# Question
Title: How can I get my NXT to turn on - all it does is softly click?
Recently when I plugged my NXT brick into my PC I clicked on the wrong option and now all it does is clicks when I turn it on? How do I get it back to a usable state?

# Answer
If you are using NXT-G, the software that comes with the NXT set, then here is what you do:

1. Get into NXT-G, start a new program.
2. Select the **tools** option, and from the drop-down menu, select **"Update NXT Firmware..."**
3. Plug your **USB** cable (one comes with the set) into your NXT. Don't try using bluetooth, as it won't work.
4. Click the **download** button on the interface which popped up at the end of step 2.
5. Don't unplug your NXT, wait until it **reboots** with its **firmware** loaded.

Congratulations! You have just brought your NXT out of SAMBA mode!
> 6 votes

# Answer
This means your NXT is spoiled and needs reseting. This is usally caused by unplugging before the program downloaded.
To reset
1) Completely disconnect your NXT from the computer (no USB connection).
2) Remove all external BlueTooth dongles from your computer, and turn BlueTooth off on the computer (just to be sure).
3) Reboot the computer (this is to make sure no other application is trying to compete for the USB port).
4) Restart the Mindstorms application (and, if possible, don’t start any other applications).
5) Remove one battery from the NXT for a couple of seconds, then reinsert it.
5) Push the NXT reset button firmly for five seconds (make sure you actually press it, and press it for the whole five seconds).
6) Now (with the NXT clicking and the environment up and running), connect the NXT to the computer via the USB cable. Preferably use a “primary” USB port, one on the computer itself and not on a keyboard or monitor.
7) On a PC, you can go to the device manager and check to see if the NXT shows up in “Firmware Update Mode” (if not, you may need to uninstall and reinstall the software and drivers)
8) Update the firmware to 1.03 using the “update firmware” under the tools menu.
9) If this does not work, try *briefly* (one second) pushing the reset button again.

If the above sequence does not work, try repeating steps 1-9 but using a different USB port on the computer.
> 1 votes

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Tags: nxt, repair
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# Question
Title: What's the best way to machine LEGO pieces on a mill?
Does anyone have experience with modifying LEGO pieces on a mill? Any suggestions on cutting speed?

# Answer
> 2 votes
I don't have any experience modifying a brick with a mill but I have had success using a drill press, knife, and dremel. I can't imagine there being any problems while using a mill.

If you're looking to clean out the pipes inside a brick, I've found higher speeds with a drill work better. At a lower speed, the bit cuts into the pipe but doesn't remove any of the plastic. When the bit is spinning faster, it doesn't cut into the pipe but shaves the plastic off.

Lego is ABS plastic, I believe, so doing some research on working with ABS, rather than specifically Lego, might give you more answers too.

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Tags: manufacturing
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# Question
Title: What is a normal range of reading of the Light Sensor using EV3 Raw Sensor block?
EV3 software does not support the Light Sensor. It does support the Color Sensor.

The solution is to use the Raw Sensor Block.

What is "normal" for raw sensor block readings?

I'm getting readings between 450 and 700, with brighter readings at the lower end of the range. I expected brighter to be the larger number. Is there an expected range of values?

Is it because the software is running on an NXT brick?

# Answer
> 3 votes
My FLL team wrote a light sensor myblock that converts the raw value to a number between 0 and 100. They run it on the EV3 so they can use their existing NXT light sensors. It should work on the NXT brick as well. Here is the video they posted to explain how it works.

http://youtu.be/I7Bqvk-uMLk

# Answer
> 2 votes
You can consider this the "official" answer based on the EV3 firmware source code.

This file is used for scaling the values that you see in "Port View" on the EV3 brick itself.

The NXT Light Sensor is defined in these two lines:

```
2 0 NXT-REFLECT 1 1 3 0 2 119 0x32 3372.0 445.0 0 100 0.0 100.0 20 0 pct
2 1 NXT-AMBIENT 1 1 3 0 2 119 0x30 3411.0 633.0 0 100 0.0 100.0 20 0 pct

```

This means that in NXT-REFLECT mode (LED is on), a raw value of 445 = 0% and a raw value of 3372 = 100%. In NXT-AMBIENT mode (LED is off), a raw value of 633 = 0% and a raw value of 3411 = 100%.

To change to NXT-AMBIENT mode, you might be able to use the NXT Sound Sensor block. Select the port that is connected to the light sensor and set the mode to "dBa".

# Answer
> 0 votes
Is it because the software is running on an NXT brick?

YES, The raw value range of light and sound sensor is 0~1024 on NXT.

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Tags: mindstorms, nxt, ev3, programming
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# Question
Title: Good EV3 iBook for programming or building
I am a participant in a Lego mind storms competition soon using EV3. I would like to know if there are good, free iBooks for me to download (PDF or iBook from the apple iBook store). Preferably the book should be about using EV3-G or building playing field style robots.

# Answer
First answer is google: FLL EV3 PDF
EV3 and PDF are obvious. FLL is short for FIRST Lego League, which may or may not be for "playing field style robots".
Clinics for coaches and kids at HighTechKids.org use FLL Programming 101 as a starting point.
The EV3 is new enough, that some of the best programming advice for FLL is directed at the NXT.
> 0 votes

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Tags: mindstorms, ev3, ev3-g
---


title: How to restore old, scratched plates

text:
# Question
Title: How to restore old, scratched plates
I have some old lego plates that are quite scratched. They look rather dull compared to the newer pieces in my collection. Is there any way to restore (even partially) the shiny look between the studs?

I'd heard that using toothpaste can help smooth out transparent pieces, so I tried putting toothpaste on the plate. However, it seemed like it would be insane to try to rub the paste manually between all the studs... so I used a nylon brush to brush the plate. That didn't seem to help much, but didn't make it any worse. Would it have worked if I'd manually rubbed the paste in? Is there a faster way of doing that?

# Answer
> 6 votes
Brasso (yes, the metal polish) works better than toothpaste in this case. It is a bit more grainy so works faster but doesn't damage the parts. It does take some work though that may or may not make sense depending on the rarity of the elements.

And yes, with either toothpaste or Brasso, you actually have to vigorously rub the surface to buff it up. It might be easier and cheaper just to replace the worn parts with new ones if they really bother you.

LEGO getting scratched up a bit is normal. In most colors you won't even notice it, but there are certain colors where scratches are more visible — with black being the worst. So it actually helps to store black parts stuck together to prevent rubbing against each other in storage.

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Tags: repair
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title: Legal free NXT-G download

text:
# Question
Title: Legal free NXT-G download
Where can I get a legal, free copy of NXT-G for mac?
I lost my disk when I bought my NXT, and I need to get a new program.

# Answer
> 5 votes
LEGO has recenlty made this easier to find:

http://www.lego.com/en-us/mindstorms/downloads/software/nxt-software/

# Answer
> 0 votes
Try looking around here: http://service.lego.com/en-us/helptopics/products/themes/mindstorms/mindstorms-nxt/nxt-software-download Or here: http://service.lego.com/en-us/helptopics/products/themes/mindstorms/mindstorms-ev3

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Tags: nxt-g
---


# Question
Title: Is it safe to remove PC (polycarbonate) arms from minfigures?
I would like to replace the clear PC arms on the Chima ice figures with opaque ABS. Would I still be able to use the clear PC arms with other figures after I have removed them?

I know that removing and replacing arms makes them slightly weaker and can only really be done once, what I am interested in is the relative durability of PC and ABS in this regard.

# Answer
> 4 votes
The clear PC arms are more brittle, however you should be able to replace them at least once, since the torso you are placing it into is ABS - so there is a bit of a give/flexibility on that side.

One thing to be careful of, is when you take out the PC arms (and when you put them in a new torso), do not hold the arms by the hands! This will put pressure on the wrists and can make the more brittle PC plastic crack. Either hold the arms further up, or even better, take out the hands first, then the arms. Hope this helps.

---
Tags: disassembly, plastics
---


title: Are LEGO bricks recyclable?

text:
# Question
Title: Are LEGO bricks recyclable?
Yes, I know that it is kind of a dumb question, as no one would want to dispose of LEGO bricks.

But it's a curiosity thing: are LEGO bricks recyclable?

# Answer
According to this website, LEGO bricks are made from a type of plastic called *acrylonitrile butadiene styrene* or ABS. We do have the technology to recycle ABS, however you would need to check with your local/national waste disposal service whether it is in use. Dropping unwanted bricks off at a local charity bin or childcare provider would certainly be the easiest way to "recycle" LEGO :)
> 36 votes

# Answer
The LEGO Group's sustainability report covers a few key areas, although it's not completely clear.

At the most basic level, they see passing your bricks on to relatives or friends as the most environmentally friendly way of "disposing" of your bricks:

**Sustainable Play**

> We believe that the LEGO Group should produce and market high quality products that last for generations and are safe online and offline. It is about continuing to develop a systematic approach to creativity and play to enhance learning and to help pass on the joy of play from generation to generation. We call this Sustainable Play.
>
> All LEGO bricks are compatible across time and product line, giving each brick a very long lifetime. LEGO bricks never become redundant, as each one can be reused to build new ideas and to unfold children’s creativity. Bricks that are not passed on to family or friends are often sold second-hand. We call this Sustainable Play. The resilience and long-life of LEGO products supports our Play Promise by extending play value over time. It also opposes a culture of ‘play and throw away’, helping to support our Planet Promise.

However they also touch on the option of recycling the bricks themselves when they talk about reusing them as the raw materials for new products:

**Design for disassembly of LEGO elements**

> Design for Disassembly is about designing a product so it can be separated into base elements of materials at its end-of-life. Each element can then be reused as raw material for new products. When it comes to sub-assemblies and the electronic elements of our products, we also see an opportunity to encourage innovation by our suppliers to support cost reductions and environmental optimisation at the same time.
> 6 votes

# Answer
**Short answer:** No, but you can make sure they are reused by sending them to us (go to www.brickrecycler.com for info on sending in your LEGOs and getting postage reimbursed if you desire and live in the US).

**Long answer:** We personally researched or called over 35 recycling programs that serve a population of over 30 million customers (top 30 cities with highest population, plus several more). Only one Curbside Recycling Program claims they can recycled mixed LEGOs. Only the City of San Fransico (proper) bales them up and ships them to China, but doesn't know what they make out of them). All the other cities (including NY, Dallas, Chicago, LA, San Jose, etc) said they cannot use them; either because: they are mostly ABS, some contain rubber, some contain batteries or wires, are "Type 7" but are not labeled, are too small, etc. Even cities whose web sites said "we accept all plastic types", sent us emails saying they couldn't take them for these reasons (except SF).

