, but they'll be fine.

I still have my cargo ship LEGO from 25 - 30 years ago.   It was designed to be immersed in water.   My daughter now uses it daily as a bath toy.

Cheers, hope she treats it well!

As long as you don't want an air bubble, it should be fine. Normal bricks do not create an air tight seal without glue.

Nothing will happen except that some pieces might float. By the way lego is waterproof, so it's okay to keep it in water.

Personally, I have dunked all the LEGO models I created (Ships and planes) into water to see if they float properly, and besides that water gets into every hole, there is not problem with LEGO bricks and water.


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Can the rcx work without the infrared tower
I'm getting a rcx 1.0 or 1.5 and it's not coming with the tower. Can I still program it, using some sort of cable?

No you can't. But IR towers are pretty cheap, especially the older serial ones (you have to add an USB to serial converter to use the latter version on modern computers)


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Which program do I use to program my rcx 1.0 or 1.5
I am getting an RCX and I know it is ether a 1.0 or a 1.5. Which program do I use to program my RCX?

Here's an answer Ambo100 posted:
http://bricks.stackexchange.com/questions/2572/where-can-i-get-rcx-1-0-software

You really have two major choices:

Try to acquire, install, and run the official Lego software for the RCX.
Use some third-party tool to develop programs that can be uploaded and run on the brick.

(1) is getting harder and harder to do on modern computers. Personally, I would not bother trying.
(2) means choosing some third-party tooling. The other answer that refers to BricxCC falls into this category. (You should check out the "RCX" section at that link for more information.) Many of the third-party tools for the RCX brick are pretty much no longer under active development.
But this does not mean that they don't work, or aren't useful.
Some decisions you need to make are: do you need an IDE? Are you comfortable at the command line? What platform will you be hosting the development tools on? Do you want to use the default firmware, or use a third-party that replaces the default firmware?
For example, there is a tool called NQC which is a C-like language and brick API with a facility for uploading compiled brick programs and firmwares to all RCX bricks. It can also set the clock, launch specific programs stored on the brick, and even use the brick as a datalogger. It requires an RCX 1.0, 1.5 or 2.x compatible firmware.
LeJOS is a tiny Java compiler and runtime that needs its own firmware which it loads onto the brick. I think people have figured out how to use Eclipse as an IDE for LeJOS.
Full disclosure: I maintain my own fork for NQC on GitHub, and I'm pretty sure it is the only fork under semi-active development. If you need official firmwares for the RCX brick, I've included them in this project as a convenience. Remember that you can use any compatible firmware on a 1.0 or 1.5 brick. That is, if you want a 2.x brick, just install the 2.x firmware.

I like http://bricxcc.sourceforge.net the best for the RCX! Keep in min that the RCX will loose it's firmware if your batteries are empty or - when powered via 9V - it loses it's power.

sorry but I don't like or trust this program.

Well I have often used it in my high school with students so don't know why you should not trust it. The firmware is an RCX problem, has nothing to do with brickcc.


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Can I safely dissassemble a 74569 motor (the old, fast 9v one)
I have an ancient 74569 motor:

Unfortunately, it's broken: The shaft spins freely by hand, but when I connect power to it, it doesn't spin at all.
I would like to see if I can just open it and place a new DC motor inside, but without breaking it if possible – has anyone opened one of these before or posted instructions as to how?
I was thinking something like this motor:

would fit inside it, but of course I would check the dimensions first and make sure it's not a bad solder joint or something else.
I see Philo has disassembled its replacement here, but I don't see anything similar for the 74569.

Well, I opened it up without much success, and took some pictures of the process:
At first I tried pushing/prying the light grey tabs away from the dark gray "bottom", but those weren't budging

So plan B: wedge it apart:

It was opening, but I was also distorting the plastic in the process - perhaps if I had a hot air station or something, I could have of softened it, but eventually it gave way:

I didn't open it just yet, but rather went to work on the other side - I made my way around from the front/back, as it seemed easier than going at it directly from the side. Anyways, it was much easier than the first side, and I got it open:

Nothing fell out, and I didn't rip any wires out by opening it, so I proceeded to take out the motor:

This is where something finally fell out - there was a little "spacer" disk (visible in the top-left) that was between the end of the axle and the back side of the plastic housing.
After that, the electrical connection assembly slid off easily - not sure what the component is or how to test if it's good, but it seems like it was made such that it's replaceable - no solder was used, just metal "crimps"

This is where I found out that the motor itself is good if I just connect a battery to it directly, so I think I may end up drilling some holes and have a DIY wire coming out the back - all the contacts on the inside seemed good and clean, but unfortunately the bottom seems to be rusted to the point of not making contact anymore.
I think it will snap back together just fine, but it will have scars from the surgery.
For anyone curious, the motor itself is a mabuchi 70586, but any FC-280 motor should fit.

You were lucky that the snap fit joints didn't break. I attempted basically the same thing in order to strap a PF plug to such a motor and broke about half of them in the process. Had to use super glue to put everything back together.

Some precisions: the shiny disk is a resettable thermal fuse aimed at limiting current in the motor if it is stalled for a long time. The black cylinder is a 15V surge suppressor, limiting voltage spikes caused by motor brushes.


text:
How to make LEGO unbreakable
I would like to build a LEGO model which is unbreakable.
What is the best approach?
I am not looking for just glue here.
EDIT:
I don't just want to strengthen the bond between the bricks, but the model as a whole. The level of force to withstand is in the area where it would actually break a single brick.
/EDIT
Has anyone tried the kind of spray on film you can use to protect your car from bumps? How does these kind of product react with LEGO plastic?
Also important is that whatever I would use should not add a thick layer on top of the LEGO, it needs to retain it's original size to some extent. A millimeter or maybe two in some places could be ok.

