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Are 10682 "Creative Suitcase" and 10695 "Creative Building Box" compatible?
I just wanted to be sure if these two sets 10682 and 10695 are compatible.

Yes. These two sets, and basically every other LEGO set that has been produced, are compatible with one another. The major exception to this rule is DUPLO, which is twice the size of regular LEGO system bricks. However, even DUPLO is compatible in some ways.
These two sets are both essentially just boxes with lots of bricks in them. They may include some instructions and ideas, but they are designed to allow children to build creatively. Combining pieces from both of these sets will only add to fun!


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Is there a site where I can put in a set of individual lego bricks (by part ID) and get an optimized list of stores to buy (to minimize shipping)
I'm new to this site, so please forgive me if this is a duplicate.
Background story
I got my 6 years old the Lego City Arctic largest set, and then realized he had previously had 2 other arctic sets, that sadly, he lost some parts for...
I have sorted through all of his legos (yes, I do have a life, but this was rewarding on unbelievable and weird levels) and checked marked all the pieces he had. I narrowed it down to the few that he was missing and got their ID number.
I Googled my way into http://www.wallofbricks.com/ and was able to find stores that sell all those pieces!
Problem
The big problem as you might have guess is that it would cost more than re-buying that set again. The difference is not the individual piece cost of course, but the shipping.
The issue stems from the obvious reason that not all stores have all pieces, so you just pay a lot in shipping...
Now, I'm sure that if I cross reference the online stores that sell all the parts, I'll be able to find some, that might not have the cheapest price, but have more than one piece in stock.
Question
This is a very interesting optimization problem to solve, and I was wondering if there is any website that lets you answer the give question:
Given a list of missing pieces and quantities, and the original set cost - finds either the combination of stores such that the piece costs + the shipping is less than the original set, or suggest that buying the original set will be cheaper.

Have you looked at BrickLink or BrickOwl yet? BrickOwls Wishlist feature allows you to fiddle and optimise the (whole) price. Additionally, if you have the part numbers, you can call Lego and they might be able to ship all of them directly.

See also: How can I minimize the number of merchants for given set of requested bricks?

Here link to BrickOwl Wishlist mentioned by @tl8 http://www.brickowl.com/wishlist

There are two pieces of software that lets you do this for Bricklink: Brickficiency and Brick Wizard. The latter seems updated more often, but I don't know if they produce different results.

source: Stack Exchange

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

sort: votes


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Can anyone help id this partial build/set?
I found this partial set bagged at Savers, looked interesting. But searching thru peeron, I cannot figure out what set this might belong to. Is anybody familiar with what set this might be associated with ? Back and front designations are really just arbitrary, as I don't exactly know what I have here. The black bricks hanging out on the top of the "back" side view are technic bricks 1x16 with holes. The sides of the base, if you will, are composed of 6 technic bricks 1x14 with holes, 3 on each side.

This is from the Clone Turbo Tank.

You nailed it gev, thank you for the quick response (so much for the guidance/recommendation on not posting comments like +1 or thanks). Peeron doesn't have an inventory, etc for this set, 8098-1, although its listed as a set from 2010. Now, off to find out how much I'll have to pay for 10 of those tires !

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


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How to run two LEGO electric trains at the same time?
I have a LEGO city built with a train encircling it. The track is the classic style with metal railings running through it. I have a switch track as well that is connected to an NXT robot to switch the track each time a train comes by.
The problem is, there are areas where the trains run into each other because there isn't enough power running through certain areas of the track or too much power. I have 2 of those power consoles connected to the tracks.
Does anyone know how I can have these two running at the same speed without slowing down and crashing into each other?

I'm assuming you're  using 9V rail, is that correct?

This probably isn't going to be solved without either changing to remote controlled PF trains or creating a complex control system.
Even if you were able to supply the exact same constant voltage to both trains, they'd both need to have precisely the same motor characteristics, weight, and aerodynamic properties. That's going to be difficult.
One way to address this is to create track blocks that are electrically isolated and can be controlled independently. You can isolate the track sections using tape at the joints, or you can physically cut the metal rails. You could then connect these blocks up to your NXT and build some sensors to determine what speed the trains need to run in these sections in order to not hit each other.

I know that Lego Trains expert Michael Gale (not sure if he has an account here on StackExchange) is working on a DCC module for Lego 9V trains. He has details and pictures up on his Flickr Feed. This would allow you to control multiple trains on the same 9V track, without needing to do electrical isolation. You would still need to build some sort of sensing (either accellerometer or IR distance sensor or something like that) to make the speed of the trains the same to compensate for motor and wheel characteristics. And you would need to invest in a DCC controller trafo.


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usage of ev3 ultrasonic sensor in lejos behavior based programming
I'm using ev3 ultrasonic sensor. And I'm writing a behavior based lejos code. I want to do some tasks when the ultrasonic sensor detects an object which is not further than 30 cm's. And this is my code:
public UltrasonicSensor(Port port)
    {
        sonar = new EV3UltrasonicSensor(port);
        sonar.getDistanceMode().fetchSample(value, 0);
    }

    @Override
    public boolean takeControl() {
        // TODO Auto-generated method stub
        return value[0] < 0.3;

    public void action() {
        ....
    }

    @Override
    public void suppress() {
        // TODO Auto-generated method stub
        suppressed = true;
    }

But I think it is not the right way. How can I implement it in the right way?
Thanks for help,

You can use the lejos.ev3.robotics.RangeFinder abstraction class:
EV3UltrasonicSensor sensorUS;
RangeFinder sonar;

public UltrasonicSensor(Port port) {
    sensorUS = new EV3UltrasonicSensor(port);
    sonar = new RangeFinder(sensorUS);
}

@Override
public boolean takeControl() {
    return sonar.getRange() < 0.3;
}

Use the float getRange()  method to retrieve the distance to the nearest object.


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Is there a modern equivalent for windscreen piece 6152?
For a creation I'm building, I am using a white windscreen piece (part ID 6152).

Looks like this piece was last produced in the late 1990's. Is there a modern equivalent that preserves this general shape?

Maybe a bit later than the late 90-s, I have lots of these in early 2000-s sets...

The windscreen you mentioned has been retired, however you can still get it on BrickLink. It is available inexpensively in several colors: http://www.bricklink.com/catalogItem.asp?P=6152
If you want to use a modern version, this wedge is pretty close in shape and is available in current sets: http://www.bricklink.com/catalogItem.asp?P=6153b
As a reference, here are all the LEGO windscreens LEGO ever made. You can browse them by year released and sets they appear in: http://www.bricklink.com/catalogList.asp?catType=P&catString=115
And here are all the wedge elements LEGO ever made. They tend to use these more often these days, most likely because of the stronger/thicker walls: http://www.bricklink.com/catalogList.asp?catType=P&catString=42

Great, thanks! Unfortunately 6153b won't cut it here. I'm happy to settle for the windscreen, even if it means using a old-style part.

No shame in using older/retired LEGO elements. There are many great parts that have been retired, but they can still add nice details and make your creation even more unique. :)


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How do I move assembled LEGO sets?
How do I move large sets put together?  We do not have the instructions or original box.  We are moving from one home to another.

See this question for advice on where to get instruction booklets for the inevitable repairs.

Carefully. Ba dum tish.

Take a photo before moving models. If bits fall off, you'll know where they go.

Some of the advice in this question may be useful although doesn't apply to everything.

When I was a child and our family moved, I took apart the larger sets into easily manageable pieces. For example, taking off wings and antennas of starships. Then I tetrised all the pieces into shoe boxes and other closable, stackable containers that could then be transported by almost any means. This method required reassembly at the destination but thanks to the planned breakdown it was easy to do. If I remember correctly the boxes were lined with cloth to dampen vibrations and prevent scratches, so nothing really got damaged.

We moved the Death Star into our office by hand. When we needed to move it to another place, we use a plastic bag to wrap it up and put it in the backseat of the car, so that even if little parts fell off, we could still find it in the bag, instead of trying to find it in the car.

A couple of suggestions:

Put them in plastic bins/bags or some other type of container, so that any pieces that come off will not be lost
separate models if you can; having pieces from different models mixed together will make them harder to repair
remove sections beforehand that are likely to fall off; put them in separate containers/bags
label all containers/bags
use some sort of insulation, such as inflated plastic baggies, small balloons, packing peanuts, or blankets to wrap the models in to protect them from any impacts

These protected my collection during a move, so they should keep yours pretty safe.

Wrap the sets in stretch wrap to keep the parts together and then in bubble wrap to protect from external forces.

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What is this minifig and is it from Atlantis?

Saw this on Facebook, what is this minifig?
Some people say it is from Atlantis but I'm not so sure.

This minifig is indeed from Atlantis, it is a Atlantis Manta Warrior

It is indeed the manta warrior. It is one of the several undersea warriors in the theme, although it's discontinued.

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


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Advanced set for 5.5 years old
My son had great success building a lot of Lego models, including complex sets, such as the Family house set.
And I want to meet him with an advanced model, that includes some gears and more functional.
I thought about 3 models, all of them are a little old but I really love them and I don't know which one to buy. The models are 5893, 4993 and 5767.
I'll be glad to receive an advice, which set is most recommended, considering my son's age (5.5) and props of each set.
I'm open to new suggestions.