We even called an ABS recycling company (yes some of these exist). They said, even with pure ABS LEGOs, they would need over 1,000 pounds to make it worthwhile to them to touch it.

We have sent hundreds and hundreds of pounds of LEGOs on to "new lives", including donations to: children in Haiti, orphanage in Zimbawe, LEGO clubs, libraries, doctor's offices, etc.

We called dozens of thrift shops throughout the US and were please to find that at least "some" of them claim they can used mixed bricks, but a lot of them don't touch them, especially if they are not in complete sets. Our local Goodwill said they just dump them in the citywide recycling. We cried, then called the city recycling program, and they said they painstakenly sort them out, then dump in the landfill. We cried some more, then started this great program to give "the world's most awesome toy" a chance a 2nd life.

LEGO pieces will not decompose even after 100,000 years, which makes them an excellent choice to "pass along to a curious child".

We will be posting more details and actual emails from many curbside recycling centers soon.
> 3 votes

# Answer
Acrylonitrile Butadiene Styrene (ABS), the material that most LEGO bricks are made of, is also popular for using in 3D-Printers. There is an Open Source Ecology project to create a plastic shredder that makes the raw material for 3D printing. People also use 3D printers to create LEGO compatible parts, so one can recycle bricks to create bricks again!
> 2 votes

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Tags: manufacturing
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# Question
Title: Is there an organization who repackages old LEGO bricks into sets to give to underprivileged children?
Does Lego have a program by which we can return old LEGO parts so they can be reassembled into packages for underprivileged kids? My kids, and now grandkids, have always played with LEGO bricks and I have a large collection of parts, not in their original boxes and would like to give them to an organization who would reassemble them into workable sets for disadvantaged kids. I hate to just throw them away as I must have several hundred dollars worth of parts.. Any ideas?

# Answer
> 7 votes
Another option is to locate a nearby BrickLink vendor and request them to sell the pieces and donate the proceeds to charity. So far as I know, this is the best way to donate, as the pieces are sold for their appropriate value and the money can be donated as you wished. You may consider donating the pieces to Creations for Charity as well.

If you really want to donate parts, the best way would be to use the money from other suggestions to purchase general purpose block sets, and donate those.

# Answer
> 6 votes
I don't know of any such global organization, but if you're willing to part with LEGO toys, you may want to consider helping an organization in your neighbourhood. Hospitals will most certainly welcome any donation for their children's ward, and I suppose schools may have a use for it as well. I don't think they would care that much if sets are incomplete, as long as the parts themselves are still in good playable shape.

That's the path which has been chosen for the Brickset charity raffle, for example.

# Answer
> 5 votes
Recreating a LEGO set from mixed up pieces is extremely time consuming. Even if you are just missing a few pieces, since LEGO makes tens of thousands of shapes and sizes. Even simply verifying that a "set of 352 pieces" has exactly the correct "352 pieces" is very time consuming. The good news is kids and adults LOVE using mixed up pieces to create their "MOCs" (MOC means My Own Creation).

www.BrickRecycler.com is a great place to send LEGO pieces, and know they will end up being used, and loved. They even offer to pay for postage if you are sending from anywhere in the US. They work with nonprofit organizations too, and have shipped hundreds of thousands of pieces. There is more information on the web site, including a link a really encouraging video of kids in Haiti having a blast with bulk LEGO pieces.

# Answer
> 1 votes
sorry I am a little late to the game...I am founder of a new charity in Kansas, USA that accepts donated LEGOs and sorts them into sets based on original LEGO sets. We gift these sets to underprivileged kids through foster care associations.

If you are still looking for a place to donate your sets - I will take them. Unsorted, any condition, with instructions or not. Feel free to contact me for more information.

Matthew Gould (as yet unnamed Lego charity) USA-9 one 3 - two 0 six - six three 0 0 @mdgouldkc

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Tags: sets
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# Question
Title: What lego set is this? Possibly a pirate ship?
my wife picked up this lego set at a garage sale. The owner claimed it was a ship, perhaps a pirate ship, and that the set was complete. It does have something resembling a bow, and several tall poles, but no sails, which sounds suspiciously non-ship like. The most distinct piece is something like a black bicycle chain / rope ladder on a gear, attached to what looks like a 4-piston engine. There's another smaller chain as well. The entire set is in a beige / brown / black color scheme. Images below - can someone help me identify this?

(I already tried searching for the piece on rebrickable, but could not find it under any description I could think of.)

# Answer
> 8 votes
It's a ship alright.. a heavier than air airship: Wright Flyer.

Quite a fun, if rickety. build.

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Tags: set-identification
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# Question
Title: What's the purpose of the clutch gear in Power Functions set?
I have just bought this set and wonder the purpose of the white gear in the middle:

How can you use it in your Lego Technic projects? Is it available in other sets?

# Answer
> 13 votes
When your function (such as an extending crane boom) gets to one limit or the other, this clutch gear ratchets instead of binding up the motor and all the gears in between.

ETA: Forgot the second question. It has appeared in many sets, most recently the Fairground Mixer.

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Tags: technic, gears, piece-usage
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title: What does BURP or BURPS stand for?

text:
# Question
Title: What does BURP or BURPS stand for?
Came across this one a few times (most recently here) where it links to a number of mountain elements:

> you still end up with some neat **mini-BURPS** and other useful pieces

# Answer
I've heard variations on "Big Ugly Rock PieceS".

However, I've also seen the term used to describe any large piece that the builder thinks has little reusable value due to its shape being pretty specific to a certain use. Obviously the mountain pieces are built to look like pieces of rock. But there's also some tower elements in the Harry Potter sets that often fit description.
> 7 votes

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Tags: terminology
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# Question
Title: Ideas to slow down RC PF train motor (Item: 88002)
I'm wondering if you already tried to slow down such a motor. I would like the train to run slower at all the supported 7 speeds. Anyway, at speed 7, the train just flies off the tracks.

# Answer
Unfortunately it's direct drive so gearing it down really isn't an option. That leaves changing the electrical system.

What battery are you using? Fundamentally, any change to the electrical system is going to amount to "use a half flat battery", and if you're using a high-voltage battery now the easy option is to switch to lower-voltage rechargeable batteries. But that only works if you're currently using disposable AAA batteries in the 88000 battery box (or 6 AA's in the bigger one that I don't think I've ever seen in a train). If you are, switching to either NiMH AAA batteries or the the Lego LiIon battery pack 8878 will give you the effect you want.

Based on Philo's extensive comparisons but it's the speed/voltage graph that you probably care about more:

What you want to do is lower the voltage at each setting of the controller, and that means adding a resistor in series with the motor.

If you're currently using rechargeable batteries, the only option I can see is to modify the motor or IR receiver. It's just adding a resistor in the cable, so it's relatively easy to do and also to undo, but it's going to look messy and it will be more fragile than the unmodified item. If you're unsure (which I assume you are, since you're asking here rather than just doing it), it's probably better to buy an extension cable and modify that.

Your motor draws about 1.3A when stalled, and from the speed/power charts lower down, about 0.4A when running. I'm going to guess you want to lose about 1V from the 7V output of the receiver, so you need about 1/0.4 = 2.5Ω. Since that Needs to cope with about 1A, it would ideally be a 3W or 5W resistor but you can probably get away with 1W. I suggest using 2, 5Ω 1W resistors in parallel since resistors typically come in 1W and 5W sizes, and in 10% increments so you actually want 5.6 ohm. RadioShack sell them, as should any other electrical part supplier.

Again, Philo explains what the wires do (2/3 down the page), and the easy way to do this is to put the extension between the battery and the IR receiver. That way you put the resistor on an outside wire of the four. If you can solder the resistors in place it'll work better, but if you can't just stripping the wires and twisting them in place then holding it together with tape will work.
> 4 votes

# Answer
When my train was flying off the tracks, I solved the problem by adding more cars to it, or adding extra weight to the existing cars.
> 3 votes

# Answer
Whilst that element is designed to be a "direct drive" system, you could try lifting it up and then stacking some gears on it - however you're going to have some issues with the width of the train/wheels and the track gauge and the amount of gearing you can reliably use because of the size of wheels.

In other builds I've seen, the builders have used the smaller motors and some bevel gears to transfer the power correctly.
> 1 votes

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Tags: trains, motor, power-functions
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title: CAD model of the LEGO monorails

text:
# Question
Title: CAD model of the LEGO monorails
I was wondering two things, Is it legal to share CAD models of LEGOs with other people as long as it is not for profit and Does anyone have A CAD model of the LEGO monorail track that was made in the late eighty's and early ninety's?

# Answer
First question; yes. as long as they are your CAD models you can do that , for example on Brickshelf Second question: In LDraw , A CAD program for Lego they have monorail parts, here

this may also be usefull Monorail Network Planner Tool
> 3 votes

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Tags: cad, monorail
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# Question
Title: Any substitute / schematic for Mindstorms 2.0 IR tower?
I came across a used Robotics Invention System 2.0 set, but in addition to a few missing bricks, it is missing the IR tower. Is there any generic replacement that I can use to program the RCX or does anyone know where I can find a schematic to build my own? Thanks...

# Answer
> 3 votes
There is no non-LEGO product that can substitute the infrared tower used for communicating with the RCX, as the USB and Serial towers use a very specific protocol that does not match that of other Infrared devices. Nonetheless, it does appear that there are schematics available for the IR Tower, courtesy of Mark Bellis:

I'm no expert on low-level electronics, but it looks like this site has a lot of additional information that could be useful if you want to replicate/manipulate the IR tower.

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Tags: rcx
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title: Is there an XML format for Lego?

text:
# Question
Title: Is there an XML format for Lego?
I've seen some pretty neat applications using customized XML formats. There is a Musical Notation XML so that a user can create sheet music on XML. With the right software, that XML can be converted to ACTUAL sheet music, and other plugins even convert this XML to a MIDI output that plays the music.

I'm wondering if there is an XML format for Lego? I would assume it would follow a procedural output where Step 1 is take a 2x2 piece and attach peg Top-Left to 4x1 piece bottom slot. Or something similar.

Just wondering... if there isn't, I feel like there should be. With a Javascript app written for it you could have people converting Lego instruction books to XML or creating custom instruction books with walk-thrus available with a Javascript app.

# Answer
Yes, there is LXFML \- which is if you like an "offical" XML format for LEGO models - in that it's produced and maintained by The LEGO Group.

The `.LXF` format used by LEGO Digital Designer is a compressed archive containing a thumbnail in .png format and a model definition file in LFXML.

As I noted in the answer to that question, the LDD team have shared both the documentation and XSD for validating this.

