text:
What are all the different third-party accessories that I can get for an RCX?
What are all the different third-party accessories that I can get for an RCX?

Accessories as in, sensors, motors, gear, books, official, unofficial etc?

Oh, sorry @Ambo100 I've edited the question to fix that.

About 8 to 10 years ago there was more RCX-compatible sensors makers on the web.  Today, I don't think we'll find them unless we dig into the Internet Archive.
It looks like Techno-Stuff is still making some RCX-compatible components.  Also, Mindsensors was making RCX-compatible components also but I couldn't find links to them through their website main page (It might be discontinued).  You can probably still buy some through eBay.  Here are two of their RCX compatible products:

UltraSonic Proximity Detector v2
Motor powered Sharp GP2D12 infrared distance sensor interface

My favorite third party accessory is the Playstation 2 controller interface for the NXT.
http://www.trossenrobotics.com/store/p/5709-Sony-PlayStation-2-Controller-interface-for-NXT.aspx
Also you can check out their entire listing here:
http://www.trossenrobotics.com/store/Search.aspx?searchTerms=nxt&submit=true&type=AND
They have some really great third party accessories that are not that expensive.

Sadly this question was about the RCX brick, the previous generation from the NXT :(


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Can custom content be imported into LEGO Creator?
I was reading this Wikipedia article that states:

Some people have uploaded custom (Lego) model creations for others to
  download into their version of Lego Creator. Tools used include LDraw,
  LegoDigitalDesigner and other LCA model format model software.

Is this possible, and can custom shaped or coloured bricks be imported?

Purely out of curiosity, is there a reason you want to use Creator rather then LDD or something else a bit more modern?

Probably because Creator allows you to interact with models instead of simply view them. Do you know someone that shares lca models?

Normally a statement like that on Wikipedia would require a citation - odd that it's missing... Anyway, digging around elsewhere, the Brick model files had more than just the model data - they had actions, etc. associated with them, so aren't the same format as the LDD elements. http://www.rockraidersunited.org/topic/2944-lego-creator/

Unfortunately, that's not a factual statement.  I contacted the Wikipedia user who added that content, and he informed me that that statement was in error.  You can add custom models, but not directly from LDraw, LDD, or similar tools.

source: Stack Exchange

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

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

sort: votes


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What is the difference between nxtG and nxt 2.0?
I'm familiar with NXT 1.0 and 2.0 but I've also seen reference (program samples, etc.) to NXT G. What's the difference?

NXT-G is the graphical programming software that comes with NXT 1.0 (8527) and 2.0 (8547).

The NXT-G software has been improved for the second version of the set which also comes with a few different bricks (including different tyres) and a different box design.

I seems like NXT-G is version 1.0. According to the Wikipedia article on the Lego Mindstorms NXT:

NXT-G v1.0 is a graphical programming environment that comes bundled with the NXT.

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


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Is it possible to connect an RCX to an iOS device?
I have an RCX and want to know if it's possible to connect it to an iOS device. If this is possible, how do I do it?

The iPhone (2007) and RCX (1998) are a generation apart. I'm not saying it's impossible, but it's unlikely anyone has tried to connect the two devices.

@Ambo100 That's true...

Communication with the RCX Brick was via the Infra Red tower (or IR Remote Control) which connected to the computer with either a serial or USB cable.
As neither iPhone nor iPad have an IR port, there's no way to connect directly between the two.
You might be able to do something with a docked iOs device, but that strikes me as somewhat pointless.

zhaph is right. no way to do it.

There are ipad adaptors for iPad, iPhone.  Some connect to the data port, but others connect to the headphone jack, so are eminiently programmable - you presumably just need audio samples.
Alex

Wow, that is quite impressive.

I guess some of them work like the old universal remotes where it can learn the codes needed by pointing the original at it? Depends how configurable the app is for linking commands together, i.e. motor 1 forward/reverse etc.

You could do it using a computer as an intermediate. Basically, you have a wireless connection between your iPhone and your computer, then the IR link between the computer and the RCX. It would be technically challenging but not impossible. The IR tower uses a serial port and the protocol is detailed here http://legolab.daimi.au.dk/CSaEA/RCX/Manual.dir/RCXManual.html. The connection between the computer and the mobile device could simply be achieved via wireless connection using TCP sockets and wouldn't have to follow any very specific protocol at all. All of this could be achieved with any number of programming languages, but Python and Visual Basic would likely be the easiest. I could help you write the software to do this if you are very determined, but I only have experience with Windows, so the computer itself couldn't be a Mac.


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Why does my NXT colour sensor not recognise colour on my iPhone?
If I point the colour sensor to my iPhone it does not recognise it, but if I point it to a piece of paper, it does.
Does anyone know if there is a solution for this?
I found some documentation online, and saw this video, he's doing pretty much what I want.

if its the iPhone screen it probably has to do with the glare/glossiness of the screen

Yeah that's right

The robot in the video has a custom light sensor, a more advanced HiTechnic color sensor V2 which can detect an extended range of 15 colours. The stand colour sensor can detect six (white, black, red, blue, green and yellow).

The sensors are based on different principles. LEGO sensor uses a RGB
  LED, and successively shines red, green and blue light on the object.
  Reflected light is collected by a light sensor sensitive to all
  wavelength. HiTechnic one has a white LED, and a specialized color
  sensitive chip. This chip has three sensitive areas covered by red,
  green and blue filters. An added advantage of HiTechnic method is that
  it can detect the color of light sent on it (in passive mode, with the
  white LED shut off).

[Source]
A direct LED light against an iPhone's screen will reflect the light back into the sensor, making it difficult for the sensor to detect colour.


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Where do I find Mindstorms building plans?
I have the Mindstorms NXT 1 kit. It includes a printout of the first robot model building plans. The plans for several other robots (e.g. the scorpion bot) are included in the NXT software. However when I run the software, everything works, but it does not display the building instructions, only the programming instructions. Can I download those plans somewhere?

Official building instructions for NXT 1 models can be downloaded here: http://mindstorms.lego.com/en-us/support/buildinginstructions/8527-/T-56.aspx

The above link now forwards to https://www.lego.com/en-us/themes/mindstorms?domainredir=mindstorms.lego.com which is the product page for the EV3.

You can get almost every building instruction directly from lego - just type in the set number.
For 8527 (which seems to be your set) there are 7 downloads available (note: I'm not sure if the ones you're looking for are contained, because I don't know the set - but they should be there).

Thank you. But unfortunately that link only supplies me with the printouts that where contained in the set (seven downloads for seven languages). What I need are those instructions that are only digitally in the NXT software.

too bad, sorry. but i'll leave my answer here for future visitors who might look for this.

This link seems to have the original building instructions, Alpha Rex is confirmed.
http://www.learningfun101.com/2013/02/lego-nxt-instructions/
also try
https://manuall.co.uk/toys/lego/lego-mindstorms/


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Are the older (hollow underneath) brick elements considered "collectable"?
I know. I know. All LEGO elements are collectable. I mean are the older, tubeless bricks valued above and beyond the fact that they are still viable pieces to build with?

Something like this?

Despite being rare, I doubt many people are looking to buy them.

Browsing through the price guides available for the various classic colors of the 1x2 Brick Without Tube part on Bricklink it would appear that the answer is generally yes. The Average US sale price in the last 6 months is about double for the classic 1x2 Brick Without Tube vs the modern 1x2 Brick (with tube) with the exception of Yellow which goes for a bit more then it's modern counterpart.
Avg 6mo Sale Price in US$ for 1x2 Brick Without Tube

Black: US$0.07
Blue: US$0.08
Red: US$0.07
White: US$0.07
Yellow: US$0.08

Avg 6mo Sale Price in US$ for 1x2 Brick (with tube)

Black: US$0.03
Blue: US$0.03
Red: US$0.03
White: US$0.03
Yellow: US$0.02

Do note however that just because a brick does not have tubes doesn't mean that it is absolutely older. The LEGO Group still produces bricks without tubes but generally only in the transparent colors. The transparent colors also tend to become cloudy with time which factors heavily into their price and can be harder to judge from a text listing. It's probably also worth noting that despite the slightly higher prices there are a couple of orders of magnitude fewer sales so older parts may take longer to sell if that is your aim.


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Will my LEGO bricks discolor in indirect sunlight?
I have a bunch of new LEGO sets because of my new status as an AFOL. I've got them sitting on the dresser in a room that gets indirect sunlight (see below). There is no direct rays hitting the LEGO sets. Do I need to worry about discoloration?
Here are some pics of the room:

no. they will not. only megablocks may.

I have to disagree somewhat with the other answer in that I do not think it is quite as cut and dried as a simple "no".
There are several factors to consider:

How old is the glass in the windows in the room?
Older glass tends to be less effective at UV diffusion/blocking though really if the glass has been made in the last 50-70 years it's probably fairly safe for UVA, but not necessarily UVB. UVB does not discolor things as quickly but still has an effect. Part of that as well is how many panes are there. Older and/or less expensive windows tend to have fewer panes while newer and/or more expensive windows tend to have more panes and thus more filtering.
What type of glass is in the windows?
If it's just plain clear glass then there is less protection then mirrored, tinted, or specifically UV filtering glass.
(Possibly most importantly) What is the exposure for the windows in the room?
If the windows in the room get a lot of direct exposure (Southern exposure in the Northern hemisphere/Nothern exposure in the Southern hemisphere) then there will just be more UV coming in and thus more discoloration over time. If the room doesn't have a lot of exposure then there will be less. Your pictures seem to indicate that you might not have a lot of direct exposure, but it's hard to tell and even partial exposure (morning or evening light) can make a difference.
Are there some predominant colors being displayed? Some colors, notably White, seem to discolor more noticeably over time. So if you've got a lot of white on display don't plan on it staying pristine for long if you've got a lot of direct exposure in that room.

That all said if you're really worried about it then run some tests to find out. Make a few small stacks of bricks in a few common colors, for example pairs of 2x4 bricks in White, Red, Bley, and Black. Try and make sure you use parts that are very similar in quality, age, and color at the outset. Then place the stacks in various locations. One on the window sill, one on your chosen display location, and one in a closed and opaque box somewhere away from heat sources. Then check on them every couple of weeks and see what results you get. If you haven't seen an appreciable difference between the stored stack and the one in your display area after a month or two you're probably fine. Comparing them against the one in the window sill might even tell you if you'd be safe closer to the window in that particular room. Adding stacks in other locations would just give you more data points to make determinations.
If you do run the test, I would love to see the results. Latitude would also be useful for calibrating your results with what someone else might expect to some extent. :-)

A friend of mine also mentioned that putting a trans-clear brick into the stack might also be a good idea since they have a slightly different formulation.