I'm going to suggest that unless you're getting these sets at their retail price, don't bother getting any of these for a 5 year old. Instead, just get a current set, such as 31017 Sunset Speedster, which is still available at its regular price. Or check out the line of Speed Champions.
My reasoning is that a small child does not care about the vintage of a set and is not completing a collection, so any particular set is equivalent to any other. The sports car model is one that Lego refreshes every so often and there is almost always one available for sale, and you can usually get it at a discount. But all retired sets increase in price on the secondary market and I'd say you are getting zero value for your extra money if you hand this set to a child. They will love the set but not care at all if it's rare or hard to find.
As for how age-appropriate such a set is, it depends on the child. The Creator sets are fairly easy to build, usually. My 5 year old has little difficulty building them, though he has a fair amount of Lego experience. If your son has already built several models, these sets should be fine, even if the ages say 7 or 8 and up. I find that Lego's age recommendations are too conservative for my household, but YMMV.
Addressing your point about wanting to build with gears, etc. Most Creator models have minimal gears involved. Certainly the sports cars do not have working steering or anything like that. Creator sets almost never feature that sort of functionality except on the largest models. When there are moving parts, they are typically just hinged.
If you want something that features actual gears, steering, etc, you need to peruse the Technic line. Most of that is fairly complex. It's aimed at an older audience and I'd wager your 5 year old isn't ready for it - at least, mine wouldn't be. If Technic is too complicated, you might try one of these:
Fairground Mixer
Ferris Wheel
They are large models, fairly expensive, that feature both brick-built devices and mechanical movements. Both can be motorized by adding a motor (sold separately). Both are large sets that display well, but feature lots of play features. The Mixer, especially, is very cleverly constructed. I'd say both are too advanced for a 5 year old, but with a parent's help, and some patience, they should be possible.

Thank you very much ! but the two models seems for me too much easy and the latest models are really very expensive...

The car models I suggested are of the same difficulty add the ones you asked about. They should also be comparable prices. The two Creator expert fairground rides are expensive but definitely not easy. However, the older sets are usually much more expensive than the later sets. If you can find them at a good price, they'll do just fine. But there is little technical difference between the creator car models on a yearly basis. They just refresh the model with new colors or updated parts.

@ Nr, Shiny - Thank you very much! I'll take one of them

The 4993 seems to be just a static display mode with no gears or functionality apart from the opening hood, doors and roof.
The 5893 in contrast has working steering, suspension, winch, etc. These provide playing and learning possibilities.
The 5671 has some odd colors and a working steering wheel, but nothing more than this.
To sum it up, if I were you, I'd buy the 5893. Disclaimer: I don't own any of these sets, I only saw them online. I might be mistaken about what I wrote.

Thank you very much ! btw, maybe you have an idea of another set? Thanks again!!

It's been quite a long time since either myself or a close relative of mine was 5.5 years old, so I don't really know what are his interests and skills. In my opinion, LEGO enthusiasts can be grouped in three categories: Builders, Players, Collectors. These might overlap though. I seriously doubt your son would be a collector (as in keeping sets in mint condition, behind glass), so that leaves builder (builds, expands, invents, alters models) and player (roleplaying with figures and models). These two tend to enjoy different sets, but a good compromise surely can be found.

It's my old question but want to share with "new" lego I found, called Kluntz Lego.
The Kluntz Lego is for complex structures, gears, etc.
Here is an example.


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How to build a limited slip differential?
Lego provides a couple of ways for building a differential, such as this:

and also provides a limited-slip gear like this:

http://www.brickowl.com/catalog/lego-technic-differential-with-one-gear-28-tooth-bevel-with-open-center-62821
What's the simplest way to combine the two mechanically such that if you have one motor driving two wheels, they can turn at different speeds (i.e. they aren't locked to each other), but at the same time, they will both receive a reasonable amount of force (i.e. if one wheel does not make contact with the ground, the one that does will still apply some force, as opposed it it not spinning at all and the free-hanging one going at twice the speed)?
The simple solution is to just use some belts to drive both wheels, but I would like a geared solution if possible

https://bricks.stackexchange.com/a/10251/9416

If you haven't seen it, Sariel's limited slip differential technique might do what you want, but it's a little different than what you are asking for:

This setup doesn't provide a clean way of producing a fixed amount of torque to a wheel if it's partner is running free. It instead simply disables the differential if the wheels have been running at different speeds for too long. This isn't a perfect solution, but it is very simple and may work for you depending on exactly what you are trying to accomplish.

This would be great if it somehow reset itself when the two did spin at the some speed, but it will act like a fixed gear at times when it shouldn't

The question is old, but as noted in the accepted answer ("little different"), that does not actually illustrate how to use the Limited-Slip gear. With the limited-slip gear, you can even do without the differential. Note that the weels are on two different axels and the Limited-Slip gear is on the same axel as the opposite normal 24-tooth gear. The Limited-Slip gear does not touch the Crown gear.

Of course, it is possible to combine this with a differential:

It is also possible to combine the Limited-Slip gear with your type of differential as illustrated here: https://www.eurobricks.com/forum/index.php?/forums/topic/143133-mod-9398-limited-slip-diff-friction/

The very first comment on Eurobricks says "That's not a limited slip differential, but the opposite..." and OP agrees with this statement.

I agree. It is just an answer to this OP here, but not a real differential. As far as I know, a proper differential can't be made with this slip-gear and I'd use worm gears in a Torsen-style solution like the types discussed here: http://www.technicbricks.com/2009/03/tbs-techtips-22-torsen-differential.html

It should be gone by now.


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Strongest LEGO structuce - (1) Pillars
What is the strongest LEGO structure?
I am going to build a LEGO computer case. Different from Mike Schropp and greenyouse, I am planing to build an upright case.
(This is a general "strongest LEGO structure" question. Using the structures in building the computer case is just an example of applications.)
To make it more challenging (and more perfect), the case will have handles (like this type) for carrying the whole thing around, and it will have "legs" (like this bar type) to lift the whole case up for ventilation.
For better reference, here is the coordinate notation:

There are 4 parts (for now I can think of) in the case which has to encounter different types of strength challenges:

The pillars (Red)
The floor (dark grey)
The joints (purple)
The handles (yellow)

For the white bricks, they do not require special strengths, do they?
FYI, here are the LEGO dimensions:
Horizontal pitch, or distance between knobs:  8mm.
Vertical pitch / Brick thickness:  9.6mm.
The horizontal tolerance:  0.1mm.
Plate thickness: 3.2mm.

Above is the common information across the 4 questions.
Below is the question for this specific part.

(1) The pillars (Red)
The pillars do not have many requirements while the PC case is sitting still on the table. But when the PC case is lifted up by holding the handles, the pillars become critical to support the weight of the entire PC.
Normal stacking up the LEGO bricks or plates must not work. The bricks/parts will be separated very easily.

What is the strongest LEGO structure when using as Pillars?
I have come up with a structure (below left). I pile up the plates along the Y axis. So when tension is applied to the pillar, the knobs (many knobs) will lock each others, such that (as long as the LEGO plates themselves do not break) the pillar will not break into two parts.
There is a problem. Although the pillar will not be pulled apart along the Z axis, the plates might be separated along the Y axis due to the tension. So I made a "doughnut" to secure the pillar (below right). When the pillar wants to separate, it is a force along the Y axis. The knobs of the "doughnut" will (hopefully) act against forces of X and Y axis.
5 plates (3.2 x5 = 16mm) = 2 pitches (8 x2 = 16mm), so the pillar fits exactly in the "doughnut" (with 0.2mm (Y axis) & 0.4mm (X axis) tolerance).

Such that, the pillars have to be 6 pitches thick, which is 4.8cm. If this structure is possible, can we make the "doughnut" 1 pitch thick, and the pillar 4 pitches thick?
I assume using longer plates will be better than short plates, because fewer gaps along the Z axis, lower risk to separate, isn't it? However, I believe more plates stacking up along the Y axis, which will have more knobs, will make the pillar stronger. Which means using plates here is better than using bricks, isn't it?
In this PDF page 4, that research suggests using pegs. Obviously, the number of pegs can be used in the pillar will be less than the number of knobs in my suggested structure. And I afraid the peg itself will break, as pegs are hollow plastic, while knobs are more "solid".
Which structure (the above one, the research paper one, or your suggestion) is the strongest?

Generally LEGO Technic structures (pins and beams with holes) tend to be lighter and stronger as System structures (classic bricks). The generally accepted best practice among amateur and professional LEGO builders is to have a light and strong internal structure (either Technic or other materials, like wood or steel) that can then be decorated on the outside.
In your case the computer case should have solid walls that provide adequate dust protection and is capable of directing airflow, but Technic is quite difficult to get reasonably airtight. Aesthetics can also play a large role, therefore it is understandable if you wish to have a brick-built outer layer.
What I'd recommend is building a Technic frame, using multiple beams grouped together with various overlays and reinforcing them with other beams in triangle configurations (look at bridges, both real life and LEGO for inspiration). Then you can apply an outer shell to this frame, built by whatever means you'd like, since the Technic beams will hold the structure together and give the wall panels stability.
Especially if you wish to lift the case, it will need to be able to hold its weight by the handles. Regular System bricks are typically too heavy for this kind of build, and while it can be mitigated somewhat using tricks like your doughnut (which I personally find quite genial), they increase the mass and structural volume significantly, and soon you will arrive at huge values regarding cost, weight and volume.
Regular bricks also have only one direction of assembly, providing little to no extension and joining points, but a trivial direction where force can pull them apart. Technic beams are, on the other hand, capable of supporting multiples of their own weight in any direction, so they will not be pulled apart easily, especially when used with pins that are locked in place with bars.

Thanks for your inspirations, especially the triangle structure with beams. As i mentioned in question #2, the toughness using beams with holes will depends on the pegs. Do you worry about the pegs toughness? Btw i dont really need so airtight, as i will make higher air pressure inside, so most dust will be forces outwards.

More important. I understand using beams with holes and pegs will have high toughness in terms of its own weight. However, in thr case of a PC case, the main weights come from the PC parts, which most are heavy iron. Although using classic bricks will make the structure itself heavier, but if it can make the case a bit stronger, should we consider it?

The pins connecting the beams are quite strong, due to their cylindrical shape that is further reinforced by axial ridges. There are a few professional-quality reports on the strength of these connections, one mentions that two beams connected by two pins required over 100N force (10kg) to pull apart lengthwise: https://dl.dropboxusercontent.com/u/3550991/LegoTesting.pdf
The other shows likewise: http://eprints.usq.edu.au/20528/1/Lostroh_LegoTesting_2012.pdf

As for the strength of the case, since you mentioned handles, I suppose you will move it, in which case forces will be acting on it in various directions. The Technic connection system was mainly designed with such forces at mind (opposed to the System line, where the inspiration was building blocks that only have to resist gravity). You can test this easily by building something smaller, like a basket from System and Technic parts and observe the difference in size, weight and supporting capacity.

