# Question
Title: Technique for multifacteted roof without 3049
I'm working on a project with a fairly complex roof in Dark Bley. In many areas, it seems to be necessary to use part 3049:

Unfortunately, this part doesn't appear to have ever been released in Dark Bley. Are there any alternative building methods to achieve the sort of effect that I'm looking for without using 3049?

For clarification, here's one simple example where I'm not sure how best to finish the roof peak without using the missing part (shown in red):

# Answer
You could also replace the part with a 3048 which does exist in dark bluish grey.

Sure the roof will look a little strange, but the effect might be interesting enough that you'd be willing to do that.

Another solution would be to replace all roof points by tiles.

In both cases, you can also start the weirdness one rank lower (in the last case, having tiles on 4 studs instead of two).

Since you won't be able to to it exactly as you could if you had a 3049, the key is to experiment until you find some new combination which looks satisfying enough to you.
> 2 votes

# Answer
Would it be possible to just use a black one, or old dark gray? It would add a little variation to the roof, which is not a bad thing - it would look more natural. Perhaps the other color could be added to some other places here and there as well, so the colors all pull together nicely.

Other than that you could always add a chimney, but as you mentioned you will have several places where you will face this issue. I can't think of any other piece that could serve the purpose exactly like 3049. You might also consider angled plates, which are other commony used pieces for roof-building. But without seeing your project it is hard to tell if that would work.
> 2 votes

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Tags: building
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title: Are these trees LEGO parts?

text:
# Question
Title: Are these trees LEGO parts?
I've come across some trees from some bulk purchases I've made, and I can not determine if these are LEGO or "compatible" parts. Any ideas? The tree on the left is an official tree but the one in the middle is an odd aqua color, and the one to the right is very similar. Neither the middle nor right trees have any LEGO stamps on them anywhere, which is why I'm pretty sure they are from something "compatible" but figured I'd see if anyone else could identify them. My apologies for the photography.

# Answer
A full list of LEGO tree parts can be found on Bricklink. I'd encourage anybody looking to identify a brick to use the part catalogue.

The two trees on the right are definitely not LEGO parts.
> 12 votes

# Answer
Not sure about the other tree. But the center tree is from Tyco.
> 11 votes

# Answer
The rightmost tree may be a bent original Lego tree. I am not sure as I was not a kid in the 60's or whenever they started coming out with the interlocking stud-type sets.
> 1 votes

# Answer
The first one on the left is definitely LEGO, and the other two are just poor copies.
> -3 votes

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Tags: part-identification, 3rd-party
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title: How to repair cracked/peeling decals?

text:
# Question
Title: How to repair cracked/peeling decals?
Does anyone have any ideas on how to repair and protect cracked/peeling decals, like these pictured in my 10019 set:

Some kind of film or lacquer?

# Answer
Oh, those look sad! Stickers with white designs on them are notorious for peeling/cracking.

I have found that the best way to protect stickers like these is to apply a thin layer of clearcoat to them while they are still new. Wait until the clearcoat dries, then apply the sticker to the LEGO set. You can use pretty much any acrylic clearcoat, medium or varnish available at hobby and craft stores. Anything in the scrap-booking/decoupage section should be safe, but it is a good idea to test them on a small corner of the sticker-sheet. Always apply the clearcoat thin. You only need a thin layer over the sticker. If you apply too much the clearcoat can yellow with age.

Once stickers are already damaged it would be pretty much impossible to repair them. Even if you try to put a clearcoat on an already damaged sticker, it will continue peeling, so it is not worth it. It is much easier to just get and extra sticker-sheet for any LEGO set on Bricklink. The stickers for your set above are here.

I have actually made it a habit to always pick up 1-3 extra sticker-sheets on Bricklink when I buy a new set. While the set is still new and readily available the sticker-sheets are much cheaper (often just a few pennies) than trying to get a pristine stickers-sheet for a set that is 10 years old. Just place them in a ziplock bag, and store them away from heat and direct and sunlight. They won't deteriorate that way.
> 3 votes

# Answer
Replacement stickers from a third-party site are an option, but they can be expensive - the sticker sheet for this set is currently between $75 and $200!

You can repair printed paper stickers, if you want to take the time and care to do it. The basic steps are:

* Remove the sticker from the piece. I use a razor blade. Hold it nearly flat against the brick and very carefully start around the edges of the sticker until you have enough pulled away that you can hold an edge with your fingers. Then it's a matter of pulling evenly at the sticker while separating it with the razor blade. This takes patience. Go slow.
* Once the sticker is removed, flatten out the wrinkles and re-align the torn spots as much as you can. I usually do this on a piece of waxed paper. Any glue left over on the sticker will hold on the waxed paper, but it can easily be peeled off. Once you have it flat and smooth again, put another piece of paper over it, then a piece of cardboard, then some heavy books or even a brick. Leave it under weight for a couple days.
* Clean the sticker residue off the brick. You might be able to rub most of it off, but I have also used products like Goo Gone (which is petroleum-based, so use *very* sparingly). After getting the residue off, wash the brick with warm soapy water.
* Take your sticker out from under the weight. You can do some cleaning of the sticker, if needed, using a kneadable eraser. If the sticker is mostly intact - that is if the layers of paper haven't peeled apart - you can now carefully remove it from the waxed paper and reapply it. In some cases, there will be enough glue on the back that you can just re-apply it to the piece as is. In other cases (like the example above, for instance) glue is missing or the layers of paper have peeled apart.
* In the case of peeled layers, you can re-glue them together using a thin layer of glue - like from a glue stick. Carefully apply it to the top of the lower layer of paper, position the printed paper smoothly over it and put it back under the weight to dry. If part of the backing paper has torn away (and is left stuck on the piece, for example) you can replace it with very thin tissue paper.
* If the layers are intact, you can restore the stickiness using "repositionable" glue. This is glue that you apply and let dry for a minute before putting the sticker back on the piece.
> 0 votes

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Tags: repair, stickers
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# Question
Title: Is this piece some kind of rare/modified 200?
I have this piece which vaguely resembles 200, Technic Rack Winder Axle (Rebricked) but one end is different. It is 5 studs long, axle is 1 stud long, the gear lies between 3rd and 4th stud and the axle hole is approximately 1 stud deep.

There is no branding on the piece so I am not sure if it isn't something other than Lego.

**Edit:** The axle hole holds axles really tight, but the axle end doesn't hold other things too well. As for the gear teeth, they are exactly the same as in 3647 (the same shape number and size), although they are slightly moved, 10 degrees or maybe even less.

As mentioned it *is* possible it's not Lego, but I personally don't recall ever buying any technic-like non-Lego sets. Can't vouch for my brothers after who I've inherited most of my collection.

# Answer
It is about the right size and shape to be the main shaft of this wind-up motor from set 4093:

Here's another view:

These pictures show the piece as white, but it might be a variant. I do not have one of these windups to take apart to check.
> 7 votes

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Tags: part-identification, motor
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# Question
Title: How can the 12v Train 7823 Container Depot be used to load container ships as per Lego Catalogue
As I kid I was always confused by the description of the 7823 Container Depot in the Lego Catalogues:

> ..."The crane can be raised so container ships can be loaded."

An example can be seen in this scan of a 1988 UK catalogue.

Now as an AFOL I am still confused by this. I still have the set from my childhood and although the end of the crane gantry does hinge up, it doesn't give the crane any extra reach. I suppose it is possible that the train track could be removed and the base plate be placed right next to the 'dock side' to use the crane to load/unload ships, but even then is it really necessary to raise the end of the gantry? There is already a lot of height clearance even without the gantry end raised.

Can anyone shed any light on what the Lego Group meant by this description?

# Answer
Whilst there is quite a bit of clearance on the crane as it stands, the Container Ship (4030) was quite a high sided beast - although you can see that better on the catalogue page:

I would think that a bit of extra height from the hinge would be useful to make it over the edges of the ship - assuming you haven't raised the crane's base.

The alternative answer is that they are trying to make the model more real-world accurate, where the cranes lift up as the ship comes in, and then go back to flat to load:
> 4 votes

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Tags: sets, trains, vintage
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# Question
Title: Ultrasonic problems with the red and blue balls?
I'm still new to NXT, I try to make the robot locate a ball using the ultrasonic sensor, while there I should be in a square area marked by white color.

How can I make the robot locate the object (by ultrasonic), stop, get the distance, then move until it stops exactly in contact with the object?

Here is my project

# Answer
The ultrasonic cannot detect the color of objects. It's just to detect the distance between the sensor and an object in it's line of sight.

To find objects in the surrounding area of your robot you have to look all around. This is simply done by rotating your robot or your sensor. When you measure a distance in a certain range (best results between aprox. 10-50cm) you can stop rotating and you have your direction. Then you start to move and check for better results every 10cm or something like that again if you are still facing the right way.

Stoping exactly in contact won't be possible unless you can say I am Xcm away and now can move exactly Xcm in this direction since the ultrasonic sensor cannot measure distances below a certain level (around 5-10cm depending on the size/shape/material of your object).
> 5 votes

# Answer
Regarding the white square on the ground, the robot can not sense this using the ultrasonic sensor. This is because the ultrasonic sensor uses echolocation to navigate (hence the name "ultrasonic") If there is a white square on the ground such as a piece of paper which is essentially 2 dimensional, the sensor will not 'notice' the square. Try another method, perhaps using a 3 dimensional object, and a color sensor while you're at it.
> 2 votes

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Tags: mindstorms, nxt, programming, balls
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title: Pull back motor 552 x2

text:
# Question
Title: Pull back motor 552 x2
I have these wheels and want to find a set/booklet where it is used. No combination of the numbers give any result. It says Lego Group 2011 522 x2

Found it

# Answer
> 4 votes
It looks very much like pullback of the promotional LEGO sets with ferrari an shell from 2012.

They have got the set numbers 30190 to 30195 and there is an additional crew pack (30196).

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Tags: motor, wheel
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# Question
Title: Accidently Deleted System files on Nxt 2.0. How to restore system files?
I have accidentally deleted the system files from my NXT 2.0. It is making a continuous clicking sound. How to I restore system files. I have the system files, but my computer can't detect it!