I was trying to get a decent photo of my discoloured white clone troopers, that were in indirect sunlight behind modern double glazing - they are noticeably yellower than some of the other pieces. Infant as the discolouring is even across the elements it can't be purely sun damage.

The glass is less than 10 years old and it's east facing

So you're probably double glazed and will block nearly all of the UVA, but kind of hard to say on the UVB and will likely only get direct light in the room in the morning. Could be worse. Depending on your latitude the amount of discoloration you get might be seasonal. The closer to the equator you get the more even seasonally. I still think running the test with the stacks will give you the best indication for actual results. I'm not sure there's an easy way to say otherwise.

What is your point of view on the title question "Will my LEGO bricks discolour in indirect sunlight?"? (emphasise mine). Your answer mostly address the problem of direct sunlight.

It's the same question. Light doesn't quite follow direct paths, so the direct light in a room tells you a lot about what sort of effects you will see in the areas of the room that are not directly lit by that source but are impacted due to reflection and refraction.

@NathanStohlmann Thanks, in fact I was wondering if UVA or UVB rays are reflected, if these invisible rays are stopped while visible light is reflected.

I once built a white piggybank that was standing in a room for several years, also with indirect sunlight. It was discolored to a yellowish color after a couple of years. As @Nathan said, white is more affected (at least more noticable) than other colors. The window in the room had UV filter (although maybe one of the first that came on the marked, so not sure about the quality...).
@Zaph commented that his white bricks are evenly discolored over time anyway, but I am seeing that the piggybank bricks are yellow on the outside, and white on the inside where it's not exposed to light.

I'll have to take a look inside my Troopers...

i have had a big box of legos in my room for about 2-3 years now. they are right near a window which gets the hot after-noon sun. i have seen no discoloring, and have been "legoing" ever since i was in diapers. the only bricks which you should worry about are maybe megablocks. these may dis-color. of course that is just my opinion, and some other people's legos may have dis-colored, but mine have not.
but, this may confuse you, because there is a difference in color between "old" lego bircks and "new" ones. the older ones will have a slightly yellower color than the new ones. this is not because of age, however, it is because Lego has changed the color slightly for the molds.

The main reason for discoloration is the UV-part of sunlight (for everything, not just LEGO). Normal glass filters out a lot (almost all) of this, so even direct light through a window isn't a real problem - and even lesser with indirect light.
At least, a litte bit of bleaching will happen every time, but the only way to avoid that would be to store LEGO in a very dark and cold place, which is... boring.
Conclusion: No, you don't have to worry about discoloration as long as you don't put your LEGO outdoors for a long time (some weeks/months/years).

I've got some white elements that are noticeably discoloured evenly across the element, so while it's not sun damage, some bricks/colours do change with age.

I never said bricks don't change color, sure they will do by aging - but that wasn't the question here and can't be avoided, aging always happens.


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How do I know when current sets will retire?
As the title asks, how is the easiest way to find when current sets on the Lego website will be retired and no longer sold.
For example, the 10197 Fire Brigade has been around since 2009, same as 10193 but both are still selling.  While Ninjago is currently changing and set 2258 suddenly is no longer for sale in the Lego Store at Disneyland and not available online.  Yet that series only came out this year.
So how can I find out when sets are retiring.
(side question: why does lego.com drop items off my wish list without notifying me)

I think the bigger question is why does shop.lego.com remove products from it's index instead of just saying they are not sold anymore. Links at say, technic.lego.com will link to products on shop.lego.com that are not there anymore.

See also the related question: How long are Star Wars exclusives usually in stock for?

The LEGO Shop online website has a page where you can see which sets are marked as 'Retiring Soon'.
 USA - LEGO Shop
 UK - LEGO Shop

I'll take a stab at starting to answer this one, but I'm pretty sure it's going to need some refinement as it goes along since the answer does not appear to be quite consistent across all themes.
In general you can assume that a particular set will only be available for one year after it has been introduced.
The exceptions to that general rule seem to be:

Basic brick sets seem to stay mostly the same from year to year, though occasionally there is a tweak to the price or part assortment for whatever internal reason.
Sets over US$100 appear to stay in production for around two years.

You can find out when a set went into production by checking Peeron, Bricklink, BrickSet, or any number of similar fan databases.

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


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Rebuilding the Millennium Falcon 7965 with unsorted bricks?
After a week of building the Millennium Falcon 7965, we were nearing the end.  My son became excited and literally started jumping for joy.  As a result, he accidentally landed on the model and thus caused major portions of the super-structure to pop out of place.
I attempted to reinsert the bricks but found myself having to gently stretch out a section of the hull in order to snap the brick into place correctly.  Of course this action caused more bricks to pop out.  Of particular difficulty is the 'girdle section' that encircles the outer hull.
Now it seems I have been left with a very expensive pile of gray, dark gray, and yellow Lego bricks and a very fragile super-structure into which they should go.  We threw the bags away, and don't know at which construction stage the various pieces belong to.  Of course we have the manuals.
I was minded to consign the whole project to the rubbish bin, but this would create a heart-broken child...
For those with experience in this sort of thing, what is a recommended strategy?  Are we talking about a reboot from square 1 without the bags as a sequential guide?

I hope 'consigning the whole project to a rubbish bin' was purely metaphorical? I would cringe at the thought of perfectly good LEGO going to waste.

@Ambo100 - That option was originally considered, but met with virulent expostulations from my 7 year old.  I am going to accept your answer and attempt to rebuild it from square 1.

Lego is not a "one time build"-model. It's more like "build and enjoy, and after a wile destroy and use the bricks to build something else of your own imagination and after a while find the instructions of the original set and build it again, this time with the enhanced complexity of finding all the original pieces"-model. I'm afraid you just have to make the best out of it. With a big model like this, I understand your frustration, though - after a long building process...

Only ever throw out LEGO that has sustained actually irreversible damage, bricks that have been bent beyond repair or snapped. It so rarely happens that I can find a suitable picture. In this case, I would assume the longest plates and tiles would be more likely to be damaged.
I'd go through the painful process of dismantling the model and starting again, replacing any broken pieces (if any) or at least starting again from the last significant building stage. Many large models are build independently and combined at a later stage of building. These independent 'building stages' often match a numbered set of plastic bags.

Yes, sorry for the confusion.  The individual pieces are intact.  By 'damaged' I mean that they have become unmoored from the places they were supposed to snap into.  And when you try and snap them into place, other pieces become unmoored.  And in some cases I was not watching where exactly they became unmoored from.  But all of the pieces are still in very new condition.  Does that help clarify?

I will suggest you carefully dismantle sections of the construction so that you can see all the bricks and can recognize the hidden parts against the instructions. Then build up different sections with the aid of the instructions.
If there are larger parts of the construction that are not damaged, you can keep these intact, and just take apart sections that need to be re-built to get the structure stable.
And lastly: NEVER THROW AWAY LEGO BRICKS THAT ARE NOT PHYSICALLY DAMAGED! These are building bricks that can be used to build anything - not just part of a model. The joy of LEGO is the ability to tear down and build something else when you get bored of the original model. Some LEGO sets come with instructions for 3 different models that you can build with the same bricks.

+1 for "NEVER THROW AWAY LEGO BRICKS". If you really want to dispose of LEGO bricks, and you aren't bothered about selling it, at least consider giving them away. And if you're ever struggling to find someone... yes, I will pay the postage. ;-)

In addition to the excellent answers given here, I will add this one, which was learned the painful way and now given in hindsight...
DON'T BUILD A COMPLEX MODEL ON THE FLOOR.
Use a table or other elevated space.  Building it on the floor with an excited child around is just asking for trouble.

If you have a large enough large tray this is even better for later portability, as well as containing the current bags pieces within the lip ;)

The most important is to sort out the technic beams and plates as these really restrict doing any search on smaller pieces.
I have been rebuilding this set with "unsorted" bricks a couple time.
Something that works really well for me is to simply keep the brick sorted in a traditional way, using ziploc bags... (So, I'm suggesting that you first sort your unsorted bricks, then build)
See this post about a proper sort method.


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What is considered the most valuable LEGO set?
Which Lego set is considered to be the most valuable set to own?
I'm not talking about the most expensive set, and clearly it has to be out of production already, but when trying to collect complete sets from LEGO history, there must be one or a group of sets that are prized possessions for collectors.
Which are they?

This question seems to be more likely to be specific to a particular collector then something that would have much of a consensus. For example, Castle fans would probably value the older Castle sets more then the Space sets and a Classic Space fan would probably value the opposite. Heck, I know someone who values the Samsonite sets more then others, but that's his thing and it's interesting to see his collection.

@NathanStohlmann Everyone has their favorite set, but that doesn't mean it's worth a lot in the collector's market.  Some older sets are worth more than others simply because of high demand vs low supply — I'm simply interested in knowing what those sets are.

As a rule of thumb and as can be seen in the various answers, unopened sets will usually fetch a higher price (which makes next to no sense to me, but I'm not much of a collector myself)

On the basis that this question appears to be devolving into a list of people posting their one or two set suggestions, and user23 has sadly moved on, I'm going to turn this into a Community Wiki and merge some of these answers.

I believe it's the Ultimate Collector's Edition Millennium Falcon (10179).
With a $500 MSRP, it was already one of the most expensive sets available when it launched in 2007. In 2012 it is rare to see it for less than $1500 used but intact, and closer to $2000 if you want it new. There may be some smaller sets that have a greater percentage gain (a set that was $2 going to $20, for example), but I suspect at $2000 and a $1000-1500 difference, this is the largest magnitude.

Expensive Star Wars sets in mint condition are generally a good investment. The only non-Star Wars set that comes close would probably be limited edition sets like the  10182 Cafe Corner, 10184 Town Plan and 10189 Taj Mahal.

I thought about the Taj Mahal when writing my answer and looked it up - it's not even close. $300 MSRP and you can still find it for under $1000.

Why oh why did I not put that set on my Christmas list years ago.

This is by far my favorite set that I've got on display.  Also, I agree with the answer.  It's got the highest markuped value.