Sorry for the late reply. Thank you very much for your informative helps. I have settled using Tachnic to build the structures. I will choose your answer as the solution. You are the first one to reply and point out the Tachnic direction. It is especially appreciated that, in your added paragraph, you have pointed out Regular Brick Structures will break easily when forces are applied in different directions. In real life, the direction of forces will not precisely fit into one axis. However Technic is tough on this. In addition, quoting reports of experiences is also highly appreciated. Thanks

You are welcome, please post a link to the result when you are finished with it, I would love to see the final model.

Sure! I would love to share my BIG PROJECT too!

@midnite Just stumbled upon this post and wondered if you have gotten around to building it, how are things going?

I am also going to recommend Technic as the stronger support option, but I would make the case out of "normal" Lego, and then implement 2 Technic rectangular "rings" around the case at the place of your pillars, joined at the top and bottom (on the top the joint could form the handle). Make these rings or braces by overlapping Technic pieces and joining them with Technic pins. Then, in your case, insert a few pieces that can also accommodate a Technic pin (1x2 brick with center hole) and secure the brick-built case to the Technic rings that way. If you think this through, you could make that connection easily removable, so that you can slide the brick-built case out of the 2 rings and have an opening side panel allowing access to the internals - a very flexible but still very strong design.
I have mocked up this case, see the below pictures. No comments on the sloppy building style - I had to work with whatever my son did not have incorporated into one of his builds :). The Technic rings obviously need some more bracing in your final design, but I think this shows the concept of using 2 rings, a handle, and pins to secure and remove the central case pretty well:

Sorry for my late reply. And thank you very much for your answer. It is really impressive that you actually build a model and do experiments for me. I am now designing my computer case with the Technic frame. Your ideas of removable frame and side panel opening inspired me a lot. I would really want to accept your answer as the solution too. But sadly I can only choose one. Your answer definitely worths upvotes +++. Hope you will give me some ideas of the Handle and Joints (probably with experiments) in the future ;)

my pleasure - as @zovits already mentioned - let us know how it turned out :)

Sure! My pleasure too!!

A 3-D Box frame using Technic bricks or beams has the highest potential for rigidity and strength. The 3-D box frame strength comes from its use of distributing any external force across multiple joints.   Classic bricks works better than Technics at creating a desired form - like a wall-  but classic brick clutch power is too weak. However a classic brick wall can be strengthen by using Technic bricks and beams to brace(bind) the walls along Z axis (the axis parallel to the studs and cylinders). For example, a wall composed of 4x1 technic brick, 4x1 plate, 4x1 plate, and 4x1 technic brick can be braced by a 3 hole technic beam  on both sides of the brick wall that would very resistant to external impact.


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How do I control one EV3 using another through bluetooth and LabVIEW?
I have LabVIEW 2014 and I'd like to control make one EV3 move forward using another through bluetooth using LabVIEW, and I don't want to have to use the computer as a relay. How do I do this?

This is not EV3 and does not use LabVIEW, but maybe you can use it as a reference to develop real time Bluetooth communication between two systems: http://www.philohome.com/nxtjoystick/joystick.htm


text:
Can you use a beveled gear as a pinion?
I would like to use the PF servo motor for steering, however it is very large - I was playing with the idea of having it mounted vertically, and then using bevel gears to change the direction of the motion, however that introduced too much play into the steering system (even with only two 12t double bevel gears)
I would like to know if there is any good gear/spacing for driving a rack via a bevel mechanism, preferably as small as possible and with a vertical PF servo motor
(P.S. - yes, I know the micro-motor would probably be better for this..)

Seeing a picture of your progress would help tremendously.  The way the question is worded, it sounds like you were wanting to drive the beveled gear directly from the servo to the rack at a 90 degree angle.  This won't work for two reasons: 1. The majority of Lego racks are not beveled.  2. The rack moves fore and aft as it moves side-to-side, which would disengage the gears.
I threw together a rough, working rack & pinion setup with beveled gears to get a better understanding of the play you may have been referring to.  You didn't mention which type of beveled gears you were using so I tried it with two of the most common types.  My only 2 "PF Servo Motors" are deeply embedded in other vehicles at the moment so I used an "M" motor in it's place.  Because of this I could not compare the two for "play" in the output shafts.
In both applications the majority of the play I observed was coming from the motor itself, not the gear mesh.  I also don't have a clue as to how you built it verses the way I did.  Because the gears and size of the assembly seemed to be your priority, I placed the motor in a more compact position.  The orientation of the motor and which way is "up" can easily be modified per application.
The first test uses the "32270 Technic, Gear 12 Tooth Double Bevel".

The second test uses the "32198 Technic, Gear 20 Tooth Bevel" to drive, and a "87407 Technic, Gear 20 Tooth Bevel with Pin Hole" for an idler gear.

Both set-ups had very similar play, all of which appeared to originate from the motor.  I did try the smaller "6589 Technic, Gear 12 Tooth Bevel" but it seemed to exaggerate the play. This is possibly from the lack of an idler gear and/or from the greater angle of the teeth, needed for the smaller gears to mesh.  I therefore excluded it from "working prototypes."  When comparing the "play" in the assemblies that I built verses the steering on my 2 vehicles with the Servo Motor (set# 41999 & MOC using 88004) there was no noticeable difference.  In other words, I think this is as good as you can get using modern Technic pieces without some bulky over-engineered steering assembly.
My last thought on this takes us back to my earlier comment, "The majority of Lego racks are not beveled."  Another option, and perhaps the easiest and most compact, would be to retro-fit the older rack pieces parts# 2790, 2791, 2792 into your build.  These parts were pretty much made for this type of thing.  Here's a couple pictures from set# 8832 for reference.

Too much backlash (play) in LEGO gears is an universal problem that unfortunately can't really be mitigated since all compatible LEGO gears are designed with very loose tolerances compared to professional gears.
According to Sariel the bevel gears you tried using already have less backlash than regular gears, so you can't really expect any improvement by switching to another gear type. You could however try using worm and larger bevel gears, this would supposedly provide the most precision achievable with gears.
If you plan on mounting the servo motor vertically then you could skip rack and pinion steering and connect the steering rods directly to the axle of the servo, eliminating all gears and their inherent problems.

Any comment on using the bevel to drive the rack?

You can certainly do that, I can easily imagine a setup with a vertical servo, a gear attached to its shaft, and a rack turned 90 degrees to the side. The only problem I could imagine is when in the extreme positions the plane of the rack could move away from the shaft, possibly disengaging the gear.

Any way to drive the rack without having to rotate it? (as that's kind of the point of a bevel gear.. to change the plane of the torque)

Honestly I haven't seen this kind of setup, but it could work. I wouldn't bet on it though. If you have more space in your vehicle you can also try using two universal joints at 45 degrees each and see if their backlash is less than the two bevel gears'.

I haven't seen the setup either and haven't been able to assemble a decently sized and right-distance one yet, which is why I am asking - two universal joints seem to have more backlash than the 12t double bevel joint though

You could make the rack double wide, like a fine trailer home.


text:
Is LEGO Junior compatible with regular LEGO?
Does LEGO Junior fit with regular LEGO? Say for 8-12 year olds? I want to make sure it is not obsolete and can be used as the child grows alongside the LEGO collection.

Yes. These sets are fully compatible with other LEGO sets.
LEGO Junior is simply a theme within the LEGO System (just like City or Star Wars). It uses exactly the same bricks as regular LEGO. The models in Juniors sets tend to be simpler and use more basic bricks, but the bricks are all compatible.
The main "incompatibility" within the LEGO System is from DUPLO to regular LEGO, but there is even quite a lot of interoperability between these as shown here:
Are DUPLO blocks compatible with LEGO blocks in any way?


text:
What is wrong with a Lego pneumatics system that won't go?
I own a LEGO Technic Unimog U-400 (part number 8110) and have been very pleased so far with the performance of its pneumatic system. However, after storing for just a month or two (after a good 5+ months of hard use), the pneumatic actuators in the crane did not work, even with brand new batteries. I disconnected all of the hoses and felt that the actuators had more friction than they had previously had when the model was working well, which led me to oil them with vegetable oil, along with the pneumatic piston pump.
When I reconnected all of the hoses, switches, connections and tried it out, the second actuator (the one controlled by the middle switch) and the third actuator (the one that powers the claw) still didn't work, while the first actuator (the one controlled by the first switch from the left) worked as good as new. I have checked and double checked the connections. What is the problem
 here and how can I fix it? Apologies for bad grammar and/or bad formatting.
EDIT: I tested several times and the first cylinder actually isn't working well either. So really none of the three is working now.

I fear that after "oiled it with vegetable oil" you've ruled out help from Lego, and you've done something few of us have ever done. Typically vegetable oil oxidises and turns sticky when exposed to air, so you may need to clean that off and use silicon grease like the stuff Lego uses.

Thanks, wish I had looked into vegetable oil in the first place. That crud's probably going to be really hard to get off.

I was going to recommend lubricating the pistons, but seeing you already did exactly that, I can only say you should try to isolate the source(s) of the problem.
Since you have at least one working cylinder, the compressor and the feed tubes should be all right. This leaves the following possible points of failure: switches, subsystem hoses, working cylinders. Try disconnecting the hoses from the switches to see if the valves work well, and try connecting the compressor directly to the hoses the valves control to check the individual pneumatic circuits.
If a hose has developed a leak, you can also find it using a long hose (to protect the electronics) that is known to be leakproof and a bowl of water.
If the pistons are proven to be stuck, you can try the steps outlined in this answer.

I just submerged the entirety of the lower part of the Unimog's pneumatic crane (all switches and many of the connections), then powered it up and tried it out. I did the same with every part of the pneumatic system, and found that there was no air leakage anywhere. I am thinking that the problem could be deterioration with the seals inside the cylinders, but this seems unlikely given the storage conditions: dry, 60-70 degrees, no sunlight, no exposure to chemicals or other contaminants- and the fact that all three cylinders failed rather than just one or two.