Please help soon!

# Answer
> 2 votes
You need to reload the firmware. If you use NXT-G, this can be found under the Tools-\>Update Firmware menu.

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Tags: mindstorms, nxt
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title: Part assortments for creative building

text:
# Question
Title: Part assortments for creative building
I've been shifting away from collecting sets to doing more MOC building. I also recently moved and I'd like to reduce the overall size of my LEGO collection. I'm trying to decide which parts I'd like to get rid of and which parts I'd like to keep.

I'm interested in keeping large numbers of versatile parts while selling off parts that tend to serve a single purpose. I'm hoping to find example part assortments (not necessarily official sets) that are most useful for MOCs and rebuilding.

To explain what I mean, here are two example sets. The first is the new Architecture Studio set:

The second is the Hobby Train set from 2007:

These both contain a good mix of pieces that can be reused in all sorts of models. Are there other sets, parts packs, or lists that provide a good platform for creative building?

# Answer
It very much depends on how and what you like to build so personal recommendations are difficult. As you're new-ish to MOCing it may take some time to figure out what pieces you like the most.

That said, I'll offer a suggestion - I find 10230 Mini Modulars and interesting range of small pieces in various colours incuding some rare ones. Check out the inventory to see if it appeals to you too. I'd also suggest looking at the Creator sets in general.
> 5 votes

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Tags: building, sets
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title: LEGO stormtrooper variation

text:
# Question
Title: LEGO stormtrooper variation
I found several LEGO stormtroopers on a toy box. They each have a plain yellow head and the words "LEGO 2002" in big letters in their backs. Did they come from a set?

# Answer
These are promotional items. Not from a set. They can be related to a store-opening, a give-away, other special events, etc. Looking through the Bricklink catalog I found one listing with a stormtrooper torso that you might be referring to: http://www.bricklink.com/catalogItem.asp?P=973pskac01

If you can add a picture we can probably identify them more precisely. Hope this helps some...(c;
> 2 votes

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Tags: minifigures
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# Question
Title: 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?

# Answer
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:

1. All sets that are new since January 2011 are glued.
2. 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).
3. Any re-releases will be glued.
4. 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.
5. 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:

1. Be happy that some sets were produced unglued.
2. Encourage LEGO to produce more battle packs by buying existing ones.
3. STOP buying the glued sets, and make LEGO aware that we don't like them.
4. Lobby LEGO to produce unglued magnet sets where licence restrictions don't exist.
5. Encourage LEGO to make statements about gluing more prominent on the glued sets.
> 28 votes

# Answer
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.
> 5 votes

# Answer
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.
> 1 votes

# Answer
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/
> 0 votes

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Tags: minifigures, cleaning, accessories
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# Question
Title: Can I download a programm written in C# into brick?
I use C# language and http://www.mindsqualls.net/ library. But I could not find how to download my program into brick. Actually, is it possible? Or I just have to control my nxt 2.0 robot via bluetooth? Are there any languages/libraries which allow to download programs into brick or it is only possible for mindstorms nxt 2.0 visual editor?

# Answer
> 7 votes
It doesn't seem to be possible. To quote mindsqualls' site:

> MindSqualls is a .Net library for controlling a LEGO MINDSTORMS NXT or NXT 2.0 robot via either a Bluetooth- or an USB connection. It is written in C# and requires .Net v. 2.0 or newer.

Which means it allows you to control your NXT brick from the PC, and from the PC only. It does not offer any possibility to create a program which you would download on the brick.

But fortunately, the second part of your question has a more positive answer: yes, there are alternatives to the visual editor provided by LEGO, and there are actually a lot of them. This has been covered extensively in another question, so I won't get into the details again, but a good start is this list of alternatives compiled by Steve Hassenplug. Note that Mindsqualls is on that list, in the section devoted to software that only runs on the PC ("remote controls").

# Answer
> 2 votes
This is not currently developed, but I think it is a good thing to check out when it is done. http://www.dcl.hpi.uni-potsdam.de/research/lego.NET/

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Tags: nxt, mindstorms
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# Question
Title: Programming the NXT brick using an ipad app
for the past few years, I have been using netbooks to program the NXT. I would like to move into the 21st century and use ipads. Is there an ipad app for programming the NXT brick?

# Answer
You may want to try these:

None of these are offical and you will have to use bluethooth to download and run programs.
> 3 votes

# Answer
There are no programming tools available on the currently available iOS devices, including iPads.

Technically speaking, this is because the iPad lacks support for the correct Bluetooth profiles that would allow a direct connection. iPads also have no USB port that can be used in host mode to directly connect the NXT (the USB to dock adapter from the camera kit does not work!).

Theoretically it should be possible if you take part in the Apple Hardware Development Program and write your own driver. But this is possibly out of scope for the rest of us ;-)

A mentioned workaround is to create an application on the iPad for source code editing and use a Proxy-PC that communicates over WiFi with the app, compiles the source code (e.g. NXC) and sends the binary to the NXT. If someone has done this, please let us know!

With the new EV3, things will change as this brick is able to communicate over WiFi. And Lego announced some kind of iPad and Android IDE for EV3.
> 2 votes

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Tags: nxt, mindstorms, software
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# Question
Title: Can anyone identify this octagonal dish piece for me?
It seems like this piece would be named "**Octagonal Dish 2 x 2**" but I can't seem to find it on any of the usual sites. Is this named something else or is it not a real LEGO element?

# Answer
I believe it's yet another MEGABLOKS part. You can see it on the top of 9321 Cyborian rover holding the yellow antenna, for example.
> 7 votes

# Answer
I'm going with "This is not a LEGO piece", assuming completeness of this Brickset page: http://www.brickset.com/parts/browse/categories/?category=Plates,%20Special%20Circles%20And%20Angles which seems to be where it would be if it existed in genuine LEGO...
> 2 votes

# Answer
It is very obvious that it is a Mega Blok.

1. Mega Bloks are always thicker than Lego bricks.
2. It would have Lego markings on it.
3. It would be listed here.
4. Have you seen a Lego piece with those big bumps? I have seen them on lots of Mega Bloks.
> 2 votes

# Answer
It could be the extension to the gun like objects in the Lego Life on Mars set.
> -1 votes

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Tags: part-identification, clone-brands
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title: No software with the EV3 robot?

text:
# Question
Title: No software with the EV3 robot?
We bought EV3 robot but it looks like there is no software and we have to pay an additional $99 for the EV3 software. Is this true?

# Answer
> 8 votes
For the retail version, the link is: https://www.lego.com/en-us/mindstorms/downloads and for the education version, the link is: https://education.lego.com/en-us/educationdownloads/freeproductspage

# Answer
> 5 votes
The EV3 software (for home use) is available on: http://www.lego.com/en-us/mindstorms/downloads/software/ddsoftwaredownload/

# Answer
> 3 votes
The home edition software will be a free download available from LEGO's website as of September 1st. It will include programming for the ultrasonic and gyro sensors and will be compatible withe the education version of the EV3 brick.

# Answer
> 1 votes
The retail edition of the NXT kit doesn't include software in the box, and provides only limited printed building instructions (presumably to save on costs).

However, as indicated on the box, you can to download it from LEGO.com/mindstorms directly, and for free.

Currently, the software is on the download page.

The instructions can be found on the products page, under "EV3 Starter Robots" and "EV3 Bonus Robots". You can download them as PDF or view them interactively online. You can also install a mobile application to view them easily while building.

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Tags: software, ev3
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# Question
Title: Is the Antikhythera clock design available as Open Source?
After reading and watch the video about the Antikhythera Clock, I am curious if the design reference (or better yet the instruction manual) is available as OpenSource.

Why? Because it would be cool to have one of this sitting on top of my desk.

# Answer
If you could not get it, then you might try Hans Andersson's clock :) http://tiltedtwister.com/timetwister.html

And here's the instructions manual: http://tiltedtwister.com/tmtwdownload.html
> 2 votes

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Tags: instructions, design
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# Question
Title: Where to find older sets (eg. Classic Space)?
Can people share their experiences on how they locate older sets? Have you had luck with flea markets, garage sales, thrift stores, etc.? Or is everything done through eBay and BrickLink? Any comments appreciated.

# Answer
Some of the places you can buy old (discontinued) sets include:

**Online**

* BrickLink
* eBay
* TradeMe
* Amazon marketplace
* Generic on-line toy stores that carry old stock
* Some LEGO discussion forums have areas for buying and selling

**Locally**

* Toy shops and LEGO stores sometimes carry old stock
* Stands at exhibitions and shows
* Garage sales
* Thrift stores
* Charity shops
* Flea markets
* Car boot sales
* Jumble sales
* Through newspaper ads
* Lego User Groups
* Other AFOLs

**Other Alternatives**

* Buy the parts separately and assemble the set from them
> 3 votes

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Tags: sets, shopping, space
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# Question
Title: Can I buy an add on educational kit for my retail EV3?
We ordered the retail version of Lego EV3, and my son loves it and wants to do more.

Are there any add on kits we can buy to expand upon what we have, ie add on motors or special tech pieces, or an educational kit?

# Answer
There is an expansion set, as well as a selection of additional sensors, etc. you could purchase, listed on the products page of the LEGO site's Educational Section:

Note that these tend to more expensive than the retail kits, and tend to have slightly different items in them.

There have previously been a number of 3rd party suppliers making sensors for the NXT and RIS systems, so I'm sure they will also provide support for EV3.
> 2 votes

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Tags: ev3, education
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title: How can odors be removed from bricks?

text:
# Question
Title: How can odors be removed from bricks?
I recently purchased some used bricks. They currently smell like cigarette smoke. What is the best way to clean these parts to remove the odor?

# Answer
Background info:

I recently started collecting Duplo blocks to build toys for our sugar gliders (small, exotic marsupials); I've also got some regular Lego blocks in the mix that my boyfriend's had for who knows how long. To get the most for my money (especially when it comes to avoiding figurines and random pieces that don't suit my purpose), I've been buying large lots of Duplos off of e-bay (all of them are specifically Lego brand - you couldn't pay me to use Mega Bloks or other crummy knock-offs, lol).