I think, as @zovits mentioned in their answer, you should clarify what kind of model you are building and what kind of damage you expect it to withstand. Also keep in mind that some pieces are more fragile than others. Finally, consider that the Lego company just glues models when they want them permanently assembled.

This is really nearly impossible unless you have a lifetime supply of super glue.
A good structure using Technic LEGO bricks will provide better support and a lot more "stick" to each other, making the creation less breakable. Building the structure in which the strongest side will take the most hits/pressure should be an excellent way to make the model unbreakable. Joining a Technic skeleton with other bricks should improve your model's durability. Technic and regular LEGO bricks create the best possible way for models to not fall apart.
Overlapping bricks (longer bricks preferred) like bricks can make a strong support for each other. Each piece helps each other support a piece, having no weak points unless layered unevenly.
Try making your models fall and see where they break most often. The place where they break off is probably a weak point and needs more support or the pieces used are just too weak for the job. Replace/rebuild to improve the overall structure of the model. Of course, long bricks are preferred as the pressure is more evenly placed, making the hits seem pitiful against the strong model.

Thanks for the answer, but I did not mean literally unbreakable. I was mostly asking for techniques other than glue to harden the model.

Is there a specific scenario in which it should be unbreakable? You definitely should use different techniques to prevent a spaceship from falling apart when dropped from a meter and to prevent a brick wall from separating when hit by a rolling football.
For System bricks using larger, longer bricks in overlapping configuration (think real life bricklaying) will certainly strengthen a model. You can also experiment with SNOT building to better withstand forces from other directions too.
For larger models a Technic skeleton can be built to be surprisingly strong, especially if you can anticipate the direction of the force and build accordingly.
Another approach to consider is to not build a single unbreakable model, but to plan it so that it has a few predefined breaking points where it will come apart. Then you can always put it back together easily. But of course it depends on your specific use case.

It's hard to answer this question without knowing more about the model in question. Something like a small Lowell Sphere would probably be made 'unbreakable' by a little squirt of expanding foam insulation inside. A Technic vehicle would be a whole different problem.

You could glue each brick together from inside the brick.


text:
How to design ackermann steering with lego wheel bearing front?
I wanted to use a steering system based on the 11949 part:

But I am not sure how to use it in an ackermann system - I would like to be able to have drive and suspension on the wheel, and this piece seems like the only "reasonable" solution for combining the two into something that is relatively compact + sturdy, so is there any possible way using this piece?

Here is a possible implementation using this exact part: Video .
There are also several other solutions with different pieces if you need more inspiration or explanation: Animated GIF, 4 wheel steering, Top-down view.

Err.. In that top-down view, the turned wheels are parallel, not Ackermann

Close to paralell, but not exactly. You can see more clearly if you check the length of the steering rods compared to the main support beams that the rods are 1-1 stud shorter.

Ah, your right - but what exactly is that wheel hub from the top-down view image or the animated gif, as it's not the one with dual pre-attached knobs like the one I was thinking of (and I don't think the video one actually shows ackermann steering either)

The setup shown in the gif uses the 8880 Supercar's wheel hubs, the first item in this inventory: http://www.toysperiod.com/lego-set-reference/technic/model/traffic/lego-8880-super-car/ The top-down view seems to use wheel hubs built from individual pieces. The ball joints are obscured by the support beams so I can't say for sure whether they are a single piece or built but the steering linkage is clearly built from individual pieces.

In the Ackermann system the lines through the rotating point of the wheel hub and the trackrod joint intersect on the rear axle. This works when the trackrod lenght is shorter than the hub turning point distance.

For this part to work, you need to have a fixed ratio between axle track and wheelbase. So a long narrow car won't work and a short, wide car won't either. Find the ratio by extending the line with a thead or string.

Not what I am looking for, you failed to mention the 11949 part


text:
Renting LEGO Service in UK
Has anyone used the LEGO rental service, www.letsgoplay.co.uk? I'm not quite an AFOL, but I do enjoy building the larger sets, and although it would be great to keep some of them long term I just don't have the space or cash to buy them all. Seems like a pretty good deal and they list some pretty rare sets.

Hi Paul, and welcome to LEGO Answers. We're a little different here in that we're not a discussion site but are a Q&A site - we're great at answering questions that have clear, definitive answers. Do you have a specific question about letsgoplay.co.uk (for example quality of customer service, etc.) that isn't covered by their site already?


text:
Is it possible to use the Dexter WiFi Sensor with Robot C?
My wife bought me a Mindstorms NXT system a few years ago and I bought a Dexter WiFi sensor for it, by the time I got a chance to work with it, I found out the sensor had been "retired" and that the sample drivers no longer worked with the new versions of Robot C?
Has anyone managed to edit the drivers to a working state with Robot C 4?

According to the dexter website, there is sample robotC code which means, yes you can use the Dexter WIFI sensor with robotC. Maybe there are robotC libraries for it in the download section on that website.
This forum thread also loosley states that you can use the Dexter WIFI sensor with robotC
Hope this helped.


text:
What is the best way to create an authentic weatherboard wall?
I am working on a house where I want to create a weatherboard look for the outside walls.  I'm not certain the best way to go about this.
Currently I'm using the horizontal side of a 1x2 profile brick:

Which gives the following appearance:

I am wondering though if there are any better techniques to create the weatherboard look:

It seems that the 1x2 profile brick has its ridges roughly twice as dense as a true weatherboard exterior.
One advantage of these profile bricks is that their reverse side gives the interior a VJ (tongue and groove) look, which is the interior look of the house that I am trying to model.

However, the lack of anything larger than 1x2 and the overly dense ridges means that I'm leaning towards looking for other options.

Perhaps something like this?