There is still the possibility of either stuck cylinders or deteriorated seals. Can you feel or otherwise sense air escaping the cylinders? If not, then they seal well, but might be stuck. In this case can you move them by hand? If they can move under pressure and while being assisted, then they might need just a few (or a lot) of these assisted cycles to even the lubrication inside.

I have checked all of the hoses and connections, there is no leakage from the actuators, hoses or any of the connections. I have actuated them by hand many times to even the lubricant (olive oil), but no dice. the one small actuator on the claw is especially sticky. I can think of no conceivable answer to why they should be acting like this, and its driving me nuts. Please Help!


text:
How important is a center differential on a 4WD model?
I am looking to make a 4WD, single-engine powered vehicle, and I have seen others such as this which use three differentials to distribute the power to all 4 wheels:

http://www.eurobricks.com/forum/index.php?showtopic=79535&st=0
I am not quite understanding the need for the center differential - what would happen if you simply had one gear drive two followers, i.e. one for the front and one for the back? traditionally a differential is used when one side would spin more/faster than the other, such as when a vehicle is turning, but I am not imagining a situation where the front end will travel more than the back end, so why was it designed like this?
P.S. - yes, there is all sorts of discussion in that thread already about the center differential, and the tldr version is that it's dead-simple to replace if you want to, and many people have their own opinions, but not so much "why" or where the forces go/what it would look like if you do remove it

There are all kinds of situations where the front and rear axle may not rotate at the same speed.
Imagine for example a bicycle taking a turn while remaining vertical. When viewed from the top (using a planar projection), the bicycle rotates around a point that's at the intersection between lines perpendicular to each wheel.
Here's an ASCII-art illustration of the situation:
   / front wheel
  /.
 /    .
         .
  |         .
  | - - - - -  x rotation axis
  | rear wheel

The front wheel is further from the rotation axis than the rear wheel, thus it moves faster relative to the ground.
This is the same with a four-wheeled vehicle : the speed of the center of both axles relative to the ground is not the same when turning, hence the center differential.
The smaller the turn radius, the more difference there will be between axle speeds.

Well, the center diff allows the front and rear axles to turn at different speeds, which is useful to put less stress on drivetrain parts that are constantly moving around. However, for a Lego model it is probably not required, since it most likely would not move at speeds required to necessitate one. Building one in would add realism, but you would need to keep in mind that with a center diff, the torque all tends to go to the axle with the least traction.
EDIT: Why the front and rear axles sometimes move different speeds, why it matters
Imagine a four-wheel-drive vehicle, with a center diff, moving at a decent speed. It encounters a bump in the shape of a half-sphere, approximately 2 inches across, on the right side. The right front wheel will encounter the bump first. As the vehicle drives two inches over the bump, the rear wheels both travel two inches. However, the right front wheel, following the shape of the bump, travels pi x 1 (the radius of the bump) inches, or approximately 3.1 in. Since the right front wheel covered a farther distance than the rear wheels during the same period of time, it went faster than they did. This translates to a slight difference in speed between the front driveshaft and the rear one, which is easily handled by the center diff. However, the same scenario applied to a vehicle with no center diff could bend or break the driveshaft, as the rear section and front section try to go at different speeds. At LEGO scale, however, this difference could probably be absorbed by the flexibility of LEGO parts without incurring any damage.

Why is the speed relevant? (as opposed to difference in speed between front/rear) at what speed would it become relevant? under what situation would the front/rear be moving at different speeds?


text:
What are those 6 extra studs for in 42000 Grand Prix racer?
I recently purchased a set, Technic 42000 Grand Prix Racer, that I am very happy with. However, I am perplexed by the fact that the set came with 6 extra transparent 1x1 round plates (studs).
As you can see, this was clearly not a mistake, as they are shown in the instruction manual. So my question is, does anyone know what these are for? My guess was that perhaps the Designer is signing his/her name to the set in a quirky way. Can anyone explain?

Sariel's video explains it - they aren't used in the A model, but if you scroll down into the comments, it's explained that they are for the B model

@user2813274 - You should probably post this as an answer - I know we prefer longer answers if possible, but I think there's not much more to it here ;)

Sariel's assembly video shows that he ends up not using those 6 studs for the car assembly
but wait! if you scroll down into the comments:

he explains that the pieces are used for the B-model:

Then why show them at all if they are not used ???? I spent time searching for answers myself. It must have been a mistake. There were other left over pieces that you assume are used for the other model and they were not shown as part of this model. Very strange.

@JonStephens my bet is - to show you they are not connected and you haven't missed anything.


text:
Where can I get a large number of LEGO bricks cheap?
Yes, I see other people's amazing MOC's all the time, and think, "man, I could totally do that if I had enough bricks." The problem is, I don't really know where to look for a whole bunch of LEGO bricks that aren't in set form. I would really like the pile to include normal and Technic bricks, as well as some specialized parts such as gears, transmission pieces, wheels and tank tracks, but don't need any minifigure parts.

MOC-ers use BrickLink.com, the Unofficial Online LEGO Marketplace. It is similar to eBay in the sense that buyers and sellers are from all over the world, but BrickLink is only for LEGO. All elements are neatly organized into categories, and every LEGO element ever made is catalogued. Link to BrickLink Catalog Page: http://www.bricklink.com/catalogTree.asp?itemType=P
You can build up your Wanted List, then purchase the pieces you need from various sellers. (By building a Wanted List you can find sellers who have most of the items you need, thus reducing shipping fees.) Most BrickLink sellers have very reasonable prices and excellent service - they are LEGO fans themselves. Just make sure you check their feedback and terms before purchasing.
BrickLink is a MOC-er's heaven. :)


text:
What is the "Module" of a LEGO gear?

Module, m this indicates the tooth size and is the number of mm of
  pitch circle diameter (p.c.d.) per tooth. For gears to mesh, their
  modules must be equal. Gear ISO standards and design methods are now
  normally based on the module. EG a gear of module 3 has 16 teeth, its
  pitch circle diameter is: 3 x 16 = 48 mm.

Source: Plymouth University. Gear Tooth Nomenclature.
I am curious as to which non-LEGO gears will mesh well with LEGO gears, but this is one of the more important numbers as far as figuring that out, yet I don't see the concrete number mentioned in any of the various LEGO gear descriptions/tutorials that show up when I search for it
To be very clear, all I am looking for is either single number, or an answer of "LEGO doesn't follow the mentioned Gear ISO standards".

Quick answer: LEGO gear module is 1 (metric).
See Section 3.4 at this link: http://bdml.stanford.edu/Main/CrawlerNotes
The consensus seems to be the following:

Lego gears have a metric module of 1, which is the same as a pitch of 25.4 teeth per inch of diameter.
Pressure angle is likely to be about 20 degrees. (This is the most common angle with modern gearing.)
Face width is approximately 1/8 inch. Perhaps more precisely: b = 0.14 inches? - according to a measurement somebody took with calipers in 2011. But note that not all LEGO gears have the full face width. In particular, the crown gears (LEGO's version of bevel gears) do not have a full face width.

From http://orionrobots.co.uk/Lego+Specifications:

In the Lego system, technic gears have a ratio that the number of
  teeth are 8 times the diameter, or 16 times the radius in stud pitch.
  Conveniently - the number of studs, and Diameter in Millimeters seem
  to be the same. Note: one "stud" is 8mm. So: 16 tooth gear is 2 studs
  = 16mm => diametral pitch = 1mm.

Also, I have personally 3D printed custom gears with a pressure angle of 20 degrees and a module of 1, and these meshed perfectly with my other LEGO gears.

How did you know that my next question was going to be what the pressure angle is?

How interesting that when trying to find more information about this, I end up back at the answer - referring back to my Orionrobots site. Does anyone have an up-to-date link for the Stanford document there?

authors: Христя Галів


text:
Which set includes a large white mask
I bought a sealed bag at Goodwill but It did not include any information on what set it is from.
Pieces look like large white body plates, skeletal/Stormtrooper mask and tusks.

The mask in the first picture is from the Hero Factory set Witch Doctor.
The other pic looks like it's from the same set.


text:
What year did the minicon "micro BrickCon" first appear at "BrickCon"?
It seems like minicons (a minicon is a LEGO display consisting of minilander figures looking at miniland scale tables populated by microscale MOCs) are popping up everywhere lately.
The last known sighting was in Melbourne, so the theme has officially gone global. Before it became a theme at LEGO conventions across North America, and now the world.
What year did the first micro BrickCon go on display at BrickCon in Seattle?

In the blog of Tom Aplhin he mentions regarding Microscale

Steve Oakes, a long-time LEGO builder in Seattle area started a tradition 4 years ago to re-create the BrickCon Public Convention at a smaller scale. His display is called “Micro BrickCon”

(Edit: The conversation between Tom and myself was in a loud room with lots of activity. He is correct about everything except the year.)
After building and displaying an 8.5 foot stern paddle wheel ferry boat at BrickCon 2011, I decided it would be easier to build smaller MOCs. I kicked the idea around for a while, and then came up with the concept of making a micro-con. Mariann Ansunuma, former miniland builder at Legoland, and current maker of awesome microscale Lego jewelry, liked the idea and took me under her wing. I built 2 tables, displays and minilanders to display at BrickCon 2012. I was very pleased when Mariann brought along a third table, displays, and minilanders to add to mine.
After the initial Micro BrickCon MOC was displayed, Mariann, who travels to various cons with her vendor booth, took her portion of the MOC and introduced it to cons across America. It has since become a theme featured across N. America, Canada, Germany, and Australia.
In 2012, the MOC was just a MOC. However, micro BrickCon was so well received, in 2013 it became and remains it's own theme. In 2012 7 builders contributed one thing or another to make the MOC better. In 2013 and 2014, 22 builders contributed, and this year, 2015, 29 builders joined in.
                                                                 -Major Stackings


text:
How can I build a LEGO structure based on a real building?
I have a grandson who wants to build a LEGO building that looks like the high rise building I live in.