Our gliders are our babies and on top of that, I've got high-end breeding pair (ie rare colorings/genetics) and a "pet only" pair that cost a combined total of $1800 - in other words, their safety is a HUGE concern for me and I'm adamant about cleaning and sanitizing any Duplo blocks I buy as soon as they arrive. Also, gliders can't be potty-trained and inevitably use my Duplo creations as toilets... meaning pee sometimes gets in the crevices between blocks. To top it off, they scent-mark everything. As a result, I've got to disassemble the toys I've built and re-wash them 1-2x a week to keep things sanitary.

Like toddlers, gliders tend to "taste test" their toys at times (and even if they don't, they walk all over the Duplo blocks and then eat with their hands and groom themselves with their tongues). That means I have to use cleaning products that are very safe, yet still effective (particularly when it comes to odor control, as gliders really do stink things up!).

My cleaning method:

The way I've been washing the Lego Duplo and regular Lego blocks is to fill a clean kitchen sink with a 50/50ish mixture of hot water (hottest the tap can provide, that is) and white vinegar, then add the blocks. I soak them for a few hours or possibly overnight, then scoop them into a large colander\*, rinse them thoroughly with warm-to-hot water (iirc 104F+ is "unsafe" for Legos; hence why I mix the really hot water and the vinegar together before adding the Legos) and lay them out on towels to dry (inside, with a box fan blowing across them, flipping them over every few hours until they're totally dry). If anything is particularly soiled, I use the soft (ie non-scrub-pad) side of a clean sponge to give the blocks a gentle scrubbing as they soak in the warm vinegar water; for anything stuck in difficult-to-clean crevices, I use a baby bottle brush and/or q-tips.

\*Based on a recommendation I saw on this site, I ordered a salad spinner to spin-dry my Duplos and regular Legos (and bunny veggies and dinner salads)... best thing ever - I LOVE it. GET ONE!

Vinegar is very popular as an odor eliminator for a WIDE variety of odors. It was the first and only cleaning method I tried because - despite all the pet odor eliminators and pet cage/habitat cleansers on the market - the vast majority of glider owners stick to a simple 50/50 blend of water and vinegar. It's very effective for removing urine, feces, scent marking oils, stuck-on (sugary) foods, etc. and all the related odors from glider toys and cages (not to mention bunny and cat litter boxes)... plus it's dirt cheap, gentle, pet (and child) safe and doesn't leave residue behind.

Because I haven't actually had to get cigarette smoke odor off of Legos and wanted to see if I could find some info to back up my hunch that it would work on that as well, I just did a cursory Google search for "remove cigarette smell with vinegar" and got a ton of hits confirming that it's very effective. I then searched specifically for info about using vinegar on Legos and found an article that provides some great tips and additional information on using vinegar to clean/deodorize Legos (and the article really focuses on difficult-to-remove cigarette odors) - http://www.brickwarrior.com/?p=1
> 10 votes

# Answer
I have found that laundry detergent with warm water works best. It's usually a stronger detergent than dishwashing liquid (which is commonly suggested). Either way, look for something that's as close to a pure detergent as possible - no scents, fabric softeners, dish-shiny-makers etc. I try to avoid anything that is known to change the bricks - peroxides are great for whitening old yellowed bricks, but I don't want to do that if I don't have to (I've done it for 8880 wheels, for example).

With cigarette smoke in particular there's often multiple layers of sticky residue, so I find that a bath or sink full of warm water, soak for a day or so with periodic additions of more warm water and a bit of stirring. To avoid small parts going down the drain use a strainer to scoop all the Lego out before pulling the plug. Rinse well, then spread on towels to dry (out of the sun, but with a breeze). Expect to do this more than once.

I spent a while experimenting and that was the least awful way I found. It's not worth it for low-value stuff, but I had a rare set that I didn't want to resell.
> 4 votes

# Answer
I suggest following the "Lego Whitening" advice given here: http://www.mocpages.com/moc.php/155077 There are a number of tutorials that involve various solutions, but this one works great for me and uses OxyClean and Hydrogen Peroxide, both readily available where I live. The cleaning process will remove the odor with the added advantage of making the bricks shine like new!

Quick summary: Put 2%-3% Hydrogen Peroxide plus a tiny scoop of OxyClean powder in a glass or transparent plastic container. Add Lego elements. Leave it in the sun for most of the day (10-20hrs). Stir occasionally to reorient the bricks. (This may not be necessary; I am not a chemist.) Remove and rinse when the bricks look good. If you are only worried about the smell, take some out at 8 hours and check, then check every two hours after that.

You don't want to leave them in any longer than necessary, as this process does seem to weaken the plastic slightly.
> -2 votes

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Tags: cleaning
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# Question
Title: What is the best way of getting muck out of bricks?
I purchased a large bulk load of bricks for my 7 year old. Most have washed up quite well, but some of the bricks have various substances stuck in their underside.

The types of foreign substances vary, eg. mud, playdough etc.

What are good ways of getting the muck out of the bottom of bricks?

# Answer
best way i found so far is simply using a plastic-toothpick (wooden ones should also do the job). just get the muck out as good as possible and then wash the bricks again the remove the rest.

if the muck is too hard for a toothpick, use a metal needle or a very thin screwdriver - but only do this if you can't avoid because you might be scratching/damaging the blocks (wich shouldn't be so problematic to the inner- and underside, but anyway you should avoid it).
> 10 votes

# Answer
I suggest to let them soak in water for a long period of time (2 days) before trying to clean them. The water will not affect the Lego plastic but some other elements (especial dirt and food) will soak it up. This makes it a lot easier to simply rinse out or scrub off the dirt.

The plastic toothpick (like @oezi suggested) is great for very small corners. For the tougher crud, I suggest wood tools (like sculpting tools) since they won't scratch the soft plastic but are hard enough that they don't just bend.
> 7 votes

# Answer
You could also get yourself a can of compressed air - it works on very small areas on my motorbikes so I'm sure it'll do an equally good job on some lego bricks. Here's some on Amazon...
> 2 votes

# Answer
Soaking in water for a long period of time (a few hours is usually enough) and then using a pipe cleaner to sweep out the residual muck has proven to be very effective. The pipe cleaner is gentler than some of the other things that I've previously used (toothpicks, small screwdrivers, etc.). A Q-tip with a very small hide should also work well.
> 1 votes

# Answer
For larger quantities of really tough muck that's stuck in the tubes on the bottom of bricks, I've had some success with scewing in a cross-headed scew and then pulling it out.
> 0 votes

# Answer
I have to wash my Legos (mostly Duplo, but also some regular ones) regularly, as my creations are actually used as toys for my sugar gliders (small exotic animals), who can't be "potty trained" and often use their toys as toilets. I soak the blocks for a few hours or possibly overnight in a 50/50 solution of hot water (hottest I can get from the tap) and white vinegar, adding the blocks after the water and vinegar are mixed since temps above 104F can damage Lego pieces.

The warm vinegar/water solution takes care of most of the cleaning and disinfecting on its own - remaining debris can often be removed just by rinsing the piece in a strong stream of warm tap water. For more stubborn muck, I've had good luck using the small (nipple) end of a baby bottle brush and for crevices where that doesn't fit, I use pipe cleaners (in both cases, after the pieces have had a nice, long soak).
> 0 votes

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Tags: cleaning
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# Question
Title: Is it safe to try different firmwares on EV3?
I have prepared a SD card to run Lejos on EV3, as said on Lejos Sourceforge page and I'm about to test it. What worries me - will I still be able to go back to original Firmware if something goes wrong or I'd like to go back to this original Lego visual building software? Will removing SD card be sufficient?

Thanks for any information.

# Answer
I tried Lejos and removing the SD card and rebooting was enough to go back to original firmware.
> 7 votes

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Tags: ev3
---


# Question
Title: When and where was the first "official" fan organized Lego Convention held?
I just attended BrickCon 2013 here in Seattle (I wore my new StackExchange T-shirt). When and where was the first "official" fan organized Lego Convention held?

# Answer
According to the What is BrickCon? page, BrickCon claims to be the "longest running fan-based LEGO® convention". Its first edition took place in 2002.

Note that there are events which are older (LEGOworld in the Netherlands for example which I believe started in 2001), so I suppose BrickCon's claim is specific for conventions, and not exhibitions - although I doubt the line between both is very clear to start with (While LEGOworld is definitely directed to the public, there are fan-only happenings in the evenings)
> 4 votes

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Tags: history, afol
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# Question
Title: How to use NXT device as a keyboard key for computer
Is there any way for me to set up my Mindstorms robot so that when I push one of the touch sensors it sends a signal to the computer to press a key?

# Answer
> 4 votes
**Yes**, this is possible.

First, you'll want to connect your NXT to the computer using Bluetooth. Make sure you can connect to it with the official LEGO Software programming environment, NXT-G, and that the computer connection will show up when you go to Bluetooth \> Connections.

Next, you'll want to create a simple program in NXT-G and download it to your NXT. It should basically send a Bluetooth message to the computer, using Mailbox #1 and a number variable containing the value of the key pressed. If you need help with this part, I can provide detailed steps.

Finally, you'll want to use a program called InstantEXE 3.0 (the free version works!) to receive the Bluetooth signal and use the command "Keys" to simulate the key or key sequence that you want to be triggered when the button is pressed. You can expand this with your sensors, e.g. when touch sensor #1 is pressed send it with a value and intercept this on the computer, using InstantEXE 3.0 to convert it into a keysequence. If you need help with this part, I can provide detailed steps and/or a sample program for you to use. You could use some basic labels like the following script:

`:Left`

`Keys "L"`

`:Center`

`Keys "C"`

`:Right`

`Keys "R"`

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Tags: nxt, mindstorms
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# Question
Title: How to simulate Lego Mindstorms programs written in C#?
I am going to do some programming for Lego Mindstorms in C# using

http://www.mindsqualls.net/

and have a question. Is there any good simulator to see result of my program without uploading the code to the robot?

