# Question
Title: RCX 2.0 Firmware downloaded successfully but "Run" does nothing
I recently was able to install RIS 2.0 for the first time since I just got a 32bit Windows 7 machine.

I got the IR tower to download the firmware to the RCX 2.0 and it showed exactly the same screens the guide showed, but when I got to the point where I test the motors, I found that the "Run" button does nothing.

I tried installing the firmware 3-4 times and still have the same problem, so I'm assuming the RCX itself has a defective Run button.

Does anyone know what's possibly going on? All the other buttons work, they beep and change the screen when pressed, nothing beeps or happens when Run is pressed.

# Answer
Could be the button indeed. These buttons are conductive rubber pressing on the circuit boards integrated contacts. Might need some cleaning there...

Disassembly of the RCX is not easy but can be done. You have to remove the screws in the battery compartment, then pull slightly to disengage and remove the black IR front. Once this is done, you can pull out the PCB and battery case from the top cover. **Important note**: the PCB is connected to the battery case through metallic blades that can easily bend and no longer make contact. So when you pull the PCB+case, you must pull on the PCB itself, not on the battery case.

Once done, you can clean the button area with alcohol and/or swap buttons to hopefully repair the Run button ("View" button is useful, but not mandatory...).
> 1 votes

# Answer
Two things spring immediately to mind:

1. Are the motor cables connected properly?
2. Have you uploaded an actual program to the brick?

There is at least one way to connect the cables, at either end, such that the motors will not work. For this test, make sure the cable wires go out toward the "back" of the brick and the motor.

And, AFAIR, "Run" doesn't do anything with the motors unless you have uploaded a program that actually turns the motors on. I'm no longer familiar with the shipped software, so I don't recall if the process you describe actually does more than upload a firmware.

So, ensure that you are actually putting a program on the brick that turns the output(s) on, and those specific outputs are actually connected to a motor in the correct manner.

My quick test is usually to use the IR remote to tell the brick to enable A, B, or C outputs in either direction. You can also use the lamp to test; if the lamp lights then the output is on, and will also drive a motor.

Also, if you press the View button a few times, it will show a cursor next to an input or output. If the IR remote or program toggles an I/O, you will see the display change to indicate the state of that I/O.

(I see that I missed a key point: the Run button does not beep or change the display. This indeed points at a hardware problem, and not a config issue as I discuss here. If so, a quick-ish solution might be to get some of that contact cleaner stuff \["CRC QD Electronic Cleaner"\], pull the batteries and squirt a little of that into the spaces around the button.)
> 0 votes

---
Tags: mindstorms, rcx, robotic, discontinued
---


# Question
Title: The Mindstorms EV3 Software crashes on OS X Yosemite 10.10.3. What do I do?
It's crashing on startup which is really irritating. When debugged with terminal it says this:

Unhandled Exception: System.UnauthorizedAccessException: Access to the path is denied.

\[ERROR\] FATAL UNHANDLED EXCEPTION: System.UnauthorizedAccessException: Access to the path is denied.

What should I do? I've already tried reinstalling it.

System specs: MacBook Air '11, Late 2010, Mac OS X 10.10.3

Latest version of Mindstorms software

# Answer
> 0 votes
The error is caused by the underlying MS Silverlight runtime. As stated in this stack overflow answer, the error may be caused if

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

Possible ways to find a solution:

• Open the Console application and see if the error shows details about which path it cannot access.

• Repair file permissions of your partition via the Disk Utility application.

Search for Mindstorms EV3 files in your `~/Library/Caches`, `~/Library/Application Support` and `~/Library/Preferences` folder and delete these files (backup files first! or make sure TimeMachine is set up). Normally an application will re-create files located in these folders at start.

# Answer
> 1 votes
Updating the iOS version to 10.10.5 seems to have solved the problem for me. Hopefully this helps someone else out there.

# Answer
> 0 votes
I tried to duplicate this on my 10.10.3 MacBook Air 13. No luck. I did see in the readme file that the minimum resolution is 1024 by 768, and the native resolution of the Air 11 is 1366 by 768.

Try the following if you have not already:

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

---
Tags: mindstorms, ev3, programming, ev3-g, robotic
---


title: Can you ID this part?

text:
# Question
Title: Can you ID this part?
I am trying to id the three grey bars on the left-hand side of the image.

Any ideas?

Many thanks.

# Answer
It's 32294 Wishbone Suspension Arm:

This is listed as part x136 on Bricklink.
> 6 votes

---
Tags: part-identification
---


# Question
Title: Is there a way to buy a customized minifig?
I have a design I want to replicate into a minifig. I also want to add additional accessories to it (i.e. a calculator and glass beaker). Is there a place I can order online to get this done? Is there even such thing? One of the place I visited said it's difficult to fulfill small orders due to the cost of printing. Other places require you to select their pre-designed parts.

# Answer
> 1 votes
There are a few options, however many of them either use standard parts, or require minimum order quantities (Minifigures.com for example requires a minimum run of 50).

A couple of options for bespoke, one-offs seem to be:

Of the two, I've seen Minifigs.com at shows and the quality is very good, and the price seems reasonable (especially for the engraved options which don't require a set-up fee).

Alternatively, as suggested in this answer, you could look at doing it yourself with water decals and varnish, depending on your art skills.

---
Tags: design, customization
---


# Question
Title: What is considered the most valuable LEGO set?
Which Lego set is considered to be the most valuable set to own?

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

Which are they?

# Answer
> 17 votes
I believe it's the Ultimate Collector's Edition Millennium Falcon (10179).

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

# Answer
> 9 votes
I feel I need to represent the **Classic Town and Train** fans with the following sets:

6399 Airport Shuttle

Bricklink items for sale

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

---

1490 Lego Bank

Bricklink items for sale

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

---

7750 Steam Engine with Tender

Bricklink items for sale

---

**----UPDATE----**

In terms of increase in value over original purchase price as a percentage, it may be hard to beat the Collectible Minifigs Series 10 'Mr Gold'.

From the original price of $3 to prices of $500+++ that is a seriously valuable 'set'.

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

# Answer
> 8 votes
If you look at what a box is worth compared to the original price, I would say 3724 LEGO Dragon. It went for $99, And now you can not find it for less than $350, up to $800 for a mint in box version.

# Answer
> 5 votes
There is a website that tracks price changes on Amazon, Bricklink and E-bay in order to try to compile an index. It has an interesting page called top retired sets, ranking sets by gain compared to initial purchase price.

At the time of this writing it lists 6166-1 (a big tub of LEGO) as number one with 65% gain, and 7200-1 (final duel) as number two with 31% gain. The previously mentioned Millenium Falcon is also on the list, with 21% gain. Seems like a good indicator.

# Answer
> 4 votes
I think by actual worth sometime down the road, the most valuable set will be Lego Castle 6075, known to fans as "Yellow Castle".

http://www.classic-castle.com/sets/archives/0375.html

# Answer
> 4 votes
The most valued sets, when not using price as a criterion, will vary from collector to collector, based on their interests.

In my experience doing LEGO Customer Service, collectors of all ages tended to focus on particular themes. While the Ultimate Collector's Edition Millennium Falcon may be the most prized jewel to a Star Wars collector, it may have little to no appeal to an avid Train collector. It was very hard to talk about any themes outside the fan's specific interest. Even then, a Trains person may have interest in the MAERSK ship(not a train, but related), but none in the Hogwart's Express. Another sought-after set is the Grand Carousel, which isn't likely of interest to someone that only collects licensed sets.

For myself, the most prized LEGO toy I could attain is an authentic wooden set from the pre-ABS era. The closest thing I have to it is the 2011 employee-only duck that resembles the pre-building system era wooden duck draw toy the company made (post-yo-yo fad, using the leftover yo-yo halves as wheels).

Other categories of collectors are completionists who may value SDCC Bizarro minifig or a limited UK Sun bag as their most prized possession (similar to the Mr. Gold mentioned before.)

The currently-selected answer is worded to be exclusively about how expensive the item is, which the question specifically requested not be used for this judgment. However, lacking any other criteria, it's not feasible to give a specific answer.

# Answer
> 3 votes
There are now loads of sets which could be considered to be the most valuable. Here is a list of my choices

1. 10179 UCS Millenium Falcon
2. 10182 Cafe Corner
3. Mr Gold
4. 10196 Grand Carousel
5. 10184 Town Plan
6. Chrome Gold C3PO (only 100 made)
7. 10189 Taj Mahal
8. 5004590 Bat-Pod (only 1000 worldwide and will surely increase in value tremendously)

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

# Answer
> 1 votes
I must say, a very valuable one would be the exclusive Maersk container ship. the original 2004 set (not the 2011 reissue!) is worth a lot of money, considering they only made a handful. other than that, the Unitron Monorail can go for quite a bit MISB (Mint In Sealed Box) nowadays.

---
Tags: sets, history, investment
---


# Question
Title: How do I make a remote control car without LEGO motors?
I have no LEGO motors In my collection, what are some household materials I can use?

# Answer
> 6 votes
It sounds like you are asking how to motorize your own custom LEGO creations using motors that you may already have around the house rather than purchasing official motors.