I have made a few edits to your question. If you have any specific information please include them in your question. e.g. Are you scaling your building to fit minifigures? Do you have a particular budget? What have you tried?

Take pictures of your building, of as many sides as possible
Take measurements or find blueprints of the building. Length, width, height, height between floors, size of balconies etc.
Convert these dimensions to LEGO dimensions. For this, figure out the scale you want to build in first (e.g. 1:40, which is "minifig scale" - but check out this post for some caveats). You can use Sariel's calculator to find out what this means for how many bricks you need.
For best results, design the whole building in LEGO Digital Designer (LDD) or LDraw first. This will save you from making unnecessary brick purchases before you have finalized your model
Get a brick inventory from LDD/LDraw once you have your final model.
Use a service like Bricklink or BrickOwl or Lego's own Pick-a-Brick to buy the bricks you need in the quantities necessary, after accounting for all the bricks you already have. Alternatively, you can look at other available sets to see if some of them carry the bricks you need in large quantities - this might be cheaper (you could even sell the not-needed bricks back via BrickLink etc.).


text:
Can i change the way the ir remote works?
I bought an EV3 and the first thing that I want to do with it is control models with the remote.
I finally discovered how to do this after a long search.
It can control the Formula EV3 racing car with rack and pinion steering (where the angle of the 2 front wheels change instead of the 2 back wheels turning in the opposite direction to turn the car) When you use wheels it doesn't turn like when you use the other type of tires.
I'd like to use the remote that comes with the EV3 to do this, but I'm not sure how to modify the remote to support this type of control?

What EV3 model have you built, is it one of your own or one from the instructions provided with EV3?

The formulla race car

If I understand your question correctly, you are asking how to use the following remote to control traditional car that has front wheel rack and pinion steering rather than a vehicle that skid steers using the rear wheels. Here's the remote:

This isn't ideal for controlling steering because both sets of buttons point forward. The easiest solution is to attach a wheel on the side of the remote that actuates one set of controls like this. Here's an example using the PF remote that could be adapted to work with the EV3 remote.

I don't know what your vehicle design looks like, but you may also want some sort of return to center steering system on the motor controlling the orientation of the front wheels if you haven't already built one. Here's one simple example of this:

Its the remote from the ev3

Ah. Of course it is. Sorry about that. I've updated my answer.


text:
Is there a good way to buy molded LEGO boxes?
I'm considering some new storage options, and there are some official LEGO boxes that I'd like to use as they already fit in my existing shelving system. The following sets contain the boxes that I'd like to use:

I wouldn't mind picking up a few copies of the classic brick box for the parts, but I'm less excited about the others. I'd like to get a variety of colors of these boxes, and they aren't widely available on Bricklink.
Is there a good way to get these boxes without buying several copies of each of these sets?

I have considered this as well as the boxes look nice and they are stackable. However after taking into consideration how difficult it was going to be to acquire these boxes in sufficient quantity, be able to expand the system as my collection grows, and the fact that even the largest box is quite small, I decided against it. It is just not worth it.
Also, the boxes are not really practical for storage. They are narrow and deep, meaning it is hard to find pieces. I prefer wider and shallower containers where it is easier to see what's inside. It is best to go with a generic storage system readily available at department stores. They are made to be practical for storage, they are cheap, and can be expanded as your collection grows. If you would like to have the LEGO-ish look, you can always paint your shelves in bright colors, add posters, LEGO stickers, etc.
However if you really-really want these boxes, you might want to team up with eBay or BrickLink sellers who don't really care for the boxes but sell the parts. Try to reach out to larger sellers who buy sets in quantities, so you can get a number of boxes at a time.

Thanks for that. I'm only thinking of using these as part of my storage system. I primarily use 3700 series Plano storage, and these boxes have a similar footprint so they'd fit on my shelves nicely. I was thinking I could use them for awkward large pieces such as battery boxes, BURPs, train track, etc.

That's a good solution. If you don't have to depend on these boxes and they are just part of your storage system (as you mentioned), then yeah, they can be a nice supplementary option. They are well-made and strong, and they are stackable. Plus they do look very LEGO-ish. In my opinion they are a lot more practical than those awfully designed storage boxes that are made to look like LEGO bricks.

I suspect that cheap quantities of the duplo box will be hardest to find since virtually all who buy it will be buying it for small children and will probably keep the box to store the bricks. Also, it probably wouldn't occur to anyone that there might be resale value to the box itself. These boxes will likely end up getting played with until they're too beat up to use as nice display boxes, and/or will end up in a recycling bin somewhere.
Depending on how determined you are to get these boxes, I'd see if you couldn't find a toy store that would let you post a notice near the duplo boxes stating that you're willing to buy them, or that would pass your contact info to customers who buy a box. Failing that, I'd buy a pile of the yellow ones and paint them.


text:
Where can I find 'Dolphin', the 3D model to LEGO software?
It was created at the École Polytechique Fédérale de Lausanne.
But it seems it is no longer available for to download. Does anybody knows what happened?

Is is this that you are looking for?  http://lgg.epfl.ch/publications/2013/lego/ Description matches, but not the name (Dolphin)...

@Philo - this looks like the right answer, why don't you make it an actual answer?

There is this available from LEGO which may prove useful: http://ldd.lego.com/en-gb/

You are probably looking for this: http://lgg.epfl.ch/publications/2013/lego/


text:
Which combination has a lower gear friction?
I need roughly a 1:3 reduction and I see a couple of ways to achieve it:

using a 8t gear and a 24t gear (1:3)
using 2x 12t gears and 2x 20t gears (1:2.779)
using a 16t gear and a 40t gear (1:2.5)
using a 12t gear and a 36t gear (1:3)

Now, size issues aside, and assuming all axles are held by at least two beams, how do these combinations compare as far as wasting the least amount of power due to friction? What about torque? (where the 8t gear may have an issue)
This is for a high-RPM, low torque situation, so I am not exactly super concerned about backlash or torque forces, just efficiency and friction.
I would be open to other gears as long as the reduction is in the same rough ballpark as the aforementioned, especially if it's more efficient somehow.

According to Sariel's gear tutorial in chapter 5, Efficiency:,
- the less gears, the better
 - the smaller gears, the better
Based on this principle the first setup looks the best, but you are right that the 8 tooth gear is the weakest of all and it has the most backlash too, if any of these are valid concerns for your build.
Note that gears can be strengthened by using them in parallel by putting some 24 tooth on one axle and the same number of 8 tooth on the other, mating them together all at once.
If you are concerned by backlash, you can experiment with springs, rubber bands or other ways to put a constant load on the system.

Not too concerned about backlash, but doesn't that imply more friction as well (looseness, not meshing tightly)? or is the smallest gear (8t) the most efficient, because of it's size? would putting two of them in parallel help lower the friction or raise it?

I'm not a mechanical engineer, so don't sue me if I get it wrong, but I think the looser the gears mesh the less friction is between them. Parallell gear setups would seem to have increased friction, but again, I could be mistaken.


text:
Brick Compendium: BIONICLE LEGO
Is there a comprehensive compendium of the old Bionicle pieces?
For example, what is the part name for:

Tahu Mata's flame sword?
Lewa Nuva's twin blades?
The Zamor Sphere's holder, as used by the Toa Ignika?
The Midak Skyblaster?
The zipcord whirly-peg thing for the spinners?

You will find most LEGO pieces, including those that are specific to the Bionicle theme on Peeron.
For example here are your particular mentions:

Technic Bionicle Weapon Flame Sword 2 x 12
Technic Bionicle Weapon Blade 12L
Technic Bionicle Toa Inika Zamor Sphere Magazine
Technic Bionicle Weapon Midak Skyblaster with Black Housing
Technic Bionicle Rhotuka Spinner Ripcord 12L with Hand Grip


text:
Lego 3804, Mindstorms Robotics Invention System 2.0 on Windows 10
I gave my grandson (11 years old) the LEGO 3804 Mindstorms Robotics Invention System 2.0. He built a couple things and when he tried to install software to program what he built, the computer would not accept the download. He is running Windows 10.
As a result he can't really use the system. Are there any suggestions or advice from anyone out there to help. I feel terrible about this.
Thank you for your time and expertise.

Works for me:

Download Oracle Virtual Box
Download Microsoft Windows ME (4.90.3000) (OEM Full)
Get the stuff to work
Last but not least: download the VBE9X drivers and install them in Windows ME

That set has an RCX in it, is that right?  I have several suggestions for you:

Have you tried running the software/installer file in compatibility mode?  I understand this software was designed for Windows 95 or 98.  If this is the case, there is an option in Windows to 'run in compatibility mode' by right clicking the .exe file, selecting 'properties' and then under the compatibility section, select whichever operating system the software was originally designed for.
I have found this article which may provide you with a
tutorial.  I am not personally familiar with the set, but I assume this software will work.
Failing all else, I suggest you try Brixc Command Centre .  This uses a derivation of C for programming your robot which, as I understand is not too different from the original Lego software.  This is freeware and allows you to program not only the RCX, but other versions of Mindstorms robots if that is of interest.  I personally use this all the time with my Mindstorms NXT sets and it works a treat.  It's a great way to introduce programming to people as well!

Hope these suggestions are of help!

I found I could not get the Mindstorms NXT 2.0 software to load on my Windows 10 PC because LEGO revoked the security certificates and wants you to run the newest software. The latest version of Mindstorm software (EV3) seems to load and run a Mindstorms NXT 2.0, however, you lose the remote control via Bluetooth and the ability to update NXT Firmware on the brick if you use the latest. If one has a real need to load the software on Windows 10, I found a method to do so.