Cloud city, in 2005 it cost $100. Now for a new set it costs at least $1000

I feel I need to represent the Classic Town and Train fans with the following sets:

6399 Airport Shuttle
Bricklink items for sale

The only town monorail released by Lego and one of only a hand full of monorail sets in total.
As is the case with many classic sets that are hard to find 100% complete, it includes many stickers that easily become lost or worn over the years.
Includes at least one element unique to this set - 2619 Red Monorail Motor Cover

1490 Lego Bank
Bricklink items for sale

Rare limited release set
Many stickers unique to this set and almost impossible to find

7750 Steam Engine with Tender
Bricklink items for sale

Many stickers unique to this set
Red 12v train motor (not unique to this set but VERY expensive as an individual part)
Large train wheels unique to this set

----UPDATE----
In terms of increase in value over original purchase price as a percentage, it may be hard to beat the Collectible Minifigs Series 10 'Mr Gold'.
From the original price of $3 to prices of $500+++ that is a seriously valuable 'set'.

Only 5000 were produced and so completing a series 10 collection is expensive if you were not lucky enough to find one.

7750 was also one I could think of, and indeed the 4 new ones on sale now are priced quite high (which isn't a guarantee they'll sell). By the way, although it's the only set that contained the large train wheels, these were also available as spare parts.

@Joubarc - Thanks, I should have mentioned the spare parts. They are also very expensive considering they are just two sets of wheels per pack.

Upvote because monorail

If you look at what a box is worth compared to the original price, I would say 3724 LEGO Dragon. It went for $99, And now you can not find it for less than $350, up to $800 for a mint in box version.

Hi Dirk, welcome to bricks.se, nice to see you and your expertise here!

There is a website that tracks price changes on Amazon, Bricklink and E-bay in order to try to compile an index. It has an interesting page called top retired sets, ranking sets by gain compared to initial purchase price.
At the time of this writing it lists 6166-1 (a big tub of LEGO) as number one with 65% gain, and 7200-1 (final duel) as number two with 31% gain. The previously mentioned Millenium Falcon is also on the list, with 21% gain. Seems like a good indicator.

I think by actual worth sometime down the road, the most valuable set will be Lego Castle 6075, known to fans as "Yellow Castle".
http://www.classic-castle.com/sets/archives/0375.html

My sister and I saved our pocket money for Yellow Castle. How cool if that prediction comes true. Still have most of the pieces amongst the kilos of lego I hope :-)

Certainly sentimental value, at the moment they are going for around £150-£200, which is probably an order of magnitude more.

http://www.brickset.com/detail/?Set=375-2 has some for sale

Just out of curiosity: is there anything unique about this set on a piece basis?  I never followed the castle series, but it looks like I can duplicate it (mostly) with just the bricks from my collection.  Minus the stickers, of course.

@LarsTech: The biggest issue would be finding pieces in the right color - e.g. yellow Slope Brick 75 2 x 2 x 3 Double Convex was only used in one other set even though the piece is common. On the other hand, nostalgia aside, it would probably look nicer in the modern mixture of grays and red highlights used for Castle sets.

The most valued sets, when not using price as a criterion, will vary from collector to collector, based on their interests.
In my experience doing LEGO Customer Service, collectors of all ages tended to focus on particular themes. While the Ultimate Collector's Edition Millennium Falcon may be the most prized jewel to a Star Wars collector, it may have little to no appeal to an avid Train collector. It was very hard to talk about any themes outside the fan's specific interest. Even then, a Trains person may have interest in the MAERSK ship(not a train, but related), but none in the Hogwart's Express. Another sought-after set is the Grand Carousel, which isn't likely of interest to someone that only collects licensed sets.
For myself, the most prized LEGO toy I could attain is an authentic wooden set from the pre-ABS era. The closest thing I have to it is the 2011 employee-only duck that resembles the pre-building system era wooden duck draw toy the company made (post-yo-yo fad, using the leftover yo-yo halves as wheels).
Other categories of collectors are completionists who may value SDCC Bizarro minifig or a limited UK Sun bag as their most prized possession (similar to the Mr. Gold mentioned before.)
The currently-selected answer is worded to be exclusively about how expensive the item is, which the question specifically requested not be used for this judgment. However, lacking any other criteria, it's not feasible to give a specific answer.

There are now loads of sets which could be considered to be the most valuable. Here is a list of my choices

10179 UCS Millenium Falcon
10182 Cafe Corner
Mr Gold
10196 Grand Carousel
10184 Town Plan
Chrome Gold C3PO (only 100 made)
10189 Taj Mahal
5004590 Bat-Pod (only 1000 worldwide and will surely increase in value tremendously)

This list is only my opinion. Value is very dependent on condition and personal preference. The best way to fully know a products value is to check completed item prices on eBay and current listings on Amazon (not as accurate). Sites like Brickpicker will give you rough prices.

I must say, a very valuable one would be the exclusive Maersk container ship. the original 2004 set (not the 2011 reissue!) is worth a lot of money, considering they only made a handful. other than that, the Unitron Monorail can go for quite a bit MISB (Mint In Sealed Box) nowadays.


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Can we program Nxt2 in C++ under Visual studio 2010?
I'd like to know if it is possible to develop C++ software for NXT2 using Visual Studio 2010 as IDE. I know there are small online projects for NXT but I can't find nothing about NXT2.... Any suggestions would be more than welcomed
about libraries, software and firmware that is required to achieve this goal: C++ and Visual Studio for NXT2.

There is no practical difference between the bricks in the NXT 1.0 and NXT 2.0 sets.

This should be on Stack Overflow, or something.

@muntoo Happy to get your take on this on meta - Are questions about programming NXT on-topic?

I think that all you might need is the Microsoft Robotics Developer Studio. The examples that I could find all refer to C#, VB.Net, or the included VPL languages but there isn't any reason you wouldn't be able to reference the same objects from managed C++.
It does look like there might not be a full set of services for all of the more recent parts judging from some of the comments in one of the examples that I saw, but the author of that article does have a few other notes elsewhere.
After installing and playing around with it a bit myself, I did find a link to the MSDN documentation for using NXT with MRDS that you can look through before you get started. (I wasn't able to give much of it a try yet because I'm out of batteries with my NXT brick.)
Beyond that a Google search for "mrds nxt" found the following likely useful items:

CodeProject example (C#) with a link to a previous article on the same site.
An MSDN tutorial.
A whole slew of examples on CodePlex

There are some answers to this on Stack Overflow: C++ OOP Library for Programming the Lego NXT
NXT++ is the best choice with dual USB/Bluetooth support.
The C++ communication library has more features, but it's Bluetooth-only.


text:
How much does the Luke's Landspeeder (8092) weigh?
I am considering buying Luke's Landspeeder (8092).

However, because I will be traveling soon, I would like to know the set's weight first. LEGO.com doesn't list the weight, only the piece count and size, neither of which are too important to me.
So, including the minifigures if possible, what is the weight of the Luke's Landspeeder set?

I have created the tag [set-information] as it seemed the best for the job. If anyone finds a better tag, feel free to remove mine and add the other!

Thanks, everyone, for all your help! I will be buying the set shortly! :)

Bricklink's set database keeps track of weight and dimensions. The weight listed includes packaging.
Luke's Landspeeder weighs 272 grams.

Quick unit conversion with Google: 272 grams = 9.59451765 ounces.

Accepted this answer, as it is the clearest (and most upvoted).

I just put the box on my balance, and the weight is 275.26 gr.
Yes, I have this in my shop.

Cheers for that Eric :)


text:
Which sets currently contain pneumatic LEGO equipment?
When I was younger my dad bought me 5218-1, a technic-based pneumatics set, which, combined with the old motor system to provide a mini compressor system created quite a bit of entertainment and it got adapted into various other builds, including a sliding pneumatic bank door.

Now, as far as I can tell, the only kit like this nowadays is the Lego Education Pneumatics Add-On Set, 9641-1, which comes in at around £39.99, for 31 pieces.

While I could add this to the Lego Education Simple & Powered Machines Set that's not cheap either, at around £100 for a more reasonable 390 pieces.
Ultimately, is there a list of all the technic (or lego) sets that include pneumatic kits, and, ideally, are any of them still avalible, apart from the ones I've previously listed?

Lego Educattion/Dacta set are usually overpriced

@Ambo100, yeah (from working in education) I kinda gathered.

BrickSet has a list of all Pneumatic Technic Sets as well.

Ooo...cool! I didn't even know that Lego produced pneumatic sets!

In the UK shop, there are currently two sets:
The Unimog U 400 [set:8110] which uses the motorised "compressor" to supply the power (as opposed to the manual sprung pump).

And the Tractor with Log Loader [set:8049] which uses the manual pump:

The other sets that look like they have piston arms (such as [set:8043]) are actually using "linear actuators", which work with an internal screw thread to lift up the piston, powered by Bevel Gears or Universal Joints:

[part:61927c01]
These provide a much finer level of control over the Pneumatic sets, which is probably why they are being used in more and more sets.
The issue with locating the pneumatic sets is that there have been a few subtle changes to the elements over the years, as well as different lengths in various sets, so tracking them reliably isn't easy:
BrickLink search for Pneumatic Pumps

Looking at the manual, that's quite a set. Probably better value than getting the Pnuematics set, the simple and powered machines set and another motor.

(I do mean the Unimog U 400).

@tombull89 I guessed ;)

Linear actuators seem to be cropping up in recent sets as an alternative to pneumatic pumps. It may be that linear actuators have a finer degree of control as well as reliability. I don't know for sure as I don't own any.

@Ambo100 Yep, I certainly remember the frustration with moving a crane arm using the pneumatic controls. The arm wouldn't move until you'd built up sufficient pressure, and then would overshoot the mark.

@Ambo100 From my experience that's exactly what is going on. The LAs provide such fine control that they're pretty spectacular really. Not quite as much fun as the pneumatics though. :-)

so, how do the "linear actuators" work? Does it take rotational input and change that to linear? As for this picture for 8043 Motorised Excavator I can't see how they are powered.

my god, just looked at the build manual for 8043...that's insane and brilliant.