One option would be to use the relatively new bricks with masonry profile:

If you aren't aware, the reverse side of these bricks includes the horizontal lines but leaves out the vertical ones. This allows you to create something like this:

This solutions provides the advantage of less dense horizontal lines, but being that this is a newer part, it also really limits your color selection.
Your pictures make it look like you are trying to build a white house, which is currently impossible using this part as it isn't available in white. The best that you could do is light gray, which is what I used in my example.
There is a 1x4 version of this part that would make construction much easier and sturdier, but it's only available in medium dark flesh at the moment:

This construction also leaves you with a brick pattern on the inside of your wall. It doesn't sound like this is what you want. One solution would be to create a double wide wall, but that may not be feasible in your case.

This would be a good solution, except for the colours.  I am creating a white house.

There are a number of brick-intensive approaches to this.  Here's a few:
This flickr user (Andrew) has an example, but the "how to" image on the next slide is hard to figure out: https://www.flickr.com/photos/8215600@N03/5223554342/in/photostream/
This is one for a roof, but the same technique could be used for a wall: https://flic.kr/p/a3PcXk
Also, I suggest taking a look at the Lego Techniques Flickr group for different wall techniques: https://www.flickr.com/groups/788191@N24/

This definitely looks gorgeous, but will cramp the interior.  I really like this solution though.


text:
Where is this turban headpiece from?

Where is this turban headpiece from?

It's a LEGO minifig head with a headdress on .... Can you be more specific about what piece you need identified?

I believe that this is a non-LEGO custom turban piece:

It is manufactured by BrickForge and is available for purchase directly from them. It's currently not available in Sand Green though, so if you're hoping to get your hands on this exact piece, you'll need to check BrickForge resellers or secondary markets such as Ebay.

Thank you so much! I had a feeling it wasn't official lego, but that is okay for what I am needing it for. My dad collects nativity, and I wanted to make him a nativity for christmas, but I plan to spray paint all the pieces the same color, so actually this is awesome cuz I really hate to ruin real legos. Makes a great head piece for a shepherd.


text:
LEGO Technic Interface A
A few days ago, a friend offered me one set 9750 LEGO Technic Interface A with the Interface Card and Cable (IBM compatible) but without software.
Can someone share the installation software (LEGO Lines, LEGO TC Logo or Logowriter Robotics) or where can I download the original software for IBM PC-DOS??

The person behind this link says they have software and cables to interface with this device: http://lgauge.com/

I had already found the site mentioned by jvd. It contains lots of useful information about the Interface A.
What I wanted was to find the original software, especially the LEGO TC Logo for IBM (MS-DOS).

If you goal is only to be able to use it, it seems faster to hack it using an Arduino and than control it through USB.

This link to a google drive ZIP file seems to be the ISA card installation documentation and PC-DOS application you are looking for.
More information on using the LEGO Technic Interface A with an Apple II or Commodore 64 can be found here.

There was at one point also an interface for the ZX Spectrum too although I realise this is not too relevant to the original question however mentioning it as other 8 bit systems were also noted.

There was an interface for the Sinclair ZX it just wasn't made by the Lego Group. It was made by Datel Electronics Ltd (UK) in 1984 called the Datel Robotek. A companion book "Make And Program Your Own Robots" by William Clark, Lionel Bender was also published.

Thank you for the correction. I see you are completely correct now.

The software for Technic Interface A is said to be the same for the lego DACTA interface (aka 'interface B').
Try this download link for lego DACTA control Lab
This eurobricks thread may also be of some use


text:
Identify brick with internal battery, light and sound
I just bought a bulk lot of second-hand bricks and found this odd one inside. It has a black panel on one side and when pressed it plays a screeching sound. Through the transparent purple top I can see two LEDs and a circuit board.
I'm guessing the battery is so low it can't make them glow and the chop isn't getting enough power to play the real sound. It has the LEGO brand on the bottom so I'm pretty sure it is genuine, but I can't identify the piece or the set it could have come from.
Once I identify the brick I'll try to find out if it can be opened without breaking it, so I can replace the battery.

This is part # bb0042 : Electric, Light & Sound Siren 4 x 2 x 4 Jack Stone
and here you can hear the sound
it is from Set 4621-1: Red Flash Station
don't know if the battery is replaceable

two dead links in this post :/

@X-27wantstoReinstateMonica Thanks! I've fixed the links.

URL with sound leads to webpage, which no longer has audio file available.

If anyone is interesting in whether the battery can be replaced, the answer's yes-ish.

As you can see in the picture, it's powered by a CR2032. The only hurdle here is that it's welded to the contacts. Not insurmountable though. Also it was glued (or ultrasonically welded) shut, I had to put the orange part in a vise (with some cardboard to protect the plastic) and carefully yet forcefully pull it from side to side. I was surprised at how much force I had to use, so be warned.
EDIT: the fix and putting it back together
Because the top battery contact was spot-welded on, I had to pry the end a bit upward with a knife so I could grab it with pliers and sorta roll/pull the contact off, as you can see below.

The battery's also glued to the circuit board, just gently pull it off making sure you don't pull the bottom contact off as well:

I don't have a picture of the next part, but it's pretty straightforward. I straightened the top battery contact so that the new battery would fit in between. Then I carefully put the circuit board back in the case, and pushed the new battery in between the two contacts (mind the polarity). It should be a very tight fit. At least in my case it was, and it was impossible for the battery to move.
After that I put some really good glue (something like Pattex Extreme Repair, not a fan of superglue for this application) on the orange top of the case and closed the case.
I used a clamp to keep it that way for the next 24 hours:


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Chima Speedorz game -- how to play?
Lego Chima Speedorz sets include cryptic instructions on how to play the game, but I'm unable to fully understand them. I'm looking for a comprehensive answer or guide that details the game rules.

I think this might help you, its a pretty nice writeup on how to play:
http://thebrickblogger.com/2013/01/lego-legends-of-chima-speedorz-game/


text:
Where does the EV3 software store its crash reports?
I cannot find where the crash reports generated by my EV3 software are stored. I have looked where it tells me to, but I can't find any.