Activate the Administrator account on your Windows 10.  I found the only method that worked for me was to Search for from windows menu "Computer Management" and run this.
Open the folder Users, and double-click the Administrator account.
Uncheck the option for Account Is Disabled, and click OK or Apply.
Exit Computer management
Click the windows button and select "Switch User" from arrow button on shutdown
Click to enter Admin account
Start Powershell as an administrator
In Powershell, type, D:Setup.ext where D: is the location of the mindstorms NXT 2.0 Setup file.
When you are done, it would be wise to re-hide the administrator account to avoid someone accidentally going into it and causing damage to Windows.

I needed this because our NXT system has some special 3rd party sensors that drivers exist for NXT 2.0 only.
As with any bypassing of windows security features, be wise about how you make use of this approach and touch nothing more than is noted.  There are plenty of "how to activate administrator" account help pages but nobody seems to note that Powershell run under the administrator account allows you to load software with revoked certificates. Never load anything you are not 100% sure is truly safe to run with an approach like this.  You could load potentially dangerous software if it is not verified as safe. I hope this saves someone the frustration and days of time I spent figuring this out.

authors: Преводи и Легализация Варна СА


text:
How exactly does the pull-back motor (12787) work?
I've got the 42034 Quad for my birthday and it's been really fun to play with technic after so many years.
I am very curious about one thing, though - how does the pull-back motor (12787) work and look internally? I'd unscrew mine but I am afraid I'd damage it.
I am guessing it probably uses some kind of spring and/or rubber bands to build the pressure but I'd love to know it's internals precisely.

Another type of pullback motor has a detailed structural disassembly here: Imgur album.
I think your motor should work mostly the same way, but I wasn't able to source such internal pictures.

LEGO Micro Pull-back Motor Reassembly

Micro Pull-back Motor Parts
Gear A: Pin shaped like 'E' for attachment to Spring on Chassis
Gear B: Smallest (of 2) gear with a pin
Gear C: Largest gear with 2 levels, smaller gear at the bottom, larger gear on top, with teeth for meshing with Axle F
Gear D: Smallest (of 2) gear with a hole
Gear E: Medium gear with 2 levels
Axle Assembly F
Gear Assembly G
Not shown: 5 X-head screws
Note: Gear A may be detached from Spring.
I attached it such that it won't fall out when flipped upside down.

Install Gear B
Place Gear B with pin downwards into slot in Gear Assembly G

Install Gear C.
Place Gear C into the hole in Gear Assembly G.
The larger gear is on top.
Gear C will cover Gear B and mesh with it
(though Gear B has some play since it is in a slot)

Install Gear E.
Place Gear E into the small depression in Gear Assembly G.
The larger gear is at the bottom, and will slide under Gear C.
There is a pin facing up. Gear E will mesh with Gear B.

Attach Gear D to the Axle Assembly F.
Gear D has a small hole which fits on the pin on Axle Assembly F.

Attach the Axle Assembly F to the Gear Assembly Cover G.
Flip the Axle over.
Gear D should stay attached to the Axle Assembly.
Align the Axle Assembly and snap down on the protruding pin on the Gear Assembly.
Pinch the two parts (F & G) together at the lower section using thumb and index finger, and try to spin the axle.
The gears should only rotate when the axle is spun in one direction, and not the other.

Reattach the Gear Assembly G to the Chassis.
This step is tricky.
You will need to pinch the Gear Assembly to keep parts in place,
then place the Chassis on top of the Gear Assembly G, and move it around
until Gear A connects with the correct hole and mesh with the other gears.
Then, holding everything tightly, flip it over, and start installing and tightening the screws in a diagonal pattern.
Don't over tighten the screws, you should install at least 3 screws first (one on top, two at the bottom), and test that the spring is engaged with Gear A and you get a pull back action when the wheels are turned.
After that, install the rest of the screws and tighten all of them.

The pull back action works, but I can't figure out how to fix the torque on the spring.
So the car is no longer a race car but a jalopy!

The Picasa album you referenced appears to be a dead link.

Thanks for the heads-up, it seems Picasa as a service has been retired. I have found the images and reuploaded them to Imgur, hopefully that will not go away soon :)

The imgur link is now also dead, can you upload them again?

@Ralph Strange, I'm still seeing all of the pictures by clicking on the link.

My mistake, works in Chrome, not in my Firefox, must be something my end, proxy maybe

@Ralph No problem, glad that got sorted out :)

And now it's broken AGAIN.

@mindstormsboi It seems to work for me, are you sure it's broken from your perspective?

@zovits Yes, it's giving the 404 page: https://i.stack.imgur.com/B6wXF.jpg Why don't you go click the "ask question" button and upload the photo using the markdown imgur uploader? I'm thinking that any other method can cause it to not work.

@mindstormsboi I have embedded the images in the post to take advantage of the SE-Imgur collaboration.


text:
EV3 - At what time DIRECT_REPLY is sent by brick?
For example: I've sent DIRECT_COMMAND_REPLY to rotate the motor for 720 deg. When EV3 brick should send reply:

before motor finished rotation (right after my command was received) or
after motor finished rotation?

Now, I have feeling that reply is sent right after my command was received by EV3 brick.

I have the same observation as you, it seems to be sent as soon as the brick receives the command.
A workaround that I have found is to send a "stop motor" command after every movement, this way you know when the motor is stopped for sure.
Out of curiosity, what library are you using?
EDIT:
Have you been capturing the packets that the EV3 sends back to the computer?

I'm trying to write my own framework in Objective-C:

WiFi for iOS based on GCDAsyncSocket and GCDAsyncUdpSocket
Bluetooth for OS X based on IOBluetooth.

For better understanding this helped me a lot: http://stackoverflow.com/questions/24253509/using-c-to-get-data-from-a-lego-ev3-sensor.
I'm using Lego Mindstorms EV3 Home Edition Software with EV3 brick connected via Bluetooth and PacketLogger for capturing sended/received commands.

The DIRECT_REPLY is sent when all of the operations in the DIRECT_COMMAND are completed. (Side note: you can have more than one operation in a direct command).
So the better question might be "when does the motor rotation operation complete?". It completes immediately and moves to the next operation in the direct command. This is why you get a reply before the motor movement is completed.
You could try appending opOUTPUT_READY to your direct command to see if it will delay the reply.


text:
EV3 Error and VM Program Instruction Break
I'm making a program which is very complex and large but it does not contain any Arrays in it. Weird thing is, last night it worked fine but today when I downloaded the exactly same thing into the EV3 it shows a triangle with exclamation mark symbol with orange status light.
This happens halfway when it tries to run a switch with a Logic Variable. Occasionally I would get a "VM Program Instruction Break". Any idea how can I solve this?

UPDATE: It turns out there was a compiler issue in the EV3 desktop programming software. LEGO has released a fix in v1.2.2 of both the Home and Education versions. Upgrading your software will fix this problem.
Read more about the problem and the fix in this pdf from the Seshan Brothers.

ORIGINAL ANSWER:
Some suggestions from the LEGO MINDSTORMS EV3 Facebook group:

Too many named loops in your code
Too many blocks in a loop
Try to avoid using too many loop interrupts
A problem with the copy/paste - delete the pasted portion of the program and make it from scratch


text:
Color Sensor/hi-tech and EV3
I want to create a line follower by EV3 using hi-tech color sensor without using switch! :( I tried some former ways but the robot cannot follow the line very well!
can anyone guide me?

Can you be more specific about a particular a part of the problem you are facing?

This is from page 87 of a document showing how to run NXT bricks using EV3-G software.

It uses the light sensor, not color sensor.  You'll want to set the mode of the color sensor.
Inside a loop that will stop following a line if the left button on the brick is pressed.
Basically, the steering value of the motors is taken from the light sensor reading.


text:
Any issues with this non-standard gear combination of 12t gears?
I don't see any "accepted" gear ratios for a stud-less direct-diagonal gear combination on sariel's excellent gear coupler

but by shifting 12t gears such that they mesh off-center, it seems to work (i.e. spin correctly)

Any potential issues with this? will they wear down faster? will they not deliver as much torque as normal? is it less efficient than other combinations for those positions?

In your setup, the space between both axles is about 11.31mm (1 stud brick = 8mm).
On the central part of the gear (the band where teeth protude), the pitch diameter is 11.9mm (outer diameter of 13.8mm, root diameter of 10mm). Hence the gears would not mesh if mounted in the same plane (because 11.9 > 11.31).
However, if you consider the beveled part of the gear to be like a smaller spur gear, its outer diameter is about 12mm (possibly smaller) and the root diameter is at most 8mm (more likely 7.9mm). The gears mesh because (12+10)/2 < 11.31 and (13.8+8)/2 < 11.31.
You can check the measures with a caliper.
What might be a problem is that in this setup, gears will be forced to rotate at the same speed while having different pitch diameters depending on the part of the gear, so the gears are likely to wear down faster.
Now, the bevel gears are made of a softer plastic which whistands deformations better than other gears so it might just do.

even with a digital caliper, I am not having much luck measuring sub-millimeters due to the roundness of the surfaces


text:
What's the first block in MoveAbsolute for programming the T-Rex, in The LEGO MINDSTORMS EV3 Laboratory book?
On MoveAbsolute2 and 1 for The LEGO MINDSTORMS EV3 Laboratory book by Daniele Benedettelli, programming the T-Rex, I don't know what the first block is, can i please have help?

Can you post a picture for those of us that don't have the book?

I believe David was asking for a picture of the blocks you're trying to locate, rather than a picture of the book.


text:
need help identifying which set these 3 bags are from

I ended up with three lego bags but need help identifying them.
mostly light grey and dark grey with some blue and burgundy.
The bags say 2011 lego on recycle symbol.
There are two clear half spheres  as well as a plastic ring 4580665

The two black sprocket wheels and the transparent dome from bag 4 suggest that this set is the Malevolence, but many easily identifiable parts are missing. However, your set also seems to miss at least a few bags (numbers 2 and 3), so it is highly probable that you have a partial set.

thanks,could be. I have some random bags but these 3 are all consistent so I assume they go together. the grey and blue and bubble definitely match, if it is the star wars set, would the red ones be on the interior?