@tombull89 If you take a look with the Zoom feature on the LEGO Shop (http://shop.lego.com/en-GB/Motorized-Excavator-8043) you should be able to see the bevelled gears and universal joints seen here: http://www.doodle.co.uk/UserFiles/Image/BevelGears.png http://www.doodle.co.uk/UserFiles/Image/CabArea.png http://www.doodle.co.uk/UserFiles/Image/UniversalJoint.png

Note that the first image is from the alternative build "Tracked Loader".

Crikey. I didn't think it was such tiny detail. /me adds 8110 and 8043 to "want" list.

@tombull89: This vending machine concept is powered by a home-made linear actuator. The Linear Actuator bricks sold by LEGO are smaller.

The set that had the most pneumatic cylinders was the Lego Technic Backhoe, with something around 10. Unfortunately, this set is discontinued. You can, however, buy it on Bricklink.

It is, by far, the coolest pneumatic Lego set ever released.

That, without a doubt, is pure awesome. I'd hope to see a re-release at some point, maybe even it could be fitted with power functions and automatic compressor...granted it would be expensive but my god it would be an awesome kit.

holy mamma that is one awesome set


text:
How many themes have been released by LEGO?
I would like to know the various themes, current & discontinued, that LEGO has released in brick/element form.

Many bricks/elements are used in multiple themes, do you mean sets?

Any such list would be constantly out of date.

@ Z-BD:I was thinking of general themes. Town/city. Castle. Space. etc. A set count would be gigantic.

@ Joe: As of 1/5/2012

But it's nearly 1/6/2012! Why would I want your old list?

In much the same way we had with the question on categorising bricks, I think this is something better handled by other sites out there:

BrickLink's list of Set Categories, or from their main catalogue page you can see a dropdown with themes listed.
Peeron's Theme Tree starts here, with the core LEGO System themes starting here.
BrickSet also has a list of themes, as well as the Theme Browser which lists the most popular on the page, and the complete set in a dropdown.

Since there should be a concrete answer to this LEGO question, this seems the perfect site to seek the answer.

That's what I thought about the categories one as well, but I was out voted ;)

Thanks! I checked all of your suggested links. I liked Bricksets theme browser best. It is an eye opener. I knew there were more themes than I could bring to mind, but I had no idea there would be so many.

The count hovers right around 90 themes. I would have guessed 50.

@MajorStackings Don't forget that some themes also have sub-themes: http://brickset.com/browse/themes/?theme=Alpha%20Team lists two proper sub themes for Alpha Team, and City has around 13 core sub-themes, like Police, Fire, Space, Trains, etc. which you can see in the right hand column.


text:
What is the male:female ratio of gendered minifigures?
For many years now, Lego has provided more detail on the face and bodies of minifigures. One of the effects of this is that the usually visually gender-neutral minifigures of my childhood (with the rare exception of a sloped piece as a dress) have been replaced by clear male and female faces and body shapes.
But in packing away my Atlantis sets to make room for my wife's new Super Star Destroyer, I've noticed that there's only one woman. And yet, oceanography and marine biology have some of the highest ratios of female graduates and employees in scientific fields, approaching 50%.
So of all the minifigures who are gendered (either explicitly by Lego in character biographies, or via secondary sexual traits like facial hair, or via cultural traits like wearing a dress or lipstick), what's the ratio of male to female minifigures? How does it break down year-over-year, theme-by-theme, and by recommended age group?
(As you might guess, there's an ideological agenda behind this question, and yes it's inspired by the ridiculous new "Lego Friends" line of figures. But what I'm most interested in right now is hard facts.)

If it's any help to your agenda, the first female Minifigure (a nurse) was released two months after the first male Minifigure, both in 1978. The precursor to the minifigure (the ones made out of bricks) also had male and female hair pieces in fairly even ratios (certainly I had about the same amount of both). But purely going by the Minifigures collections, male figures heavily outweigh female ones.

A lot of this is probably down to the market - Boys tend to prefer playing with (and watching) male characters (hence a lot of TV shows with male leads), while girls tend to accept playing/watching with either gender happily. This isn't to say that girls don't prefer to play with female characters, just that they tend to be more accepting of the imbalance. Certainly my sons are disappointed when we open a Minifigure packet and it's a lady in a dress.

Yeah, well, boys need to get over it. Maybe you need to talk to your sons about how not to be sexist.

I do, don't worry, that's also why I ensure we do occasionally pick one out - also they quite like the "action girls" - skaters, surfers, zoo-keeper etc., and that said, they seem to enjoy the Geisha head and hair - it's just the slope/dress they don't really like.

I did a quick check of the released sets in the Freinds theme. There are 23 female figures and one male figure (Peter).

In a rather cheeky way, I refer the honourable gentleman to this question "My daughter loves to play with LEGO sets but she is really wants to play with pink or 'girl' LEGO", while we all do our best to educate our kids some things seem to get ingrained :(

There's worse than lady, there's C3P0

I found this interesting comment by J on a blog post about LEGO female oriented sets.

I did a count of male and female mini-figures by theme in the 2011
releases for which we have visual evidence. The modular house line
always tends to be more balanced so there’s still potential there but
the City theme is particularly bad this year. Here’s the results
(aliens/creatures are excluded except where male-female
differentiation exists:
Alien Abduction: 9 male, 1 female
Atlantis: 7 male, 1 female
Castle: 15 male, 1 female
City: 59 male, 5 female
Collectible Mini-Figures: 37 male, 10 female (omit 1 alien)
Creator: 2 male, 0 female
Dacta: 33 male, 19 female
Duplo: 16 male, 4 female
Harry Potter: 20 male, 3 female
Ninjago: 30 male, 3 female
Pharaoh’s Quest: 9 male, 1 female
Pirates of the Caribbean: 32 male, 4 female
Star Wars: 43 male, 7 female
Trains: 3 male, 0 female
TOTAL SYSTEM: 299 male, 55 female
TOTAL DUPLO: 16 male, 4 female
TOTAL: 315 male, 59 female
That’s greater than a 5:1 ratio and if you remove the Dacta and
Collectible Mini-figure sets from the equation, you get a pathetic 8:1
ratio (245 male, 30 female). I’ll say it again. If Lego wants girls to
take interest in their products, they should make a better effort to
include figures through which girls can identify.

The survey only takes into account 374 minifigures of the last year. It would be interesting to compare this data to minifigures released, 10, 20 and 30 years back to see how the gender ratio has changed.

Collectable Minifigures Series 1-9 & Team GB
I've performed my own test, this time with Collectable Minifigures.
(Feel free to correct me on any of the ambiguous minifigures.)

Series 1: 10 male, 2 female, 4 ambiguous (Tribal Hunter, Circus
Clown, Robot, Demolition Dummy)
Series 2: 12 males, 3 females, 1 ambiguous (Mime)
Series 3: 11 male, 3 female, 2 ambiguous (Mummy, Space Alien)
Series 4: 13 male, 3 female
Series 5: 11 male, 4 female, 1 ambiguous (Small Clown)
Series 6: 9 male, 5 female, 2 ambiguous (Classic Alien, Clockwork
Robot)
Series 7: 11 male, 5 female
Series 8: 10 male, 5 female, 1 ambiguous (Evil Robot)
Series 9: 10 male, 5 female, 1 ambiguous (Battle Mech)
Team GB: 6 male, 3 female
TOTAL: 91 male, 30 female, 11 ambiguous
The ratio can roughly be simplified as 9:3:1 (m/f/a)

Download .CSV [?]
Collectable Minifigures REVISITED (December 2014)
All the genders of ambiguous minifigures have been confirmed using the gender pronouns used on the official LEGO Minifigure minisite character page.

Series 1: 14 male, 2 female
Series 2: 13 males, 3 females
Series 3: 11 male, 3 female, 2 ambiguous (Mummy, Space Alien)
Series 4: 13 male, 3 female
Series 5: 12 male, 4 female
Series 6: 11 male, 5 female
Series 7: 11 male, 5 female
Series 8: 10 male, 5 female, 1 ambiguous (Evil Robot)
Series 9: 10 male, 5 female, 1 ambiguous (Battle Mech)
Series 10: 11 male, 5 female
Series 11: 10 male, 5 female,  ambiguous (Evil Mech)
Series 12: 11 male, 5 female
Team GB: 6 male, 3 female
The Simpsons: 13 male, 3 female
The LEGO Movie: 10 male, 6 female
TOTAL: 166 male, 22 female, 5 ambiguous

The share of unique female Collectable Minifigure from the main series have improved from 1/8 in Series 1 up to ~1/3 in Series 12. Collectable Minifigure that are not part of the standard series (Team GB, The Simpsons and The LEGO Movie) tend to vary.
Download .CSV [?]

Yikes! The 12:1 ratio for City, which Lego has 100% creative control over and could easy just put in more women, is probably the most surprising/depressing.  This is very close to what I'm looking for - I'll leave the question open for a few days in case anyone can pull up good historical data, but otherwise this is a great answer.

I did notice the Horizon Express set has exactly 50:50 ratio, including a female driver. Which is a start.

My guess would be that only LEGO has the answer, and I'm sure they'd never tell. But for what it's worth, looking at the BrickLink.com stock, I came up with a ratio of 4:2:1 for  male:neutral:female heads.
I looked at heads because I feel like many figs aren't so cut-and-dried with respect to gender (or could be considered both/either), while it's pretty clear with heads where you stand. This doesn't take into account multiple copies of the same fig in sets, but it does take into account older minifig designs, which had a tendency to be less gender specific.
Anyway, in case anyone's interested, here's a post with more details on my findings, including my sources and methods, as well as further musings on the gender-LEGO issue:

This ratio has improved significantly in recent years, moving from 10% female mini figures in 2011. In 2017, almost 40% of figures in the City and Creative Expert ranges display female traits.
While there are many female figures in LEGO Friends, If you don't count duplicate character names,  there were around 38% male characters in 2017
A review of 2011-2016 can be found here
A summary of 2017 can be found here

Based on this great info-graphic data, the male to female ratio is at 18:1


text:
How do you store your built models for long-term display?
My wife and I recently started to re-enjoy Lego and had a lot of fun building the Grand Emporium and a few other pieces but now they're collecting dust and we're lucky enough to have a few spare rooms about the place to keep them in.
What sort of thing do you guys use to cover your built models?
I've found one company that's local that'll make custom clear-plastic covers (well five-sided boxes really) but they're a little expensive, just thought I'd ask the experts!