Within the definition, there is scope for a `<BuildingInstructions>` element that can contain one or more `<BuildingInstruction>` elements. These in turn contain `<steps>` which reference one or more parts or contain sub-steps:

```
<BuildingInstructions>
  <BuildingInstruction name="b6206_" cameraRefID="4">
    <Step name="b6206_s1">
      <Step name="b6206_s2">
        <PartRef partRefID="0"/>
      </Step>
      <PartRef partRefID="1"/>
      <PartRef partRefID="2"/>
    </Step>
    <Step>
      <PartRef partRefID="3"/>
    </Step>
  </BuildingInstruction>
</BuildingInstructions>

```

Note that the `<PartRefs>` are Ids to parts in the `<Model>` elements, which define the actual element, colour and orientation.

The default steps created within LDD have been known to be a little hit and miss, adding multiple elements at once and not always visibly or in a valid order (although that may have improved since I last used it for step creation).
> 9 votes

# Answer
As Zhaph - Ben Duguid said, there is the .LXFML format which is basically an XML document detailing a LEGO model. Another format you might find of use if the .ldr format. .ldr files are used in various LEGO virtual building programs that make up what's called the LDraw system of tools. As an example of the .ldr format, this:

Can be generated by pasting this into a text document and renaming it .ldr:

> 0 Brick test
>
> 0 Name: Brick test.ldr
>
> 0 Author: HaydenStudios
>
> 0 Unofficial Model
>
> 0 ROTATION CENTER 0 0 0 1 "Custom"
>
> 0 ROTATION CONFIG 0 0
>
> 1 4 50 0 0 1 0 0 0 1 0 0 0 1 3001.dat
>
> 1 7 50 -8 0 1 0 0 0 1 0 0 0 1 3020.dat
>
> 1 4 50 -32 0 1 0 0 0 1 0 0 0 1 3003.dat
>
> 1 4 50 -56 10 1 0 0 0 1 0 0 0 1 3009.dat
>
> 0

All LDraw applications rely on having a base LDraw installation to refer to which contains files for 3D models of all LEGO parts available in the LDraw parts library. If you wanted to write a Javascript that interprets LDraw models, you'd need it to have an LDraw parts library stored somewhere to refer to, such as on a server.

Each tool in the LDraw system of tools has its own "actions" that it injects into an LDraw file when you edit it. One such program, LPub, is specifically designed for making instructions for models constructed using any LDraw-compatible tool:

It allows you to set up each page, and saves your setups for each page into the LDraw file so that it can be read by any program that knows how to read LDraw files and LPub's formatting.

This and the .LXFML format are the only two file formats I know of that are along the lines of what you described. One potentially deciding factor in which format to choose is the different ways they handle instructions. For LDraw files, you have to manually make the steps as you make the models, whereas LDD automatically generates the instructions. While this can save the builder a lot of time, the order in which the pieces are added may not make as much sense as if they were made manually. Whether this is a pro or con is really a matter of personal preference.

Altogether, though, I'd personally recommend using LDraw files due to LEGO Digital Designer's relatively limited part library, as well as the fact that the former is generally more favored among the late teen and AFOL community.
> 5 votes

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Tags: software, instructions
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# Question
Title: Unknown brick/piece information (curved, decorated slope)
Recently, I got a huge box of LEGO sets all mixed together. I have been slowly identifying the sets that are there. Some are complete, while others not, but I have been managing so far.

Still, there is one piece that I failed to discover what it is. I remember seeing it a while back but can't say from where.

Can someone help me out and tell me what brick this is?

Thanks.

# Answer
It would be a Slope, Curved 2 x 2 Lip, No Studs with Island Xtreme Stunts Logo and Flames Pattern.
> 9 votes

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Tags: part-identification
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# Question
Title: How can i use my iPhone to scan a barcode and send it to my EV3 brick?
I'm trying to build a sorter that scans the barcode on the brick using an iPhone and sorts it accordingly to the barcode. I cannot use colours due to amount of things to sort.

# Answer
> 2 votes
You will have to write an application for your phone that can scan the codes and then send the information to the EV3 via bluetooth or wifi.

If you don't know how to write iOS apps, start here.

For scanning bar codes there seems to be good info here. It appears that bar code scanning is built into iOS 7. If you have an older version, the the zxing library sounds like a good choice.

For communicating to the EV3 over bluetooth, this has been asked before. However, I have yet to come across a good example.

You should be able to figure out the communication protocol for communicating with the EV3 from the LEGO firmware documentation, VM documentation and source code.

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Tags: ev3, ios
---


title: Where can I find LDraw examples?

text:
# Question
Title: Where can I find LDraw examples?
Where can I find LDraw files to download?

I would like to have a collection of simple Lego examples and want to create step-by-step instructions for my youngsters.

# Answer
> 5 votes
The models included in AIOI as mentionned by HaydenStudios is also available as **separate download** There is also a huge collection of LDraw models of official sets available on **Eurobricks forum**

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Tags: instructions, ldraw
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# Question
Title: Is there a program to tell me if a specific parts list is available in a given colour?
I want to build some models using the new 1x2 curved slopes which come in limited colours at the moment, the models need to have single solid colours if at all possible.

Is there a program or site that will let me put in the parts needed and preferred colour, and then tell me if they are all available in that colour?

I know about Bricklink and Brickset (but not a registered user of either), so I can do it part by part if I need to. I could also use LDD Manager to get a list of buyable bricks from a LDD file containing all bricks in all colours, although I would still need to check another site to find out what sets they are in.

Is there an easier way?

# Answer
> 4 votes
If you're up for a bit of programming, Rebrickable.com has an API that can query part+colour and return matching sets.

> Get Part Sets
>
> Use this service to get a list of all sets that a specific part/color combination appears in. This is best used after calling the get\_part function to retrieve the list of available colors.
>
> URL /api/get\_part\_sets
>
> Method GET
>
> Parameters key - API Key
>
> part\_id - The Part ID to look up (e.g. 3001)
>
> color\_id - The LDRAW based Color ID to look up (e.g. 0 = black)
>
> format - How to display output data. Valid values: xml, json
>
> Returns INVALIDKEY - The API Key is invalid
>
> NOPART - The part/color could not be found or has no sets
>
> Output data.

---
Tags: inventory
---


# Question
Title: What do factory markings on the inside of DUPLO pieces mean?
In addition to LEGO and DUPLO names embossed inside the pieces of early DUPLO figures, there are a variety of number formats (one to three digits, some hyphenated) and in the case of 1977, the year.

Is there an explanation for what these numbers mean - and can they then be associated with a particular set and/or year?

# Answer
> -2 votes
The markings are the Batch number and element id.

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Tags: piece-information, duplo
---


title: 21104 NASA Mars Curiosity Rover?

text:
# Question
Title: 21104 NASA Mars Curiosity Rover?
Has Lego made a public statement why they stopped producing the Curiosity Rover set? Each of its few production runs **sold out in hours**. Why won't they take my money?

More importantly, how do I get a set for my kids (and me)? Speculators sell them in the vicinity of $100, but I'd rather not reward their hoarding if there's another option. None of the stores on Rebrickable have the full parts list. Does Pick A Brick keep everything in stock?

# Answer
> 4 votes
Gev already answered the question about availability. LEGO Ideas sets are produced in small quantities. Perhaps this will change in the future as LEGO Ideas is now out of beta testing and was brought in-house by LEGO. The Curiosity is not going to be back unfortunately. I just called LEGO about this a couple of days ago.

As far as the Curiosity inventory, BrickLink has the full parts-list here: http://www.bricklink.com/catalogItemInv.asp?S=21104-1. None of the parts are rare or difficult to find. You can use the parts-list linked above, add them to your wanted list on BrickLink, then quiry your wanted list by shop. This will show you which stores have all the parts you need in stock. And you can download the building instructions from LEGO's customer service website here: http://service.lego.com/en-us/buildinginstructions/

# Answer
> 3 votes
I don't recall an official statement, but one story I read said that they made a deal with the original designer to limit production to one run, but that seems almost apocryphal.

As for buying the pieces you need, I would think you'd have better luck on Bricklink.

It's possible that the PaB on S@H might have all the pieces necessary, but that seems *truly* laborious and pricier than Bricklink.

Note: this is all off the top of my head with zero research behind it, so grain of salt and all that.

---
Tags: shopping, vehicle, pick-a-brick, discontinued
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# Question
Title: Lego 7670 has two different box designs?
Does Lego 7670 (Hailfire Droid and Spider Droid) have two different colored boxes? I am seeing two different boxes on Ebay and other sites. One is a white clone wars box, and the other is a dark red and black Darth Vader box. Why are there two boxes? Also I saw that on Ebay, that the white ones were cheaper and used, but the black ones are usually New and if they are used, they Don't have boxes. Is one more valuable than the other?

# Answer
Indeed it seems there are two different boxes for 7670 Hailfire Droid & Spider Droid, but it seems the box is the only difference, so if you just want the pieces ignore which box they're selling and buy the cheapest. :)
> 2 votes

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Tags: star-wars, lego-store
---


title: How can I build a LEGO marble pump?

text:
# Question
Title: How can I build a LEGO marble pump?
All right, here's a tough one for ya'll.

How can I built a marble pump out of LEGO bricks? What would the mechanism which pushes the marbles up need to look like?

Here's an example in this video: http://www.youtube.com/watch?v=OBb-qyXFb5E&feature=youtube\_gdata\_player

Unfortunately, one cannot see the mechanism which pushes the marbles upward very well. I couldn't determine what pieces he was using - I think there was a slope, but I'm not sure as to how it moves the marbles up the pipe.

# Answer
> 13 votes
A pump is one of the most classic GBC (Great Ball Contraption) modules but is indeed difficult to get right.

One of the best illustrations I know is on this site:

Unfortunately, most of the site is in German, but the pictures are usually illustrative enough and I think it's a good source of information for ball machines in general, not only LEGO ones. The best is of course to get in touch with one GBC builder at events and ask for information. **EDIT:**

Here is a picture based on the model at aforementioned site:

Here is a video showing the mechanism in action.

# Answer
> 5 votes
Marbles weigh more than LEGO balls but there is a thriving community of avid "Great Ball Contraption (GBC)" builders... these move soccer balls or basketballs from their (standardized) input to their (standardized) output to the next module.

They use various techniques including stairstep, conveyor, helix, scoops, and every other motion technique imaginable.