Yes, see the first few pages of the instruction manual: http://cache.lego.com/bigdownloads/buildinginstructions/6015581.pdf

You are welcome :) You can also tick the mark by the answer to indicate that it was useful to you, this will show others that this question already has an answer.


text:
What is this snapping brick for / which set is it from?
I've found this DUPLO brick:

The red part can be pushed in and snaps out when the button on the top is pressed:

Any idea which set this is from or what it could be used for?

Looks like the Duplo Car Launcher and according to Bricklink this appears in at least 4 different sets: http://www.bricklink.com/catalogItemIn.asp?P=31080c01&in=S

Aha, interesting.  I could not launch any of our cars with it properly (they go off sideways), but maybe the race cars have the appropriate shape in the back.


text:
Education EV3 Software Site Licence - installation on teachers computers?
WE've recently purchased some mindstorms ev3 education sets plus the site licence of the Software.
in Switzerland many teachers do their preparations at home, so my question is, am I allowed to install the software on a computer at home or a notebook which is not constantly located at the school adress? It's really a Problem for us if that's not possible ...
Thanks for your answer

You can check out
https://education.lego.com/nl-nl/educationdownloads/productpage/?AccessLink=985ff951-4b98-467d-9f16-687487a43784&ignorereferer=true
I think this is were you can find the student version, quite similar to the teachers version.


text:
What are good DUPLO projects for around 2 year olds?
It is always good to have a bunch of (short) building projects to suggest to our toddlers.  Here I would like to collect some easy ones for DUPLO.
I'm not particularly interesting in creating duplicates of real world objects, like building animals, houses, etc.  The projects can be abstract, focus on something unexpected, or whatever.
Please share your experiences.

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

When my kids played with Duplo, they always liked building things as tall as possible, or making patterns of colours (e.g. alternating red/blue bricks in a line), or lots of repeated structures (e.g. putting 4 2x2 squares on top of one 2x2 square to make a mushroom shape).
I would usually try to suggest ways to make things stronger, then let them run with it. So a huge tower might start with me making a wide, flat base to give stability, then letting them organize the rest of it.
Depending on your child's propensity for putting things into their mouths, Lego 2x4 bricks fit well with duplo and can be used to fill in gaps or provide better binding in some cases.

Here's a site with some excelent examples of simple Duplo builds, oriented towards 2-4 year olds: http://legoideas.si/
Hopefully you'll like idea or two!

I make a selection of 2x4 duplo bricks and the window bricks, together with a base plate. Soon a couple of buildings will emerge, giving your kid a great feeling by "doing great stuff by its own!".
Happy building!


text:
Value/Where to sell my old Lego collection
I'm sure you've heard this asked a million times but I have no idea where and for what price I should be selling my old collection for.
Things I do know about what I have:

I'd assume they're "clean" (no dirt or wear, right?)
Weighs right around 85lbs for everything
Contained into two boxes, ~50lbs/~30lbs
A lot of figurines from various places, I'm unsure if they have value.
I have this thing and a train set: Train Switch
Some soccer field like set with parts, balls, and players.
Sets: 3826, 6211, 7621, 4956, 6206, 10176
There's more sets than I know of, those are only the ones I brought out and remembered.

Images of Lego
- the last two images are of RokenBlok, if you knew anywhere I could sell those as well it'd be a lot of help.
Where would you price this? I'm in no rush to sell it, but I'm going off to college so unless it was particular reason to fish a set out, I'd sell in bulk for reasonable prices. If you need any more information please ask.

possible duplicate: http://bricks.stackexchange.com/questions/1578/how-to-sell-massive-vintage-and-unsorted-lego-collection-with-manuals

I would sell it on Bricklink, but if you need alot of money, go on ebay or amazon.

Another possible duplicate: https://bricks.stackexchange.com/q/9716/56

Generally, I see LEGO collections like this sold by the pound.  I don't generally pay more than $8/lb (including shipping, if applicable) on large used lots, because they are rarely 100% clean, like-new condition LEGO bricks.  Most collections include poor quality pieces, as well as many non-LEGO brand and non-LEGO-compatible toys that have somehow been thrown in.
If you guarantee 100% clean, like-new condition LEGO pieces, the price would go up to maybe $12/pound.  However, in my experience, very few collections that have actually been played with will meet this standard.  Play wear isn't terrible, but it's definitely not like-new.
In the US, eBay is a common way to sell.  You might also try Craigslist to avoid the shipping hassle.
Some items are more valuable and are worth selling separately. In particular, train components and licensed minifigures (like Star Wars, Spiderman, Avengers, etc.) are probably worth the time and hassle.  Other minifigures (like town, space, western, etc) I would just include with the bulk lot, as separating those out and selling them individually will be a lot of work for minimal gain.
If you really want top dollar and are willing to put your time time, the best way is to probably start a BrickLink store, and sell all the parts individually.  This might be a great opportunity to start a side business.  It will, however, require you to inventory your entire collection, as well as manage the shipping, customer challenges, etc.
Good luck with selling your collection!

In the past, I have sold my LEGO sets on Craigslist and eBay. I also sold them at a garage sale.
The LEGO had some use tear-and-wear, but they only were Lego, and I cleaned and sorted them into boxes. I sold it at $10 per lbs, but I gave them free shipping, handling, and 1-2 business days.
I used United States Postal Service to ship it to them. I sold 100 lbs in total, and buyers who came back to me got a free pound of Lego pieces.
I used this for disinfecting wipes to clean them and a LEGO 2-Piece Sorting Divider Set for storage.


text:
Making an ATM with an EV3
I am building an ATM using my LEGO Mindstorms EV3, but I  ran across a problem. The problem is that I want to be able to input the amount of money that I want to get out of the ATM but I can only have a maximum of three touch sensors because I'm using the fourth for the ability to have a key so my siblings don't steal money.
How can I can make an ATM with a maximum of three input to decide how many 20s, 10s, 5s, and 1s I want.

The possible solutions involve realizing that you can multiply the number of possible inputs by implementing long clicks, double clicks, click-and-holds, simultaneous clicks, etc. on the buttons. If I were you, I'd also include a Confirm and maybe a Cancel buttons, but the latter can be substituted by a timeout. You could ease your job if you don't handle the separate bills as individual amounts, but set the requested amount of money and write a function that splits an amount into separate bills (e.g. splitting 58 into 2×20, 1×10, 1×5, 3×1).
With these in mind, have a look at these example button mappings:
Solution #1:

Button 1: Increase amount by 1
Button 2: Decrease amount by 1
Button 3: Confirm

Solution #2:

Button 1: Increase amount by 1; Long press: increase amount while being held
Button 2: Decrease amount by 1; Long press: decrease amount while being held
Button 3: Confirm

Solution #3:

Button 1: Add 1
Button 2: Add 5
Buttons 1+2 simultaneously: Add 10
Button 3: Add 20
Buttons 1+2+3 simultaneously: Confirm

Solution #4:

Button 1: Increase amount by 1
Button 2: Cancel
Button 3: Confirm

Of course each approach requires different sub-solutions (as mentioned above, timeouts, detection of long presses and button holds, simultanous presses, etc.). These are up to you, but if you get stuck, feel free to ask :)

Use a Motor as Input
You may be limited by the amount of touch sensors you can use, but you have one very useful form of input that you may not be aware of.
EV3 motors have the ability to provide a value based on rotation in degrees. Adjusting the rotation of the motor by hand, you can input very precise numbers quickly. To rotate the motor easily, attach any Technic wheel/gear to the motor using an axle.

Programming a Basic Dial Input

Create a unlimited loop block, this will ensure the current rotation value is always updated. Place a rotation sensor block, set to measure in degrees.

The rotation sensor is very sensitive, it's almost too sensitive because it makes it very difficult to select a number without jumping to another. I recommend you divide the output from the previous block by any number between 10 to 70 to decrease the sensitivity. (10 being the most sensitive).

The divided numbers are now non-integers, we don't want to be able to take out a fraction of a dollar/pound or whatever currency you are using.
Use the round block to round the divided numbers up to a whole number.

Optional: Add a currency prefix. You can use the text block to add a currency prefix, in this case I used the $ sign. EV3 only excepts the $ currency in text inputs. If you would like to use a different currency you would have to render it as an image.

Display the current amount selected using the display block.
Program Overview

Working Example

Nice MinuteBot base you have there. ;)


text:
What Technic vehicle is this in black and red?

Any help with the set this piece is associated with, would be appreciated.

I did a cross check on sets containing following pieces 'red-42003', 'blue-6632' and 'black-32250'. This looks like the B model for set 8065.

ail, @Joost I synthesized your comments into the answer, hope you don't mind.


text:
Purchase a list of LEGO parts
If I have a list of LEGO parts (exported from LEGO Digital Designer or Bricksmith) is there an easy way to purchase all of the parts either on LEGO's Pick a Brick or on Bricklink?
I know that I can go through the list one by one and order the pieces but I was hoping that there might be some tool where I can upload a list and have all of the parts automatically added to my cart.

Doing this for Pick-a-brick (which sports an antiquated UI) requires some fairly advanced hacking. See this question. It's unfortunate that there is no simple interface for importing composite sets of bricks.

With bricklink you can convert to xml with ie ms Excel

Can you elaborate on your answer by explaining the process or the major steps?


text:
At what voltage do the c1 and c2 lines run at when controlling a lego servo motor?
related: how to control a servo motor from a raspberry pi
The raspberry Pi normally outputs 3.3 V signals from it's pins, however there are logic level converters for interfacing with higher-voltage parts as well, and I am not sure if there was one in use in the linked question or not (yes, I asked it as a comment a while ago - no answer), thus this question
Philo has managed to DIY-control it, but I don't see the details from his site
P.S. If it wasn't clear, I am looking for the level at which the control signal is, not the 9v/7.4v power line runs at

The answer to the question you linked contains the answer you are looking for:

To move in one direction, send a PWM signal (1200 Hz, 0 to 100% duty cycle) on C1 and keep C2 at GND level. As duty cycle varies, servo motor will move along 7 positions on one side. See this video.
To move in the other direction and reach the 7 other positions, send PWM to C2 and keep C1 at ground level.