This may sound odd, have you considered using an upside-down fish tank? I've actually seen this used in the past after the former occupant died. It was only a smaller model on a baseplate, but the width of the glass for the tank managed to fit inbetween the studs on the baseplate and worked quite well. Granted, stacking them could produce an issue, and you might want to try plastic tanks instead of glass ones but depending on the size they might start quite cheap.
Something like this (but upside-down, and not containing fish):

Image from http://www.flickr.com/photos/nigelguy/4208026780/in/pool-lego/

I love that, can't believe I've never seen something like it before.

@Chopper3 - Something similar came up in this question: http://bricks.stackexchange.com/questions/568/are-lego-elements-safe-to-use-in-an-aquarium-with-fish

You can pick up used ones a lot cheaper on Craigslist than you would pay for custom made display cases. While not suitable for every model, they do provide a dust free enviroment when placed on a flat surface.

Isn't that, like, overkill-level heavy?

I don't keep my Lego under glass, but the IKEA DETOLF glass cabinet is the go-to shelf for 1/6 scale figurine collectors and I can't imagine it'd be any different for Lego.

They are 43x37cm, 1.6 meters high (16"x14" and just over 5 feet). All four sides are enclosed with glass (though there are small gaps at the corners), and they give a 360° view of the contents. At ~$65 they are one of the cheapest ways to get that much tempered glass, and since it's IKEA it's easy to get as many as you need, and easy to get more matching ones later.
LEGO's official dimensions for the Emporium are 25x25cm, so it should easily fit.

Thanks for that, very interesting - though in this case I want to keep a bunch of 'town' models connected as a street, but thanks anyway.

I have the same model from IKEA for displaying models and the small gaps allow a lot of dust to get into the models. The advantages having this particular display cabinet is that it can clearly display models and it's relatively cheap.

@Ambo: There's a lot of guides on the Internet for putting in rubber stoppers or otherwise blocking the corners of detolf cases.

@JoeWreschnig: Thanks, I'll have a look into that. I've found one example here.

@Chopper3: If you need something wide you could take a look at IKEA's KLINGSBO line, but the price goes up quickly and personally I don't like the style as much. I think you also may need to take out the middle shelf to have the Emporium fit. Hopefully someone else has a better suggestion.

Whatever you do, keep in consideration light will discolor your bricks put in display. I had a little A-Wing model standing on a computer for a couple year and surfaces exposed to sun light discolored.  The exposure doesn't need to be direct.
see this article about the topic

I think some fishtanks may be UV-protected or have treated glass...which might be a added bonus of the fishtank idea. Not massively effective, but better than nothing.


text:
Are the LEGO Friends Mini-dolls compatible with Minifigures?
I've seen the new LEGO Friends sets, and wanted to know if the Mini-dolls are compatible in any way with minifigs?
I'd quite like to get some sets for the new colours however I want to ensure the accessories, etc. in the set aren't going to be out of scale.

Just curious, are they actually called  'minidolls' by LEGO? I do know that hairpieces are interchangeable and the neck of a Freinds figure can fit in the 'claws' of a traditional minifig.

Yes. http://aboutus.lego.com/en-US/PressRoom/CorporateNews/article/382374.aspx - "Introducing the LEGO mini-doll figure"

Possibly with a hyphen: http://shop.lego.com/en-GB/Stephanie-s-Outdoor-Bakery-3930 "Includes Stephanie mini-doll figure"

In some ways but not others, according to this post by Catsy at The Brothers Brick:

It was near-impossible to pull the legs off–I sawed through them where they join above the knees.
The tab that connects the waist to the torso is completely incompatible with any standard System connection I’ve tried.
The hands are not angled forward the way a minifig’s are–so accessories with a pronounced rake to them may not look as expected.
The lack of wrist articulation is extremely limiting in terms of how you can pose them with accessories.
The stud connection point on the feet is in the front, under the doll’s center of gravity and more or less directly under the body. The feet are slightly oblong.
The legs have a very slight backward sweep on the way down, which you can see most clearly on the right leg above. The upshot of this is that it is impossible for a mini-doll to stand on any 1×2 area that has anything immediately behind them.
The neck is a standard 3mm bar connection rather than stud-width like a minifig neck–the heads are incompatible with minifig torsos.
The head is approximately the same dimensions at the top as a minifig head, but tapers towards the chin in a roughly egg-like way.
The nose causes complications with some fully-enclosed headwear, but not most. The chin extends lower than a minifig’s chin, so that headwear with “chin straps” obscures the mouth.
The hair is interchangeable with minifigs–and many TLC minifig hairpieces look quite good on the girls... it is made out of the same kind of soft plastic as the Exo-Force hair, and has tiny holes on the top and side of the hairpiece that go all the way through, allowing the attachment of hair accessories.
Brickarms helmets work extremely well and look great. I do NOT recommend trying to use aftermarket hairpieces, however–I tried putting a third-party hairpiece on one of them and had to use pliers to get the head back out.

Note also that the legs do not move independently of each other - both left and right legs are on the same hinge. Not really a compatibility issue, but it greatly restricts the poses available without modification.
From the official press pack:

Cheers Joe, exactly the sort of info I was after :)

The other answers speak well about technical compatibility. With the release of The LEGO Movie 2 film and its associated LEGO sets, we have official confirmation that Minifigs and Minidolls are supposed to be able to exist and interact in the same universe. For example, see set 70830, Sweet Mayhem's Systar Starship:

We see a Minidoll Sweet Mayhem alongside Minifigs of Lucy and Emmet.

It is mentioned in the previous answer that the feet are slightly oblong.  I snapped a few photos to illustrate how this impacts the level of compatibility between the two figure types.
A standard minifigure will easily be able to 'stand' within a 1 x 2 space.  In most cases, this applies to a 'Friend' as well, unless the 1 x 2 space is recessed.  The oblong feet make it impossible for the 'Friend' to be used in this way.


text:
What are all the third party (unofficial) accessories I can get for an NXT
Similar to this question but I'd like to know about 3rd Party/aftermarket options instead please.
I've heard about motor multiplexers and the like but are there others, i.e. more sensitive colour detectors etc.?

There are MANY companies that offer third party stuff for NXT:

Mindsensors, already mentionned in pcantin's answer

Vision Subsystem - Capable of tracking up to 8 coloured objects
Touch Panel
Numeric Pad
IR Obstacle Detector
Sony PS2 Controller Interface
Line Sensor Array
Accelerometer
Realtime Clock
Power Meter
IR Distance Sensors (Long/mid/short range)
Multiplexers for motors and sensors
Linear Actuators

HiTechnic

LEGO Certified Products, listed in the official answer.

Dexter Industries

Wifi Sensor - a wifi connection for the NXT
Inertial Motion Sensor - Acceleration, tilt and angular velocity
Thermal IR Sensor - Reads surface temperatures
Digi XBee Radio - Long distance radio communications
GPS
Solar panels

Actuonix Motion Devices Inc.

Linear Actuators

Rotacaster

Omni Directional Wheels

Microinfinity

Inertial Motion Sensor - Acceleration, tilt, angular velocity and tracks relative position

Codatex

RFID Sensor and transponders

Nullspace

IO Expansion

Vernier

Sensor Adapter - Allows access to over 30 Vernier sensors

Generation Robots

POB-Bridge - Allows access to the POB sensors and accessories
Reseller of other sensors mentioned above

Trossen Robotics

Reseller of other sensors mentioned above

... and I'm pretty sure I forget several!

Firgelli Technologies as mentioned above, no longer exists. They have changed their name to Actuonix Motion Devices. They still sell the linear actuators for lego.

You should add Pixy too, even though it's overpriced.

There's lots of third party SENSORS to attach (see very helpful list from Philo), but I found it hard to find any info on third party MOTORS to connect to EV3. Pretty much only the mindsensors.com extensions to connect RC servos and position encoding adapters to slap on power function lego motors. So I took to the LEGO hardware documentation and put together a small info page on how to connect a small third-party DC motor (sensored) to control it from the EV3 brick.
It's all here: http://www.biasedlogic.com/index.php/running-third-party-motor-with-your-mindstorms-ev3-nxt/
comments and feedback welcome
In short: the EV3 can power a dc motor up to about 500mA (full load) directly, provided the motor is equipped with a 5V-compatible encoder (many cheap motors are available with magnetic/Hall effect encoder wheels). It does not have to be an optical encoder like the original LEGO motors have, a simple magnetic wheel with hall sensors can do just as good a job.
Marek

Thanks Marek, that's very helpful to have :)

In addition to these helpful answers, I'd like to add that the reason there are so many 3rd party devices and options is because the NXT supports an incredibly wide variety of electronic and data protocols.
The NXT can directly interact with sensors over:
 - Bluetooth SPP
 - RS-485 (only on Port 4)
 - I2C
 - Analog
So pretty much any robotics/hobbyist device that uses one of these methods can be interfaced with the NXT. See the NXT Hardware Developer Kit for technical details and specifications. Note that in order to use many of these devices you'll have to use a 3rd-party firmware solution as well, such as NXC or LeJOS.

The thing is, both nxt and ev3 have bus connections on sensor ports only. So all motor interfaces that need these, occupy at least one sensor port, of which there are not so many...

@MarekLewandowski That may be true, but the most common interface is I2C, which natively supports addressing. You can attach MANY I2C devices on a single sensor port just by assigning them each different addresses.

True! On the other hand it's important to remember, that both ev3 and nxt see a motor as a rotary sensor too, which might seem not so important until you realize, that in that configuration the actual motor part of the'motor' is not necessary and may even not exist. So you have a native support for up to four (ev3) or three (nxt) incremental encoders (rotary or linear, as position sensors or just user interface knobs). It's expanding on i2c option, not competing with it


text:
What set is this brown (wall?) element from?
While sorting out some old Lego finds, I stumbled across this piece:

I have absolutely no idea what this element could be for other than some kind of wall part, and even then I have never seen anything like it before. It is the same colour as some "wooden" elements I have,but I honestly have no clue.
Any information about the piece and any set(s) it was present in would be great.

It's a Swivelling Door element, allowing for Skeletons to "pop out" and scare the knights ;) You can see a similar element in use here: http://www.peeron.com/scans/9376-1/7/

@Zhaph-BenDuguid Yes I now see that, very cool. But sadly, I can't seem to find the door-frame to make this work. :(

Keep rummaging, it might be in there :)

It looks like this piece; Door 2 x 5 x 5 Swivel, Flat Base.