Before I answer this, I just want to make sure that you are aware that you can purchase the PF motors individually on LEGO.com for fairly cheap. You don't have to buy large, expensive sets in order to get motors. The basic PF motor set which includes a battery box, motor, wiring, and lighting is $30 USD. Unfortunately, as pointed out in the comments, this kit doesn't include a proper RC remote, so you'd need to buy an IR receiver and IR remote as well, which would add another $25 to the cost.

The first thing that you'll need to do is find a suitable motor. Old toys are probably your best bet. If you're going for small, you could also take a pager motor out of an old cell phone. This is what Phillipe used to make a motorized city-scale vehicle in another question:

The main challenges with using custom motors are:

# Attaching the motors to LEGO bricks

The strongest connection will likely be created using some sort of glue or epoxy. Most two-part epoxies should be sufficient for small motors. Here's an example from Eurobricks:

You could probably get away with using screws or even rubber bands, but it's a bit trickier to make everything line up the way you want.

# Converting the output of the motor to rotation of a LEGO axle

Assuming that the motor axle is relatively small, it is possible to drill out the center of a Technic axle and slide it onto the motor's axle. This can be a little tricky to get right, but it does work. Here's a video that explains it.

If your motor already has a pulley attached, it's easy to just run a belt between the motor and a Technic pulley.

# Powering and controlling the motors

If you don't mind your creation having a tail, the easiest way to power the motors is to simply run a wire to the vehicle from some sort of controller. It's fairly easy to put together a working system if you have old wired remote controlled toys like this one laying around:

If you have any radio controlled toys laying around, it's also fairly easy to just rip the electrical parts out, put those on your LEGO model, and wire up your motors. You could also use the motors from the original toy. Then you don't even need to do any wiring. You would have to find a place for batteries and the receiver hardware on your creation, though.

# Answer
> 3 votes
A few years back I ripped motors, controlcard and batterypack out of a broken car. I then fitted some legopieces to it and got a superfun setup to use with my old technic lego.

I mounted a piece of a normal (old black) axle on the motor shaft. But just as @jncraton describes it *This can be a little tricky to get right*. If you are just drilling freehand as in the video it is very hard to align everything right.

So instead of fastening the drill in the powerdrill I did it the other way and fastened the axle in the powerdrill and the drill in vise. That way I know that the axle is spinning around its own center and that any small misalignment will be automatically fixed by the flex of the thin drill. To get the axle centered in the drill I sacrificed 2 bushings.

---
Tags: electronics, remote-control, diy
---


title: Hanging template for Large Minifig Case

text:
# Question
Title: Hanging template for Large Minifig Case
I've been happy to see LEGO came out with a way to display the *myriad* of minifigs out there:

And I was also very happy to find that I can hang these on the wall with the convenient eyelets on the back:

Yet despite earnestly searching I can't find anybody that has created a template for installing these. How far should the screws be apart? How far apart should the holes be if you want stack them like so:?

I'd prefer a printable template that I could drill through, but if you have measured these accurately that'd be a good start.

# Answer
Since no answers were given for two days, I'll convert my comment to a full answer:

If you haven't found anything yet but have access to a photocopier, you could try making a copy of the back side that contains the eyelets. The resulting print will be a 1:1 paper version of the back side, which you can tape on the wall intended for hanging the cases and drill through the images of the eyelets:

Be sure to align the sheet correctly, using a bubble level or such.
> 4 votes

---
Tags: minifigures, size
---


title: Bulk LEGO as presents

text:
# Question
Title: Bulk LEGO as presents
I've bought a couple of bulk LEGO bundles with the idea of gathering up the identifiable sets, printing out the instructions (via BrickSet or similar) and then giving them as presents to my kids over the years along some of my sets from when I was a kid. However, very few of the sets I can identify from this big pile of bricks are complete. Some of them could be completed with the wrong colour pieces. What I'm trying to work out is a a good strategy for giving these bricks to my kids. I could give them a scoop of random bits every now and again. Or build the sets with alternative parts (but then the instructions won't quite match), or try to buy the missing parts from BrickLink/BrickOwl. Any other ideas?

There's also a tonne (well, 200+) of minifigs, I have thought about making treasure hunts to find new parts every now and again.

Slight complicating factor. My son is 3.5 and daughter 1.5, so I'll be giving him some now, but will have to keep some back for her until she stops trying to eat them.

# Answer
> 5 votes
Sorting random kits out of a bulk lot and building them can be fun, but it's often quite tricky to determine what you actually have. Also, unless you did quite a bit of sorting up front, you might find that it gets harder and harder to pick out a full kit as time goes on. You could let the kids figure it out, but probably not until they're older, and can look up inventories on bricklink. You could also make it a game: you identify a set candidate, the kids help you build it by finding parts from the lot, and if you succeed in building it you give it to them to keep. If it's a really close build, using bricklink to fill in the missing pieces would make a lot of sense. I once tried to build every single Lego kit my brother and I owned as kids and made a list of all the missing parts. I never got around to it, but a single Bricklink order might be able to clear out that list.

If, instead of sorting out official kits, you sort out the parts by type/colour, you could probably make up some nice little lots of parts that are useful for building. Maybe a bag full of spaceship parts, or castle parts, or car parts. Each of these could become a sort of "kit" on its own, and you could gift them to your children whenever you feel like it.

You could also make some little creations, or large creations, and treat them as "kits" as well. It might be possible for you to recreate the Monthly Mini Models that the Lego company gives away, or small Creator sets, or other similar kits.

Alternatively, just spread the whole thing on the floor and tell them "Build! Share! Tidy Up After!" and let them go crazy with it.

# Answer
> 4 votes
If you'd like to test and improve their creativity, give them a scoop of random bits and tell them you have lost the instruction for this "set", but you are sure they can figure it out :)

Or consider making an advent calendar, like the official ones, but with more diverse "sets" and more pieces and minfigs per day.

Treasure hunts can be quite fun, but you could also hide one or two pieces every day, so they will find the pieces at random times and at random places.

---
Tags: sets
---


title: What Can I Build With This

text:
# Question
Title: What Can I Build With This
I have a set of LEGO pieces that I bought second hand. I know it's a full set, because the bag was unopened, but I have no idea what I'm supposed to build with it.

# Answer
> 9 votes
Based on the occurrence of the 2x2x3 brick in white and the 16 trans-blue garage door panels, I think this is a bag from set 7744: Police Headquarters.

From the picture it looks like your bag builds the bottom right part of the station - the 2 car garages and the platform under the stairs.

---
Tags: city, set-identification
---


# Question
Title: Difference between gyro sensor and compass sensor
Does the HiTechnic compass perform the same function as the gyro sensor? I have been trying to find out the difference.

# Answer
> 4 votes
I haven't personally used the HiTechnic sensors, but the difference between a gyroscope and a compass is that one measures **absolute orientation** and the other measures **change in orientation**.

The compass measures absolute orientation via a magnetometer that measures the effect of the Earth's magnetic field on the sensor. The gyro sensor uses some form of MEMS to detect changes in orientation. The compass also only works in two dimensions, while the gyro likely operates in all three dimensions of orientation.

You might also be interested in this answer from electronics.se which includes more detail than mine and also compares accelerometers to compasses and gyros.

---
Tags: technic, 3rd-party
---


# Question
Title: What ball-joint cup piece or configuration of pieces is shown in this render?
What is the name of this particular ball-cup, or piece combination that forms the thigh component circled below?

I have been unable to identify the gray cup piece when comparing it to other parts in the LEGO Digital Designer. I have ruled out this as a third party part, as the original MOC shown here was created in the LDD as well.

# Answer
The top piece shown here is the LEGO Ball Joint with Ball Socket (74261 / 98613) connected to a LEGO Brick 2 x 2 with Ball Socket and Axlehole (Wide Socket) (92013).
> 7 votes

---
Tags: part-identification, ldd
---


# Question
Title: What is the best way to store LEGO rubber tires?
Should they be stored with or without rims inside?

Or should they be kept away from plastic for long term storage?

# Answer
> 7 votes
I can't speak to "best". But as a point of reference, many many of my lego tires are many years old and they are usually stored on rims. The older tires were often not removable from the rims. As I rarely build cars, I take no special care of the tires, and I've found that there doesn't seem to be any particular problems. The rubber ages over time, but this is true of all rubber in all circumstances, and the storage method doesn't seem to have affected them much. I have these large tires from an old space set from 1983

that are in excellent condition; sadly, the rims they were mounted on

were fragile and many of those are broken. But the tires are okay.

# Answer
> 5 votes
> Should they be stored with or without rims inside?

I cannot say for sure whether storing tyres with or without the rims connected affects the lifespan. In my experience it hasn't made any noticeable difference.

There are four practical reasons I can think of not to remove the tyres.

1. It can take a lot of effort to remove tyres and put them back on again, particularly for smaller tyres.
2. Tyres and rims stored together use up less space compared to storing them separately.\*
3. It can be difficult to find a tyre that tyres that match certain rims, this depends of course on how meticulously you sort and store your parts.
4. The stress on the tyre caused by removing and fixing the tyres on to a rim *may* actually degrade the tyre.

The only reason I store the '56145' rim on its own, is because it can be used with tyres and treads.

> Or should they be kept away from plastic for long term storage?

If by long-term you mean several years/generations then it wouldn't do any harm to store them separately.