# Answer
> 3 votes
Unfortunately, there are no simulators for Lego Mindstorms in C# that fit your requirements. As Sebastian Wahl mentioned, Microsoft Robotics Studio is probably your best bet. Hopefully there will be a tool like this in the future :)

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Tags: nxt, mindstorms
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# Question
Title: How do I update my NXT firmware using EV3 software
The new EV3 software tells me to update my firmware on the NXT. When I go to the tools menu and select update firmware it tells me the NXT brick can not support this function.

# Answer
EV3 software will not download firmware to the NXT brick. For that you need the NXT-G software and a downloaded firmware file from Lego. 1.31 is the latest version.

So if you're running EV3 on NXT, you shouldn't throw out the NXT-G software. Once in a while, it's still needed.
> 3 votes

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Tags: mindstorms, nxt, ev3
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# Question
Title: Compatibility EV3 software with NXT brick - known limits?
Lego says I can I use the new software to program old NXT bricks:

> Q: Is EV3 backwards compatible with NXT hardware?
>
> A: Yes. You can program your NXT intelligent brick using the new EV3 software. However not all software features are supported by the NXT intelligent Brick. You cannot program your EV3 programmable brick with the NXT Software.)

Are there any known limits programming the NXT bricks? I often had problems with *MINDSTORMS NXT* under Mac OS X and would like to replace it if possible.

# Answer
EV3 has no support for the Light Sensor, just the Color sensor. There is a Raw Sensor that can be used to create a Light Sensor MyBlock. That MyBlock can then be used to create the various WaitFor, Loop, and Switch blocks using the Logic form of those blocks.

Then there is the calibration problem. The Color Sensor block in calibration mode does not work on the NXT brick. The EV3 can also program around that using file operations.

Finally, there is the memory problem. The new firmware leaves a bit less memory available on the NXT. The programs still need to be managed carefully to avoid using up all the memory.

Yes, you can use EV3 software on NXT bricks. In general it is very easy. There are some issues.
> 5 votes

# Answer
EV3 software cannot connect to the NXT 2.0 brick through Bluetooth, only by USB. One can only hope that this is a bug and will be fixed.
> 1 votes

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Tags: nxt, mindstorms, ev3
---


# Question
Title: Program a full rotation of a NXT motor in X seconds
I'm interested in mimicking the functionality of the Arqball Spin, at $60 it isn't cheap so I'd like to make the most out of my Mindstorms parts.

I'd like to use NXT-G to program a motor to rotate 360° in 20 seconds. NXT-G can only controll the power of the motor and duration (Unlimited, Degrees, Rotations & Seconds). The power of the motor can be set from 0 to 100 seemingly arbitrary values:

I don't mind using 3rd party software to program the motor, provided it's easy to use.

# Answer
The problem can be restated: 360 / 20 = 18 deg / sec = 1 deg / .056 sec

One degree is the smallest increment provided by the rotation sensors.

NXT-G has a timer sensor with 1/100th second resolution.

In pseudo-code:

```
Set a motorPower variable to 10
Start a timer
Loop until rotationDegrees >= 360
    If timeElapsed * 18 > rotationSensorDegrees
        motorPower = motorPower - 1
    Else
        motorPower = motorPower + 1
    End If
    MoveBlock (power = motorPower)
End Loop
MoveBlock (stop)

```

Of course, use of the 8 tooth and 40 tooth gears to give a 5 to 1 reduction would give even better results. Even the best programming will have trouble offsetting bad mechanics.
> 5 votes

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Tags: nxt, mindstorms, programming, motor, nxt-g
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# Question
Title: Where can I buy replacement stickers for the set 8018?
I need replacement stickers for set 8018. I've bought a used set and I'd like to change around the sticker position.

# Answer
You can get replacement stickers on BrickLink. Here is the link to the 8018 stickers: http://www.bricklink.com/catalogItem.asp?P=8018stk01
> 1 votes

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Tags: stickers, replacement-parts
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# Question
Title: Is there a fix for an NXT reporting "File error!" when running an EV3 program?
I downloaded the new EV3 software from Lego and installed it on Windows 7. The EV3 software runs. I plugged in an NXT using a USB cable. EV3 can edit the memory on the NXT and remove programs/sounds/text files.

I created a program that uses the large motor to spin the B motor 1 rotation at 75% power. The end program block finishes the very small program.

It downloads without complaint. Run it and the NXT complains with "File error!".

Is this a known problem? Is there a fix?

The NXT has firmware 1.05 loaded.

# Answer
> 4 votes
I needed to update the firmware. 1.05 was too old. 1.31 works.

Download from: http://mindstorms.lego.com/en-us/support/files/default.aspx#Firmware

I did need to run the old NXT-G software to download the newer firmware. I did not try to download the firmware using EV3.

# Answer
> 1 votes
First off Ev3 and Nxt are different machines. However, it's most likely the firmware. I've just downloaded my firmware for Ev3 and I also tried out a program I made. It downloaded perfectly but when I tried to start it, it said "FILE NAME ERROR", which I believe is similar to your problem. I either recommend re-downloading the firmware or turning the Ev3 or Nxt off then trying it again.

---
Tags: mindstorms, nxt, ev3
---


# Question
Title: What is the difference between 8T gears "Type 1" (3647) and "Type 2" (10928)?
On Bricklink I can see that there are two types of 8-toothed gear - a "Type 1" (3647) and a "Type 2" (10928).

It's obvious these parts are not the same, but what is the **functional** difference between them?

# Answer
The new gears are stronger and do not slide into the holes in bricks and liftarms.

If you look closely at the holes in a brick (or liftwarm) there's a shallow, wider hole forming a step. This holds (for example) the collar in the middle of Technic pins, allowing them to hold bricks close together.

Unfortunately that hole is big enough for the non-teeth part of the old style 8 tooth gear to slip into. That means that the gear will slip sideways rather than sitting in the centre of a gap, and thus not mesh exactly with other gears. It sits offset, in other words. There's speculation that this allowed it to fall further into plates with holes back in the Expert Builder days, but the reasons have never (AFAIK) been officially disclosed. This EuroBricks Thread has more discussion and some nice photos

That feature makes old style 8 tooth gears fairly useless of high torque applications, as they will inevitably slip sideways and the teeth will break.

The extended teeth on the new gears prevent this from happening, making them much more reliable in high torque applications (and in general). They are also stronger, but not slipping sideways makes them much stronger where it's needed as well.

I suspect that one reason the extended teeth are not full height is to keept the gears compatible with worm gears. Those cross the teeth at an angle, and if the teeth are too wide the worm gear will hit two teeth on the 8T gear at the same time, making the friction even worse.
> 4 votes

# Answer
I don't believe there is any significant functional difference between these parts in terms of what can be built with them. The 10928 variant is simply a reinforced version of the original.

This gear is widely used, but because of its small size, it has always had problems with breaking under high torque. It looks like this new variation is attempting to address this by reinforcing the teeth so that they don't snap off as easily.

Similar minor strengthening changes have been made to other gears as well. Here's the 16 tooth reinforcement for example:

TLG has been known to make this type of structural change to lots of other parts as well. The most prolific example is probably the 1x1 plate with vertical clip that has seen a number of changes to address structural issues:
> 4 votes

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Tags: technic, gears
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title: Does anyone make a self-driving car?

text:
# Question
Title: Does anyone make a self-driving car?
Mapping and localization are the hottest trends in robotics today. And what's more exciting is they can be both implemented with a low-cost robotics kit like LEGO Mindstorms!

I tried to make a self-driving car, after Google's famous car, but I got stuck on the mechanical side of things. I can't figure out how to build a revolving ultrasonic sensor on top of the robot, in order to do mapping and localization.

Any help is highly appreciated!

# Answer
> 5 votes
It sounds like you want to use the Ultrasonic sensor as a revolving radar dish. This is definitely possible. Note that because of the wire, you probably want the sensor to pan back and forth rather than go around in complete circles. Here's an example of what this could look like:

There are building instructions for this project available here:

http://www.nxtprograms.com/radar/

---
Tags: mindstorms, nxt, building
---


title: Strongest Vertical LEGO beam

text:
# Question
Title: Strongest Vertical LEGO beam
In the LEGO house episode of James May's Toy Stories, the engineers built the beams with studs facing upwards: around 9.5 mins into http://youtube.com/watch?v=mEFPhXl3QQY

How much stronger would it have been (if at all), if they had built them staggered with studs sideways, as below, with the same number of bricks?

How much stronger still, if they had used large plates instead of bricks?

If it is any better, why did they not do that (did they just not think of it, or was there an instruction from LEGO or the producers that studs must be on top)?

# Answer
Depends very much what you mean by "strong".

Vertical crush resistance would be highest as the Lego house people did it because that gives a continuous vertical wall down the edge of each stack of bricks. Offsetting as you suggest means that the edges of each brick are resting on the flat top of the brick below. If they needed to link the bricks horizontally they would either use a row of 2xN bricks or a later of plates. Plates would be heavier and more expensive but somewhat stronger, if wall spreading was an issue (which it did not seem to be in the show).

For beams layered plates would be ideal, possibly in a traditional C or I beam shape, with something to hold the layers of plates together. The easy option there is a layer of Technic bricks top and bottom with Technic liftarms or beams linking them.

For catenary members (like suspension bridge "cables") I'd follow the teams in Australia who have obviously done a lot of research and experimentation, and go with Technic liftarms joined with half-width liftarms and axles.

If instead you're looking at a MythBusters-style giant Lego ball and you want that to stay intact as it rolls then many layers of plates would be useful (the MythBusters ball was made of big Lego-brick bricks, IIRC about 24x48 studs and perhaps 10 or 12 layers tall. It fell apart quickly (and so did not do much damage to anything). For that you would probably also want to use some technic bricks with axles linking them to make internal 3D tension members to hold it together. But you will end up with a tonne of Lego rolling down a hill in that case... not necessarily a good idea.
> 5 votes

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Tags: building
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# Question
Title: Will playing with a PF train motor by hand damage it?
If one pushes a PF-motorized train by hand, will it cause damage to the motor, or any of the other parts (IR Receiver, Battery box)?