I think looking through their designs will give you lots of ideas

This great site by Phillipe Hurbain ("Philo") should get you started, In particular, look at the Ball Pump and Jigsaw module, which have instructions included

# Answer
> 3 votes
I found this question and used Joubarc's and Peter's answer to guide my pump build:

The video of it's operation is here. As per Joubarc, it was very tricky to get right. Here are some subtle things I learnt/did during the build:

* The blue down wedges in the ball feed are not symmetric horizontally. Putting them on alternate layers helps stop the 14mm beads getting jammed.
* The ball feed needs to be narrow at the bottom (beams with a 2 stud gap, no wedges) to avoid ball jams and ensure the balls drop down with gravity into the intake.
* Needed a gradual ramp in the slider/feed section (yellow) to prevent ball jams and ensure the balls would drop into the intake
* Older bricks that have been nicked from drops, rough play tend to jam the slide mechanism as they brush past each other. Use newer/non nicked bricks.
* Use longer horizontal beams in the slide mechanism and adjacent walls. Every vertical vertice is an opportunity for the slider to jam. Long horizontals reduce this.
* Use window pieces in the slider to reduce slide contact and friction (see white slider section)
* Needed a long slide (white section) to increase clutch power holding it on to the bottom plate. With a smaller slide section it didn't take long for it to pop off due to push/pull action from the piston.
* a 2x1 beam with two holes was used to mount the piston. This aligned the piston just right to not jam during rotation. A single hole 2x1 beam didn't work for me.
* Needed to bias the balls at the top of the chimney to pop them out into the race section. Did this with the mini cheese wedges mounted vertically.

---
Tags: building
---


# Question
Title: Why are Lego products so expensive in Europe?
Comparing a few Lego products at the official online store, I found U.S. prices seem to be consistently around 70% of those in Europe given current currency exchange rates. That's a surprising difference. Given that U.S. import tariffs apply to products manufactured in Europe (such as Lego), one would expect the price difference to be the other way around.

**Edit:** Found a relevant quote in a book written by Alex Stewart:

> America is by far the cheapest country in the world for buying Lego; believe it or not sets are much more expensive in other countries.

*What is the primary reason for this price differentiation?* Better competition in the U.S.? Lower taxes? More wealthy Lego fans in Europe?

# Answer
> 5 votes
To answer this question, we must first check the accuracy of your observation that "*U.S. prices seem to be consistently around 70% of those in Europe given current currency exchange rates.*"

Using data provided by Brickset, which pulls data from the online listings at shop.lego.com, we can compare the prices of sets released in 2014 that are listed with prices in both USD and EUR.

I downloaded this data and used a spreadsheet to analyze the prices. Using the 2013 average USD to EUR exchange rate of 1.3282465 I converted retail prices from EUR to USD. On average, the retail prices on the US site are 77.06% of the retail prices on the sites where prices are listed in EUR.

So your observation is close to the apparent actual difference in listed prices, although it is closer to 80% than 70% on average.

The member states of the EU each set a value-added tax (VAT) on items sold in those countries. This rate currently varies from 15% (Luxembourg) up to 27% (Hungary). LEGO includes the VAT in the listed price in countries where it is collected. This means the listed retail price is higher than the actual base price of the set. If you assume a VAT rate of 25% and adjust the list prices accordingly, then comparing the USD prices to the EUR prices shows that US list prices are actually about 96% of EUR prices. This is an average - many sets sell at a similar or lower actual base price in Europe than in the US (when expressed in USD).

For example Set 60045 Police Patrol sells for $44.99 USD in the US. It sells for 39.99 EUR in Germany. The VAT in Germany is 19% and today's exchange rate is 1.3398. To get the base price of the set in EUR, divide the list price by 1.19. That gives us a base price of 33.60 EUR. Multiply that by the current exchange rate and the USD price you would pay in Germany for this set is $45.02 - just three cents more.

Here is the data I use in a spreadsheet format, sorted by their prices in USD. The calculated columns on the right show the EUR prices converted to USD and the bases of EUR list prices assuming 25% VAT.

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Tags: shopping
---


# Question
Title: Identify minifigure torso - yellow with blue "N" on front
I've got a yellow torso (with yellow arms). The front (I believe) has a large blue letter 'N' with a orange drop shadow. Otherwise the torso is plain.

I've tried loads of search terms on bricklink to no avail, but sometimes the description on bricklink is bit hard to predict...

# Answer
i think you mean this part

Yellow Torso Nesquik Bunny Large 'N' Pattern / Yellow Arms / Brown Hands

from 4051-1": Nesquick Rabbit

or 4049-1:Nesquick Rabbit Film Set
> 6 votes

# Answer
Is it possibly from Quicky the Nesquik Bunny figure?
> 3 votes

---
Tags: part-identification, minifigures
---


title: Help to identify a unique minifig head

text:
# Question
Title: Help to identify a unique minifig head
I have a minifig head that I can't find on the Brickset website or else where. Not sure where it came from but found it amongst a pile of odd bricks my kids had collected years ago.

The head is probably from before 2002 (last time any of them played Lego). I thought maybe from the Legend of Chima range, but couldn't find it in the sets or minifigs and don't have any other models from that range.

I don't have a figure that might match it but I'm just intrigued to know what it is.

# Answer
> 11 votes
It's one of the Indians from the Western theme, from 1997: http://brickset.com/minifigs/ww016/Indian-Tan-Shirt-Quiver

---
Tags: minifigures, part-identification
---


title: What is this model number please?

text:
# Question
Title: What is this model number please?
I don't have the instructions for this and I have no idea what model number this is.

Can anyone identify it?

# Answer
> 8 votes
It appears to be a partially-constructed 8242-1 Slammer Turbo

---
Tags: technic, set-identification
---


title: Preparations for outside display

text:
# Question
Title: Preparations for outside display
I am thinking of using LEGO to make some outside yard art, (large minifig scale castle) and wondered what I should do to prepare them for being outside in variable weather conditions (in the Seattle area).

I am aware that Legoland glues their displays, but have not found any other details on their technique.

Discoloring in the sun is not a big concern of mine, other than I will probably avoid too many white elements which tend to discolor more noticeably.

As it's ABS plastic I imagine water wouldn't be a problem, and I should just be able to wash them down if they get dirty. What about snow/ice freezing temperatures?

Does anyone have any experience with outdoor displays?

# Answer
I once talked with a Lego Builder at the Florida park. He told me they use a glue that actually melts the Lego blocks together. With that in mind, I searched and found this article (on Facebook). It says Lego Park Model Makers

> use a solvent based plastic weld. It heats the bricks up so the edges bind together. Obviously it has to be very strong to withstand weather conditions.

A quick search on that found this from Google shopping.

The article also talks about color fading and model life time (about 5 to 7 years), after which the model can either be rebuilt or cleaned:

> We clean them using a shot blasting technique. They are sprayed with a fine salt spray, which takes a very thin layer off the bricks, and then they are lacquered with a UV coating. This gives them another 3 years or so.

I hope the project goes well.
> 5 votes

---
Tags: building, durability
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title: Where can I buy engraved LEGO bricks?

text:
# Question
Title: Where can I buy engraved LEGO bricks?
What is the cheapest site to buy engraved LEGO bricks?

I am searching for the cheapest site to buy engraved 2X4/2x6 bricks so that I can put names on them and send them to people. Any insight is greatly appreciated.

# Answer
> 6 votes
Online I would recommend BrickEngraver

I think your best bet would be to find a local trophy shop, most will engrave items. Take them some LEGO to test and they should be able to provide what you need without the need to pay shipping.

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Tags: 3rd-party, customization
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title: EV3 bluetooth controller for mac

text:
# Question
Title: EV3 bluetooth controller for mac
Is there a suitable EV3 controller for mac? It should be a compatible alternative from the official EV3 controller in the iOS app store or google play.

# Answer
> 1 votes
You could try the MonoBrick Communication Library. It is supported for Mac OS and does use Bluetooth as a way of communicating with the EV3 brick.

MonoBrick was listed by IntroRobotics with three other software development resources for EV3.

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Tags: ev3, remote-control
---


title: How can I motorize City-scale wheels?

text:
# Question
Title: How can I motorize City-scale wheels?
I'd like to build city-scale (6 studs wide) vehicles motorized with either PF motor or clockwork. The primary problem right now is connecting wheel(s) to motor. Are there small enough LEGO wheels with axle hole? Any other idea on how to connect it to motor (with gears, friction, or by any other means)?

# Answer
> 13 votes
If i remember right, the tires of the small LEGO City wheels fit perfectly on a Technic 1/2 bush which then gives you an axle hole, but note that this is very flat on the ground. I don't know if its high enough to add a very small gear and build up the connection to your motor.

# Answer
> 11 votes
There are a number of pull-back motors for system wheels. Look through the Motor, non-electric section of bricklink. There is even one rechargeable electric motor.

There was also an all-rubber tire with an axle hole in some of the old space sets, though that may have a rounder shape than you're looking for.

# Answer
> 11 votes
Ever since this question was asked I wanted to build something that would fit that scale. Here's the result:

I know this is not using only LEGO pieces but, I thought that there was no way to make the LEGO motors fit 'inside' a normal looking LEGO City vehicle. So, this is basically a homemade motorized brick made of a 2x2 brick glued to the 2x2 wheels-brick. I then gutted out the insides to make place for all the electronics.

It's controlled by an ATtiny chip (similar to the Arduino chip) and uses a 3.3V LIPO battery. The motor is a small 'pager motor' that I got from an old toy. The chip is programmable and can run the motor at different speed. I'm pretty sure I could figure out a way to make a steering mechanism to go with it and, if I go really crazy, a BlueTooth brick to remote control it...

You can see it in more details in this video, see it run in this video and I have more pictures on my blog.

# Answer
> 6 votes
Most vehicles in modern city sets use wheels with ∅20×12 mm tires. Such tire can be put on 12 tooth double bevel gear or combination of narrower ∅11×8 mm wheel and 12 tooth bevel gear to connect with axle. The only problem I see with this solution is that tires are swollen a bit by gear so they are not freely turned when covered with mudguard with arch.

# Answer
> 0 votes
You could try connecting your wheels using the friction pin/axle

This provides some friction to the wheel hub while also giving the motor an axle to turn. It won't work if there is too much resistance, but for small setups it might be okay and it will fit in all the existing pin-connected wheels. If you're feeling crazy, you could always glue the axle into the wheel hub, or use a bar piece jammed into the pin to increase the friction. Not that I would recommend such techniques!

There are also some wheels that are turned by axles, such as this one. In fact, on this page you can see many wheel/tire assemblies that Lego has shipped, and there are lots where the wheel hub is connected with an axle. Any of these can be easily motorized, though not all of them will be small enough for 6-wide city scale.