---

<sup>* A comparison of a rims of six wheels of the same type stored without and with connections. This can make a big difference in a large collection.</sup>

---
Tags: storage, wheel
---


# Question
Title: Lego EV3 - Get output device type, opOUTPUT_GET_TYPE
I would like to know what kind of motor (XL, L) is connected to EV3 output port (A|B|C|D). I need to use direct command:

```
Instruction        opOutput_Get_Type (LAYER, NO, *TYPE)
Opcode             0xA0
Arguments          (Data8) LAYER – Specify chain layer number [0 - 3]
                   (Data8) NO – Port number [0 - 3]
                   (Data8) *TYPE

```

so request should looks like:

```
unsigned const char opOutput_Get_Type[] {
    0x09, 0x00, // bytes in message
    0x00, 0x00, // message counter
    0x00,       // DIRECT_COMMAND_REPLY
    0x01, 0x00, // 1 value will be returned
    0xA0,       // opOutput_Get_Type
    LC0(0),     // LAYER 0, first brick in chain
    LC0(0),     // port A
    GV0(0)      // returned value
};

```

When I send it to brick a get response:

```
04000000 0400
          ^-
          DIRECT_REPLY_ERROR

```

which stands that error occurred. Motor is connected to port A. What am I doing wrong?

# Answer
Checking the source code, it appears that the `opOutput_Get_Type` command is not implemented. In both links, it is mentioned in the comments, but there is nothing in the actual code.

Unfortunately, I am not finding a different way to get this information.
> 2 votes

# Answer
The one who wants to know device type should use direct command:

```
Instruction        opInput_Device (CMD, ...)
Opcode             0x99
CMD                GET_TYPEMODE = 0x05
Arguments
                   (Data8) LAYER – Specify chain layer number [0 - 3]
                   (Data8) NO – Port number [0 - 3]
Returns
                   (Data8) TYPE
                   (Data8) MODE - Device mode [0-7]

```

In order to discover all ports we should send

```
unsigned const char opOutput_Get_Type[] {
    0x35, 0x00,                                 //Message size = 53 bytes (0x35 hex)
    0x00, 0x00,                                 //Message Counter
    0x00,                                       //DIRECT_COMMAND_REPLY
    0x10, 0x00,                                 //16 values will be returned... 8 pairs (type, mode)
    0x99, 0x05, 0x00, 0x00, GV0(0), GV0(1),     //opInput_Device, GET_TYPEMODE, LAYER_0, PORT_A, TYPE, MODE
    0x99, 0x05, 0x00, 0x01, GV0(2), GV0(3),     //opInput_Device, GET_TYPEMODE, LAYER_0, PORT_B, TYPE, MODE
    0x99, 0x05, 0x00, 0x02, GV0(4), GV0(5),     //opInput_Device, GET_TYPEMODE, LAYER_0, PORT_C, TYPE, MODE
    0x99, 0x05, 0x00, 0x03, GV0(6), GV0(7),     //opInput_Device, GET_TYPEMODE, LAYER_0, PORT_D, TYPE, MODE
    0x99, 0x05, 0x00, 0x10, GV0(8), GV0(9),     //opInput_Device, GET_TYPEMODE, LAYER_0, PORT_1, TYPE, MODE
    0x99, 0x05, 0x00, 0x11, GV0(10), GV0(11),   //opInput_Device, GET_TYPEMODE, LAYER_0, PORT_2, TYPE, MODE
    0x99, 0x05, 0x00, 0x12, GV0(12), GV0(13),   //opInput_Device, GET_TYPEMODE, LAYER_0, PORT_3, TYPE, MODE
    0x99, 0x05, 0x00, 0x13, GV0(14), GV0(15),   //opInput_Device, GET_TYPEMODE, LAYER_0, PORT_4, TYPE, MODE
};

```

In return we'll get response i.e.:

```
13 00 00 00 02 7e 00 7e 00 7e 00 7e 00 08 00 07 00 07 00 7e 00

```

which stands (based on http://ev3.fantastic.computer/doxygen/types.html)

```
13 00   //message size = 19 bytes
00 00   //message counter
02      //success
7e 00   //nothing on port A
7e 00   //nothing on port B
7e 00   //nothing on port C
7e 00   //nothing on port D
08 00   //M-MOTOR-DEG on port 1
07 00   //L-MOTOR-DEG on port 2
07 01   //L-MOTOR-ROT on port 3
7e 00   //nothing on port 4

```
> 0 votes

---
Tags: mindstorms, ev3, programming, motor
---


title: Lego Micropolis tutorials?

text:
# Question
Title: Lego Micropolis tutorials?
I love the Micropolis cities (http://twinlug.com/micropolis-micro-city-standard/) and would like to try to build something myself.

Does anyone know good resources for learning to build according to scale and with details? Any tips would be appreciated:.

# Answer
As the person who maintains the standard, I should probably start by apologizing for not trying to do more to make something like that available. I had hoped that the FAQ or the comments on the spec page would help with some of that but it's obviously not enough. In particular my answer to someone's question about building an airport is probably my own better writing on the topic.

For buildings in LEGO at almost any scale I can recommend the new "LEGO Architect" book from No Starch Press. It covers micro scale building, though not Micropolis specifically, and has some really good techniques for replicating the details that can make a building look great.

If you want opinions on specific topics or ideas from many of the current people building for Micropolis most of the main traffic for discussion is on Flickr in the Micropolis group.

Or you can start with two points.

The first point is to look at the scale guide right at the top of the spec:

> Scale: 1 brick is 9 feet, 1 plate is 3 feet and one stud is 7.5 feet. These are for reference only. The blocks are smaller than the blocks in a real city. Scale your buildings accordingly.

Next measure some real life things to see how that works out. For example a lot of US houses have between 8 and 10 feet between floors so if you've got a house with a flat roof then including protruding foundation and internal spaces it's likely to be about 24ft high, or (24ft divided by 3) 8 plates high. This ends up showing up in a lot of Micropolis modules as a brick (3 plates high) and 1 plate per floor. Expanding on that, a 10 story office building should probably be at least 13 bricks and 1 plate high.

The second point is to be flexible. Since most LEGO parts aren't very adjustable you can start to run into issues with items that are a bit smaller or a bit larger in real life but can be roughly translated into the scale. A great example of that is the standard Micropolis car, which is a single jumper plate with a 1x1 tile on top. However if a stud is 7.5ft on each side, then that jumper plate makes every car a 15ft 1970's land yacht. Most modern cars aren't much longer than 10ft which is actually closer to a single stud than two studs but a 1x1 plate with a 1x1 tile on top doesn't look like much more than a box.

Another example is the Micropolis city blocks themselves. Ignoring that in most US cities blocks are actually rectangular, at 32 studs our blocks are only 240ft long compared to the 260ft average of the short side of US city blocks. The long sides average 900ft. We experimented with that a bit when we were working on the original spec and there were several problems but the big ones included having too many different kinds of sub-block modules to make it work easily for a large layout and that while it was more "real" it just didn't look right to just about anyone. So we went back to the original idea for 4 16x16 quarter blocks to make one city block.

A good rule of thumb I've recommended to other people is to have a couple of those jumper and tile cars and put them next to whatever you're building and see how it looks. If the car looks too big then the building should probably be bigger. If the car looks too small, maybe take the building down a bit. You can make a lot of use of the various imagery options on the various mapping systems, both overhead and streetview, to give you an idea of what a car next to a building should look like in real life.

With both of those points in mind then the big takeaway is to try to both approximate scale but in the end be flexible about your implementation to fit the constraints of the medium and in the end build what you like and as long as it's got the roads, sidewalks, technic holes, and base height right it's a Micropolis module whatever anyone else tells you.
> 4 votes

---
Tags: city, modular-buildings
---


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

# Answer
> 1 votes
You can check out https://education.lego.com/nl-nl/educationdownloads/productpage/?AccessLink=985ff951-4b98-467d-9f16-687487a43784&ignorereferer=true

I think this is were you can find the student version, quite similar to the teachers version.

---
Tags: ev3
---


title: EV3 IDE flickering

text:
# Question
Title: EV3 IDE flickering
I'm using the Mindstorms IDE for EV3 on OSX.
Everytime I'm moving the cursor the screen starts to flicker.

See https://www.youtube.com/watch?v=q3JkonowmD0&feature=youtu.be .

Any ideas what's wrong?

# Answer
After all rebooting the Mac stopped the flickering.

However I reinstalled Silverlight and the Mindstorms IDE before rebooting. So I'm not 100% sure what part of the procedure solved the problem.
> 1 votes

---
Tags: ev3, software, ev3-g, mac
---


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

# Answer
> 3 votes
As far as I know, no such project or software or site exists. The closest one I could find is (was?) a thread in the Eurobircks forum, where exactly this topic came up. The members there tossed about various ideas, mentioning Akiyuki's brick sorter device (with the factors that made its job easier than the one you propose: uniformly lit background with known color, precision scale, only one piece at a time, a few hundred possible parts), some proof-of-concept code was written to test the capabilities of the OpenCV library, but then the interest faded and the topic was abandoned.

There are several problems in this proposition that are highly difficult (if not straight impossible) to overcome:

1. Lighting conditions

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

2. Overlap

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

3. One point of view

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

4. Differences only visible from one side

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

---
Tags: part-identification
---


title: Is there a LEGO podcast?

text:
# Question
Title: Is there a LEGO podcast?
I have tried to find a podcast about LEGO but haven't found any currently active. There seems to be some old ones out there with a couple of episodes, but nothing new that I could find.