It is essentially working as a generator when turned by hand, so will that current damage it?

# Answer
Unless you do extreme things it should be fine. All the gears insides the Train motors, Power Function motors and the NXT motors are made of Nylon while the pinion attached to the motor is made of metal.

*Image Source*

Since Nylon is much stronger than ABS plastic (normal LEGO plastic), the ABS would twist, tear or brake before damaging the nylon gears.

In fact one of the activities in the NXT manual (page 34) is to manually spin the motor by attaching a wheel to it and rolling it like a paint roller. LEGO seems to trust that it is made to survive that kind of usage.

As for the electricity generated by rolling the motor, I'm pretty sure that the NXT brick is protected for that (given that LEGO expects this kind of manipulation). On the other hand I would not connect a sensor directly to a motor and do this. I would assume that the trains components are also protected since it is very likely that kids would roll the train by hand.

Extra info:

* Link to other LEGO trains motors opened.
* Link to opened Power Function motors.
* Link to opened NXT motors.
> 16 votes

# Answer
What you are describing is called backdriving. I teach my students, in principle, not to backdrive the output shaft of a gearbox, motor/gearbox, or servo/gearbox unless they know what's inside of it because you can damage the unit. I use a variety of different robots in my class so what I'm explaining applies to gear drives in general.

If you grasp the orange output shaft on an NXT motor (servo/gearbox) and rotate it, it rotates quite easily. You can tell it's going to rotate as soon as a small force is exerted. The NXT motor is really a servomotor and gearbox combination and the geartrain is inside the housing. I know from experience that Lego allows you to backdrive the NXT motor.

Read the following thoroughly before trying - if you break anything, it's your fault!

Backdrive Experiment: Build a drive axle extension that is attached to the drive end of an NXT motor so that you can add some gear reduction. Place an axle through the orange output shaft and then slide an 8 tooth gear onto the axle. Now, mount an axle with a 40 tooth gear onto the extension you've built. You want the 8 tooth gear to drive the 40 tooth gear. A good design will support both sides of the axles and gears.

Make sure the gear alignment and mesh are correct. The gear ratio of this combination is 40/8 or 5:1. You multiply this gear ratio, times the gear ratio of the NXT Motor (servo/gearbox) to get the final drive ratio.

Careful here, you can break something!

Now, apply force incrementally and try to rotate the 40 tooth gear or a small wheel attached to its axle. You won’t' break the gears inside the NXT motor, but you may damage the motor housing, gears, axles, and structure parts. Depending on how well you built the drive axle extension and whether you try to rotate the axle/wheel or 40 tooth gear, you will have surprising results if you have never done this before.

Additionally, some robot gearboxes have worm gears which prevent backdriving by design. Trying to backdrive a gearbox with worm gears will break it. The worm gearbox is useful in a robotic arm so that when power is not applied to the motor, the arm won't fall down. The OWI 535 Robotic Arm Edge uses worm gears and regular gears in its motor/gearboxes. Clutches are used in each motor/gearbox to prevent overload or backdriving that will break the gears.

If you need a picture of how to design the drive axle extension and geartrain, let me know.
> 6 votes

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Tags: motor, trains, power-functions
---


# Question
Title: Which "Real World" Company was the first to have its' name featured in an actual (numbered) Lego set?
Excluding the *Lego* company, which "Real World" Company was the first to have its' name featured in an actual Lego set?

# Answer
The 1955 Bedford Esso truck sets that oddTodd refers to were the earliest appearance of a company name/logo on a product in the LEGO system, however these trucks were sold separately as part of the Town Plan, without bricks (although some versions of the 1251 set came with 1x1 bricks that were used as oil cans). An accessory set from 1955 included gas pumps and a printed Esso sign, but no building elements.

The first regular building set to include a company logo or name was 1310 Esso Filling Station from 1956. The next building sets to include a company name and logo were 306 VW Garage and 307 VW Auto Showroom, both released in 1958. (The first use of the VW logo was on the first 1:87 scale car LEGO produced in 1956, the VW Bus.)

Usage of the Esso name ended in Europe and Australia in 1965 and in the US in 1966. In 1966 the Shell brand name was first used in set 325 Shell Service Station
> 6 votes

# Answer
Esso (aka ExxonMobil) showed up in one of the first sets ever, released in 1955. Bedford, a truck maker, was also represented in the same set (and others from that year). I do not know if there were Bedford sets released before the Esso/Bedford sets, since they were all released in the same year.
http://www.bricklink.com/catalogItem.asp?S=1250-2

Esso also shows up on an actual printed brick in this 1958 accessory set:
http://www.bricklink.com/catalogItemInv.asp?S=226-1
Note that 1958 was the start of the current stud-and-tube technology.

Ferguson plastic tractor (1951):
http://aboutus.lego.com/en-us/lego-group/the\_lego\_history/1950
> 4 votes

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Tags: piece-information, history
---


# Question
Title: Best mini LED spotlight for Lego display case?
I am currently building the Creator Sydney Opera House and planning a display case for it. I would like to light the canopies with spotlights just like the real thing, but have not found LED spotlights that are small enough to be proportional to the set. I live in Indonesia so perhaps my choices are limited. The ones I have found are big ones like for cabinets and shelves. Would appreciate your suggestions from around the world. Thank you very much.

# Answer
I'm not sure exactly how many lights you are looking for, or the exact effect you are trying to create, but you may be able to get what you want using individual LEDs:

These have a diameter of 5mm, so the nose is able to fit snugly into an antistud. I've used them successfully in Technic holes and Erling bricks. The main advantage here is that you can actually brick build whatever lighting you would like to use, or just integrate this into the main model.

Here's an example of using these with Erling bricks that I saw on Eurobricks:

If you aren't comfortable wiring these up yourself, you can buy them prewired with a controller from LifeLites.

If you would like to be a purist, you could also use a number of the PF lights (8870), as they are roughly the same as using 5mm LEDs. PF lights are 3mm LEDs encased in plastic so that they fit snugly into Technic holes.
> 9 votes

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Tags: storage, lighting
---


# Question
Title: What are the memory requirements of EV3-G software blocks running on NXT bricks?
The NXT brick has about 130K memory available for user programs.

With the newer firmware required for downloading EV3-G programs that memory has been reduced to 118K.

How much memory is used by the various blocks available in EV3-G?

What tricks can be used to cram many programs onto the NXT brick's limited memory space?

I'm a coach of an FLL team that is using the NXT brick. Should they use EV3-G or stick with NXT-G?

See Comparison of 10 blocks shows memory usage of NXT-G and EV3-G are nearly identical.

# Answer
> 1 votes
The move steer and move tank blocks take 5kb each while the large motor block takes 4kb. If you have a long string of move blocks in your program, it will take up big chunks of memory. We've gotten around that in the past with using myblocks. Myblocks are only copied to the NXT once and called each time it is needed in the program. A pivot myblock might take 7kb but you can use it as many times as you like without taking up more memory. We make a myblock for just about every common move used in our programs. It pays to make a myblock if a string of code will be used more than once.

I would stick with EV3 software if you plan to move to the EV3 hardware in the next season or two. I personally liked NXT-g better but we upgraded our hardware to EV3 this year.

Edit - I just compared the NXT blocks to the EV3 blocks and there is quite a difference. The NXT-g move block only takes 2.4KB and the motor block takes 1.1KB. Our pivot myblock that takes 7KB in EV3 only takes 1.6KB in NXT.

---
Tags: nxt, ev3, programming, nxt-g, ev3-g
---


title: What are LEGO's best selling products?

text:
# Question
Title: What are LEGO's best selling products?
I am doing a school project on LEGO.

I have two questions for you. How much profit does Lego make each year? Also what products have been the biggest sellers and in what years?

# Answer
> 10 votes
You can find some of The LEGO Group's financial information in their annual report. Note that the financials are in Danish kroner, so you'll need to do some currency conversion. For example, the net profit for 2012 was 5.6 billion DKK, which works out to about 1 billion USD.

I'm not aware of a reliable way to get official sales numbers for individual products or even product lines. The Mindstorms RIS 2.0 set was the best selling individual product as noted in this article from 2008:

> The Mindstorms RIS 2.0 is the #1 selling product in the company's history, and there are over 1 million RCX bricks that have been sold.

TLG does occasionally release some product sales information, as shown in this Brickset post.

If you are interested in the current bestselling sets, there is a page on LEGO.com with this information. Brickpicker also has a section for the current bestselling sets on eBay.

---
Tags: history, lego-group
---


# Question
Title: Is there an easier way of threading Technic pins into other elements?
I've been using Lego Digital Designer to recreate a few models I've built in real life. One model in particular uses many Technic axles which need to be inserted fully into other Technic bricks (like the \[part:32014\] shown in the image below).

**(Click image for animation)**

If Technic axles aren't inserted all the way, it causes more problems later on in the build, when the same group of parts are duplicated and used elsewhere.

In some cases, moving the camera angle around can help, but the axle continues to flicker around the screen as the axle is inserted.

# Answer
> 7 votes
As someone who also argues with LDD occasionally, have you tried using a placeholder technic beam to get two connectors at the right distance and then adding the axle into both connectors before deleting the placeholders?

If the placeholders are in a different colour from the rest of the model, you could use as many as you need and then delete them with the Colour Select tool, leaving just the parts behind.

# Answer
> 0 votes
One possible solution, but I can't tell if it would be easy, might be to edit the .lxf file yourself to check/correct the position of the axle.

Unfortunately, I'm not sure there is much documentation on the subject; at the very least I think the .lxf extension is just a zip container, so changing .lxf to .zip is the first step. (of course, backup the whole file first...)

Considering there are ways to convert files between LDD and LDraw, I would tend to think it's possible somehow. You could also convert the file to LDraw and check/correct the axle position within an LDraw editor (they usually give you the coordinates somehow, and at the very least you can check the .ldr source easily as it's text-based). You could also use LDraw altogether, if you find out it helps you place parts (maybe it would).

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Tags: technic, ldd
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title: Pushing LEGO city train

text:
# Question
Title: Pushing LEGO city train
Are you able to push the LEGO city train around the tracks without damaging it or do you always have to use the batteries to make it go?