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Tags: power-functions, city, vehicle
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# Question
Title: What set does this minifigure head come from?
I came across this picture:

I think the body is from The LEGO Movie Pajamas Emmet polybag, but have no idea where the head is from.

# Answer
It's from Fairground Mixer (10244).

Also, the rest can be had way cheaper than Pyjamas Emmet polybag in the form of Sleepyhead from Collectible Minifig series 6.
> 5 votes

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Tags: minifigure-identification, the-lego-movie
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# Question
Title: Is there a time mechanism that can be added to an NXT program?
I wanted to create a system where an NXT block would be set into function at a certain time of day (maybe 5:00 and then 5:10 and so on). I would want the timing function to be embedded into the NXT program. Is this a possible function? I have looked for documentation on the web but have not found anything useful..

# Answer
To get the actual time of day, you can use the mindsensors.com Realtime Clock Sensor.
> 5 votes

# Answer
Time is thought of as a sensor value, measured in seconds. The Timer sensor can be used directly, as part of a Wait For block, as part of a Loop block.
> 2 votes

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Tags: nxt, programming, automation
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# Question
Title: How to make NXT bricks communicate information?
Is it possible to connect, in some way, two NXT bricks that has program functions running on both. For example, Brick one would tell brick two that it is okay to start a program. Are there any sensors that could facilitate this type of communication?

# Answer
You can use the Bluetooth mailbox feature to pass messages back and forth between 2 NXTs.

If you want to use sensors, you could use the HiTechnic NXT IRLink Sensor (NIL1046) and NXT IRReceiver Sensor (NIR1032).
> 3 votes

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Tags: nxt, programming
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# Question
Title: How to build an automatic Lego train system?
I was wondering if anybody has ever tried using the IRLink NXT sensor to make an automated train system and if so, what kind of setup did you have to make it all work?

I have been working on a train station for a while now and would like to create an automated system that will stop the train inside the train station for a set amount of time (maybe 30 seconds). As of now, I had an idea to use the touch and IRLink NXT sensors to make the system work. When a train approaches the station it will somehow hit the touch sensor. Then the IRLink sensor will send a signal to the IR receiver stopping the train inside the station. Then after 30 seconds, the IRLink sensor will send another signal to the IR receiver which starts the train. This will be continuous as the train track setup, as of now, is in a loop connecting both ends of the train station. I would also apply the same system on the opposing tracks in the station.

Am I overlooking anything that might make this not work? Are there any better alternatives to the touch sensor? Does anybody have any ideas as to how to avoid a collision within the train station if two trains are approaching less than 30 seconds apart? And finally, are there any experienced NXT programmers that could give me some advice on the programming aspect of the system?

I like this system because the train does not need any positioning awareness on the track for it to stop within the station every time.

# Answer
I think I'd use the ultrasound sensor instead of the touch sensor (or the brightness sensor with the light turned on in a dark tunnel). I haven't tried this but I'd worry about the touch sensor derailing or scratching the train. Otherwse, your system sounds pretty doable. The collision risk could be addressed by setting up the sensor a little further before the station and sending a stop signal to the second train if it triggers the sensor while the first train is still at the station.
> 3 votes

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Tags: nxt, programming, trains, power-functions, automation
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# Question
Title: I need information on LEGO part #3001 in Milky White with Sparkles
Have a 3001 part i have come across with a color i've never seen before. It seems to be a milky white but with glitter in it. New style logo with pip on short side.

Any ideas to where it came from?

# Answer
According to a comment from Jan.k 1974 on the source you mentioned (in your comment to 62Bricks answer):

> The milky white brick dates to 2005 and has been been made exclusively for the Allianz Arena (Munich soccer stadium) model in Legoland Günzburg. I remember they sold spares of these in packs of 5 for 1.99 after the grand opening

This is confirmed by Maxx3001 in reply (emphasis added):

> \[…\] that's the left brick *with slight sparkle* in it.

At the time of posting, ND Toys was listing these at $2.39 on BrickLink under "Milky White" with the description:

> MILKY WHITE 2X4 BRICK WITH SPARKLES (from LL park spare parts)

The arena, and the milky white bricks can be seen in this shot on the LEGOLAND website:
> 5 votes

# Answer
You may have what is commonly called a "test brick." Many of these were manufactured by the Bayer company in Germany. LEGO had Bayer test various designs and colors for their evaluation before deciding whether to put them into regular production.

One recognized authority on these bricks is the collector Maxx3001, who documents his extensive collection on Flickr. In his comment on this trans-red glitter test brick, he makes reference to the existence of milky white glitter bricks. He may be able to give you more information on your brick.
> 2 votes

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Tags: colour
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# Question
Title: Does anyone have a picture of the Lego Club alphabet code from Bricks and Pieces magazine?
Somwtime maybe in the early eighties, I read a Bricks and Pieces magazine with a small panel showing the brick alphabet code and it would be great to have a picture of this if someone has it.

This code used an apparently random brick construction for each letter of the alphabet, and it would be fun to write messages into MOCs using the code, or to see if anyone else has already done it.

# Answer
The code was introduced as a puzzle in the spring 1981 issue and is explained in the summer 1981 issue. (Page 7 at the bottom of the page).

the issue can be found found at: http://www.1000steine.com/brickset/miscellaneous/BricksAndPieces/1981-2%20Summer.pdf

And here is the code:

Enjoy!
> 4 votes

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Tags: history
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title: How much does the NXT brick weigh?

text:
# Question
Title: How much does the NXT brick weigh?
I am working on a project that involves LEGO Mindstorms bricks but for some tasks I want to know the weight of the NXT brick, so I would be pleased if anyone can help me.

# Answer
> 7 votes
Without batteries installed, the NXT brick weighs 159.3 grams, so that's about 0.351 pounds.

Do take into account the added weight of what ever batteries you have installed, though, as that will almost double the weight, and not all types of AA batteries weigh the same. If you're using a rechargeable battery, then for reference, the original NXT rechargeable battery weighs 155 grams (~0.341 pounds), and the newer rechargeable battery weighs 136 grams (~0.2998 pounds).

The weight of a single AA battery according to www.allaboutbatteries.com are:

**Alkaline:** 24g

**Carbon-Zinc:** 19g

**NiCad:** 29g

**NiMH:** 26g

**Lithium Ion:** 25g

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Tags: piece-information, nxt, weight
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# Question
Title: How should I go about selling a large number of unsorted LEGO sets?
Here is my problem. Over the years my son had me buy a large number of Star Wars sets (including 10179, 10188, 6211, 7676, 7675) and he built them. Then he traded (or lost) most of the mini-figs except for those in the death star. He has all but 3 and they are for sale on e-bay.

They all were taken apart and I am sure that 99% is in all of the 10 plastic staorage boxes I have.

My problem is how do I sell them and what to ask? I see that the 10179 is going for 2400.00 new in box. Really? Who would pay that much. It is just a Lego. I have a huge list of other star wars kits totaling 24 in all. I can get all the kit numbers if you like. Plus, I have 60-100 dollars of gift cards for the LEGO store that I will throw in to help get missing pieces or whatever from LEGO itself.

I am in the Sacramento area of California and found this site. Thought I would throw it out there.

# Answer
> 16 votes
You have three basic choices, depending on how much time you want to spend:

1. Sell the collection as-is (with as much honest description as you can muster and great photos if you're selling on-line).
2. Sort the collection into sets and sell them as-is with parts / figs missing.
3. Sort into sets and replace missing parts / figs.

These three are not mutually exclusive.

Personally, I'd go with the first option unless you have a *lot* of time on your hands and are a real enthusiast. Otherwise, your time is probably worth more than any additional profits you might make. At the same time, there are plenty of us who would *love* to take on a collection like this.

# Answer
> 9 votes
One of the issues I see is that you're missing most of the minifigs, these generally aren't available individually through the LEGO store.

As you've seen for a complete boxed set of some of these kits are very expensive to buy second hand; they are no longer in production and some people *are* willing to pay that much to own them.

In terms of selling what you've got, if you can sort them back into their correct sets that would help in terms of maximising your potential profit, however there's clearly a trade-off with your time to do that. If you do go down that route there are a number of sites that have inventories for most sets, even the older ones that don't have them listed in the manuals:

Brick Link is the site to use for selling LEGO bricks, many sellers on there sell bricks individually (albeit with a minimum order), which may be an option but is quite a lot of work. Alternatively you could try contacting a local seller and see if they are interested in taking your stock on.

Finally you could look into finding some local brick fairs and trying to sell it there, either in bulk or parts.

# Answer
> 3 votes
Unfortunately, what you have is a gigantic pile of unsorted LEGO that came out of sets that you originally spent nearly $3,000 on. With a gigantic pile of unsorted Lego, that may have a couple of minifigures in it, you probably won't get very close to $3000.

You can try your best to get them sorted into their original sets, but your best bet is to create 1 pound lots and auction them on Ebay, or try to sell them individually - you might be able to offer them for sale for something like $10 per pound, or more.

If you try to sell the entire lot all at once, you are probably going to see offers come in at around $5 per pound.

Sorting used LEGO is a lot of work, and if you aren't willing to do it - you'll take a hit in terms of what you are likely to get.

# Answer
> 0 votes
You should check the value of the used sets on this site: http://www.brickpicker.com/

For 10179, you can get easily 1600$: http://www.brickpicker.com/bpms/set.cfm?set=10179-1

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Tags: shopping, star-wars, trading
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# Question
Title: Cheap Lego sets for Kindergarten classroom?
I am wondering what is the best way to get a set of Lego bricks for my kindergarten classroom? The children love playing with them and I no longer own them due to a transfer of grade levels.

# Answer
If there is no need for the bricks to belong to specific sets (as in, it's not important to be able to build some official models from them) then I'd say the best way is to look for ebay bulk brick sales. For around 100$ you can get several pounds or around a thousand semi-random pieces. Try searching for "lego pieces".
> 2 votes

# Answer
You have a lot of resources at hand as a teacher in your community. Have you considered sending home a request for gently used LEGO Bricks in your student's folders at the start of the year?

The parents of your kids may not have any on hand, but will certainly know someone who does!

-Brian
> 2 votes

# Answer
You may also consider renting them from Pley. Their website allows for set rentals at a discounted rate. I'm sure if you emailed them they might have something special for educational institutes as well. I heard they are running a school program.
> 1 votes

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Tags: set-modification
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# Question
Title: I bought a second hand pack of pieces and it looks like it may be a specific set
Hoping for help to identify a set of lego pieces. It definitely has a car wheel base, and the base boards are green.close

# Answer
A lot, but definitely not all, is likely from Race 3000.
> 6 votes

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Tags: set-identification
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# Question
Title: Decals for LEGO Pharaoh's Quest Flying Mummy
Do all LEGO sets have decals? I am specifically looking for decals for LEGO Pharaoh's Quest Flying Mummy.