Anyone knows any?

# Answer
> 5 votes
The All Us Geeks podcast regularly has a segment on LEGO called the Brick Breakdown that is run by William and Sarah Reed. Here is the link to the latest episode (scroll down to see when the Brick Breakdown section starts): http://www.allusgeeks.com/2015/08/episode-60-dead-men-tell-no-tales/

My guess is that because LEGO is so hands-on and so visual, it is kind of hard to run a fully dedicated podcast about it. William and his wife mainly talk about things like the history of LEGO, investing in LEGO, etc. That's pretty much all you can do through a podcast.

# Answer
> 2 votes
Beyond The Brick was a podcast that featured interviews with AFOLs and reports on Lego-related news. Although they have since moved to a video format on YouTube, their current interview content is very similar to their old podcasts: https://www.youtube.com/user/BeyondTheBrickTV/

There are a couple more-specialized podcasts that are active:

ttvpodcast (Bionicle)

http://www.stitcher.com/podcast/inside-dimensions (Lego Dimensions)

# Answer
> 1 votes
LAMLradio was a long running LEGO podcast: http://lamlradio.com/ They stopped updating it in 2012, sadly.

# Answer
> 0 votes
*Yes! I will make a proper answer out of the comment by @GreenBaron80J11.*

I have not found any other pod thats alive than All Sorted. But after backtracking a couple episodes I would say its a supernice pod. Go listen, I certainly will :-)

---
Tags: popular-culture
---


title: Is this LEGO an authentic original?

text:
# Question
Title: Is this LEGO an authentic original?
I found this LEGO piece in a second-hand LEGO stock. I have never seen a brick like this, and I can't even find the LEGO write on it.

Is this LEGO brick original, maybe vintage or some kind of special edition or is it just fake?

# Answer
> 14 votes
This is a Minitalia brick - Lego produced different bricks for a while in the seventies for Italy (per Gary Istok's latest information: because the original LEGO was deemed too expensive). Minitalia bricks have weaker plastic (which shows on the studs on your brick) and don't use the Tube system underneath the brick, but an older patent which has the X marks. The gripping power of the X marks is less good, but you will find that the X marks actually allow for half-stud offsets, which you cannot do with the tube bricks :). All this is detailed in Gary's wonderful book/DVD

# Answer
> 6 votes
It's definitely Minitalia and since you're Italian let me suggest a very recent Italian article with the most recent findings about the history and the actual reasons behind the existance of the Minitalia line!

I also recommend Gary's book, it's really great (and he's working on a new edition that will include these recent findings).

---
Tags: piece-information
---


# Question
Title: What are the various LEGO motors that have been produced over the years?
RCX, NXT, WeDO, EV3, Technic etc. How many different motors have been released over the years??

# Answer
> 8 votes
For a comprehensive enumeration and measurements on all motors, refer to Philo's excellent page on this topic: http://www.philohome.com/motors/motorcomp.htm

There are some LEGO motors that are missing from this list since they predate the 9V era, like the 4.5V motor, or the 4.5V train motor, but these are probably only of interest if you already own them, in which case you don't need to be told about them :)

There are other elements that might be considered motors, like the PF servo motor (Thanks to Phil B.), but one might argue that the servo motor is not a motor in the strict sense, since it has a fixed range of movement instead of being able to turn continuously.

Also there are pieces that incorporate motors with other functional elements, like the main part of the 4095-1 Record and Play set, the Spybotics module, the Micro Scout in the Droid Developer Kit or the Cybermaster main unit.

The WeDo theme uses a Power Functions M motor (Source).

---
Tags: mindstorms, motor, power-functions
---


# Question
Title: Where can I get threads compatible with LEGO pulleys?
Have LEGO threads ever been produced? Even the biggest LEGO rubber band is too short to meet my requirements.

I need them for this year's WRO challenge. Note that the challenge only allows Lego products, so I can't just buy the rubber band I need elsewhere.

# Answer
There are many kinds of LEGO string, which are compatible with pulleys, but they are not closed in a loop, but manufactured as a single thread. You could tie a knot on them to form a loop, but the string lacks the traction of a rubber band, so you should definitely consider this if you plan to transmit power via a belt drive made of a string.
> 3 votes

# Answer
Many office supply/stationary stores will sell rubber bands large enough to do a similar job.

I've managed to find a large rubber band 200mm long and 12.5mm in width. It would be too wide to fit on a standard TECHNIC pulley, but you can attach it to any TECHNIC wheel rim wide enough such as 56145. The grooves on either side of the wheel rim should keep the band from slipping.

I don't know exactly what you plan to build, but you might want to also consider other ways of ways of transmitting power, could you perform the same function as efficiently using a drive shaft.
> 3 votes

---
Tags: technic
---


# Question
Title: What is this black brick with red tubes inside?
In an old plastic bag with heterogeneous Lego bricks, I found three or four like this.

I can't recognise them: does anybody know what they are? In which set(s) were they used? What for?

A few more details. The small red tubes sound like they are slightly loose inside the brick. The one that connects the long sides is unobstructed (while of course it interrupts the other two).
From above, the brick looks like normal 2×4 black one, apart for the holes on the sides:

# Answer
> 15 votes
This is a 7049b - Wheel brick. It was used with the first LEGO wheels back in the 60's to create vehicles like this:

This was a very common piece (in white and black) when it was produced between 1959-1992 and was used in 176 sets according to BrickLink.

Per @GalacticCowboy's comment: As shown in the inset, the wheels had a metallic axle that snapped into the holes. Because they were modular, you could use wheels in whatever configuration you desired.

---
Tags: part-identification
---


title: Sizesorting machine

text:
# Question
Title: Sizesorting machine
I am quite new to LEGO Mindstorms, and can't seem to wrap my head around this one.

I am making a size sorting machine, sorting brick sizes depending on the time they take to pass the lightsensor.

So I am wondering if it's possible to time how long the lightsensor has a different value from normal, and then use this value to choose where to throw the brick.

Basically I need the time the lightsensor is "not" or doesn't receive light.

# Answer
> 2 votes
Yes you can do this in the standard EV3 software.

Make a block that waits until the Light Sensor goes "dark". Connect this to a Timer block, and start a new timer (reset Mode). Connect that block to a new Wait block, which waits until the Light Sensor goes "light" again. Then use another Timer block, this time in Measure Mode, to get the duration since the start of the timer (which is the time since the sensor went "dark").

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


# Question
Title: Unidenitified LEGO set - Star Wars stormtroopers and droids and stickers
Can anyone assist me to identify this set of LEGO. It's probably from between three to eight years old. I found the pieces but no instructions. I'm not sure if the orange pieces in the bottom right hand corner belong to the set or not.

# Answer
> 4 votes
I don't think all the pieces are from one set. You have definitely got parts of the 8015 Assassin Droid Battle Pack in there (the grey and white tipped parts on the purple curved slope pieces are for sure from that set).

But you seem to be missing most of the droids (only two droid bodies and a few arms, no heads). The two Star Wars figures are from another set - the one with the black hands appears to be minifig number sw201 - Clone Trooper Clone Wars, but since minifigs can be recombined this might not be correct.

Both Stormtrooper minifigs seem to have the same torso (at least from what I can make out from the photo) but one of them has yellow hands - I cannot find such a stormtrooper on BrickLink nor a set that has both black AND yellow handed stormtroopers.

The cupola shaped bowl is from 8086 Droid Tri-Fighter (and the part is unique to this set). This is also likely where the chain of bricks on the top comes from - it forms the arch of the Tri-Fighter. The propeller-blades are part of the nose of this model.

# Answer
> 3 votes
As has been mentioned in other answers, the dark blue pieces, yellow technic bricks, long rubber spikes, and long grey guns all appear in 8015 Assassin Droids Battle Pack. It also looks like you have parts of the droid minifigures.

It appears that the collection also contains parts of 8014 Clone Walker Battle Pack, which was released at the same time as 8015 Assassin Droids Battle Pack. The grey triangular plates, round tiles stickered with the Republic logo, and two clone troopers all appear in this set. The yellow hands and head would have been mixed up by the set's previous owner.

# Answer
> 1 votes
I'd say you have multiple kits there, but a big chunk of it appears to be the Assassin Droids Battle Pack (Item No 8015-1 and instructions are available).

The Assassin Droids only came in that pack.

Kit 8015-1 does not include any Stormtroopers so those came from somewhere else. There are lots of Stormtroopers out there. I couldn't find those helmets on BrickLink.

---
Tags: set-identification, star-wars
---


# Question
Title: Why do LEGO sets have a minium age rating?
Many LEGO sets have minimum age ratings, such as 7-12, 9-14, and 16+. Why is this? Are the models really that different in terms of complexity? Also, why does LEGO often indicate that sets are not recommended for children under 3 separately?

# Answer
> 5 votes
With children 3 and under, small parts may be a choking hazard. The sets that Lego markets to the parents of small children contain larger pieces that are easier to handle and harder to swallow (i.e. Duplo).

When a Lego set recommends "ages 10 and up", it refers more to building ability and patience than safety. These sets are generally more complex and larger than, say, sets an average 8-year-old would be comfortable (or capable) of building. These are only recommendations of course, not rules!

# Answer
> 0 votes
Indeed.

My 8 year old sister is incapable of completing more difficult lego sets but when i was this age, I was already building (and making my own) difficult sets. I would say it depends on many factors.