What OS are you using (Windows/Mac)? And what is the path that it told you to look for?

Maybe the software never even crashed, that could be why.

The location of the crash logs would depend on the system you are using. I have mapped out the three candidates below:
If you are using the classic LEGO MINDSTORMS EV3 Education software:

Open your existing or a new experiment.
Go to the Tools menu and select Data Log File Manager.
Browse to the .rdf file and click the Import button. (It can be on the brick or on your computer.)
If the directory is empty, there are no crash logs (yet)

If you are using EV3 Python, you are running through Visual Studio Code, and the crash handling will be done by VS.
On Windows, this would make the crash logs appear under %AppData%\Microsoft\VisualStudio\
If you are using EV3 Classroom
On Windows, this would make the crash logs appear under %AppData%\LEGO\Mindstorms\Logs\
On OSX, you can look for them at /Applications/LEGO\MINDSTORMS\EV3\Home\Edition.app/Contents/MacOS/MindstormsEV3
If you are using some third party program, the program provider should be able to advise you where logs are stored.


text:
How to enter wifi-password on ev3dev?
After successfully installing ev3dev and getting the USB connection working I now want to get my wifi-dongle working (or rather connecting). The dongle is successfully found and my LAN is displayed.
But as expected I need to type a password, this is the problem! How do I insert a password in the brickman interface?

When the password dialog pops up, press ENTER (the middle button) to open an on screen keyboard.

It was to easy. I was probably very tired yesterday :) Thanks!


text:
I just purchased a used LEGO Studios set and had some extra pieces that don't belong
Can anyone tell me what set they might be from?

backside:

It's tough to predict where such a small number of pieces came from, but some are likely from the Hydronauts theme, specifically Hydro Crystallisation Station (6199):

This set includes the chromed headgear with studs on the back as well as the printed tile that is already attached to the back of yours.
The minifig utensils are likely from Mobile Outpost (6520):

Here are links to the sets that these parts appear in if you'd like to explore this more:

3069 - Tile 1 x 2 with Copper and White Circuitry, Red Rectangle and 4 Squares Pattern
71598 - Chrome Blue Minifig, Headgear Helmet with 2 Studs on Back
6041 - Trans-Neon Green Propeller 3 Blade 3 Diameter
2569 - Trans-Neon Green Antenna Whip 8H
6040 - Black Propeller Housing
30193 - Dark Gray Minifig, Utensil Ice Pick
3837 - Dark Gray Minifig, Utensil Shovel (Round Stem End)

Wow...that's amazing how you can do that.  Is that just from your general knowledge or do you have a way to search?  I couldn't see the numbers on the lego pieces and didn't even know what to call them to search for them.  Thank you for such detailed information...that's amazing :).

Thanks :) Once you have a pretty good understanding of how parts are organized on sites like Bricklink, it's not really too hard to determine what sets they come from.

The trans neon green helmet on the right of the first pic appears to be from any of the Aquazone, Aquaraiders I, Hydronauts, or possibly even Time Cruisers.
It's a start... :)


text:
How do I make use of the full SD-card after installing ev3dev
After writing the image to the 8G microSD-card, initial setup of network and installation of git (with apt-get) I could not install anything else since I was out of diskspace. This confused me. But df -h shows me that /dev/mmcblk0 has a size of just under 1G. /dev/mmcblk0p1 has a size of 40M.
So I got a card with roughly 7G unused and unaccessible. How do I get hold of it?
When I insert the card in my laptop (Ubuntu) it does no longer automount itself and when I try to get some info about it I get this with parted and lsblk:
$ sudo parted -l /dev/mmcblk0p1
Model: ATA HTS721080G9SA00 (scsi)
Disk /dev/sda: 80.0GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start   End     Size    Type      File system     Flags
 1      1049kB  76.8GB  76.8GB  primary   ext4            boot
 2      76.8GB  80.0GB  3219MB  extended
 5      76.8GB  80.0GB  3219MB  logical   linux-swap(v1)

Error: /dev/mmcblk0: unrecognised disk label

$ sudo lsblk
NAME        MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda           8:0    0  74.5G  0 disk
├─sda1        8:1    0  71.5G  0 part /
├─sda2        8:2    0     1K  0 part
└─sda5        8:5    0     3G  0 part [SWAP]
sr0          11:0    1  1024M  0 rom
mmcblk0     179:0    0   7.4G  0 disk
└─mmcblk0p1 179:1    0   7.4G  0 part

What can I do:

Could I resize the disk in the current installation?
Could I do a new installation an during the installation procedure set the size of the final result?
Could I create new partitions in the unpartitioned area and move the OS to that partition?

If you install ev3dev with an image file dated 1 May, 2015 or later, it should automatically expand the root partition to fill the space available on the SD card. Older releases are no longer supported.
If it does not do this, you should report a bug a https://github.com/ev3dev/ev3dev/issues. Be sure to read http://www.ev3dev.org/support/#github-issues first.

May 10? So in 2 days?

Oops. that was supposed to be 1 May. I've corrected it.


text:
Official LEGO charity programs
Many consumer-oriented corporations have official charity programs where products or money are donated to deserving causes. I was wondering if The LEGO Group has any such programs --- and if so, where can one apply for donations?
For instance, I believe it would bring happiness to hospitalized children to receive a simple Lego set (such as a polybag) to play with.

The first hit on Google for "LEGO charity" is this: http://service.lego.com/en-us/helptopics/lego-company/charity-and-donations. From that page:

What charitable activities is the LEGO Group involved in?
We take our responsibility for making children's lives better very
  seriously, so we run a number of charitable programs.
Usually, our local offices use their knowledge of what local children
  need to partner with initiatives and charities.
On a global level, we help children through the activities of the LEGO
  Foundation. If you'd like to know more about how we understand our
  responsibility and what we do, there's lots more information in the
  About Us section of this website.