In this case it was part of LEGO Set 6089, Stone Tower Bridge.

Thanks, that should be the piece and, from looking at other pieces that were mixed with it (that I thought totally unrelated), it definitely looks like that was the set it came from.

This piece has also been used recently, in some of the Harry Potter sets.
Here, in the gaudily-coloured "Gryffindor" Set (4722-1) with the portrait of the Fat Lady.

And also here, in "The Final Challenge", (4702-1) where it appears as The Mirror of Erised.


text:
How do I build a curved wall?
On my latest MOC I want to build a round tower.
This is a minifig-scale build, and the tower is going to have a diameter of about 20/30 studs.
How should I go about building the "curved" wall of the tower?

There are many ways to make a curved wall. The smallest full circle shaped wall can be made using 84 1x2 Bricks. For this scale you may require 1x1 cylinders/cones or hinges.

That looks a bit stressful ;)

Inspired by Zhaph's wall, this one is made with 1x3 bricks.  It has a radius of 12 studs (24 studs diameter).

It is connected to the base by the last two studs on each end of the arc. The middle of the wall rests on tiles.  To complete the tower you can repeat this module 4 times and use 1x2 bricks to connect them (replacing the 1x1 end bricks).
This would not make a perfectly round wall, but it's pretty close.

Fantastic, cheers :)

If you make a wall out of 1 x 2 bricks, where each layer overlaps by a 1-stud offset, and make the wall long enough, you can bend it into a smooth curve because of the manufacturing tolerance between Lego bricks.

By Eggy Pop from MOC Pages
This particular wall uses rings of 84 bricks.

Cheers, that's a bit wider than I was looking for I think, and sounds a bit stressful for some of my older bricks.

I also want to make a castle tower (round) with 1x2 bricks, but how do you attach it to a baseplate or attach some sort of platform on top of it, to allow turrets and minifigs?

I wonder if you can have a smaller radius with 1x2 log bricks instead. The look might be great in any case.

I managed to put together the following set-up for the beginnings of a slightly narrower tower:

This gives me a radius of about 7 studs if I go as tight as I can, giving a diameter of about 14/15 studs. I would have used [part:3062b] but I'm not that organised (yet), so went with [part:4589:378] instead.
I'll have to see what I can do with 1x3's and cylinders to get closer to 20-30 studs.

There are dozens of photos on brickshelf of similar builds, and lots of techniques that fans have used. You can either look in the "recent" list or use the search field to find what you're looking for. You'll have to collect pictures from shows and wip builds to source your preference to what resources you have at hand but there a lot of pictures for future reference. I've learned more in five months of looking at that site than in ten years of experimenting at home!


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Can an axle be removed from this Technic 'brick paradox'?
This blogpost on Technic Bricks briefly explains a few 'brick paradoxes' or dead ends. This particular model seems impossible to disassemble by hand:

How can I remove the axle without damaging/destroying the bricks?

There goes my "what's your smallest impossible-to-disassemble construction" question...

This is kind of a hacky answer, so I am posting it as a comment instead.  Get some glue, such as hot glue or craft glue.  Apply a tiny amount to the end of a match, and then press that against the red axle.  Repeat with the other side and leave to dry overnight.  The next morning, use the matches (which have been glued onto the axles) to pull the axles out.  Remove the glue by snapping it off of the axles.  This only works if you use a glue that is not designed to work with plastic; that ensures that it will stick but come off relatively easily.

Is there an axle in the other end too?  If not a sewing needle can be used to push the axle out from the other side.

I reproduced the problem and got the axle out using a sculpting tool (similar to an awl). It's a sharp point made of hard metal. (Soft metal will actually bend, believe me, I tried three tools.)
I inserted the point in the space left by the axle groove and pried the axle out. The point of the tool was against the axle while the body of the tool was pushing against the beam's rim. I made a short video to explain.
After looking at the pieces, I saw that it did however leave some damages to both pieces. On the axle it is barely noticeable, While the rim of of the beam has some little notches.  Because of these small damages, it's not something I would do on a regular basis.  On the other hand, both pieces are totally usable after the 'operation'.

Science. It works. Thanks for sacrificing your bricks for this, wish I could + a few more :)

I was thinking a toothpick wouldn't damage the bricks but be too brittle.

how about the tip of a mechanical pencil with the lead retracted?

@craigmoliver That would probably break/bend the tip. Try it! :)

Remember that (at least the newer) axle joiners have holes in the middle, so once you have one out you can use a long tin object to push the other out. I'm wondering if you could use the notch in the 2m axles to do this without damaging it?
I do not remember how I got it out myself when I experienced this paradox myself though. (I was like: hmm, if you do this you shouldn't be able to get it out... Oh snap...)

@pcantin Not the 0.7mm BIC Pencils, they've hooked me up plenty of times. http://www.amazon.com/BIC-Mechanical-Pencil-Medium-Pencils/dp/B00260X7F2

A pair of needle nose pliers might just do the trick, or some sturdy tweezers - however it might leave some scratches on the axle (thus limiting the no-damaging).
I assume there's another 2 axle in the other side stopping the use of a wooden toothpick or similar pushing it through from the other end? The joiner has an inner lip, but is hollow if I recall correctly?

One option that may minimize damage to the axle would be to find a mini chuck (left) or micro chuck (right) (i.e. a very small chuck, like a pin chuck) with 4 collet prongs that stick out far enough from the nose cap and are small enough to insert between the rim of the hole and the axle:

Then you could tighten it down so the 4 prongs grip the cross shape of the axle tightly enough to pull it out. The match between the 4 prongs of the chuck and the cross shape of the axle will hopefully distribute the gripping pressure in a way that keeps the axle piece from being damaged.

I once got myself into a situation much like this.
What I did was unfold a paperclip and insert the end of it into one of the four corners of open space of the hole that one of the axles was in. Then, I pulled the part of the paper clip out in such a way as to make the most friction between the paper clip and the axle, causing the axle to slide out a bit. I kept repeating this process until the axle slid far out enough for me to get a grip on it and pluck it out.
The tricky part was not pushing the axle back in when I was pushing the part of the paper clip in for another pull. I had to cause as little friction as possible when pushing the unfolded paperclip in, and cause as much friction as possible when pulling it back out so that the axle would come out with it.
This technique may be longer and more tedious than the others, but it uses an item that's almost certain to be lying around your house, and in the end it got the pieces apart without damaging them in the slightest.

I had a model using parts 18947 and 18948 built into a mechanism as shown on this page: http://www.newelementary.com/2015/01/lego-technic-new-parts.html (look for the picture on the right that says "NEW"). Unfortunately, someone had replaced the longer axle I had for driving on both sides with 3L axles. Using a pair of paper clips on opposite spaces on one of the 3L axles and applying pressure inward, I was able to pull it out and disassemble the model.

This answer will only work if there's enough of the notch in the size 2 axle available.
Use a piece of strong string (like dental floss), and tie a small slipknot in one end.
Using some other tool, such as a bent paperclip, push the lasso into the brick's hole down to the notch.
Using that tool, keep pressure on the knot area while you pull the slipknot tight. You don't want your pull to pull the string out.
If you successfully lasso the axle, you then be able to give it a straight tug out.
This should cause no damage to any parts.

I have a small pair of bent-nose needle-nose pliers in with my Lego and use them quite often, generally without damaging anything.

That picture is a 150mm set, mine are a "miniature" 80mm set designed for electronics work. One key feature is that the ends of the jaws have little teeth, so they get positive grip on really tiny things. Of course, if you squeeze too hard you will mark plastic Lego pieces, but the bent nose helps as the jaws flex a little. I found bent nose works better than straight nose as I also use them to rescue small parts from inside big models. For that a long-handle set of pliers is also helpful, but those normally live in my electronics tool kits.
For the above puzzle, note that you should grab one side of the + axle, not the diagonal - the latter means all your force is going onto the edges of the plier tips and you will mark/damage the Lego.
(Echoing Zhaph - Ben Duguid above, but I actually do this rather than theorising about it, plus I wanted to include an image)


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Minifig rotatable legs on a stick - what is this?

What kind of piece is this? Emboss says "(c)2003 The LEGO Group" and there is a 4303 number below. I browsed Peeron a little but didn't find anything similar.
There are two red handles, one rotates minifig legs back and forth, second one make it straight.
EDIT: fixed part number, it is 4303, small chance for 1303 with overburned 1

For me the same piece reads 6423, very weird lol. It looks exactly like yours.

The part in question shows up as a "Minifig Gravity Stunt Handle" (part number x817) on Peeron and a "Turntable Spinning with Sports Trick Handle" (item number bb128) on BrickLink. Looks like it appears in two sets:

Snowboard Super Pipe:

Skateboard Vert Park Challenge:

Thanks! It was in fact sport-related. I've personally never seen this sets, neither live nor in catalog.

More from Gravity Games series

@tomash: Are you saying you found this part in a different set? I haven't yet been able to find any other set besides the two above that had a part like this.

I remember both these sets, but I think I'd rather forget them.

@gnovice - I found this part in bag of second-hand bricks, so there was no clue about origin set

It's a "Turntable Spinning with Sports Trick Handle 2 x 24 x 4 1/3". I found that on BrickLink via browsing by colour, since there aren't a lot of tan parts and most of the categories are obviously not applicable (it's not a tile, for example). That page also lists the sets it came in (two of them), but none of the pictures show that part. But once you have the set number an image search turns up shots like these:

I looked it up because I've actually seen one of these in a pile of Lego and wondered what it was, and how it was originally used. It seems like a peculiarly useless part, and I couldn't come up with a use for it that made any sense.

It's for actively playing with the set, after it's built. It works best if you know how to make that particular board-on-snow scraping/swooshing sound.


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Of what fell beast did this olive drab carcass come?
I think I have assembled the remains of some dread creature:

I'm pretty sure that I wouldn't have enough elements to reassemble this, but I would at least like to know what it looked like in it's prime.

The snake from Harry Potter had some of those pieces, too.

@LarsTech Yes I actually did come across some Harry Potter tail pieces in my own(largely unsuccessful) searching.

It looks like you have SandGreen parts from probably two different sets...
The dinosaur head (x158), 2 tail sections (40396 and 40379), 2 sloped pieces (3039), and black Technic brick (3700) are likely the remains of a Baby Ankylosaurus/Young Ankylosaurus:

The wedge plate (2419) and curved brick (6091) are likely parts from a Red Planet Cruiser (also in the Alien Discovery set):

The actual theme was called Life on Mars. I have both sets.