---
Tags: building
---


# Question
Title: Why are some seemingly simple sets, so expensive?
My son has fallen in love with the Lego City series. Alas, I let him watch a YouTube from the video game, and as we look to reward good behavior with reasonable sets, we are seeing very odd price patterns.

Within the Lego City series, a simple set, like a small car or helicopter might be $10. But the police station might be 70-80 dollars. Ok, more complex set, I suppose I can accept that.

But then we look at some of the medium size sets and the prices on Amazon seem very high. (Any prices I quote for specific things are meaningless since they seem to change).

But we are seeing 200 and 300 dollar sets? That seems a bit extreme.

# Answer
Without examples, it's difficult provide a precise answer, but I'll give it a shot.

Since you mentioned Amazon, I assume that's where you are getting your pricing information from. As you noted, prices from many retailers will fluctuate based on supply and demand, and that can often explain why a set is expensive.

Amazon in particular lists many sets which are no longer in production. As an extreme example, the UCS Millenium Falcon is currently listed at over $3000 USD even though its MSRP is just $499.99. Popular items tend to be more expensive on sites like Amazon after the item is no longer being produced by TLG due to shrinking supply.

You can search sites like brickset.com and others to find information about the year a set was released and its MSRP. In general, if a set was released more than 3 years ago, it is no longer in production and you will probably pay a premium to get it new and in its original box. You can also start by shopping at LEGO.com where all of the sets will be currently in production.
> 8 votes

# Answer
Just to add one more thing to jncraton's very nice and detailed response. You mentioned that your son really likes City sets. That is actually a good thing as far as getting standard prices because City is a perennial LEGO theme. The Police station your son sees at the back of an old instruction-manual may have been retired, but you can be rest assured that there is a newer version currently available. LEGO City police, fire, construction and cost-guard sets are always available.

I would suggest that you check the Online LEGO Shop for the current selection of LEGO City sets and have your son choose what he likes from there. You can also request a Retail Catalog LEGO will send you by mail every few months which contains some of the latest sets - it is very nice to browse through it. This might be a better way for your son to pick the sets he likes.

If you still decide to shop on Amazon, shop only for current sets (the ones you have seen at the Online LEGO Shop), instead of retired sets. Current sets should be the same price or better then what's available directly from LEGO. Also make sure you are shopping directly from Amazon, and not from an Amazon reseller. Listings with the "Eligible for Free Super Saver Shipping" option included are directly from Amazon and should have the best price.
> 2 votes

# Answer
The cheapest set for basic bricks if 6177. 650 Bricks for $30 (US). Most are the tiny ones, not the standard 4X2s, but it's still the best value out there.
> 2 votes

# Answer
A great article on Medium explains this in detail: essentially it boils down to marketing costs, licensing royalties, and an obsession with quality. Think about it, when's the last time you put two LEGOs together and they didn't have a perfect, snug fit, even after years of use?
> 1 votes

---
Tags: shopping, city
---


# Question
Title: Site or example project / downloadable programme resource anywhere for the EV3 mindstorm?
There seems to be lots of available examples for the NXC version, but I can't find anything for the EV3. I thought that there would be a load of example project files with the software but there's just physical build instructions, and I can't find anything on the site either.

Can anyone point me in the right direction for downloadable EV3 project files?

# Answer
I have found a few project collections, but they tend to be hit-and-miss regarding the number and quality of downloadables.

Do these fit your needs or would you like something different?
> 1 votes

---
Tags: ev3, programming
---


# Question
Title: Differences between EV3 Gyro and Hitechnic Gyro
I understand that the Hitechnic Gyro was made for NXT but are there any advantages of using it over the normal lego gyro in EV3??

# Answer
> 2 votes
IMO there are no advantages of the old Hitech gyro: The most fundamental difference is that the Hitechnic Gyro is a analog (ADC) device while the EV3 Gyro is digital (serial). This makes the Hitechnic Gyro badly suffer from drift and oscillating offsets (both at stand still and by changing output voltages caused by electricity consumers such as motors switched on/off) which has to be filtered off. Digital sensors like the new Lego gyro are not affected by these interferences - basically - at all.

---
Tags: mindstorms, technic
---


title: Age recommendations explained?

text:
# Question
Title: Age recommendations explained?
Can you explain the rationale behind age recommendations for various Lego products?

For example, what makes a 4-7 rating different from a 6-8? Is it unreasonable to buy a set labelled 12+ for my very advanced six year old if I will be building it with him?

Is there some guideline that explains the complexity or number of pieces? Is it related to the durability of the finished project?

# Answer
> 2 votes
The complexity of the model and the expected time to complete it will increase with the recommended age.

Lower aged sets, like the Juniors line, feature builds that rely heavily on standard stacking and more basic bricks.

As the age recommendation goes up, you'll see more advanced building techniques such as offset stacking (think stair stacking), studs not on top (SNOT technique), thinner walls (think 1x4 instead of 2x4), more plates instead of just bricks, and more.

Sets for younger children are also designed for the type of play those ages engage in. And they tend to feature brighter, primary colors, which also appeal to those age groups.

Looking at set 10672, LEGO Juniors Batman: Defend the Batcave, we can see evidence of these things:

* The set uses large pieces for structure, which is a very basic and easy technique.
* The set features a car, the Batmobile, which is low on detail but structurally will hold up to the more rough play of 4-7-year-olds. Cars are very, very common for these types of sets
* The set is very open, so it's easy to access from many angles for an age range still developing motor control
* We see a lot of bright colors, including a blue Batman instead of a black or earth (dark) blue Batman suits we normally see

Now, we can contrast this with a slightly higher age range set, 75099 Rey's Speeder.

The Batman set was ages 4-7, and this Star Wars set is ages 7-12:

* The Star Wars has more pieces, 193 vs. Batman's 150
* The set itself is smaller in size, because it makes use of smaller pieces (which require more fine motor control to properly place)
* The set does not come with a play area, although that's not always the case
* The speeder itself features the sideways building techniques, where the tops of the elements don't point up
* The color scheme is more muted, featuring dark reds and and more grays, although this is also common with licensed sets

You won't necessarily be able to apply these attributes universally across sets, especially since the age-ranges sometimes overlap, as seen in 60043 Prisoner Transport, which has an age range of 5-12.

None of this is to say that younger kids can't assemble and enjoy older-ranged sets, but the ranges given are typically where the most enjoyment and least frustration will be found.

Something else you won't see on the box is the difference in styling of the building instructions. For the Batman set's (PDF), we see there's only a single task per page, and they're often broken down into smaller steps or have large, clear arrows indicating placement. In the Star Wars set's (PDF), we see that each page has *two* numbered tasks and placement is less likely to be indicated by arrow for simple tasks.

These differences in instructions are because of the expected abilities and attention spans of the intended audiences. Again, this is to reduce frustration and enable the children to be more successful building the sets without relying too heavily on the adults to help.

The LEGO company does a lot of research into what types of play are better for children at different ages, because it gives them a better product. You can seem some of the information they provide parents about types of play on their Parents website, and more involvement with child education from their LEGO Education company.

This answers comes from my experience as a consumer of LEGO product for different age ranges and as a previous customer service representative. I was asked questions about the recommended age ranges on a weekly basis, and the answer I provided to customers was similar to the answer here.

# Answer
> 0 votes
The age classifications are not related to the durability but to the longevity of the finished project to remain as a build. Kids 5 and 6 can build kits for 8 year olds, they can also build kits for 12 year olds with occasional help. What they cannot do is keep the final build in one piece as they constantly take them apart. It is impossible for a 6 year old to leave a finished build alone. If you are ok with that, then disregard the age classification. You will end up with boxes of many Lego pieces. Once a year, try to rebuild sets using the instructions. But the sorting of parts is my definition of insanity.

---
Tags: building, durability, safety
---


# Question
Title: Wiring and Controlling an 88004 servo from a RaspberryPI
My 88004 servo does not move at all. Don't know how I should connect the wires correctly.

I think the inner two cables are C1 and C2 and the outer two GND and VCC.

When I connect 6.5V to the outer two cables the breadboard connector cables smoke up. I connected one GPIO from the RaspberryPI with a PWM frequency of 1200Hz to C1 and kept C2 at GND but nothing happened.

I found a video on youtube with a wiring diagram for an Arduino to 88004 but there is also GND and VCC connected with outer cables.

I orientated my Code like from the page How to control a 88004 Servo Motor with a Raspberry Pi?

Nothing happened with this Code (but I think the problem is my wiring):

```
import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BCM)

GPIO.setup(12, GPIO.OUT)
GPIO.setup(16, GPIO.OUT)

Left = GPIO.PWM(12, 1200)
Right = GPIO.PWM(16, 1200)

Left.stop()
Right.stop()

Left.start(100)

```

# Answer
Smoking breadboard connectors are never a good thing - so check your wiring to make sure all is connected well. Also, make sure that you have the GND of your powersource connected to the GND of the RPi, so that all voltages are relative to the same ground potential. Finally, I'm not sure if the Servo will work with 6.5V - it has been designed to work on 9V. A different powersource might give better results.
> 2 votes

---
Tags: technic, motor, power-functions
---


title: Custom Power Functions plug design

text:
# Question
Title: Custom Power Functions plug design
I'm considering the possibility of making my own Power Functions-compatible sockets for a project.