Sounds like that should cover your question. Check out the www.legofoundation.com website as well.

I could not find much concrete information about charitable activities using the links provided, but corporate buzz words and pictures of happy people were abundant. I guess I have to dig deeper or contact my local Lego office.

Assuming you are looking at getting LEGO to sponsor/assist with a local charitable program (and not a big global reach effort), I think you should talk to LEGO close to you, and find out what criteria they use for sponsoring events. This should give you guidelines as to whether your idea would qualify for sponsorship/donations. The LEGO Foundation seems to be more aligned with larger programs (I can see a tie-in with Unicef on their website).


text:
What brick is this? 1x2 with holes in the short sides
This is my first time doing something like this, so here goes.  This is a 1x2 blue brick with holes on each end.  Through a hole, you get this view of the center peg and the light coming in through the other hole (pic 3).  From the bottom there is the peg, the holes on the sides, and the "Pend" from "Pat Pend" (pic 4). The "Pat" is above, but unable to be seen.

Finally, I have done a lot of research and found a grand total of nothing about it.  So, I tried some stuff out and learned that the only thing that fits in the holes are minifigure arms and thus speculated about a 4 arm guy.

Here are my tries at fitting other stuff.

Thanks for looking and sorry for so many pics!
-Erich Wacker

+1 for imagination with 4-armed guy!

This is part 3317.

It's primarily used to hold the bucket on front end loaders. It hasn't been used in a set since the late 90's. Part 3314 is about the only other part that is designed to connect to it that I'm aware of:

Here's an example of this part in use from set 6504:

While I believe that this was the only way to connect to this part used in official sets, I'm sure it may have other uses. It was used to build gas pumps in one set:

Oh the memories! I had that front-end loader :)


text:
Mindstorms Software Versions
Here is what I have:

Site licences for Mindstorms Software 1.0 (NXT) and EV3.
An upgrade to Version 2.0 for the NXT
9 NXT kits
4 EV3 kits
2 Renewable Energy Kits and Temperature sensors

My problem is that on the NXT units, the only version of the software which supports the Renewable energy/temperature sensors is 2.1, which does not appear to be an upgrade to 2.0, but is instead a education site licence version like the ones I have for NXT 1.0 and EV3. Without these I cannot access the blocks to use the Renewable Energy kits and temperature sensors unless I use the EV3 kits.
My questions:

Am I right, or is there a way to upgrade 2.0 to 2.1 or 1.0 education to 2.1?
is there a way I just haven't been able to figure out to use these sensors with the 2.0 software?
Is it worth updating all my existing material for the NXT bricks to program them from the EV3 software as well and dealing with the small issues or not?

I have tried contacting distributors, and looking online has only helped me find the appropriate sensor blocks for the EV3 software.

You probably don't need it, but the LEGO Education NXT 2.1 Software is still for sale through LEGO Education (at least in the USA). They do not advertise and upgrade price, but it does not hurt to ask.
The Energy Meter blocks are available for download on the LEGO Education website. I went to http://education.lego.com/en-us/downloads and checked the box "Blocks" under "Download Type" and it shows up in the list. It does not say if it is for NXT or EV3 though. Also, I found this for the NXT Temperature sensor.
I would not recommend using the EV3 software for programming the NXTs. There are a number of limitations, such as lack of support for 3rd party sensors and lack of support for Bluetooth. Also, I understand the programs take up much more memory this way.

Those blocks only seem to work with version 2.1 - I get an error when I try and use them with 2.0. I will try and provide more details later.

Can you provide more details about the error...

I managed to install my license of Mindstorms Edu NXT v2.0 (Windows 7 x64) and the software has Data Logging and the Temperature Sensor Block.
If you have an upgrade from v1.0 to v2.0 at least the Temperature Sensor Block will be available.

LME NXT v2.1 is now available for download (Win/Mac) on LEGO Education site.


text:
LEGO Brick Color Palette
Have any new brick colors come out recently? I haven't seen many diverse colors and was wondering if there is still an expanding palette for the bricks being produced.

We should probably update one or other of the answers on How many different colours of LEGO bricks are there? - however the Peeron list is updated as colours are seen, so it should have them all, sadly it doesn't seem to have date ranges on there for "first/last seen" although you can find one per-part: http://www.peeron.com/inv/colortable/3004?ip=0


text:
What is the purpose of this plate with door rail?
I'm looking at the this piece:

Is this piece some kind of a track on which you can build stuff that slides? I see it in sets as a decorative piece from time to time. What does "door rail" even refer to?

These pieces are frequently used for decoration now, but they were originally used for sliding doors, particularly on train sets. Here's one of the first uses from set 7838 in 1983:

While they could be used in structures, these were frequently used for putting doors on the train cars themselves:

These parts can also be used to create tracks for other things that need to slide as shown in Container Loading Crane (7823):

This class of part also has a 2xn variety that now allows whole 1xn bricks to slide within it:

This is useful for building sliding doors and walls that are a full module wide. Here's an example from 31009:

In addition to what jncranton wrote, the plate with the rail is a perfect fit for sliding in the brick with groove:

You can see an example of that technique in the Cloud City set:

And the 2 stud version was often used to secure the old 9V motor (http://www.bricklink.com/PL/71427c01.gif?0) that had two grooves on each sides, allowing it to be removed easily.

It can also be used as the eave of a building!


text:
Where does this green plane fuselage piece come from?
It has the year 2005 on it and the number 22988 I think.  Anyone know what it is?

It's the rear end of an aircraft fuselage. It's part number is 54701c02.