Yes these should be the sets. I'm very surprised to find that I do in, in fact have most of the pieces of the Ankylosaurus. I shall bring it back to life!

@RedriderX: Just be sure not to fill in any missing pieces with frog pieces when you revive it. Jurassic Park shows us it could have unintended consequences. ;)


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Are all the Magnet minifigs now glued on and how should I remove them?
A couple of years ago (around 2010 I think), I bought a number of the Star Wars magnet sets, as they looked like a (slightly) economical way of buying a number of specialist characters (including the likes of Admiral Ackbar) without having to purchase the full (and often very expensive) sets:

However when I purchased the LEGO City Burglars Magnet Set in 2011 I was rather disappointed to discover that the legs were glued to the studs on the magnet block (but the accessories aren't glued on, etc.) - is this now standard across the range?

I was able to remove the legs from the stand with a knife, but haven't yet managed to remove the remnants of the studs from the legs - how should I go about this if this is a standard feature?

All new magnet sets introduced by LEGO will have the figures glued, as will any re-makes of existing sets.
History
In 2009 LEGO started producing sets of minifigures standing on magnetic bricks. At that time, the figures were removable, although some felt that they were of lower quality than the figs in regular LEGO sets.
In early 2011, however, LEGO started to produce Star Wars magnet sets where the minifigures were glued to the magnet. The problem was that LEGO Star Wars magnet sets violated a licensing agreement which said that LEGO could produce sets that contained Star Wars characters, but that they couldn't produce stand-alone figures. Apparently, one of the other big-name toy brands who was licensed to produce stand-alone figures objected to the LEGO magnet products because they felt that the availability of LEGO Star Wars figures on magnets harmed their own sales figures. LEGO recognised that fans would be unhappy, but felt that it was in everyone's best interests to comply with requests to change their products.
To promote "a consistent consumer experience", all new LEGO minifigure magnet sets have had the minifigures permanently fixed on the magnet since that time, including the Pharaoh’s Quest sets launched the previous December.
This means that:

All sets that are new since January 2011 are glued.
Some sets that existed before January 2011 come in two versions - a glued version and a non-glued version. Confusingly, the sets have the same number and have been sold from LEGO shops simultaneously, and have similar packaging. Glued sets do have a note on the back saying that they are glued (in rather small print).
Any re-releases will be glued.
It might still be possible to buy non-glued sets. In December 2011 I was still able to buy certain non-glued sets from the online LEGO store in the UK. I assume that they were old stock.
Some parts are never glued - typically accessories like light sabres.

Some details for specific sets are available on TheBrickBlogger.com.
Incidentally, it is widely believed that one of the reasons that LEGO introduced the "Battle Packs" is to provide a way to buy minifigures that gets around the licensing issues.
Removing Minifigures
The most effective way to remove minifigures from the magnets is the "hot water process".
It turns out that LEGO does not actually "glue" the bricks, but uses a solvent that loosens the surface of the ABS plastic and allows the molecules to combine. The solvents are water soluble at certain temperatures, so hot water can weaken the seal between the bricks. Care must be taken not to overheat the water, however, as the melting point of ABS plastic is somewhat below boiling point.
Although the removal process does no damage to the LEGO, the places where the bricks were fused won't be smooth due to the fusion process itself.
Again, more details are to be found at TheBrickBlogger.com.
Disclaimer: I have not tried this myself.
Obtaining Minifigures
All this leaves us with several options for obtaining the minifigures we want:

Buy the sets that contain them (or figures that others have removed these sets). Battle packs and (for Star Wars) Advent Calendars are a good place to start.
Obtain old magnet sets that are not glued
Accept the rough edges left by the hot water method
Use parts from a combination of the above.

Response
The other thing we need to decide is how we respond to this change. My suggestions are:

Be happy that some sets were produced unglued.
Encourage LEGO to produce more battle packs by buying existing ones.
STOP buying the glued sets, and make LEGO aware that we don't like them.
Lobby LEGO to produce unglued magnet sets where licence restrictions don't exist.
Encourage LEGO to make statements about gluing more prominent on the glued sets.

That is wonderfully thorough, many thanks Kramii :)

Also: yes buying more battle packs/small sets is a good way forward, however TLG need to produce more variety so I can bick up these odd characters. Seriously though, I'm not going to not buy a Hasbro version of Ackbar (even in the "Vintage Collection") because I can get a LEGO one, I'm just not collecting the Hasbro figures any more - they won't fit with my LEGO sets ;)

@Zhaph-BenDuguid: I quite agree with you regarding the Hasbro figures. Unfortunately, TLG's hands are tied in that respect :-(.

Excellent and complete answer.

I thought that the elements were glued to the studs and therefore tried using acetone to dissolve the bond of the glue, this didn't work at all and now I know why. Thanks for the info on the ABS bond process TLG used

As usual, the answer is "corporate a*****ry"

Just put them in boiling hot water and leave them for 5 minutes then take them out, straiten the torso and it should come off. If it doesn't come off then get a knife and wobble it a bit and there will be no studs in the legs and you can take the whole body apart - I have successfully used this method.

One way to remove them would be to carefully drill out the studs.
You would need to put the legs in a vise of some sort (covering the metal jaws with something that won't damage the plastic) and use a drill bit just slightly smaller than the studs.  You would probably then need to cut out the remnants of the studs and glue, or at least cut out enough so a stud will fit in the legs again.
Another possibility is to just replace the legs.  It looks like there are several other minifigs with gray legs.

Seems my memory may be faulty - the bodies are glued to the legs :(

Here are some links to a really good explanation to what happened and some ways to remove the magnets. Oh also a pretty comprehensive list of magnets sets that are surely not glued, surely glued, and somewhere in between:
Explanation and Removal: http://thebrickblogger.com/2011/01/lego-glued-magnet-removal/
Guide to glued and unglued magnets: http://thebrickblogger.com/2011/06/glued-and-non-glued-lego-magnets/


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Which subtheme did the "Space Monorail" sets come under?
Many years ago I remeber attending a model railway exhibition and one of the railways was a Lego monorial that looked very "space" based. I've found 6990 (Monorail Transport System) and 6991 (Monorail Transport Base) but I can't find out what sub-theme they came under.

BrickSet lists 6990 under the Futuron space sub-theme and 6991 in the Unitron space sub-themes.
There was also a Monorail sub-theme of City.

Did not know about the City subtheme. Thanks!


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Were there any non "misson-x" sets from the LEGO Alpha Team Range (as in with the PC Game)?
In the LEGO Alpha Team Range, there's "Mission: Deep Sea" and "Misson: Deep Freeze", but were there any sets in the same "theme" as the computer game (and the same characters)?

I think the original Alpha Team sets are the one's you're looking for, including the LEGO Alpha Team Secret Mission Collectors Pack which includes:

[bs:6771] with Ogel
[bs:6773] with Dash
[bs:6774] with Cam and Flex

There are also:

[bs:6772] with Radia
[bs:6775] with Charge, Crunch and Tee Vee (a robot)
[bs:6776] with Ogel and two minion commanders.

Ah, yes, that's it. I remember 6773 as I had that copter with the transparent rotors. I also remember Tee Vee from the video game, an interesting combination of minifigure legs, a computer screen, and an aerial.


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Is this a fleur-de-lis hood ornament, or something else?
I came across this interesting piece:

Now, I'm not sure it is a hood ornament, but I would like to know what it is. Any help would be appreciated.

It doesn't look like a fleur de lys...

I think you may have stolen King Kahuka's tribal feather-thingy...

@Coyote I was trying to think of something to liken it to. It kind of looks like the top half of a fleur-de-lis, if you squint your eyes.

LOL, ok. PeterDC seems to be right... It's a feather ornament, it doesn't look like the ones on medieval helmets so it might be one of the tribal ones.

Looks like a minifigure headgear accessory, specifically a feathered headdress plume (no. 6029b):

It's appeared in a number of sets, most with pirate, castle, or western themes and sometimes as an extra part. It's sometimes packaged in a "Plume Wheel" (i.e. still in a circular runner with some cattle horns), and is typically used for islander minifigs:

Thanks for the identification. I now completely remember these from the Lego Racers game.


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Which pre-2000 set had a mobile crane with lights?
I had a set similar to this when I was younger (I am fairly sure this was before the year 2000), although:

The model was red, rather than yellow.
The model was more of a breakdown truck, rather than a cargo lorry.
The model used a cleveryly hidden 9V battery to power a winch and flashing lights.
There were no supporting "arms" coming out the side like in the model below.

Can anybody help me find what set it was?

I believe the set you're looking for is the F1 Hauler (item no. 6484-1):

Here are the details:

It was released in 1995.
It's a red-and-white truck for towing Formula 1 cars (and has no support legs).
It has an 8 x 4 x 2.33 9V battery box, which is hidden in the body of the 6-stud-wide truck.
It has a 1 x 4 light bar and a motorized winch driven by a 9V micromotor.

That's it! Although I do not remember the the battery box being the tool chest, I thought it was built into the model and hidden behind the panels. After reading the reviews I see the model is 6 studs wide and the battery box was 4, so it's certainly possible. I'll have to see if I can find the manual somehwere.

@tombull89: You're right about the battery box. The first image I found made it hard to tell what the width of the truck was. I'll update with a better picture.

I found my copy of the manual and took a picture of stage 14 which shows the location of the battery box.


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Can you build accurate models using 100% LEGO elements by following Megablocks instructions?
I shudder when I find errant MegaBloks in my LEGO elements, but admit to admiring certain in-the-box models offered by them. I know the pictures depicted on the MB boxes are not actually photos of a completed MB model. They are computer enhanced images of what an ideal model would look like if MB pieces actually fit together correctly. Is there a link with images of any 100% LEGO element models built using MB instructions? If there isn't a link, can someone please post an example?

The first step would be to find a some MegaBloks instructions, unless you're possibly looking for someone who's already done this?

The wording is confusing me. You want images of Megablok models built using LEGO bricks?

@Peter: Yep. Somebody must have done it. It is kind of tempting.

@Pubby: Yes. I'd like to see examples of LEGO models constructed with Megablok instructions.