# Answer
> 0 votes
I don't have any, but there are at least 67 of them available on Bricklink: http://www.bricklink.com/catalogItem.asp?P=7307stk01

(and no, not all sets have stickers)

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Tags: stickers, replacement-parts
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# Question
Title: How can I use 1 motor for grabbing/lifting and another for moving?
I am really stuck on how to use the three motors for better functions. Is there anyway in which I can use 1 motor for efficient/quick movement while turning left and right?

Another thing is whether I could use a single motor for turning objects 180 degrees on one side and lifting objects on the other end of the robot, is that possible? alternatively, is it possible to lift and grab using a single motor?

Lastly, would it be less efficient to use two NXT bricks to increase motors capacity?

# Answer
> 3 votes
> Is there anyway in which I can use 1 motor for efficient/quick movement while turning left and right?

Yes, if you use one motor to drive a wheel and another to steer the vehicle. Using an NXT motor for steering would be quite wasteful however, you should at least use gearing to convert the jittery, fast movement of the NXT motor into slower, more balanced steering. You could also look into using Power Functions parts, the servo motor being the obvious choice for steering applications.

> Another thing is whether I could use a single motor for turning objects 180 degrees on one side and lifting objects on the other end of the robot, is that possible?

If these two need to operate separately, then you will need to sacrifice some functionality. It is possible to split a motor's output into two axles in a configuration that drives only one axle depending on the direction of the motor. See this setup: How can I make a precise one-way clutch using Technic elements? This will only allow either axle to turn in one direction only, so if you need lifting AND putting back, you'll need to solve it as a circular function. Driven by the only input axle that is turning in one direction, the lift would need to raise and lower back to the original position without any other input.

> alternatively, is it possible to lift and grab using a single motor?

Using some clever mechanics, it is certainly possible. The 8868 Air Tech Claw Rig/Materials Handler used something like this to automatically grab an object, raise its arm, open the claws, drop the arms and start the cycle again. All this using a single motor (and some pneumatics). In this way though you won't get any control over the details (how high it lifts, etc) or over the sequence itself (you can't grab and release something without lifting it).

> Lastly, would it be less efficient to use two NXT bricks to increase motors capacity?

You could certainly use two NXTs and have control over 6 motors. This would however require more batteries, result in a larger and heavier model and necessitate some kind of synchronisation between the NXTs. All of these drawbacks can be mitigated, so if you can't seem to solve the problem using engineering (or have proven that it is impossible to achieve your goals using only 3 motors) then feel free to throw in another NXT.

If you need to increase the number of available motors, you could look into using third party parts, like this motor multiplexer that allows you to use two motors on one sensor port.

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Tags: motor
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# Question
Title: Guide me on how to use my Mindstorm RCX kit on OS X Mavericks
Any suggestions on how I can use my old RCX set on Mavericks? I have set up Xcode command line tools, and I am getting compiler errors while trying to download nqc through Macports. Even downloading gcc49 through Homebrew has not helped fix this issue. Is there any other option I'm overlooking?

# Answer
> 2 votes
I am currently maintaining my own fork of NQC for use on OpenBSD and OS X. As you have discovered, the recent compiler changes on OS X broke NQC in many places. Not to mention that the USB tower integration was pretty outdated. If you can compile it, it should work better than the ports version.

AFAIK, I am now the de facto maintainer for NQC. (And may Crom have mercy on my soul, etc.)

Also, If you can find the right firmware (available around the usual places) you can update the RCX 1.0 to something like 2.x (or whatever the last release of the RCX firmware from LEGO is).

I make no promises this works at all, but I recall the last checked in version worked reasonably well with a serial tower on OpenBSD and a USB tower on OS X. A serial tower on OS X *might* work with the right incantations and USB/serial dongle.

If someone else other than me actually uses this, I might be prompted to cleanup my sandbox and commit my local repo (and fix bugs others find annoying.)

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Tags: programming, software, rcx
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title: Programming RCX in 10.9 environment

text:
# Question
Title: Programming RCX in 10.9 environment
My school has 15 RCX robot kits that this year has just been sitting because all the old computers with OS X 10.4 are now gone and we are using OS X 10.9. I would like to run the original RoboLab Software (1-2.0) because it is for middle school kids. The graphic programming interface works great with these students.

Is there anyway I can do this. I would hate to toss the 15 sets as they are still very usable. We also have 6 NXTs.

What are my options here?

# Answer
For the RCX devices, if you want to use the RIS or RoboLab software on OS X, your best solution is to see if a VM image running Windows gives you what you want.

The main problem will be accessing IR Tower: the Mac doesn't have a COM port without a serial dongle (which could be had for cheap, but they can be a pain to use). And a USB Tower (if you have them) may not work in a virtualized environment. You would have to experiment.

Alternatively, you can use something like NQC or LeJOS for the RCX 1.0/1.5/2.x devices (any RCS 1.0 device will accept the latest 2.x firmware) on OS X. This is, of course, very command-line oriented.

Perhaps the latter solution could be reserved for the more advanced coders in the group.

I see that there is already an answer that enumerates some of the places you might be able to find RIS 2.0.
> 2 votes

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Tags: rcx
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# Question
Title: LEGO mindstorm - which product to use to make projects mentioned below
I'm planning to buy a Lego Mindstorms kit for the following projects. I haven't really used Lego before - my friend asked me to consult him about projects (I use microcontrollers and build robots from material I find in my garage).

1. Two track tank with a distance sensor to create a map of a room. A gyroscope sensor to measure the angle of slope would also be very useful. It would use fuzzy-logic, A\* algorithm and OpenCV if I decide to put a web camera on top of the tank.
2. Inverted pendulum (PID controller). It needs an encoder and a rather high speed motor which can change it's direction of rotation.
3. Some crawler (like a snake or spider) - models with holonomic constraints.

Now I'm considering the EV3 basic educational kit and I think it doesn't fit my needs. I also can't understand some things about software - if I buy a kit for home use, I suppose I shouldn't buy any software.

Questions

1. Which kit would be the best fit? Maybe two kits or even three?
2. Is the servo limited in rotation or can it be used as a simple electric motor? If no, then which motor can be?
3. Can I program the models using free software (downloaded from a website)? C or Java is preferable. NXC is nice too (it looks like C, but I haven't used it before).
4. How to remote control the robots? Should I buy additional Wi-Fi adapters?

# Answer
A basic EV3 seems to be enough for most of the basic projects, but you might find yourself in need of a handful of extra parts (gears, beams, etc). The basic kit does not include a gyroscope, but you can buy an extra one separately. The same stands for the ultrasonic distance sensor. The alternative is the educational set which already includes the ultrasonic sensor.

All EV3 sets come with the official software, but for any serious project you should indeed look for a more capable software. For Java there is LeJOS, for C there is NXC. Both are free and open source.

The motors sold in EV3 kits are capable of continuous rotation, but also have position encoders in them, making them capable of moving with 1° precision. For more precision you can always use gearing or other mechanics to reduce movement.

Remote controlling is possible with Bluetooth (built in) or with WiFi (via an external USB dongle).
> 4 votes

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Tags: mindstorms, programming, education
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title: Direct command lego ev3

text:
# Question
Title: Direct command lego ev3
Is there any documentation about direct command bluetooth of EV3?

Thanks, regards!

# Answer
Try http://ev3.fantastic.computer/doxygen/index.html and http://ev3.fantastic.computer/doxygen-all/

It seems to be the best option at the moment.
> 0 votes

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Tags: ev3, bluetooth
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# Question
Title: Can anyone identify this spinner with 1-5 and a skull?
My son has just inherited a large box of Lego, we're hoping someone can help identify what set this might be from.

# Answer
> 8 votes
It's the center of set 2519 Skeleton Bowling:

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Tags: set-identification
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# Question
Title: Is the LEGO Mindstorms EV3 brick waterproof?
I am trying to build a ROV (Remotely operated underwater vehicle) with LEGO Mindstorms Ev3. Is it waterproof?

# Answer
> 2 votes
**No, the LEGO Mindstorms EV3 is NOT waterproof.** Any electronic product that is capable of being immersed in water will clearly state in the packaging/manual the level of water protection provided. This may be in the form of an IP Code:

> **Ingress Protection Marking**, classifies and rates the degree of protection provided against the intrusion (including body parts such as hands and fingers), dust, accidental contact, and water by mechanical casings and electrical enclosures.

Source: http://en.wikipedia.org/wiki/IP\_Code

However, it is possible to contain the EV3 brick within a waterproof case, there are already many cases available suited to Smartphones, Tablets, Cameras and other Digital devices.

If your remotely operated underwater vehicle requires some form of propulsion (perhaps from a propeller powered by a EV3 motor) then you may required to make some alterations to the case. Any physical alteration will compromise the waterproofing and safety of the protective case. Do so at your own risk.

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Tags: ev3, safety, water
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title: RGB sensor HOWTO use?

text:
# Question
Title: RGB sensor HOWTO use?
I've got an RGB sensor (this one with the three LED thingies) and wonder how to access it using NXC.

I know I can `SetSensorColorFull(IN_1);` and then access it using ReadSensorColorEx or, for simplicity, ReadSensorColorRaw, but I'm a bit stumped wrt. the return values.

I know normal 24-bit (3x8bit) RGB colour codes. I know normal NXC return values (0/1, 0‥100, 0‥255). But I don't know how the values here work.

I've toyed around with `i = ReadSensorColorRaw(IN_1, r);` where `unsigned int r[4];`, and got values: `i` was always `1` (even if the cable was unplugged), and the `r[INPUT_RED]` aka `r[0]` values were somewhat usable, and about 0‥60 were black in general, and I got up to 1023 (when holding the sensor towards light), but if I hold the RGB sensor towards anything yellow, green or blue, the values are somewhat off. Also, I found *no* docs whatsoever as to what `r[INPUT_BLANK]` is supposed to be.

When unplugging the sensor, I got `r = { x, 0, x, 0 }` (where *x* was roughly 120) in my test program just using `NumOut` to debug the sensors, so I assume that the sensor return values are biased somewhat?

Would using `ReadSensorColorEx` give somewhat better usable values, or anything else I can use? Do I need to calibrate them first, and if yes, how? To clarify, I don't want the functions that just give back “it's red”, “it's green”, etc. but I want somewhat usable R/G/B colour tuples (and would take Intensity as bonus, although I'm using light sensors for them normally, or `SetSensorColorRed` if must be).