I'm designing a module board for a single-board-computer with motor drivers and would like to encase the SBC and module board in a 3D-printed LEGO-compatible case. Now, my current solution for plugging PF motors to the drivers is to cut PF extension cables and use just half of them, which is expensive (~3€/cable if memory serves), a bit tricky (the wires are fickle), and damaging LEGO products really hurts my feelings.

Some projects, like the SBrick came up with their own PF-compatible socket designs and I'm wondering if there are any readily-available open-hardware socket designs (CAD files and building instructions). I couldn't find any for the moment.

If there's no such thing, I'm willing to design it myself. I think I could manage to make a working CAD model of the plasic part but I'm looking for suggestions and advice as to how to make the electrical contacts.

This project would ultimately be open-sourced for anybody to reproduce it.

Regards,

# Answer
> 9 votes
I eventually made my design available for download over at Shapeways with a CC BY-NC-SA license (login is required in order to download the STL file).

I tested it at my local maker space in PLA on a µDelta 3D printer.

For the electrical contacts, I tried with pins scavenged from a DIP IC socket like Cyril suggested but the pins were a bit fickle and easily broke. I ended up cutting a sheet of conductive metal I had handy (iron alloy?) in thin bands with a paper cutter, folding the bands in two then using that as the base for the electrical contacts. Paper clips should also work.

The holes in the 3D-printed socket might have to be enlarged a bit, especially in the first layers of the print, with a needle heated with a ligher or dipped in acetone.

The resulting socket works nicely. Only time will tell how good they fare in the long run.

Cutting the metal sheet:

Resulting thin metal band:

The metal band is folded in two:

The folded band is inserted through one of the holes, folded again, then through the opposite hole:

Once the electrical contacts are in place, they are secured with hot glue on the back of the socket:

End result:

Snap!

# Answer
> 7 votes
I make a print (with silicon) of the Lego PF socket, in 2 halves.

I just need the C1 and C2 electrical contacts, so I'm just dealing with them, but you can go for the 4 contacts.

So in the bottom half, I insert two small pins from a DIP socket (for integrated circuits) in 2 tiny cuts I do with a kind of bistoury and insert the 2 pins in those two slots.

After that I pour some acrylic resin (red for that case) in the silicon mold, including the 2 pins.

The bad point is that it only deal with one half.

The other one could be done the same way, and maybe, if they are thin enough, you can join both.

On the pictures, the top face of the resin PF socket would need a kind of grounding, to make it flat and nice.

To connect it to a NXT brick, I pick up a RJ12 socket on a old electronic device and solder it with both electric wire (+some resistors)

---
Tags: technic, power-functions, cad, electronics, diy
---


# Question
Title: LabView Mindstorms - What does speed in seconds mean?
I'm trying to set a motor to spin exactly at 60rpm, and I'm using LabView for Lego Mindstorms.

However, when reading the documentation for the move motor block, it says this:

> Power/Speed specifies the amount of power, from -100 to 100, with which you want to move the motors or the speed, in seconds, at which you want to move the motors. Use the polymorphic selector below the VI icon to specify whether you want to set the power or the speed at which the motors move.

Here's a screenshot of the docs: http://puu.sh/l4FzP/c4d0b8faa7.png

So, what does the "the speed, in seconds, at which you want to move the motors." mean? I've tried setting it at one, and the motor **barely** moved.

# Answer
A speed in second makes no sense to me.

Are there more information about this motor, like to maximum rpm/power ? If so, maybe that the scale from -100 to 100 is some sort of percentage of max rpm/power, with the positives being one rotation direction and the negatives the other ?
> 1 votes

---
Tags: mindstorms, nxt, labview
---


# Question
Title: Where can I get replacement cables of this kind?
What I'm looking for:

This is a 4.5 V cable which is part of an *old* set I once had. I don't have any parts number, but I know this comes in different lengths.

Google told me about bricklink.com and I've searched there but didn't find it.

# Answer
This is an Electric, Wire 12V / 4.5V.

They can be found here:

Catalog: Parts - Electric, Wire & Connector

Just find the right length.
> 10 votes

---
Tags: part-identification, electronics, replacement-parts
---


title: LEGO Star Wars age limits?

text:
# Question
Title: LEGO Star Wars age limits?
Want to buy my boyfriend LEGO for Christmas as I know he'd love it, but am very confused about the age limits on the boxes! If I buy one age 8-14 for example, is it too simple? Don't want to offend him either as he's 20 :P Recommendations of sets would also be appreciated!

# Answer
> 6 votes
For a guy who's 20 you can ignore the age limits. LEGO used to label set with "N..99" age limits but these days that sort of humour is less appreciated. It's still true, though.

I suggest focus more on what he's interested in, and what you think he'd enjoy building. Within the LEGO Star Wars range there are quite a lot of options. If he's mostly into collecting toys I suggest starting small, but if he's into spending hours building stuff there are options that go right up to metre-long display models.

I think your main risk is social or financial. Even if you misjudge his interest, if he's into Star Wars he's likely to build it, display it, and just not ever get round to buying more. But especially the first time, don't spend more than you're willing to have him go "what? No" at, and maybe be careful about where he opens the gift. If he has judgey relatives who might say "hahaha kids toys grow up" or similar, try to avoid. It's all obvious, but many AFOLs have had experiences like that.

That said, I've given LEGO for work "secret santa" events as well as other random times, and it's usually gone down well.

# Answer
> 0 votes
Actually, LEGO sets are for all ages, but star wars are usually for teenagers and up, so it's all right to get him any star wars set!

---
Tags: star-wars, afol
---


title: LEGO minifig authenticity

text:
# Question
Title: LEGO minifig authenticity
I bought 3 mini figures from Amazon because I wanted specific mini figures and did not want to spend $30 plus doing so with bag ordering and opening. I got the figures and they look authentic.

The LEGO logos are on the nub of the torso and the little bridge part of the legs. However, not on the bottom of the legs. I have 20 something minifigures that I opened from bags, they all have the logo on the bottom of the legs. So I'm a little confused by it?

# Answer
> 2 votes
Some of the minifig parts that are officially made in China (often including the Collectable Minifigures) don't have the copyright/logo stamp on the inside toe - I noted that in a comment to my answer on What does the imprinted information inside bricks mean?

# Answer
> 0 votes
I would say that it all depends on the age of the piece. Throughout lego history they have changed through various different manufacturing methods. one of the biggest being the change from yellow to skin colour and some smaller ones being the ventilation on top of the head. It would also provide a lot of help with an addition of a picture.

# Answer
> 0 votes
There is a bootleg version of lego from china. If the minifigure print wears off in a few days, its probably bootleg. It is probably made by lele, sheng yuan, or sluban.

---
Tags: minifigures, collectable-minifigures
---


# Question
Title: Are the plastic bags inside the LEGO box recyclable?
Are the plastic bags inside the LEGO box recyclable?

Also, why aren't the plastic bags inside the box not completely filled? If The LEGO Group didn't want it completely filled then why not decrease the bag size?

# Answer
> 11 votes
According to this bricksetforum thread (and also true of the LEGO sets we have around right now) the LEGO bags are #5 plastic which is accepted by Whole Foods and some municipal recycling services.

This thread has interesting commentary on bag packing considerations. Not surprisingly LEGO Group is optimizing for efficiency and dependability. The bags and their weight also affect the QA process which includes weighing the bags.

## 2021 update - the future is getting here

LEGO is reportedly moving to paper bags. This is a double win of going with a renewable resource and wider recycling availability. LEGO themselves have a page on their sustainable packaging that says:

> We will begin to test paper bags in our boxes which means goodbye single use plastic and hello recycling bin! First, we will trial recyclable paper bags that are made from Forest Stewardship Council certified paper. They will be designed to help children understand the importance of recycling and ensure they have the best possible play experience. Our new bags will be phased in over a four-year period from 2021.

# Answer
> 2 votes
No, the bags are actually not recyclable, and the bags aren't filled entirely because TLG wants the bags to be more flexible and loose,so they fit easily in the bags!

---
Tags: packaging
---


# Question
Title: I have a series 14 Sasquatch (Square Foot) missing facial paint, is it normal?
Hi I have the camera holding Sasquatch but he does not have the black eyebrows and muzzle. The eyes and teeth are there but the rest is just brown.

# Answer
> 1 votes
No, it's not normal. It would usually look exactly like it is on the lego website. I suggest you call the lego customer service.

---
Tags: minifigures
---


# Question
Title: What is this minifig and is it from Atlantis?
Saw this on Facebook, what is this minifig?

Some people say it is from Atlantis but I'm not so sure.

# Answer
> 6 votes
This minifig is indeed from Atlantis, it is a Atlantis Manta Warrior

# Answer
> 0 votes
It is indeed the manta warrior. It is one of the several undersea warriors in the theme, although it's discontinued.

---
Tags: minifigure-identification
---


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

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

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

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

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

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

This is useful for building sliding doors and walls that are a full module wide. Here's an example from 31009:
> 20 votes

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

You can see an example of that technique in the Cloud City set:
> 15 votes

# Answer
It can also be used as the eave of a building!
> 0 votes

---
Tags: piece-information
---


# Question
Title: Sending information from one EV3 brick to another EV3 brick
I am working on a project using RobotC and multiple EV3 bricks to participate in a robotics challenge. I am wondering if it is possible to send sensor values from one brick to another through either bluetooth or USB? All of this is through code, and not using the graphical interface.