# Answer
You can definitely use the trains without batteries and push them on the tracks. In fact, a lot of LEGO trains come without the battery option, and you can add it if you want.

Most people will get the battery option as it is fun to watch LEGO trains go on their own, but it is not necessary.

You can even build raised tracks and have the train go down on them by gravity...(c:

One thing I would also add is that it is best to either pull the train from the front, or push it from behind. Don't put pressure on it from the top; like how little kids tend to push trains putting their weight on the train as they push it from the top. That could damage the axles of the train.
> 5 votes

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Tags: trains, city
---


title: Are variables always global with NXT?

text:
# Question
Title: Are variables always global with NXT?
New to NXT software. What I'm trying to do is get my motor to go one of 5 distances, but I'm not sure how to choose between those actions. What I thought of was setting 5 variables to 5 sensors. The idea is that if I activate 1 of 5 sensors (left button, enter button, right button, touch sensor, sound sensor), it will know which of the 5 variables are usable and simply does that.

# Answer
Yes, global.

5 variables may be 4 more than required. I think one is enough.

```
Set intSensor = 0
Loop until intSensor > 0
    If leftButton then intSensor = 1
    If rightButton then intSensor = 2
    If enterButton then intSensor = 3
    If bumped1 then intSensor = 4
    If soundVal > 50 then intSensor = 5
End Loop
If intSensor = 1 then moveForward(135)
. . .

```
> 4 votes

---
Tags: nxt, programming
---


# Question
Title: How to install NXT / EV3 software on Windows 8.1 RT
I have a 64 GB Microsoft Surface running Windows 8.1 RT. I am trying to install the old NXT 2.0 software and new EV3 software, but when I try to open the `.exe` file it says:

> This app can't run on your PC
>
> To find apps for this PC, open the windows store.

How am I supposed to install this?

# Answer
> 3 votes
Sadly that's a limitation of Windows RT - there's no way you can install the EV3 software on there.

Windows RT can only run apps from the Windows Store (and some specially compiled apps that MS supply such as Office RT - however I don't think the typical user can install a correctly compiled non-Store app on the Surface - as a developer you can side load your apps for testing, but they are still Store apps).

*Technical Aside:*

Windows RT is compiled to run on ARM chips, which are similar to the ones in a Phone or other tablet device - as such applications such as EV3 which are compiled to run on "x86/x64" chips will not work - it's similar to the difference between x86 and amd64 - these were different chips, with different instruction sets.

LEGO would need to produce a Windows Store version of the EV3 software, alongside any other mobile versions and - sadly for you and me (yes I've got one too) - there probably isn't enough market penetration to justify it yet...

# Answer
> 2 votes
Microsoft have just announced that they are releasing an API for Windows 8.1 and Mindstorms EV3. Hopefully this will mean some apps for the two platforms will emerge sometime in the future.

---
Tags: mindstorms, software, nxt-g, ev3-g
---


# Question
Title: How many styles of element separators has LEGO produced?
I used to use other LEGO elements to separate tightly bound pieces in my collection. My thumb nail and I were quite pleased when I first discovered an actual brick separator LEGO introduced to ease the task. How many styles of LEGO element separators has LEGO made available to the general public?

# Answer
Bricklink lists two:

OLD (in two colors):

NEW (in three colors):

There is one other 'separator', but it doesn't look like it's very good for bricks: RC Car Separator Tool - Metal

ETA: The Clickits Separator!

---

As of 2020 there is another brick separator designed for removing more tiles with a single motion and included with the Mosaic sets.

The DOTS theme added another implement in two different styles to remove individual tiles.
> 10 votes

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Tags: piece-information
---


# Question
Title: What is different between the EV3 Home and Educational sets?
The newly announced LEGO Mindstorms EV3 sets for home and education have some differences, but it isn't clear to me what they are, specifically. It seems that have different sensors, perhaps different exotic pieces (like a remote or caster wheel) and possibly slightly different software. Granted, the sets have not been released, but, what do we know about that is different in the two sets?

# Answer
Both sets include an EV3 intelligent brick.

## Hardware

The Retail (Home) edition (set 31313) includes:

* 2 large motors, 1 small
* 1 touch, 1 color, 1 infrared proximity , 1 remote IR beacon

The Education set includes:

* 2 large motors, 1 small
* 2 touch, 1 color, 1 Ultrasonic with red LED, 1 Gyro
* 1 rechargeable battery (battery charger sold separately)

## Software

The software for the education version is sold separately to the core set. As well as the programming software, includes datalogging tools, and a firmware version that allows on-brick datalogging.

There is also a difference regarding sensor support: only the education version provide blocks to manage ultrasonic and gyro sensors included in that version. NXT temperature sensor and Energy meter are supported too. And of course, models being different between edu and retail versions, the building instructions that are included in the software are different.

## Robots

Each edition includes different Technic bricks and instructions for different robots. You can find a list of those robots at the LEGO Mindstorms EV3 Comparison project, and product pictures on Robot Square.

## Parts

The EV3 Expansion Set adds many Technic bricks for even more robots and is suitable as an upgrade for both sets. However, to build all robots officially published by LEGO for either set you need to buy additional parts in any case.

The LEGO Mindstorms EV3 Comparison project on GitHub lists all parts in a spread sheet, tells you which pieces are missing from "education + expansion" to "retail + expansion" and vice-versa, so you can find out which parts (numbers + names) to order in addition.
> 21 votes

# Answer
## Hardware

| No |  | Education EV3 | home EV3 |
| --- | --- | --- | --- |
| 1 | Intelligent Brick | 1 | 1 |
| 2 | Large Motor | 2 | 2 |
| 3 | Middle Motor | 1 | 1 |
| 4 | Ultrasonic Sensor | 1 | 0 |
| 5 | Touch Sensor | 2 | 1 |
| 6 | Color Sensor | 1 | 1 |
| 7 | Gyro Sensor | 1 | 0 |
| 8 | Infrared Sensor | 0 | 1 |
| 9 | IR Beacon (Infrared Remote Control) | 0 | 1 |
| 10 | Rechargeable DC Battery | 1 | 0 |
| 11 | Transformer 10V DC | Option | 0 |
| 12 | the number of parts | 541 parts | 550 parts |
| 13 | tray |  | × |

## Software

| No |  | Education EV3 | home EV3 |
| --- | --- | --- | --- |
| 1 | Lobby（the main menu of the software） |  |  |
| 2 | Programming |  |  |
| 3 | Data Logging |  | × |
| 4 | Contents Editor |  | × |
| 5 | Robot Educator |  | △（assembly diagrams for 5 models） |
| 6 | Sound Editor |  |  |
| 7 | Image Editor |  |  |

Based on this comparison: https://web.archive.org/web/20140227052442/http://www.ev-3.net/en/archives/98

Some other direct links:

Brickset (check Parts tab):
> 3 votes

# Answer
There are differences between EV3 Education and Home set including software, hardware and parts.

# Software

A slight difference is in the firmware that comes with on-board datalogging capabilities only for Education version

# Hardware

The retail version includes a small amount of components compared with educational set, components that include one small motor, 2 large motors, and four sensors (touch, color, infrared proximity, and remote IR beacon). The educational set includes the castor wheel, 1 small motor, 2 large motors, 2 touch, 1 color and 1 ultrasonic sensor with red LED, 1 gyro, 1 rechargeable battery, and the possibility to download the EV3 software.

# Parts

There is a difference of overall 10 elements between retail and educational versions
> 3 votes

# Answer
I received my EV3 educational kit last week. Yes, it comes with the a rechargeable battery, battery charger, the castor wheel, and a code that permits me to download the EV3 software. It is disappointing that the educational kit does NOT come with the infra red sensor or IR remote. Also the educational set comes with approximately 500 more technic bricks than the retail version.
> 1 votes

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Tags: ev3, education
---


# Question
Title: Are both of these slope designs genuine LEGO?
Are both of these slope designs genuine?

I am reasonably certain that this is just a mold change at some point, but it doesn't hurt to ask. I also have two textured types in dark blue, and one smooth type in sand blue.

# Answer
> 7 votes
It looks like it could be either #3049 or #3049c. Part #3049 currently exists in Sand Blue in at least three sets. As for the change in smooth and rough texture you may wish to read this answer by Joubarc.

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Tags: piece-information
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title: Using motors to ring a bell?

text:
# Question
Title: Using motors to ring a bell?
I would like to create a motor set up so I can use it to ring a bell inside a small tower. Since I haven't used any of the current LEGO motors was wondering what the group would suggest.

1. which motor to use.
2. which battery/switch to use.

What I need is a simple switch with a motor. Something that I can turn off and on with out much trouble.

# Answer
> 2 votes
LEGO Power Functions would probably be the most suitable option. You could use a PF M-Motor (8883) combined with a PF AAA Battery Box (88000) which has a two-way switch and is more than capable of powering four medium size or two extra large motors (each item sold separately).

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Tags: building, motor
---


title: Lego MOC joining query

text:
# Question
Title: Lego MOC joining query
I have a building query. As you see the picture (attached). I really don't know how the creator can attach the "3829c01" steering wheel to the "4070". I try so many rod like parts can't get through the hole of "3829c01" Hope anyone can help.

Thanks!

# Answer
I was able to find a few elements that are able to make this connection possible. I'm guessing the designer used some type of bar-sized element which is made from a different material that is able to compress slightly more than regular ABS. For example, the softer plastic used on some minifig weapons seems to work nicely:

Another option could be flexible Technic tubing. I was able to make this work, but it feels like a very tight fit. This tubing could also be cut to length under some definition of LEGO purism.

Of course, as Kramii pointed out, this could also just use non-standard elements or part modification.
> 3 votes

# Answer
They used a "lightsaber blade", more generally called a Bar 4L or some other Bar element. Bar elements are used extensively in SNOT building since they can pass through both Technic axle holes, Hero Factory double holes, open-hole studs, as well as many other elements like the Erhling/Headlight brick with the standard bar sized hole. The standard "clip" type elements also use the same diameter and so can also be added to these combinations.
> 0 votes

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Tags: building, moc, wheel, steering
---


# Question
Title: Identify bulldozer truck -probably from early 90"s
Have a bulldozer looking truck with green rocket boosters on it and silver arrows, silver knives on each side of the dome like top

* Colours: black green, clear green dome
* figure has clear green helmet, not an alien
* bulldozer on chain and lifts by hand...