I'm using NXT Firmware 1.29, and exclusively Open Source tools. If there's anything else needed, information wise, just comment.

# Answer
> 3 votes
To understand how to use the data, it help to understand how the color sensor works. Let's take a step back for a minute and have a look. The sensitive electrical component here is just a photodiode or phototransistor that lets us measure light intensity.

If we turn all of the LEDs off we are just measuring ambient light. If we turn on just one of the LEDs and hold the sensor close to a surface, we are measuring mostly the reflected light from that one LED (and some ambient light).

When we switch to color mode, it looks like all 3 LEDs are on at the same time, but what is actually happening is that they are being switched in sequence very rapidly. off-red-green-blue-off-red-green-blue-... and so on.

This means the mysterious 4th value, INPUT\_BLANK, is the off part of the cycle - it is just measuring ambient light.

You said that you would take intensity as a bonus, but actually that is all you are getting. If you hold the sensor close to a white surface, you should get high values for all 3 colors. If you move the sensor even closer (but not too close), the values will increase. This is because the reflected intensity is getting strong, not because the surface is getting whiter.

This means the RGB values are not like the ones on your computer screen. If you do a web search for robotic vision systems, you will find that RGB just doesn't work. The common practice is to convert the values to HSV (hue-saturation-value). The HSV values can more easily deal with changes in ambient light allowing you to more accurately determine colors.

I am not sure how the normalized and scaled values are calculated in `ReadSensorColorEx`, but you can play around with them and see if they give you better results for whatever it is that you are trying to do.

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Tags: programming, nxc, sensor-colour
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# Question
Title: Is it possible to connect EV3 and NXT bricks like master/slave configuration via bluetooth?
Can I make a Bluetooth connection between LEGO EV3 bricks and LEGO NXT bricks? and If it is possible how to handle the software to make a chain between them?

# Answer
There are many possible ways of doing this. I am a contributor to the ev3dev project, so I am a bit biased in that direction.

To do this with ev3dev, I would install the nxt-python package on the EV3 and use it to remote control the NXT.

If you want to stick with the standard firmware, another possibility would be to relay bluetooth mailbox messages through a PC or other device. Here is an example (it goes in the other direction though - NXT controlling EV3).

Another possibility is to use Lejos or MonoBrick. Both have NXT and EV3 remote control libraries,
> 2 votes

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Tags: mindstorms, nxt, ev3, bluetooth
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title: What plastic do Quatro blocks use?

text:
# Question
Title: What plastic do Quatro blocks use?
I recently picked up a heap of Quatro blocks, and noticed that the plastic seems to be much softer than the normal ABS-based Lego and Duplo blocks. Does anyone know what kind of plastic was used in these blocks?

# Answer
If it is intended to mate with other LEGO products, it is ABS. Just tweaked to be more elastic. Any discussion of materials published by LEGO always says LEGO and Duplo are ABS, with some SBS for tires and rubbery things.

There is some sort of polycarbonate used for the clear pieces, but these are rare, and they don't mate well with each-other, so LEGO actually tries to limit these in production kits.

I can't find a specific statement to this effect, but Quatro is almost certainly some tweaked ABS recipe, if only because they have to mate with other ABS pieces, and the tolerances are very tight for LEGO. Mixing plastics would be tricky (as it is for the PC pieces). Additionally, getting the colours just right so they match the colours in the other sets would be a nightmare if it was anything other than ABS.
> 2 votes

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Tags: plastics, quatro
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# Question
Title: What part can I use to get the connection
This is what I have..

Would like to connect the long "thing" to the square base.. not sure which part will give me a angled elevation In case you are wondering what I am trying to do.. this is what I am trying for the same exact purpose http://www.youtube.com/watch?v=4PcL6-mjRNk

# Answer
> 1 votes
This may call for a bit of re-designing. I don't think there's a special piece for angled elevation, because you can mimic the effect with a gear.

Use a 24- or 40-toothed gear, and attach your "arm" to it. This has the advantage that you can connect it to a servo or motor using a few more gears - I assume you want to mimic the ball-throwing device in the Youtube clip.

You can connect the gear to your base in a number of ways, although personally I'd build the base from "normal" technic beams (e.g. the 16x1 types), If you insist on using your current base, you'll have to add a construction that you can put the axle through.

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Tags: mindstorms
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title: Lego Motor for cycling a tool

text:
# Question
Title: Lego Motor for cycling a tool
I am curios to know if I can utilise the Lego Power range to rotate a transducer to a set point and return to its original position and if so is it able to cycle the movements repetitively? Ideally I would like to set the motor to run to between say 0 degrees around to 240 degrees and then back to 0, 100 times although these figures could change.

Any advice/help is greatly appreciated!

Thanks

# Answer
It would be difficult to get the exact rotations that you are talking about using Power Functions parts. The servo motor would be your best option, but its range is fixed to +/- 90 degrees from center. If you use a controller with variable speed, it will rotate through 7 steps to get to 90 degrees in either direction.

If you're willing to look at Mindstorms, there is a servo motor with a built-in rotation sensor that was released with both NXT and EV3. These can both be rotated to and from any position, and they are accurate within 1 degree. It sounds like that's the best option to meet your needs.
> 3 votes

# Answer
If you don't need constant speed motion a better idea would be to use a crank running from any modern motor (ie, geared down internally). That way you can guarantee the end points. For a 240° rotation you might need to gear up after the crank, but as long as there's a spring or constant load in one direction backlash shouldn't be an issue.

Here;s a really quick sketch of what I mean. Your motor drives the black axle in the foreground, and that rotates a full 360° (continuously). That pushes the cyan lever backwards and forwards, rotating the black gear. Which in turn drives the grey gear which is your output. By judicious fiddling with the gear ratio and the crank lengths you'll be able to get just about any output rotation you want.
> 3 votes

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Tags: building, power-functions
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title: Need help to identify minifigure

text:
# Question
Title: Need help to identify minifigure
Can someone help me to identify minifigure linked below:

I´ve been searching now about three hours without luck :)

# Answer
> 7 votes
Knight's Kingdom II - the guardian (picture taken from bricklink)

http://www.bricklink.com/catalogItem.asp?M=cas264

I searched on Bricklink catalog under, 'minifig leg assembly' using the keyword, 'brown,' using thumbnails. Only had two pages to look through.

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Tags: minifigure-identification, castle
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# Question
Title: Why are some of the supports on bottom of a lego piece hollow, and other are solid?
I've added an image of me holding two 1x3 bricks, one has solid supports (not sure the technical name...) and the other has hollow supports.

Does anyone know the reason why they are different? Other than that, they are identical and from what I know they were purchased at the same time (I didn't buy them).

# Answer
Almost assuredly it is a move to reduce the amount of plastic used. It may seem inconsequential, but adding up hundreds of millions of these makes for a ton of savings. The same thing goes for the brick walls, but not in the case of the ones you show here. I haven't seen it in any 1x bricks, but in most 2x bricks these days, the walls are a tiny bit thinner (perhaps the cause of many complaints of translucency) but with little ridges there the studs touch to keep clutch at appropriate levels. One might guess that this new wall would reduce the number of times a brick will accept a stud before losing reasonable clutch power.
> 2 votes

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Tags: piece-information
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# Question
Title: How can I tell if my NXT motor is faulty?
I pulled my old Mindstorms NXT out of storage (it's been there for a few years). After patching together a test robot, I noticed that my motors behave strangely.

At first, one of the motors did not respond to move commands. After disconnecting/connecting a few cables, another motor stopped working (with a different cable, on a different port). While troubleshooting, the behaviour erraticaly switched between all three motors working (rarely and for a brief time), two not working, or one not working.

Now it's stable, with one of the motors not working, always the same one, no matter what port I plug it in. I suspect that it may be faulty, however I'm not sure due to the strange behaviour described above.

Does anybody know how I can test the motors, see which are faulty, if any? Or any other tips troubleshooting this? Thanks.

# Answer
> 2 votes
If the one motor exhibits the same behaviour on any port with any cable and the other motors are working on all of the ports with any cable, then it is safe to say that the problem is definitely with the motor itself.

Make sure you swap cables as well as motors to rule out a faulty cable.

Also, check for signs of corrosion on the pins of the cables, motors and NXT. This kind of erratic behaviour is indicative of poor electrical connections.

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Tags: mindstorms, nxt, motor
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# Question
Title: Vision Command and Exploration Mars software for Mindstorms RIS 2.0
I recently bought a set 3804 LEGO Mindstorms RIS (Robotics Invention System) v2.0 very well maintained but did not have the installation CD of the RCX program and IR tower. With some research on the Net, I managed to find the RIS v2.0 software and the expansions Extreme Creatures and RoboSports.

This set also includes the USB Camera from the Vision Command expansion but without the installation CD and the problem is that I can not find the software nowhere. Where can I download the software in English for the 9731 Vision Command and 9736 Exploration Mars??

I found a similar question here which was answered by another user with the links for the download of the software Vision Command but one was in German the other in French.

# Answer
> 4 votes
As it just so happens, I'm physically in possession of an English Vision Command CD. I've uploaded the iso here:

https://www.mediafire.com/?xo6xfjvnbzaaf7u

I didn't upload and post it in that other question you mentioned since I wasn't aware none of the Vision Command ones were English, but I've also updated the answer in that other question with this link for completeness.

Note that this software was originally designed for Windows 98. The very first thing you should do is run the install file in compatibility mode for Windows 98, otherwise you'll get an error telling you that your version of Windows is too new. And if you keep getting warning messages saying that this software has known compatibility issues, click "Continue anyway" for every one of them. I'm also wanting to say that you sometimes get an error when the camera itself is installing. In this event, just keep clicking "ignore" or "retry" or whatever until it finishes. I've been able to get the software to install and run on Windows XP, Vista, and 7, although the camera won't be recognized by your computer if your operating system is 64-bit. I'd be interested in seeing if that driver David Lencher linked you to would fix this problem for 64-bit operating systems.

# Answer
> 1 votes
I found this page: http://riskonomics.blogspot.com/2009/06/lego-vision-command-camera-drivers.html

The author says that he was able to get the camera to work with a Logitech Webcam driver is730enu.exe (which is linked on that page).

From the sound of it, the original driver wouldn't do you any good anyway unless you are still running Windows XP.

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Tags: mindstorms, software, rcx
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# Question
Title: Convert 3rd party NXT programming language code to NXT-G program?
Is there a way to convert code from one or more 3rd party programming languages used for programming the NXT into a program that can be loaded up in NXT-G? If not, do any text-based languages provide support for making custom blocks that can be imported into NXT-G?