# Answer
Currently, RobotC does not support Bluetooth messaging\[\] or USB daisy chaining\[\] LEGO MINDSTORMS EV3 programmable bricks.
> 0 votes

---
Tags: ev3, robotc
---


title: Is there a LEGO Tyre Shop set?

text:
# Question
Title: Is there a LEGO Tyre Shop set?
Is there a LEGO set of a tyre shop (garage)? In other words, a set with play features where tyres could be disassembled by a tyre-changing machine, with a lift for cars or bikes, and other tools for this kind of work?

If it does, please could you give me the set number?

# Answer
> 10 votes
Assuming you are asking for a set that has play features resembling an auto mechanic's shop, then you have a few options:

---

The closest is probably **1966 Car Repair Shop**.

1966 Car Repair Shop is a 1985 set. It does not feature a lift, but it does have a jack, and includes a wrench (and other play features) that simulate a mechanic's shop.

---

Another good choice that's still in production is **4207 City Garage**

City Garage has an elevator lift (no mechanic access underneath it), and it has a mechanics shop, including spare tires and tools to work on the cars. However, it's not as "good" of a shop as 1996.

---

Lastly, if you're ok with Duplo, the closest set is **3619 Traffic City**.

3619 Traffic City features a real working lift and mechanics shop. However, it also features other play features like 4207 City Garage.

# Answer
> 6 votes
There is a new one. It's set number 60097.

---
Tags: sets
---


title: What is LEGO MINDSTORMS?

text:
# Question
Title: What is LEGO MINDSTORMS?
I have heard of LEGO MINDSTORMS, and wondered what it is for the longest time. What is it? What can you do with it?

# Answer
> 2 votes
LEGO MINDSTORMS is the brand name for a series of robotic toys produced by the LEGO Systems A/S.

The kits are centered around a programmable brick - a micro controller in a LEGO compatible housing that can be integrated LEGO products.

The kits include software that allow the user to write programs to command the brick to control motors and read data from sensors attached to the programmable brick. In other words, you can use it to create interactive LEGO models.

With some imagination and determination, you can do just about anything with it. Do a web search and you will find more examples of what other have done with their MINDSTORMS than I could possibly list.

---
Tags: mindstorms
---


title: When did the LEGO company begin?

text:
# Question
Title: When did the LEGO company begin?
When did the awesome LEGO company begin? Who created it? What was their purpose/goal? I think it would be neat to learn about this.

# Answer
> 4 votes
The history of The Lego Group starts with Ole Kirk Kristiansen, a Danish carpenter.

After the global economic downturn, spurred on by The Great Depression, Ole found that his carpentry and joinery business in Denmark was failing. This started in 1929 and by 1931 he had to let his only remaining employee go.

In 1932 he was commissioned by a Jens W. Olesen to make toys. Until then, his business primarily made wooden products that were ready-for-market, such as ironing boards, step ladders and Christmas tree stands. However, once his toy business started it really boomed.

Around this time, the yo-yo was a very popular toy, and one of Ole’s most successful products. However, once the fad of yo-yos died down, the warehouse stores were converted to a new purpose: wheels on the infamous wooden duck toy.

It wasn’t until Ole started making toys his primary business and decided he needed a new name for the company. In order to come up with a new name, he held a contest. The winner of naming contest would win a bottle of Ole’s own homemade wine!

Of course, Ole ended up the winner, and got to keep his wine. He decided on the name LEGO, which a portmanteau of the Danish words for “Play Well”, LEG and GODT. This is when LEGO was born, and Ole’s legacy as a toymaker truly started. To this day, the ideal of playing well guides the company.

Reports vary, but the founding of The LEGO Group was said to have happened either in 1932 or in 1934. I’m inclined to believe that the company name was actually created in 1934, as the later resource shows.

Besides yo-yos and ducks, LEGO made a variety of wooden toys. Their line-up included cars, trains, boats and planes. Like now, LEGO was known for their quality products. Today, LEGO only uses the highest quality ABS plastic pellets for their products, and injections molds accurate to 2 micrometres! Then, LEGO used beechwood that was air-dried, kiln-dried, polished and given three coats of paint. Once, one of his workers, his son Godtfred even, only gave a line of toys two coats of paint. Ole made him go back to the factory and give them all their third and final coat. Only the best is good enough.

There is more history involving their wooden toy line, and how they fared during World War II. However, the next most notable event was in 1942 when a fire destroyed the entire factory in Billund and its contents. Nothing survived, and the factory had to be rebuilt.

Then, in 1946 Ole invested in a plastic moulding machine, and the next year started producing some plastic toy products. It was then that they started producing “Automatic Binding Bricks” or LEGO Bricks, based on the Kiddicraft product, “Kiddicraft Self-Locking Building Bricks”.

Plastic toys, however, were not nearly as popular as the wooden toys they were already making. It took a few years until a more popular product was created, the “Town Plan” building system, in 1955. Based on the limitations of that product, new bricks were designed in 1958. This is when the iconic tubes on the undersides of LEGO bricks were first introduced.

Later that year, Ole died and his son, Godtfred took over the company. Previously, he’d resigned from LEGO, but had come back. He continued to produce both wooden and plastic toys until *another* warehouse fire in 1960 that destroyed most of their wooden inventory—but not their plastic inventory!

Godfredt decided then that the plastic toy line was successful enough to continue alone, and wooden toy production was discontinued. This was not a popular decision, and other family members that were big parts of the company left, just as Godfredt had left a few years ago when he disagreed with his father.

Nevertheless, Godfredt continued in the production of LEGO bricks and building systems.

These days, The LEGO Group is one of the top 3 largest toy manufacturers in the world, and run by Ole’s grandson, Kjeld Kirk Kristiansen. They're still headquarted in Billund, Denmark, but have facilities around the world. They’ve set themselves apart with their “play well” ideals. Their system of play of proven wildly successful, although the company has faltered at times. They’ve learned through trial and error that they are best at making quality toys that have value in helping children play better. Attempts to make clothing and jewelry (Clickts) failed.

While “Play Well” may seem to just mean good to play with, it actually represents more than that:

* LEGO toys have strict guidelines regarding weapons. They must be clearly fictional or fantastical, or accurate historical replicas. Modern weaponry are a no-no. Furthermore, the purpose of LEGO toys with weapons is not the weapons and fighting themselves, so they avoid making weapons the central part of any set.
* Like the toy guidelines, there are similarly strict guidelines regarding violence in LEGO shows and video games. Characters are not to be seen being hit too many times in succession, and they don’t “die”, simply fall apart. As with the previous bullet, these guidelines are meant to remove the emphasis on violence, and instead focus children on play.
* Similar to the points above, LEGO won’t make toy lines that contain content that isn’t considered appropriate for young children. For this reason, they avoid certain licensed themes that other toy companies don’t, and have turned down some LEGO Cuusoo/IDEAS because they don’t fit the appropriateness level LEGO requires.
* LEGO products are made from high-quality products, using high-quality manufacturing tools and equipment. They even use MRIs in their testing process to make sure new molds don’t have internal weaknesses or defects. While some “competitors” products tend to fall apart before you’ve even finished making them, you’ll find that LEGO bricks almost always snap together and stay together. (If they don’t, their friendly customer service will likely send a replacement brick for free)
* LEGO tries to increase make their business more friendly for the environment. They’ve done this by decreasing the box sizes, using paper sourced from companies using sustainable practices, implementing better recycling policies in their facilities, and expecting their suppliers to follow certain standards.
* LEGO focuses on making products that are beneficial for children. Besides their standard playsets, they also have a LEGO Education line that has grown so big it is now its own company. By understanding how children develop, and how play is involved in development, they can design better sets for children.
* LEGO wants their products to be suitable for all children. Traditionally, many of their products were seen as “boys toys”, and boys were their primary demographic. Previously, LEGO had attempt to create various lines, such as Scala, to appeal to female children, but they were largely unsuccessful. Recently, they’ve developed the LEGO Friends line, after doing years of research, and it’s been incredibly successful. What started off as a simple theme with limited products has now spun off into multiple releases and the new Elves series. What once filled up a couple shelves in a store may now take up half an aisle!
* Along with making sure they have products that appeal to all genders (despite toys being gender-neutral anyway!), they have products to appeal to children of all ages. Their DUPLO line, for instance, is made especially for toddler-aged builders. These bricks are actually compatible with normal LEGO bricks, and come in at 8 times the size. Each dimension of a DUPLO brick is double that of a LEGO brick, which is where the name comes from. This bricks are extra sturdy and safe for children to by rough with, and don’t contain any elements that may be of safety concern. As for the older builders, many of the sets appeal to adults as much as children. The yearly winter and modular house sets, the train sets, and the very large sets are incredibly popular among adult builders.

There is so much more to talk about for this company, and there are many books and websites that do just that. What I’ve written for you here has been sourced from The LEGO Group’s websites, but also comes from my time as a customer service representative for them. Much of what I learned about the history of the company actually came from training documentary videos, and has only recently been published in as much detail on their website.

What I’ve provided here should answer your questions about who created the company and why: Ole Kirk Kristiansen created the company so that children could play well.