# Answer
This sounds like 2161 Aqua Dozer from the Aquaraiders theme.
> 3 votes

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Tags: set-identification
---


# Question
Title: How can I use System and Bionicle elements together?
I have a small collection of Bionicle elements that I would like to incorporate into my System builds but I am a little unsure how to use them.

What are the different ways to use these two types of bricks together?

# Answer
since the bionicle-pieces only have holes for technic-connections and no studs to use then directly with bricks, you'll have two possibilities:

* build some kind of "adapter" using technic-pieces. you could use pegs to connect the bionicle-piece with some kind of technic-brick.
* put the studs of your system-bricks into the bionicle-pieces technic-holes - which may not be the best idea

I'd prefer the first option - it's easy, more robust, not controversial and just need two or three pieces in most cases. for example a brick with axle-hole and a small axle or a brick with hole and a simple peg is all you need to get started.
> 12 votes

# Answer
As oezi says, Bionicle elements are usually compatible with Technic connections only, but there are quite a lot of system bricks which have Technic connections as well.

As for what to do with Bionicle elements, only your own imagination can answer that. Once you've an idea about what a specific Bionicle element is going to represent in your creation, how to connect it is usually not the biggest issue. So, go surprise us!

Of course, some green Bionicle elements are best used in wilderness, as they have "wild" shapes — allowing you a little more freedom than if you wanted to build buildings. Giant weapons on the other hand may become a cool building decoration.

The best example I can think of is this palmtree which is just brilliant.
> 3 votes

# Answer
You can also attach the first generation Bionicle masks using their, 'stud,' joint, the second generation masks are a bit looser, and the later masks have Technic connections.

I have only ever used this to provide a texture at the front of a spaceship, but if you have the right masks you could use the gaps to create gun covers, etc.
> 1 votes

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Tags: compatibility, bionicle
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# Question
Title: What's the sight of the ultrasonic sensor according to the distance of the object?
Hey I'm programming a sumobot for a first-year university Civil Engineering project. We should need the sight of the ultrasonic sensor according tot the distance of an object. For example, the sensor can detect an object that is located 30 cm away 55° to the right of the sensor, but an object 50 cm away from the sensor can only be detected to 45° to the right of the sensor (approximately). Does anyone know the relationship (maybe a function?) between the sight and the distance? Thanks!

# Answer
ETH Zurich faculty/students conducted some experiments on exactly this back in 2006. The relevant parts of their results have been reproduced below. For more information, visit their website: http://www.tik.ee.ethz.ch/mindstorms/sa\_nxt/index.php?page=tests\_us.

The chart below shows accuracy of the sensor at detecting a 14.5 cm x 9.5 cm x 6 cm block at various distances and angles from the sensor.

**Distanz** is Distance in CM, **Winkel** is Angle in degrees, and **Relative Fehler** is relative error.

According to the researchers:

> The results show that the ultrasonic sensor should always be placed in horizontal position, other positions decrease as well the field of vision as the sighting distance of the sensor. The sensor seems to be a bit 'blind' on the left eye, which can be explained by the fact that the left eye is actually the receiver of the ultrasonic wave while the right eye is the sender.
> 1 votes

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Tags: mindstorms, nxt
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title: Suspension bridge building techniques

text:
# Question
Title: Suspension bridge building techniques
I am working on a suspension bridge with my sons and have encountered two problems.

**Our technique:**

* 8x6 plates for the roadway
* 1x8 bricks (with side-holes) underneath each side of the roadway to support the roadway, connect the plates, and link the Technic beams to the suspension rope.
* Technic beams of varying lengths (2- to 9-studs) which hang from the suspension rope.
* Twine, as the suspension rope, to connect the technic beams to the bases at either end of the bridge.

**Our Dimensions:**

* 6-studs wide
* 69 studs long.

**Our problems:**

1. The twine works, but is ugly and doesn't seem like proper Lego technique - is there a more appropriate (i.e., LEGO-approved) material?
2. The Technic beams all lean as if pointing towards the center of a sphere; I added a second 1x2 brick (with hole in the side) which allowed me to pin the Technic beam in place but that seems bulky and is very inelegant. How do I construct a non-leaning, but more elegant solution?
3. I suppose that it would also be helpful to know whether there is a ratio for tower-height-to length that is most appropriate.

# Answer
> 3 votes
I've used white nylon rope / string for my Lego bridges. When I think of twine I think of the tannish, brownish, rough, fraying type of string. The nylon stuff is cleaner and in my humble opinion appears sharper. A Lego purist would not allow any non-Lego element in a creation, but when it comes to suspension bridges, there are very few options. I've viewed the use of plates (typically 1 X 6 , 8 , 10, etc.) for the main cables and suspenders, but this takes away from the cable feel and appears more like an eyebar suspension system - which were used before the invention of wire cables, but no major suspension bridge built in the past 140 years uses eyebars.

As for your issue with the leaning Technic beams... I'm unable to visualize the problem. Could the Technic beams be leaning due to the pull of the twine? That is if the twine is not going straight vertically to the maincables above then there may be a pull on the Technic beams away from true with that of the plates.

A good tower to span ratio seems to be 1:10 and that is tower above the roadway as what is below the roadway is irrelevant, with ship clearance the contributing factor there. Example... the Akashi Kaikyo Bridge in Japan has towers that are ~975 feet high. The roadway at mid-span is ~320 feet above the water. That makes for the tower above deck of ~655 feet. The span of the AKB is 6,532 feet. This is close to the 1:10 ratio. The Golden Gate is a bit different with towers ~750 feet high and a deck height of ~220 feet. That makes 530 feet of tower above deck and the span is 4,200 feet. Now we're down to 1:8. The difference is the steel in the Akashi Kaikyo Bridge's cable is much stronger due to advances in the 50+ years since the Golden Gate and thus shorter towers could then be built. The shorter the towers the more tension on the cables. Had the steel in the main cables stayed the same strength, then the towers for the AKB would then had to have been at least 150 feet higher.

Here is a link to photos of two lego bridges I've built: http://www.flickr.com/photos/suspensionstayed/sets/72157610808577323/

# Answer
> 0 votes
A team in Perth (Australia) built a pure Lego suspension bridge that is quite long. All the links I can find are to youtube videos which is not very useful (here and here, for example).

This media story has the photo I've copied below

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Tags: building, bridge
---


# Question
Title: Is it safe to drink from Pick A Brick cups?
I have a habit of drinking from the Lego Pick A Brick cups. I sent an email to Lego to ask if they were rated safe for drinking from, and they refused to endorse any use of Lego products that wasn't originally intended.

They did point out that the bricks were made from ABS, but a PAB cup is not a brick, nor did they say if ABS was rated safe for food use.

Has anyone tested the plastic in the PAB cups to see what they are, or if they are safe for food use?

# Answer
The Pick-a-Brick cups are made from polypropylene, as evidenced by the #5 resin identification code on the bottom. Polypropylene is widely considered a safe plastic for storing food and drink, and it is stable at very high temperatures (i.e., temperatures higher than your dishwasher). I would feel comfortable drinking out of one of the cups.
> 11 votes

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Tags: pick-a-brick
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title: How do I quickly count pieces?

text:
# Question
Title: How do I quickly count pieces?
I have LEGO pieces divided into partitions in something like a tackle box, each of which indicates how many pieces are supposed to be in that partition. With few exceptions, each partition only holds one type of part, like this:

One slot might have, say, 5 axles, and another might have 82 friction pegs.

How can I quickly verify if there are the right number of pieces?

I've been thinking that if I went a partition at a time, I could take all the pieces out, spread them over a surface, shine them under a webcam, and have a computer or phone spit out a count for me. Perhaps there is a mechanical way to do this, or maybe using a (really accurate?) scale would do it.

Any recommendations?

# Answer
Tackle boxes are very common for storing Lego, I use them myself. Unfortunately I've not found or seen a good way to count the pieces that are in them. The easy way is to take everything out of them, which I suspect is what you're trying to avoid.

One trick with that is to get a piece of cardboard (or plywood) twice the size of the tackle box, cut a hole in the centre, place it over the tackle box with the hole over a compartment, then invert it with your hand under the hole! With a little wiggling you'll end up with only the pieces from that compartment in your hand. Or, if you lose your grip, everything all over the floor. But when you have a lot of compartments or a lot of pieces, that method is much faster than picking pieces out of compartments by hand. Especially small tiles.

Using a counting scale is a very common way to count small items like this. Lego weigh parts, bags and sets repeatedly during manufacture as part of their quality control process - that's one big reason why so few sets have missing pieces.

The problem you have is that while it's easy to weigh the whole tackle box, that doesn't give you much information about what exactly is missing. I suspect that the uncertainty in the weight (from the variable weight of grime and water on the box) will be about the same as the weight of the smaller pieces.

Doing a search for "image analysis counting" I found this NIH paper that suggests that it's possible to do what you're looking for. I suspect the main problem will be getting images that show the entirity of each well in the tackle box, but you may find that just taking a photo from as far away as possible works. Then you have to set up and calibrate the software. I doubt it will work with irregular pieces or where you can't see every item, though. But it's worth trying just to reduce the overall effort.

Worth doing if you're going to be counting the contents a lot of times. Or you're interested in the problem.
> 2 votes

# Answer
Weighing the whole box might help if you just want to check if it's complete - unless you fear extra parts.

If you want to weigh parts or group of parts, there are scales which have an "item" function - you weigh one, then set it as unit, and then you can use the scale to give a count of the parts on it rather than its total weigh. Precision is important, but usually it's good enough.