It's from one of these two sets:

Thank you.  I'm really bad at figuring out these parts.  I guess the number I found on it wasn't the part #.  When I searched for green pieces...nothing like this large fuselage showed up. Thanks again :).


text:
Inverting motor's rotation
I've designed a robot with two motors. It works as follows:
The first motor is attached to the the person's arm, the second motor receives the calculated movement and moves accordingly.
When the person moves his hand (open/close) the other robot moves the the opposite direction; upon opening it closes and vise-versa.
I've tried to invert the movement by multiplying by -1 but the second motor keeps moving on his own. I've tried multiplying the results of both motors, before subtracting, with no success.
The 'code' does the following:

I take the movements of motors A and B
Subtract value of motor A from motor B's
Save the result to a variable-'moveDist'
Take the absolute value after subtraction for comparison
If greater than 6, pass 'moveDist' value to the second motor.

Sorry, don't know how to post my code, here's a link: http://i.imgur.com/OR2uAMP.png
Also I have a video demonstrating what happens to the hand after the multiplication(If you wanna see).

I'm not at all well-versed in the spaghetticode that comes from LEGO's EV3 software, but conceptually, isn't the "take the absolute value" part unnecessary and even wrong? Shouldn't you be moving B the difference between A and B so that B' = B+ (A-B) = A ?

That's why I used the variable 'moveDist', to save the B' value. The absolute value is used for comparison (A threshold), if I don't do so, the hand will keep on shaking.

Ok I see that now - couple of more things: You need to clarify what the issue is: is it that movements seem to be mirrored but passing -1 * MoveDist does not seem to reverse the movement? or is it that but the second motor keeps moving on his own. - i.e. motor B keeps making movements even if motor A does not register any movement (or movements below your '6' threshold)?

I found a solution: I multiplied the master motor's value by -1. So, the calculation was: (a-b) it changed to : (-a-b). The result was passed to the slave motor and it did the job.

If you want the blocks, feel free to ask.

I think the main problem is, that you use the "Motor on for # degrees". The program will wait until this command is executed (i.e. the required turn is made), and this can take quite long. The next measurement of the angle difference is taken after that. Having a high start deviation and/or fast turning rates of your reference motor, you will not get a stable result.
Instead I propose to use the angle difference for the "Power" input of the "Motor on" command. In that scenario the angle difference is measured very often, and the "slave" motor is following your "master" motor very pecisely.

Thanks for the reply, appreciate it. Won't be able to test it until next Wednesday, only then I can give my feedback. One thing, the 'slave' motor, in my project, is desired to move in 180 degrees, does the 'On' mode treat that aspect?

I want it to move by the given degree and then stop. The ev3 help says: "The motor will run until it is stopped or changed by another block".

Since the angle difference is the "power" input of the slave motor, it will only move untill the difference is zero. So it will follow exactly your "master" motor. If that master stays within 180°, the slave will, too. And don't worry about the timing, one loop cycle in above program takes only ~1ms. So the deviation is checked and corrected ~1000 times per sec.

I tested the code and unfortunately it didn't help.


text:
How many flexible tracks does it take to make a complete oval?
I have couple of straight tracks, no curved tracks, so the only option now from me is to buy the new 7499 straight + flexible tracks. Therefore:
How many boxes of 7499 tracks do I need to make a complete oval circuit?
There are reviews but none of the is actually mentioning this. No pictures either.

Each piece of flex track is equivalent to 1/4 piece of regular track. The standard train curves are 1/16th of a circle and thus an oval shape is not possible, however, with 64 pieces of flex track you could make an oval by squashing the circle a bit. 7499 comes with 16 flexible tracks, so you'll need 4 of them to make a regular train circle.
The flex track can be used to make a smaller circle than the regular track:

but as TheBrickBlogger pointed out, the flex track has performance issues and such a tight circle will be difficult for your trains to navigate. The trains tend to fall off if conditions are not perfect. Over Christmas I built a large layout under my Christmas tree and I had to remove all the flex track in order to prevent derailing. Part of that was due to my train design, part of it was due to the fact that the track was sitting on a mix of carpet and hardwood flooring, but part of it was that the train is very sensitive to bumps in the track and flex track exacerbated those issues. Depending on your engine design you might have more or fewer issues. If you are just pushing the train by hand, it will probably be fine.
Also keep in mind that the standard lego train car with fixed (not swiveling) wheels can only navigate a certain minimum radius. Lego puts the wheels 10 studs apart so that they can just barely make it around the fixed curves. If you build the small flex circle, or squash a 64-flex-track circle into an oval, your tightest curves will for sure be too tight for those cars to navigate.
Normally Lego sells curved track in an expansion kit. It seems that right now (May 2015) the only kit is the 7895 Switching track kit. That kit comes with 4 curved rails and so you'd need to buy 4 of them to make a circle. If that's not your ideal choice of parts, then Bricklink would be best. Or, use this as an excuse to buy a whole train kit, which comes with track, train cars, motors, etc. You can never have too much Lego.

The flexible tracks are not designed to make a full oval, but to add subtle, smaller curves in a train layout, using just a few at a time. If you do use too many flexible tracks next to each other they will slow down your train, they are very noisy, and can even derail the train. Here is an excellent comparison video between the regular curved tracks and the flexible tracks: http://youtu.be/fGcD_QtOcRQ
If you would like to create a full oval I would suggest that you just get the curved train-tracks on BrickLink as they are currently not available directly from LEGO (except in full train sets). They are about 50 cents each and will be much better for your purpose. You will need 16 of them to make a full circle: http://www.bricklink.com/catalogPG.asp?P=53400&colorID=85

You can also find bundles of curved rails on eBay like this one. $8 for 4 tracks. Just make sure you don't get the 9V rails - they will work but since they are no longer produced, they come at a premium price.