Not necessarily.
It really depends on what you mean by "accurate."  Most (probably 90% or more) of Mega Bloks elements have identical, or at least functionally identical, LEGO elements.  However, there are a number of Mega Bloks elements that you can only approximate with LEGO elements.  For example, Mega Bloks hinges rotate around the center of mass through 100+ degrees center at the vertical, whereas LEGO hinges rotate through 90 degrees from horizontal to vertical.  Also, Mega Bloks has a SNOT piece with studs on both sides that LEGO unfortunately does not have.
If you are willing to slightly modify the instructions and accept a slightly different model, then yeah, you can reproduce anything made by Mega Bloks using LEGO elements.  But if you want the models to be 100% accurate, then no, not all Mega Bloks sets can thusly be reproduced.

Yep, you can just see a number of elements in the photo in my compatibility answer (http://bricks.stackexchange.com/a/754/56) that I don't believe have a direct LEGO counterpart, from the hollow "frying pan" that Harry's holding, the 1x1 angular SNOT brick (the LEGO one is much thinner, and doesn't have a stud on both sides, but a hole on top), the rounded double lights and even the sloped brick they are attached to. I'll try and dig the model out and see if I can photo all the different bits.

You could conceivably do it, but the flat Megablock bricks are thicker than Legos, so the Lego creation may seem long and flat.

Yes - I remember as a child, I built the USS Kittyhawk (a set that is an absolute nightmare to build with Mega Bloks) out of LEGO parts. All of the pieces, aside from the stickers, have either an exact or pretty close LEGO equivalent. You will also need to do the deck with plates instead of the large MegaBlok plates, but this allows for much more detail and a more realistic looking carrier deck.
http://www.amazon.com/MEGA-BLOKS-PROBUILDER-USS-KITTYHAWK/dp/B00004TRZY
Unfortunately, it was so long ago that I can't find any pictures of what I built. I do remember that you need a lot of gray bricks. I would recommend this set above all the other MegaBlok sets for replication in LEGO, as its a massive build and especially fun when built with pieces that actually stick together. And its a lot more fun to plan out all the LEGO pieces you need and salvage them from the Internet than to get them all in neat little bags.


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Whose Head is this?
I've found this kind of cool looking minifigure:

Apologizes for the poor picture. :(
But after some research, I think I have determined that this body would have come from set 6584 - Extreme team challenge.
The thing is I don't think the head is right for the body:

So now I have no idea as to what set this head came from.
Where did this head come from?

This is the "Moustache Red, Headset, Red Eyebrows Pattern" minifigure head:

It appeared in two different minifigures.
The Explorien Chief minifigure featured in three sets from the Explorien theme:

And "Aquaraider 1 with hook" featured in two sets from the Aquazone theme:

Thanks for identifying it. I'm again having flashbacks of the Lego Racers game going through my head when I see these Exploration sets.

After looking around on my own, I found that this head was used in two different types of minifigures. I'll add this to the answer.

Thank you for editing it.  I was constrained by my (former) noob status and couldn't post pictures.

Well, after this you're a n00b no more! Congratulations :)


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What LEGO wheels would look like the three types used on the JPL Mars Rovers?
I would like to build the three types of JPL Mars rovers (Sojourner, MER and MSL) with the right size ratio relative to each other.  For that, finding the right wheels would be the hardest thing.  I can build the rest of the robots as long as I know the wheels will have the right look.
Here's a pictures of the three wheel types:

Important Notes:

The overall size doesn't have to be at the scale of the minifigures.  Even though this would be really cool, it would turn the Sojourner project into a micro build.  This would be much harder.
The look of the wheel hubs is not relevant. What is important is the look/ratio of the tire's outside dimensions.  Note that Sojourner's wheel (the small one) has a flat rolling surface while the others two are rounded.

Edit: The medium wheel is (appropriately) 1.8x the size of the small wheel while the big wheel is (appropriately) 1.7x the size of the medium wheel.

Here's what  found after playing with all kinds of combinations.  With this the three rovers will be at the same scale (about 1:5.8).  This scale is small enough that the big rover (MSL) would not be a monster to build.

The ratio is almost spot on and the only main problem is that the MSL wheels (the big ones) will have those big cleats.
On the positive side, they all have the right shape.  Only the medium wheels have that bulgy look while the other two have a flatter driving surface.
Here are the parts numbers:

Sojourner (small): 6014ac01
MER (medium): 6580c01
MSL (big): 64711

Well found and good luck with the build :)

I'm only missing 1 wheel (2x 64711) for the MSL rover so I'll order that online.  It won't slow me down too much since I'll start with the small rover and build my way up.  I'll probably document the build (or show the result) on my blog.

The first that came to my mind (for the MER-wheels) is the Wheel 70 x 28 mm Futuristic, with Black Tire:

It would probably be easiest to work out the which piece should be used for the biggest wheel.
The largest wheel I could find came in the 8420 Technic model. Two of which can be used in tandem to increase the surface area of the wheel:
Wheel Technic Street Bike (8420)

The medium wheel could be a rather blocky Wheel 20 x 30 Technic, the 68.8 x 24 or the incredibly useful 30.4mm D. x 20mm (four of which come with the NXT 2.0.)
The smallest wheel can be any of the tyres from a medium sized LEGO CITY vehicle such as the Prisoner Transport set.
I'd recommend having a look at Bricklinks database of wheel pieces to see what else is on offer.

Thanks for the links.  I'll dig around on Brinklink to see if I can find the right combination of sizes(ratio) and of looks.  I'm also interested in the full wheel-tire BTW (not only the wheels).

You might also be able to make wheels out of parts, such as a circle of hinges with brackets and cheese slopes.  I'm sure there are better ways, but that was the first that came to mind.

This reminded me of an old BrickVista post where that guy build a Sojourner wheel out of Technic pieces http://www.brickvista.com/features/roverWheels/roverWheelsHome.html


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How to fix Mindstorms Error Code 1003
I am using the Lego Mindstorms NXT Education Kit, software version 2.1. Everything was working fine writing programs and downloading them to the robot until all of a sudden when I tried downloading a program to the robot, I would get the following error:

Error:1003 The required file is broken

Here is a list of things I have tried with no success:

Ensuring the robot is turned on
Ensuring the USB cable is properly connected
Restarting the Mindstorms software
Restarting the Computer
Restarting the robot
Updating the firmware on the NXT (which had the unfortunate side effect of deleting every file on it!)

After I got this error when trying to download one file, I am now getting this error when I try to download any file onto the NXT. It even occurs with very simple files (just one move block).
None of the files have any MyBlocks.

As documented in this First Lego League forum post, this problem can be solved by installing the NXT EDU 2.1f3 patch.
A cached direct link to the patch can be obtained here. The patch is for both Windows and OSX.

I found the link to download the NXT EDU 2.1f3 patch, the original one was broken. Download here for windows.

I just installed the retail version of NXT 2.0 (v2.0f6) on Mac OS 10.5.8 and got the error 1003 "a required file is broken" when first starting up the Mindstorms NXT application. Turns out this is a known bug when using the case-sensitive journaled filesystem. Mindstorm tech support walked me through the fix which was to rename the "/Library/Frameworks/Fantom.framework" directory to "/Library/Frameworks/fantom.framework". (The only change is the 'f' in "Fantom.framework".)

Last one helped:
run console, sudo su and mv Fantom.framework/ fantom.framework

I ran into this issue using macos 10.8 on some new macbook airs and trying to run Mindstorms NXT for Education software, tried various 2.0 and 2.1 versions.
We eventually got a ~900meg NXT 2.1f installer package from Lego support,
If you popped up the mac console application, you would see various framework/library errors related to Fantom.framework and VISA.framework. Running the uninstallers for the old versions and reinstalling newest versions of both NXT and the Lego Driver (Fantom driver) did not work, nor did applying patches/updates to older versions.
It turned out the problem had to do with the fantom driver and the VISA.framework never being fully uninstalled/being messed up from the old versions. I went to a terminal, sudo'ed bash (to get a root shell), and deleted all of these ( i.e. rm -rf /Libraries/Frameworks/Fantom.framework    and then rm -rf /Libraries/Frameworks/VISA.framework)
Here is my recipe for fixing this/getting

Uninstall any old/other versions of NXT via running the uninstall.sh script as root/sudo from a terminal (this script is under the NXT application directory)
Install the latest NXT edu 2.1f from the large (~900meg) zip file that Lego support sent us (sorry, I don't have  a download link)
Delete the /Library/Frameworks/Fantom.framework and /Library/Frameworks/Visa.framework directories completely (VISA or something, I might not have the full name spelled correctly but it is something like that)
From the “parts” folder inside the NXT installation folder (after you unpack it), run the legodriver.pkg installer – this will put in the new/working versions of LISA and Fantom framework

I installed Mindstorm Education Kit 2.1 on a 2009 Mac Book Pro 17" running Mac OS X 10.8.1 (Mountain Lion) and received the 1003 Error code on launch.  I was able to eliminate the error by installing the Fantom Driver.

You need to download the latest patch for NXT EDU.

Uninstalling Flash Player fixed the issue for me (OSX 10.8.5). It was a tip I saw the lego message boards.


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Where can I find the LEGO fire dept. logo in high resolution or in vector format
I want print a high resolution version of the Lego fire department shield (the shield with three flames that is used on all Lego fire trucks). When I search with Google, I find mostly low resolution images.
The best would be a vector image (like SVG) or a high resolution bitmap image (PNG or the like). Has anyone created a high resolution image like this?

Going on advice from InkBlend I converted the logo to a vector graphic from a sticker sheet scanned in for the 7945 Fire Station set on BrickLink.
I used VectorMagic to convert the file and automaticaly create paths. The SVG vector file can be downloaded here. If you don't have an image editor that supports vector editing, you can also download a high-resolution PNG graphic (267.33 kB).
You could also try scanning in a sticker sheet from a set that has the sticker. With Illustrator, Photoshop or any other similar image editors, trace around the design using a pen tool and fill in the colours. Using the scanned image as a reference.
If you're having trouble finding a suitable image, I would also recommend looking at the LEGO City product page for wallpaper downloads and illustrations.

This is a good image.  The OP wants a vector graphic, so I would recommend editing the image with the GIMP to get just the logo, than importing that as a bitmap into Inkscape and path tracing it into a vector image.

@InkBlend: I've updated my answer to include both a vector file and a high resolution image.