PWM means Pulse Width Modulation, so you need something capable of generating this signal. The voltage is the same as what you apply to the 9V terminal. Only the pulse width is varied. And GND means "ground" which is another way of saying 0V.
So, to do this with a Raspberry Pi or other microcontroller, you will need a transistor to convert the voltage. There is virtually no load on C1/C2 in this case, so any size of transistor will do the job without risk of overload. See this page for some example circuits.

Not seeing the source for the fact that the PWM signal is 9v, and having the signal voltage at the same level as the motor voltage would be something quite unusual - have you tested it with 9v and it worked? have you looked at the c1/c2 lines under an oscilloscope to verify the voltage levels from a standard lego controller?

Yes, it is unusual and yes I have looked at it with an oscilloscope. On other power functions motors, C1 and C2 are actually used to drive the motor itself and the 9V and GND pins are not used at all. So, of course, C1 and C2 are full battery voltage since they power the motor. The servo motor just takes advantage of this existing mechanism as a means of transmitting a variable signal from the controller to the motor.

The C1 and C2 lines are either connected to the 9V power supply or grounded because they directly drive classic PF motors and are not just used to carry commands. The 9V and GND poles also need to be properly connected because the PF servo will draw power from those.
To drive any LEGO Power Functions motor using a single-board computer (Pi / BeagleBone / Arduino), the easiest way is to use an H-bridge Integrated Circuit, which will safely separate the SBC (3.3V or 5V) from the high-power stuff (9V motors). There are readily-made circuit boards which are easy to interface with an SBC on e.g. dx.com or aliexpress.
Don't drive LEGO PF motors with the output of your SBC directly or you may very well fry it, because motors will draw too much current.
I successfully used this L298N-based circuit board to drive up to 4 PF motors at any speed in both directions with a Beaglebone Black. It can accept 3.3V commands directly but the PWM output from the SBC better be level-shifted to 5V so that the duty cycle is really respected.
You can use something like this to shift the voltage.
The board also features a 5V power source so you can power the SBC from it using only LEGO battery boxes.
This H-brige module accepts 3 inputs per motor:

forward
barckward
enable

forward/backward inputs of the control module can be tied to ON/OFF outputs of the GPIO and the enable input to a PWM output of the GPIO. The duty cycle of the PWM can then be used to control the speed of a classic PF motor, or the angle of a PF servo motor, while forward/backward will control the direction (enabling both will result in braking the motor).
Note that you'll have to be carefull with the outputs of the RPi as those are open-collector outputs, so don't fry your SBC. Arduino and Beaglebone are easier to use.

Thanks for the clarification - I have looked at the level converter boards, but I didn't see any that go all the way up to 9v, 5v or 5.5v seems to be the common stopping point, and I imagine that the servo would still work with mostly drained li-ion batteries (2s ~ 6v or so) - any idea what the lower bound of the input voltage is like?

Level converters are for converting logic levels, not for converting low-current commands to drive a load. That's what H-bridges are for. So the circuit you are looking for is an H-bridge. The L298N I used expects 5V TTL inputs, but the input is considered high from 2.5V on so they can be driven with 3.3V outputs and this normally wouldn't need level converters. However I found that the PWM ouputs of the Beaglebone were not clean, so the amount of time the signal is above 2.5V does not match the required duty cycle, hence the level converters to "clean" the signal.

so I use an H bridge to convert the PWM signal to 9v for the C1/C2 lines for a servo motor?

Yes, you should use an H-bridge so that you don't have to connect the mass of your RPi to the 9V mass, thus avoiding any current surge that could damage your SBC (loads are active components!). The output circuit using a FET in the page linked-to by David Lechner would also work but you would need a more complicated setup to rotate the servo in both directions. An H-bridge (which is just four MOSFETs and diodes) plus logic gates, like what the L298N provides in an IC package, is easier and requires less PWM outputs (the RPi's don't have many). The LEGO IR receiver V2 uses a  DRV8833 from TI.

You can make a level converter that will safely mediate between 9v and 3.3 or 5v using a couple of resistors and a FET - the operation is a bit subtle, as it depends on a peculiar characteristic of typical FETs, but it does work. See sketch - you can buy these as ready made units with four or more level shifters per tiny board, for very little money, from the same kind of suppliers who sell arduinos etc. This design has the added advantage of being bi-directional in a way that works with I2C, too.


text:
Transfer BrickOwl wishlists to BrickLink
Is there an easy/automated way to transfer BrickOwl wish lists to BrickLink? I have wishlists on BO for each incomplete set I own and would like to move them over to see if BL can complete them cheaper.

You can try using rebrickable.com.
Here's a more detailed guide:
http://rebrickable.com/blog/2015/bricklink-brickowl-integration
In case you have an LDD version of the model you wish to build, check out my question here.


text:
Batman Arkham Knight Batmobile Instructions
Where can I find a set of instructions for the Lego Batman Arkham Knight Batmobile?

possible duplicate of Where can I find instruction booklets?

It would only be a duplicate if the OP was asking for instructions for a released set, but as I looked for it, it seemed to be either a fan model or a video game "character", so likely no official instructions exist.

The author of this Ideas project might be able to give you a copy of the instructions for his model.


text:
When was the RCX 2.0 released?
I know that the original RCX was released in 1998 and the NXT was released in 2006, but when was the RCX revision 2.0 released?

According to Brickset and Peeron, it was released in 2001.


text:
Vintage heads still in production?
Are vintage Lego heads with the classic grin still in production?
I am having trouble deciding whether the head-with-grin piece (element ID 9336, called "MINI HEAD NO.1") which is produced today (and available in the Bricks and Pieces online store) is 100% identical to the classic head used in the 70s, 80s and 90s. If not, what's the difference?

Visually I think it looks the same, but it appears that 9336 is not the code used for vintage sets.

Yes, visually the simple smileys are the same now as in the past. The difference is in the stud. Some have a stud like what you have pictured above; with an open stud and others have a solid stud. Other than that, the face itself is exactly the same. You can three all three versions of the stud here (solid, recessed open and recessed blocked) here:  http://www.bricklink.com/catalogList.asp?pg=1&q=standard+grin+pattern&catLike=W&v=2

Just to add to your answer, the smileys tend to be found in the special Creator sets, such as the modular buildings and the winter scenes. Most other themes use more customized heads with different facial expressions or facial hair, etc.

For some reason, I always found the original smiley face more attractive than the custom faces, which are frequently aggressive. As a kid, I never had issues pretending the smiley face to be angry but - as a grown-up - I have a hard time pretending that the aggressive custom faces are friendly.

In my childhood I only had minifigures with the classic smile (due to this I could pinpoint more-or-less the time I entered the dark ages). I think that this is the reason I found ALL customs faces (even the ones from the 90's) a bit strange to me today.


text:
Use for "Technic Coupling, Tight" and "Technic Coupling 3,5-6 Ncm"
Power Functions set 8293 contains these pieces http://brickset.com/sets/containing-part-6025005
http://brickset.com/sets/containing-part-6036892
and they make the set much more expensive than just buying the other parts in the set individually. By that reasoning these parts must be very special, but I can't tell what is different about them from the images compared to a regular gear wheel.

This gear can only handle a certain amount of torque. Above this torque the gear starts to slip internally. This pervents damaging the motor when the some part of the construction after the gear gets blocked.
Lego uses these gears ofter in constructions where there is a end of stroke that blocked the motor from turning, for example a winch or other string based designs


text:
pc program to receive data from EV3 via usb/bluetooth
I'm looking for a library to create a desktop program. It should receive a data from EV3 brick programmed by standard EV3 software.
Currently I consider 2 approaches:
1. EV3 brick sends a bluetooth message, PC receives it.
2. EV3 brick creates a file and writes a data to it, PC reads the file via USB.
It's more convenient for me to use USB because bluetooth is already used to connect to another brick.
I found 2 libraries how to do that, although there are obstacles:

monobrick C++ library - allows to read a file, but doesn't allow to connect to the brick via usb
Microsoft EV3 API - allows to connect to the brick via usb but doesn't allow to read a file

The MonoBrick C++ library that you linked is for NXT, not EV3.
You can find the MonoBrick C# Library for EV3 here. It works with USB, Bluetooth and Wi-Fi and can manipulate files.


text:
How to measure green/blue reflected light on EV3?
As I know there is no way to turn on green/blue reflected light on EV3 color sensor.
Is there a way to do it using NXT color sensor and EV3 controller?
Or the only way is to use NXT controller together with NXT color sensor?

There is a modified Color sensor block available here.
As of this writing, this is the most up-to-date direct link to download the block.


text:
EV3 SPIK3R on Mission 5 just keeps backing up
I completely built the Mindstorms EV3 Spik3r. Missions 1-4 worked fine. However, with mission 5, and using the pre-made program, the robot just keeps backing up, instead of facing the bug, shooting it and then moving towards it. I put the 'bug' right in front (5cm) of the robot, and it backs up. I put the bug a bit further (50cm) in front, and the robot still keeps backing up.
If I hold the bug in my hand and move it to about 5 cm from the sensor, above it (like a 45-degree angle), then the sensor detects the bug, and the robot shoots at it and then tries to crush it. But it seems pretty flaky.
Is there an EV3 program I could download to help me debug this, or at least understand what's going on? Perhaps a program that shows the ultrasonic sensor's reading in real-time on the brick so I can move the bug around and see what the readings are?
What else could I try?

Perhaps a program that shows the ultrasonic sensor's reading in real
  time on the brick so I can move the bug around and see what the
  readings are?

You can easily view the ultrasonic sensors readings in real time. To do so, turn on your EV3 brick, navigate to the 'Brick Apps' tab (second from the right) and launch the 'Port View' application.
Use the EV3 buttons to find the port which your ultrasonic sensor is connected to. The ultrasonic sensor value should be shown.

By "real-time," Jimmy probably means while the program is running, not the opposite. He will need to make a program that shows these statistics and add it to the pre-made mission 5 program.