# Answer
> 0 votes
LEGO was founded in 1932 by Ole Kirk Kristiansen. He established his business in the village of Billund, Denmark. His firm manufactured stepladders, ironing boards, stools and wooden toys.

http://www.lego.com/en-us/aboutus/lego-group/the\_lego\_history

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


title: Lego death star problems

text:
# Question
Title: Lego death star problems
I have recently got the death star but my han solo and ben kenobi mini figures have white parts in their eyes (a newer edition of the mini figure) why them and only them.

# Answer
> 3 votes
I don't have the Death Star, and haven't kept up with the latest figure development trends, so I can't be sure about this, but:

Lego frequently updates parts. The new parts are sometimes considered new, and the old parts retired, but often the new parts are considered equivalent to the old parts. Lego then uses these new parts arbitrarily, wherever is most convenient. This leads, sometimes, to a set containing a mix of old and new parts, depending on the sources of those parts during manufacturing. So if, say, they replaced a certain piece with another, nearly identical piece, any set you buy during the transition period could conceivably contain both, if the parts bags in your set came from two different parts of the factory.

If Lego updated the Solo and Kenobi head designs, for use all across the Star Wars line, those head designs may show up in new copies of older sets. Similarly, if there is still stock left of older designs, those designs may also appear in newer sets. When Lego considers the parts to be equivalent, there is no guarantee of which you'll get during the transition.

---
Tags: minifigures
---


# Question
Title: What is the most cost effective way to get basic bricks in bulk?
I've seen another question (What's the most cost effective and efficient way to buy bricks?) that asks where the best place to buy specific bricks in small quantities are. That is helpful when working on LEGO projects that require precise pieces, but I am planning on using LEGO for non-artistic projects, such as building cases for Arduino that I have. As such, I am not really bothered by specific color. What is the most cost effective way to get common bricks in large bulk quantities such as the 4x1 or 2x4 bricks in any color?

# Answer
The best and most cost effective way to get large quantities of brick, especially common ones, is via the LUGBulk program. You would need to be member of a LUG (LEGO User Group) that participates, and LUGBulk orders are due at specific times of the year. Search for a LUG near you and check.

Alternatively, you can go to your closest LEGO Store and see which common bricks they have in their Pick-a-Brick wall. If one of them is a piece you need, check with a store employee if they are willing to sell you a whole box. This used to cost $70 per box (independent of the type of brick inside) but I believe it might now be more ($100 IIRC).
> 1 votes

---
Tags: shopping
---


title: NXT Display is messed up

text:
# Question
Title: NXT Display is messed up
I have an NXT 1.0 and the LCD display only displays noise. Anyone know how to get one replaced or repaired?

# Answer
> 2 votes
There is a great video on YouTube that shows how to repair this.

https://www.youtube.com/watch?v=eCZNc7tPop0

Basically, there are some surface mount capacitors on the PCB board for the screen/buttons that need a little bit of soldering to make sure they are properly electrically connected.

I have performed this repair myself with success.

---
Tags: nxt, repair, replacement-parts
---


title: Are these real Lego figures?

text:
# Question
Title: Are these real Lego figures?
Are these real LEGO figures or custom non-LEGO designs?

# Answer
> 8 votes
Yes they are. The top figure is made out of these parts:

The bottom figure has the same torso as the top figure, and these parts:

* Head: I cannot find this as a LEGO provided minifig head print, but there are several ways to customize LEGO heads, like through minifigs.me so this could be a custom head not produced by LEGO.
* Hair: Item 4530 in Tan

---
Tags: minifigure-identification
---


title: NXT 2.0 speakers not functioning

text:
# Question
Title: NXT 2.0 speakers not functioning
I have the NXT 2.0 set, and have owned it for about 5 years now. About a week ago, the sound coming from the speaker started sounding distorted, and eventually stopped working. That time I restored the sound by simply restarting the NXT, but now no sound plays, including the click and startup sounds.

# Answer
I have had the sound go out on one or two NXTs. I was able to restore it by doing a factory reset.

On the back of the NXT, there are 12 technic pin holes. In the one closest to USB port, you will see a metallic button. With everything unplugged from the NXT and with the NXT powered on, press the button with a paper clip or other instrument that will fit in the hole. After a few seconds, the screen will go blank and the brick should start making a ticking noise. Then use the NXT-G software to reload the firmware on the NXT.

~~For more complete instructions with pictures, see http://www.neisd.net/et/robotics/documents/ResettingYourNXTBrick.pdf. Note: Step 2 is incorrect and should be skipped - there is no "soft" reset - the button in the battery compartment is for indicating that the rechargeable batter is being used.~~

UPDATE: Link above is broken, so here is a new one: http://www.legoengineering.com/clicking-brick-syndrome/. It is not quite as detailed, but still has nice pictures.
> 2 votes

---
Tags: nxt
---


title: Identification please

text:
# Question
Title: Identification please
I got hold of a lot of loose LEGO; included were three closed packages without assembly instructions. Two of these were numbered as 7 and 8 respectively, the third one is without numbering.

I attach pictures of the parts and would be very grateful, if someone could identify them so I can download instructions before my little grandson comes to visit in a few weeks :)

**Package "7"**

**Package "8"**

**Unknown Package**

# Answer
Given the size of the set (indicated by the fact that there are at least 8 bags), the occurrence of the Item 2584c003 - winch with reel and the Item 41539 - 8x8 light bluish gray plates in package "7", it looks like you have parts of set 60004 Fire Station in your hands, specifically one of the upper floors of the building, together with parts of the emergency pole.

Package "8" is also part of set 60004 Fire Station, specifically parts of one the two main garages next to the office tower part of the Fire Station, the roof of the garage and some of the sidewalk.
> 3 votes

# Answer
One of the key pieces here is the Dark Blue Part 3039 - Slope 45° 2 x 2, which is a fairly limited color.

Of the 5 sets using more than 8 of that element (your picture contains 10), there are none that contain at least 2 more of the other elements pictured.

As @PhilB commented, the 6x12 plate is also a rare piece. There are 0 sets that have both the Bright Green 6x12 plate *and* the Dark Blue slopes. The light bluish gray bricks are also not generally seen with those other two.

**This is an assortment of bricks from a number of sets.**

---

The small bag may be able to be identified to the set it belongs in, but the picture of bag is not clear enough. Some elements are partially hidden by others or glare, and the color isn't clear enough. If a picture of the bag is taken more zoomed-in and on a white background (like a piece of paper), we may be able to ID it.

I was able to find out this information by downloading a list of sets and pieces and turning it into a local relational database. I then queried that database to attempt to find sets which contained more than one of the different types of pieces pictured.

The other numbers, such as how many sets contain the piece/how rare a piece is can be done with a simple query, but many LEGO-related websites with parts listings have this information freely available.
> 1 votes

---
Tags: set-identification, city
---


# Question
Title: Is there a functional difference between bricks w/ and w/o bottom tubes?
For instance:

*3040a - Slope 45° 2 x 1 - without Bottom Tube*

and

*3040b - Slope 45° 2 x 1*

Are both of these always interchangeable? If not, what are the cases where you would absolutely need no bottom tubes?

# Answer
Parts with and without bottom tubes are nearly always interchangeable in normal building scenarios.

However, there is definitely a functional difference. Not having bottom tubes generally does the following:

* Reduces clutch power. There's one less surface for the stud to produce friction against.
* Allows for lots of different connection points along the bottom edge rather than just at both ends. This can be useful in places where you aren't always working in whole numbers of modules. For example, here's one way that you could build a wall at 45 degrees to what you would normally build by exploiting 1x2 bricks without bottom tubes:
> 10 votes

# Answer
**Are both of these always interchangeable?**

Yes and no. They are 100% compatible with the standard LEGO building system, but you may be able to use the bottom-tubeless elements in arrangements that wouldn't work with a standard brick, and vice-versa.

**If not, what are the cases where you would absolutely need no bottom tubes?**

Bottom tubes were introduced into bricks to increase support and stability. Or, as @jncraton mentioned, "clutch power". Bottom tubes have been around for awhile, but the pieces without bottom tubes have been slowly dying off.

They've almost been completely discounted as of 2002, partly for those structural reasons. In fact, only 11 sets since 2002 have used them, compared to hundreds during or before 2002.

There's one exception to the lack of use of bricks without bottom tubes: **Small translucent pieces used for decoration or to represent translucent materials, such as glass and water.** These translucent bricks are still in popular use, because the lack of the center tube makes them appear more clear. Over 200 sets have used such pieces since 2002, primarily for glass and water representation.

So, there, it's not *required*, but it looks much nicer.
> 5 votes

# Answer
jncraton and CreationEdge have both explained what the tubes are for and mentioned two advantages to not having them: nicer-looking clear parts, and connections that aren't aligned with the system stud grid. The main advantage to having them is the clutch power it adds: in a 2x2 brick such as the slope with no tube, each stud touches two walls, but with a tube each stud also touches the tube, so 50% more clutch.

As I explained in this comment regarding a pizza tile that had a variant element with a tube, the tube is a useful attachment point. The inside of the tube is a stud-hole so you can put a stud there, and this can be used to great effect with the right pieces. In the case of the pizza element, a minifig hand can be placed in the tube to hold the pizza centrally from underneath. Similarly bricks with tubes can be placed on half-stud offsets from other bricks using the tubes.
> 4 votes

---
Tags: piece-information
---