To add to the excellent answers already provided, the cheapest LEGO train set currently available giving you a full oval/circle is 60051 and costs $149.99 in the US Lego store. You might be able to find it slightly cheaper on Amazon.com (currently $127.21 in the US) or ToysRus.com (currently $149.99 so same as LEGO store) sometimes.
The equivalent purchase of 4x 7895 Switching Track is $15.99 in the US Lego Store for each set, so a total of $63.96 for 4.
If you go by absolute price, the 4x7895 is your best option, and you get 8 switches extra, which you could use once you expand your track, or sell back through bricklink or eBay (current US selling price on bricklink is around $3 per switch track) which would reduce the total price by $24, giving you a total price of roughly $40 for the oval.
The 60051 train set does come with batterybox, trainmotor, IR set etc, plus many pieces. The value of that set is probably better than 7895 gives, at a roughly $100 premium over 4x7895 with sellback via Bricklink/eBay etc.

Separately, there are 2 more options you can consider:

ME Models sells LEGO curve sets with bigger radius than the standard R40 LEGO curves. Their R56 curve pack costs $19 for a half-circle (so $38 for a full circle) plus shipping. They have several other radia as well, but those will cost more. From what I've read the fit with "normal" LEGO is very good and train enthusiasts love these rails.
If you don't mind the extra pieces, you can make curves out of straight rails by using this technique (youtube) . The train's movement will be a little jerky but otherwise it works well. You'll just need a lot of space as the radius of such an oval is very large. But most LUGs use this technique in their train layouts, so it is "endorsed by professionals". Basically, you offset the outside joint by half a stud every rail using a 1x3 and a 1x2 jumper. The upside is that you can use this technique to make the outside of the curve 1 plate higher than the inside of the curve to allow your train to "bend" through the curve just like trains in real-life do.

Wow, that second technique is really interesting that I have never seen before. Thanks for sharing!


text:
The Mindstorms EV3 Software crashes on OS X Yosemite 10.10.3. What do I do?
It's crashing on startup which is really irritating. When debugged with terminal it says this:
Unhandled Exception: System.UnauthorizedAccessException: Access to the path is denied.
[ERROR] FATAL UNHANDLED EXCEPTION: System.UnauthorizedAccessException: Access to the path is denied.
What should I do? I've already tried reinstalling it.
System specs: MacBook Air '11, Late 2010, Mac OS X 10.10.3
Latest version of Mindstorms software

Does the error say which path? It may be a read-only file or a directory.

The error is caused by the underlying MS Silverlight runtime. As stated in this stack overflow answer, the error may be caused if

the caller does not have the required permission.
the path is a directory.
the path specified a read-only file.

Possible ways to find a solution:
• Open the Console application and see if the error shows details about which path it cannot access.
• Repair file permissions of your partition via the Disk Utility application.
Search for Mindstorms EV3 files in your ~/Library/Caches, ~/Library/Application Support and ~/Library/Preferences folder and delete these files (backup files first! or make sure TimeMachine is set up). Normally an application will re-create files located in these folders at start.

Updating the iOS version to 10.10.5 seems to have solved the problem for me. Hopefully this helps someone else out there.

I tried to duplicate this on my 10.10.3 MacBook Air 13.  No luck.  I did see in the readme file that the minimum resolution is 1024 by 768, and the native resolution of the Air 11 is 1366 by 768.
Try the following if you have not already:

Use an external monitor of > 768 lines
Upgrade your version of Silverlight

https://www.microsoft.com/getsilverlight/Get-Started/Install/Default.aspx

I tried to set my Mac to 720 lines to see if I could get the app to crash, but no luck.

authors: Томшин Павел Валерьевич


text:
Mindstorms Vision Command - what shall I do with it?
I have a Vision Command camera, bricks and book, still boxed with instructions and a W98 coaster, er I mean CD, and was about to donate it to a charity shop but it seems there's no 64 bit driver for it? Windows can't find one anyway.
I'm not sure it's worth wasting their time with it. I suppose a note saying "not for new versions of Windows" might still attract someone with an older PC but I'm open to suggestions?
Regards

Have you read this post: http://bricks.stackexchange.com/questions/4529/vision-command-and-exploration-mars-software-for-mindstorms-ris-2-0? Someone says that you can use a Logitech driver to get the camera to be recognized.

I've tried with limited success to get this hardware to work with various systems. There was a single third-party cam driver for OS X that let it be used as a digi-cam. That is, there was no integration with other LEGO software or firmware.
It is some sort of Logitech, but the devil is in the details. There are no modern Windows drivers. OS X is probably no longer a viable option, though I have not checked recently (recently: last 3-4 releases). Linux or BSD is probably where experimentation might pan out.
Even so, getting the camera to work is different than getting it to work with any other era of Mindstorms equipment.
It is essentially abandon-ware or experiment-ware.
My only advice is to give it away or sell it "as-is". I did consider cracking it open and replacing the guts with more modern hardware (perhaps a bluetooth or wi-fi camera to get rid of the tether) but without any integration into Mindstorms, it's just another digi-cam. But at least it could be one that easily attaches to other LEGO.

It is a Logitech Quickcam, and yes, it still works on Linux (I've tried it on ev3dev with my EV3 and Ubuntu 20.04)

Wow, can't believe somebody else is experimenting with this in the 2020s! Did you have to install anything extra to get the camera working under Linux? What software do you use on Ubuntu to view the camera output?


text:
Control two Lego NXTs with an Arduino
I'm new here and also very noob with the Arduino. I have a basic knowledge in Java and some more in C# so code isn't a problem. I can learn it easily.
I have a project assigned. I would like to know if it is there any possibility to control two Lego NXT with an Arduino? I want to give commands/orders via Arduino or at least have communication between both of them.
I have an Arduino Uno and two Lego NXT kits (9797 and 9648).

You have a number of options.