Also, if you want to count parts manually, an easy way is to spread them and set apart the ones you've counted, per group of 3 or 4 - and count the groups, not the parts. Taking the example of the friction pegs, you'd spread them, then push 4 aside and count 1, then 4 again and count 2, and so on. After you count 20, you should have 2 left. Note that usually the remainder is enough to get an idea of what's missing or not; so the count part is nearly optional - if there are two pegs left at the end, it could be that 4 are missing, but the likeliness of that is lower. Or, you could do it twice: once with groups of 4, the second time with groups of 5 - both times you need to end up with 2 left. Basically, you just use modulo arithmetic to check only the reminder; which is like the "proof by nine" - it doesn't prove your result is correct, but catches most errors.
> 2 votes

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Tags: storage, inventory
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# Question
Title: Getting started with Mindstorms and/or Technic
I'm looking into getting started with LEGO.
Can you briefly describe the difference between Technic and Mindstorms? I've read that the parts and compatible, so I suppose it's the functions that differ. Am I correct to assume that Mindstorms is more about using sensors and programming your robot so it can act on its own, while Technic needs to be (remotely) controlled?
I'm on a tight budget so I can't just buy anything I want. Assume I can afford around €50-100 a month and I am starting with €150. Also assume I have equal interest in the above mentioned principles about Technic and Mindstorms (if correct). Can you recommend how to get started with either or both?
I see the latest Mindstorms set - EV3 - is around €250. Would it be better to wait a bit and get it, or just get some Technic sets now, and get it later (once my collection is bigger)? Is it viable to just get the control parts and not the whole Mindstorms set? I suppose getting a bigger set is better than getting several small ones.
I'm open to specific sets recommendations, or just general advice - I don't mind spending time browsing and reading on sets.

# Answer
> 8 votes
In my opinion, Mindstorms is a subset of the Technic line up (Like how Police is a subset of Lego City). So most of the parts are interchangeable. The only part incompatibility issue you will come across is the electronics.

I would say go with Technic first. Learning how to build studless and basic Lego mechanisms will be more useful than robotics (initially). Buy the bigger sets as they have more parts and lower price per part (typically).

50-100 quid a month is quite healthy. Once established, Lego has a pretty low maintenance cost (If you don't want every set). You will find Brick Owl and Brick Link a good source of specific parts.

I suggest a browse of http://sariel.pl/ and http://www.technicbricks.com/ to get some ideas on what is possible.

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Tags: technic, mindstorms, shopping
---


# Question
Title: What pieces do I need to make suit swappers from the Lego Batman video game?
My son has asked Santa to bring him Lego Batman suit swappers to use with his minifigures, both Batman and Robin versions. Can anyone advise as to what pieces are needed for these? All help is very much appreciated by Santa and his elves.

# Answer
You mean one of these?

Basically, you'll need two circle of these 4 x 4 corner bricks:

Separated by some of these Plate 1 x 2 with Handle:

I don't think the centre red tile with an "R" on it exists, so I think you'll have to make one out of card or something.
> 2 votes

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Tags: building, video-games
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# Question
Title: Unable to connect to NXT using NeXTTool via USB cable
For reasons beyond me, the NXC program `MotorControl22.rxe` in my NXT has disapeared. So i thought I'd just download it from my computer over to the NXT using NeXTTool.

This is where the trouble begins. Firstly, I have no problems listing the NXT in my devices when connected and turned on. I have also been able to upgrade the firmware twice during my troubleshooting, trying to find a solution. But for some reason, using the NeXTTool, I'm not able to connect. I've tried downloading the file using `NeXTTool \COM=usb -download=MotorControl22.rxe` and after that tried `NeXTTool /COM=usb -listfiles=MotorControl22.rxe` with no result.

This made me test just listing anything from the NXT, but even writing `NeXTTool /COM=usb -listfiles` didn't show anything, even though I have confirmed that there are several programs, sound files etc on the NXT.

* I'm currently running Windows 8.1 64-bit
* The driver is libusb-win32
* I'm running NeXTTool from Windows cmd with admin rights
* I don't get any error messages upon running the download command
* This has not been a problem earlier upon installing and verifying that everything works.
* Flashing a new firmware works just fine when in Update firmware mode using `NeXTTool -firmare="firmware.rfw"`
* Bluetooth works too, but upon running the download command, nothing happens.

Has anyone run into this problem before? Anybode have any idea how to simply download a file to the NXT and what might be causing it not to work now?

# Answer
Joubarc's idea would probably be your best bet - try downloading the file to the NXT using the official LEGO software. If this fails, you know something is wrong with your brick. If it works, it's probably a problem with your program. Did anything major happen between the time it would work and the time it wouldn't? If so, this may be the culprit. Trying it on multiple bricks is also another avenue I would suggest. There is an official Mindstorms Help Section on the LEGO Message Boards located here. They have experts who will probably be able to correct your problem.
> 1 votes

# Answer
Procedure as follow, uninstall libusb\_win32 driver; not disable activate back NXT fantom driver transfer MotorControl22.rxe with NeXTTool or TransferMotorControlBinaryToNXT.bat execute install-filter-win from directory libusb\_win32/bin for USB NXT connection it work for me
> 1 votes

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Tags: nxt, mindstorms, motor
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title: Invert motor block in EV3

text:
# Question
Title: Invert motor block in EV3
New to EV3 so this should be simple. I would like my simple wheeled robot to go backwards. So I put two invert motor blocks, one for port B the other for port C followed by a move steering block. The motors ran forwards! I then tried an invert motor black followed by a large motor block and that worked just fine. Does invert motor not work with move steering or am I missing something obvious?

# Answer
In EV3, use a negative number for the power to go backwards.
> 4 votes

# Answer
We experimented with the invert motor block at the beginning of this year's FLL season with disappointing results. The invert motor block only worked with the large motor block and not the move steering or move tank blocks.

Use a negative number in the power field to go in reverse.
> 2 votes

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Tags: programming, motor, ev3
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# Question
Title: Where I can find the pieces needed in a set?
I own this set, LEGO® Kingdoms King's Castle 7946.

One day I let my wife's best friend's kids play with it.

(Not the best idea in the world but they had a blast!)

Needless to say, the castle ended up being torn to pieces pretty much.

It has sat in a box for a few months now and I really want to dig it back up for a rebuild.

**The problem I have now is I don't know every piece I need.**

I'm sure some of the pieces have been lost but I have a massive box of extra pieces. Is there a website anywhere that contains the piece count of a set and what pieces are included in the set?

Any ideas on what I can do? or do I have to try my best to rebuild it?

# Answer
> 4 votes
If you don't physically have the instructions, you can look up the set ID on LEGO's Customer Services page dedicated to providing building instructions.

The inventory list is usually found right after the final building step. For #7946 the parts list can be found on pages 74-75.

If for whatever reason you cannot access the instructions from the LEGO site, perhaps the file has been removed or you're unable to view PDF files you can still find a part list on sites like Bricklink and Brickset (see parts tab).

# Answer
> 0 votes
Let's not forget Peeron. You can lookup the parts in your sets, and the site will keep an inventory of the parts you have.

The parts for set 7946-1 on www.peeron.com

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Tags: sets
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# Question
Title: Can I use the NXT 2.0 programming software with my educational set?
I have bought the 9797 NXT base educational set. It didn't include any software.

I know that I can freely download the NXT 2.0 software (which was included in the 8784 retail set). Is it possible to use this version of the software with my education set?

# Answer
Yes, you can - I have done so on numerous occasions, and actually prefer to use the retail software over the education version even when working with the education kit.

The NXT bricks in the two sets are exactly identical. You might need to update the NXT's firmware before using the brick with the retail software, however.
> 2 votes

# Answer
Yes, I do this with mine because the consumer version of the software has more features than the education (but no datalog and you won't have the pieces for the building instructions that come in the software in your kit)
> 1 votes

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Tags: mindstorms, nxt, software, education
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# Question
Title: Do you know where I can get a Brick Vac?
I am in dire need of a Brick Vac. The 2 boys 5 and 7 are building daily, but still have plenty of strays on the floor and the end of the day. With the growing popularity of Lego City building sets, along with Star Wars sets and Legos in general, we need to get Lego to start making the Brick Vac again, to save on mom and Gramma's feet. !

# Answer
> 1 votes
If you really want one, these can still be acquired on Bricklink:

http://www.bricklink.com/search.asp?itemID=45363

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Tags: organisation
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# Question
Title: Can I open my old NXT program files in the new EV3 software so I don't have to rewrite the entire program?
I would like to use or convert NXT-G 2.0 programs for use with the new EV3 software. Is there an easy way to convert them besides just building them from scratch in the EV3 environment?

# Answer
> 3 votes
No.

Unfortunately there are no shortcuts. EV3-G can not open programs written in NXT-G.

To quote Lego:

> 9.5 I have a LEGO MINDSTORMS NXT2.0 (8547) set; will there be an upgrade/conversion kit from NXT to LEGO MINDSTORMS EV3 (31313)? No, but LEGO MINDSTORMS EV3 offers backward compatibility to NXT. You can therefore use your NXT Intelligent Brick together with Intelligent EV3 Bricks in many situations. However, if you want the full benefit of LEGO MINDSTORMS EV3, you will need to transition to Intelligent EV3 Bricks.

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Tags: nxt, ev3, programming, nxt-g, ev3-g
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# Question
Title: How do I unlock the sunday surprise on the 2013 Star Wars Advent Calendar?
I'm trying to enter the code on the back of door number 1 into the Lego Star Wars site but it doesn't work. Does anyone know how / where to input the code?

# Answer
> 2 votes
I just found this website:

http://www.lego.com/en-us/starwars/games/web-games/advent-calendar

it has special stuff each day, the place you enter the code is the image of jango fett in the bottom middle.

# Answer
> 1 votes
By "the build instructions" you mean how to assemble the day one model? It's right there on the flap. I doubt there's anything more to be had.

# Answer
> 1 votes
The instructions to build it are on the back of the flap and to enter the code go to lego.com/starwars and go to fun and games or something. It mentions games. Anyways, there is a game called "Advent Calendar" and you click on a button torwards the bottom of the game screen (which you can make fullscreen) and enter the codes. They just unlock minifigures that you can be while playing the game.

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Tags: star-wars, advent-calendar
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