# Answer
> 2 votes
No, there is no automated way to convert source files from other programming languages into un-compiled NXT-G code. The .rbt format is very complex, so writing a program to interpret programs written in other languages and generate a proper .rbt file with properly placed and configured blocks would be an incredibly time-consuming and tedious task that wouldn't be worth the effort. You'd be better off manually translating each program manually.

As for your second question, it is possible to make custom blocks for NXT-G, although not in any text-based languages. Custom blocks are made in LabView, a graphical programming language that has a wide variety of uses, including programming NXT robots. See this tutorial on creating custom NXT-G blocks if you're interested:

ftp://ftp.ni.com/evaluation/mindstorms/NXT\_Creating\_MINDSTORMS\_Blocks.pdf

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Tags: nxt, software, nxt-g
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# Question
Title: What are some 3rd party mini-figure gun makers that distribute in Canada?
I'd like to buy some flint-lock era mini-figure guns for my collection, something like these guns. What I don't want is to pay the outrageous customs fees to get them to Canada. Does anyone know of either some Canadian makers or Canadian distributors?

# Answer
I have never paid customs fees on orders from BrickForge or BrickArms. The key is to ship via the US Postal Service. Shipping via couriers like UPS usually results in customs brokerage fees which is what drives up the cost.
> 4 votes

# Answer
I simply googled and found brickrepublic based in Pointe-Claire, Qc

Trick : I usually arrange with visiting/traveling folks to bring small packages in Canada and avoid the outrageous custom fees.
> 2 votes

# Answer
You may want to try Modern Brick Warfare. They have a ton of custom LEGO-compatible weapons.
> 0 votes

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Tags: shopping, 3rd-party
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# Question
Title: Resources to learn useful common Mindstorms mechanical construction patterns
I'm currently working on building a small scale CNC-like (X-Z, no Y axis) machine to cut glass mosaic tiles.
I decided to give it a go using my EV3 set and I'm having some trouble with the Z-axis movement.

I find I'm loosing too much time figuring out by myself how to build what I'd expect are known elementary construction units, or what I'd call "patterns" (get my SW Eng bg? :-)). For example: a circular-to-linear movement using the medium servo (push vs pull), commonly used gear assemblies, duplexing servo movement axis, etc.

I'm looking for resources where to learn some basic construction patterns that would help me speed up building more complex structures. For example, a while ago I saw a book that seemed to contain some construction patterns -\> combining gears, how to build strong structures, ... I can't find it anymore.

Any available online/offline resource that could help is welcome.

# Answer
> 2 votes
I've had trouble finding good examples as well. One of the most interesting one is, sadly, in Spanish, but the images (and some help from Google Translate) helped me some. Hopefully it can be a start.

http://www.hispalug.com/foro/index.php?topic=11730.0

# Answer
> 2 votes
There are two sites I can think of that describe commonly used gear assemblies. Both sites make use of animations to illustrate how the gears work.

## LEGO Education: Constructopedia

This web article produced by The LEGO Group introduces common, basic usages of gears and pulleys. It includes alterations to the direction of gears, idler gears, gearing up/down and pulleys at angles.

## TECHNICOPEDIA: Building Fundapementals

Technicopedia: Building Fundapemtnals describe more advanced usages of gears and different gear types such as bevel, worm, rack and differential gears.

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Tags: mindstorms, building
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# Question
Title: How can I use the EV3 educational firmware instead of the retail version?
I have an EV3 brick from the retail kit, which is currently running the retail firmware. I would like to replace the EV3's firmware with the educational version. How can I do this?

# Answer
**Update:** LEGO Education software is now available for free.

https://education.lego.com/en-us/downloads/mindstorms-ev3

Original answer:

You need to purchase the EV3 Education version of the software. It includes the EV3 Education version firmware.
> 6 votes

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Tags: ev3, software, education
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title: Substitutions for vintage hinges

text:
# Question
Title: Substitutions for vintage hinges
I've recently gotten back into LEGO and I'm trying to restore old space sets (late 80's era) by buying parts on Bricklink. I've noticed that some of the hinge pieces are extremely expensive (e.g. parts 4275 and 4276), often making a single hinge assembly cost over 5$ if using "new" parts.

It seems that Lego has discontinued these parts some time ago, so I was wondering the following:

* Why were the parts discontinued? Were they prone to breaking?
* Which newer parts can be used to substitute these and are they really better? I don't mind if they don't look exactly the same as long as there is functional equivalence.
* I'm assuming that there is no substitutions possible for the old canopy hinges (e.g. part 4315)?

# Answer
> 9 votes
What I remembered of those parts was that force was needed to snap them together, and I believe I also have some that are broken over the years.

The part was introduced in 1983, updated in 1985 and the last sets were released in 2002 with one set in 2004.

In 2003 the parts are replaced by Hinge Plate 1 x 2 Locking with Dual Finger on End Vertical' (44302) and Hinge Plate 1 x 2 Locking with Single Finger on End Vertical' (44301). These parts have a number of fix angles in which the hinge can be placed. This finger shape is also added to al kind of other parts, like the canopy

There is also a version for non fixed angles Plate, Modified 1 x 2 with Clip Horizontal on End and Plate, Modified 1 x 2 with Handle on End - Closed Ends and these can also be combined with other parts

# Answer
> 3 votes
Joost answered eloquently, but I'd like to add that while 44302 and 44301 were made to replace the finger hinge they won't work in all situations. The geometry of 4275 and 4276 allowed useful techniques - you could use it to reverse studs by 180 degrees in a small amount of space, 90 degrees, and more. The new pieces can't do the same, which is a shame.

(Side note: the finger hinge are my favourite pieces ever. I even got them tattooed on my arm :)

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Tags: piece-information
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title: Teleoperated arm trouble

text:
# Question
Title: Teleoperated arm trouble
I have built a robotic arm with the lego Mindstorms ev3. My goal is to control its motion via teleoperation, that is , to have a gyro sensor strapped onto my arm and have the robot mimick the up and down motion of my forearm. However, I am completely stumped concerning the programming. I need a reliable way to read the gyro sensor readings while taking into account any bias in the sensor. Second, I would also like the sensor to read the rate of change in my arm and translate that into power for the large motor. If anyone can show me how to do this with the ev3 programming environment, the help would be greatly appreciated.

# Answer
> 1 votes
Disclaimer: I have never used the EV3 interface, only the text based programming languages for the NXT. Therefore I might be proven wrong.

> I need a reliable way to read the gyro sensor readings

I think the gyro sensor should have come with the appropriate instructions to do that. If not, you can find many tutorials online, such as this: http://robotsquare.com/2014/06/25/tutorial-gyro-ultrasonic-sensor-ev3-home-edition/

> while taking into account any bias in the sensor.

Bias can be accounted for by using a previously known position to calibrate the sensor. You could start your program with the gyro (and your arm) in one of the extreme positions and measure movement relative to that.

> Second, I would also like the sensor to read the rate of change in my arm and translate that into power for the large motor.

This sounds like a simple differentiation task. You measure the angle and store it along with the current time (in milliseconds or whatever the most precise measurements available). In the next iteration you make another measurement, take the difference of the current and the previous angles, and divide it by the difference of the current and previous times. The result is the rate of change. This can be translated to motor speeds by using either trial and error, or calculations based on the characteristics of the motor, the gearing and the gyro.

However, I would rather use a command to turn the motor a specified number of degrees to match the measurements of the gyro.

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Tags: mindstorms, ev3, programming
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title: Faulty NXT Motor

text:
# Question
Title: Faulty NXT Motor
I have a motor that prevents the program from running. It simply allows a few slow movements forward with stops in between. It seems very stiff to rotate manually. Any way I can repair this motor?

# Answer
I agree with HaydenStudios, it is impossible to disassemble completely NXT motor without breaking the orange axle hub. You can nonetheless half-open it enough to see what's happening inside (you need a Torx screwdriver - T10 size if I remember well - to open it. See photos here http://philohome.com/nxtmotor/nxtmotor.htm. Anyway, first try to see what LEGO support can do for you!
> 2 votes

# Answer
I had a similar problem with the RCX about a month ago. Check the wires for shorts or fraying, and if you can open the case and look for shorts in there. I fixed my fraying wire with electrical tape.
> -1 votes

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Tags: nxt, motor, repair
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# Question
Title: Brick-built alternative to "Door 2 x 5 x 5 Swivel, Bracket Base"
I am trying to make a brick-built alternative to the swivelling door piece that's frequently used to provide secret entrances in castle sets.

Example: this combination (images from Bricklink)

The pre-fab Lego piece has several advantages but is also fairly ugly for use in builds that don't rely on panels for walls. Its main advantage though is that it is compact and swivels around the centre, which is possible because the inner piece is very thin and slightly narrower than the outer piece.

I have achieved a similar pattern using the 2x2 turntable tile but getting the turntable positioned under the wall so that the wall spins on its centre means I need to use two levels of jumpers, both at the top and bottom of the wall. This consumes a lot of vertical space and also juts out horizontally at the top (Why doesn't Lego have an inverse jumper? one stud-hole on the bottom, two studs on top?)

Here are pictures of my creation. I'd appreciate any tips on how to make it more compact. Note that the round 1x1 bricks are needed on the sides to make enough room for it to swivel. It still rubs a bit but it's fine.

The first layer of jumpers offsets the turntable so that the wall spins on its central axis. The second set of jumpers allows the wall to be centered over the turntable. On top, I have to hang the jumpers out, then repeat with the turntable and then more jumpers. In this prototype the dark grey layers are jumpers and the black layers are turntables.

# Answer
Why not use just two jumper plates (3794), one on the top and one on the bottom? No more additional are pieces required.

You can also replace the stack of 1x1 round bricks with a single Support 1 x 1 x 6 Solid Pillar (43888) piece. The piece is used in conjunction with a large swinging vault door in the Bank & Money Transfer (3661) set. The brick is stronger then a stack of 1x1 round bricks and the round part of the brick (at five bricks high) is tall enough for most minifigures.
> 13 votes

# Answer
You could try something like this if you have Technic beams available:
> 9 votes

# Answer
Ok, not quite what was asked, but this might spark some new directions for other people.

As to your statue, a few 2x1 plates at the base instead of the tiles could attach to the legs.

This solution would allow weapons, etc, to be displayed on the secret walls.

Re-edited to include final improvements.

Using tiles and inverted tiles lets the wall be two plates thick, which allows movement without looking ugly, this build is surprisingly sturdy. All in grey this would look much like a castle wall.
> 4 votes

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Tags: building
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