Since you mentioned you know C# the best, have a look at http://monobrick.dk. They have a C# library that lets you remote control the NXT. Then you could use something like http://playground.arduino.cc/Interfacing/Csharp to do the same for the Arduino. UPDATE: MonoBrick project doesn't seem to be around anymore.
For Java, there is a similar NXT remote control library from http://www.lejos.org/. I imagine you could find something similar for Arduino as well.
If you want to connect the Arduino directly to the NXT, you can use USB or Bluetooth. Then you can use the information in the NXT Bluetooth Developer Kit (available from http://www.lego.com/en-us/mindstorms/downloads) to develop a program for the Arduino what will be able to communicate with the NXT.


text:
Where did these small tan bricks come from?
I was going through an old box of LEGO bricks from the 70's and 80's and I found a number of small bricks that appear to be about 2/3 size. They have the LEGO logo, and appear to be the official tan color (05). I can't find a reference anywhere as to their origin.

These look like Modulex bricks:

Modulex was a building system that was designed for adults. It was developed by The LEGO Group at the same time as their Modulex sets were produced from 1963 until 1965, and were exclusively available in parts packs by colour. The LEGO Group made Modulex a separate company in 1965, and the text "LEGO" was removed from the studs and replaced with "M".
Modulex bricks were formed with a cube type 5 to 5 width/length ratio, meaning that, unlike very nearly every product produced by The LEGO Group, they were not compatible with LEGO bricks, which have a 6.5 to 5 width/length ratio. Modulex bricks were available in a wide array of unusual colours, shapes, and sizes.
from Brickipedia

Also: If you absolutely need more Modulex product: http://minibricksmadness.com/


text:
Using the NBR 1036 Barometer with the EV3
I just purchased the HiTechnic Barometer from LEGO, thinking the Block was available for the EV3.  Theory says that I can use NXT Block in the EV3.  Can anyone point me in the right direction?

I'm not sure where you got your theory, but no NXT blocks will not work in EV3 software.
You may be able to use this with the LEGO EV3 software using the generic I2C block developed by Dexter Industries.
Otherwise, you should look into using a 3rd party programming environment/OS for the EV3 (EV3Basic, ev3dev, leJOS, MonoBrick, etc.)


text:
Slow down the mindstorms EV3 motor so target position is not overshot
I have Debian jesse installed on a mindstorms EV3 and I'm using the ev3.lego library: https://github.com/topikachu/python-ev3
I want to be able to slow down the motor as it reaches its target destination because if it's going full speed when it gets there, it overshoots its target proportional to how fast it was going.
Example Python code: When I use this code to spin the motor:
from ev3.lego import Motor
b = Motor(port=Motor.PORT.B)
b.run_position_limited(position_sp = 100, speed_sp = 300)

The motor spins to position 100 on the tachometer with speed of 300.
When it gets to its destination, the momentum carries it to position 125 or so.  So next time I tell it to go to position 100.  It spins up, then overshoots to position 75.
What is the best way to try to minimize this error so I can tell the motor to move to position 100, and it either slows down before it reaches its target, or otherwise freezes the motor when it reaches the destination?

There are two attributes in the python ev3dev Motor class called:
ramp_down_sp
ramp_up_sp

Link to documentation: http://ddemidov.github.io/ev3dev-lang-python/
ramp_down_sp Ramp Down SP: read/write
Writing sets the ramp down setpoint. Reading returns the current value. Units are in milliseconds. When set to a value > 0, the motor will ramp the power sent to the motor from 100% duty cycle down to 0 over the span of this setpoint when stopping the motor. If the starting duty cycle is less than 100%, the ramp time duration will be less than the full span of the setpoint.
ramp_up_sp Ramp Up SP: read/write
Writing sets the ramp up setpoint. Reading returns the current value. Units are in milliseconds. When set to a value > 0, the motor will ramp the power sent to the motor from 0 to 100% duty cycle over the span of this setpoint when starting the motor. If the maximum duty cycle is limited by duty_cycle_sp or speed regulation, the actual ramp time duration will be less than the setpoint.
Example:
from ev3.lego import Motor
b = Motor(port=Motor.PORT.B)
b.ramp_up_sp = 1000
b.ramp_down_sp = 1000
b.run_position_limited(position_sp = 0, speed_sp = 300)

What the ramp_down_sp does is when the motor is 1000 milliseconds away from its target (doing its own estimations) then ramp down the power from 100% to 0% over exactly 1000 milliseconds.
ramp_up does a similar thing, except ramps up the power from 0% to 100% over 1000 milliseconds.
This helps avoid unnecessary strain on the motors for applications where building up momentum is important.


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Will playing with a 12V train motor by hand damage it?
This question is similar to one for PF motors.
The 12V motor bogie has considerably more resistance than does the newer PF bogie motor, which may be moved very easily when not operating.
So, if one pushes a 12V-motorized train by hand, will it cause damage to the motor?
See title "Set 7865: six wheeled Lego® train motor (12V, 1980 - 1990)" on this page for the specific motor I'm referring to.
Side note: I've noticed that the connected headlights in the train don't illuminate when pushed by hand (and have asked a question specifically in regards to this).

As you can see in the picture below the friction has to do with driving the worm wheels via regular gears while pushing the unit by hand and yes, I guess the gear teeth on the wheel axles could be damaged because of the gear ratio.

This looks like an early version of the 7865 motor.

How did you remove the wheel from its axle??


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How did the LEGO 7862 Remote Controlled Decoupling and Signal work?
I've never seen this set in person, although it appears occasionally in 12V Lego train system images. I've never seen it used, or described.
How did the LEGO 7862 Remote Controlled Decoupling and Signal 12V work? What is the 'Signal' component of the decoupler?

It basically forces the coupling magnets to separate via the pins pointing downwards from the magnet holders:

Here's a demo.

That's a cool video!