text:
Can I still motorize Universal Building Set 8034 and other from that time with modern elements?
Set 8034 was supposed to be motorized using 8700. Of course,  this is way outdated and kinda pointless to buy motor this old.

Current set for this purpose is 8293. Problem is, old motor was 5 studs long, new one is 6, and new set does not provide rubber band for power transmission. Can these be easily fixed? And is there anything else I  should be aware of?

The length of the wire is another thing to be aware of. The wire attached to the motor in 8293 is only slightly more than 20 centimeters (might be a few centimeters more, I don't remember), you can double that by putting in the switch which has about the same length of wire, but it's still not much. I don't know how long the wire in 8700 was, but it looks longer.
You should also be aware that the new motor doesn't have a pin sticking out that rotates, but a pinhole, if you put in a 2L axle it will look about the same, but the notches on the newer (part 32062 - the older part 3704 didn't have notches) are in a different position (I believe they are in the middle of "each L", while the pictures show that the notch on the axle extending from the old motor is in the middle of the "half L" closest to the motor, the belt wheel was about ½L thick), so you'll have to think about how you place the belt wheel if you want to use a rubber band directly from the axle to transfer the motion. You can work around that with a (half)bush on the axle, but that significantly changes the circumference the rubber band goes around, as thus the gearing. (This section was significantly extended to address Michael Verschaeve comments, thanks goes to him for pointing out the issues I believe I have now addressed)
I don't know set 8034, but from the pictures it looks like it would be hard to fit the new motor due to the increased length.

I'll wait with accepting 'till I'll have a chance to assembly this car again, but I'm afraid you may be right that cable length and motor length will make it fail. Also, good catch about notches on 32062 - I didn't even thought about that to be an issue

If the notches indeed do not align, easily adressed by putting a bush or halfbush on the 2L axle ...

Also, I doubt I have ever seen the notches in a 2L axle being used as a pulley for a rubber belt, I kind of doubt they are deep and wide enough...

I have extended the answer (the middle paragraph) to address those issues. (It became a rather long comment and felt like something that belonged in the answer).

8700 came with two wires.  The short one was about 20 cm (suitable for adding a battery trailer to your self-powered vehicle), while the long one was 75 cm (suitable for a remote control).

Agreed with the issue of the notch in the 2bar, a better option might be the technic smooth half-bush?


text:
New Lego Star Wars Character Encyclopedia
I am wondering when the newest version of the Lego Stars Wars Character Encyclopedia will be released?   The latest version is from 2015, I believe, and does not incorporate the new movies.
I would greatly appreciate any information you have on release date.
Thanks!

Hi Chris, welcome to Bricks! We're not actually part of The LEGO Group and don't have advance details of when new products are released - indeed as a Recognised LEGO Online Community we are not allowed to re-publish leaked details

source: Stack Exchange

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

sort: votes


text:
How to use the direct command to make EV3 motor backward?
I write the java language. I use ev3 direct command make ev3 motor to run,
example:
"opOUTPUT_POWER,LC0(0),LC0(0x01),LC0(20), opOUTPUT_START,LC0(0),LC0(0x01)"

In this case, the power is 20 so I write value (byte)0x14 resulted ev3 forward.
When I want to make the ev3 backward, how can I do??
I think change power 20 to -20, but I don't know -20 hex value.

The LC0() macro treats the value as a signed 6-bit integer.
From bytecodes.h...
#define PRIMPAR_CONST_SIGN 0x20
#define PRIMPAR_VALUE 0x3F

PRIMPAR_VALUE is where the 6 bits come from. PRIMPAR_CONST_SIGN means that the 6th bit is the sign. This means it has a range of -32 to 31, inclusive.
We must also keep in mind that computers use the 2's complement for negative integer values, so we can't just use 0x34 (0x20 | 0x14) and expect it to be -20.
0x20 will be -32, which is the lowest number possible. So, to get -20, we would need -32 + 12 = -20. In 6-bit hex 0x20 + 0x0c = 0x2c. But, you don't actually have to use hex formatted number. We can let the compiler figure it out like this: (-20 & PRIMPAR_VALUE). This trims the number -20 down to 6 bits. In fact, this is what the LC0() macro does internally, so we can just write LC0(-20).
If you need values larger than this range (e.g. -100 to 100), then you need to use the LC1() macro, which uses 8-bit signed integers. It has a range of -128 to 127. So, this will work too: LC1(-20).

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

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


text:
The center button does not work on EV3 brick
My son has the Lego Mindstorms EV3 brick. The brick turns on when he pushes the center button, but he can't use it in the menu. What's the problem?

FYI, the center button is usually intended for launching programs and opening the Brick Apps. To prove that you're not being confused, try making a program for the EV3 (on the Mindstorms software, not the brick) and create a program that moves it's motors when the center button is pressed. If that works, then it's just you getting confused with the functionality of robotics.

It is somewhat common for the buttons on the EV3 to stop working. This is usually caused by the failure of the adhesive that holds the metal part of the button in place.
You can always contact LEGO customer support to see if they can help.
For the do-it-yourself person, it can be fixed fairly easily though. This is how I do it...
First, you will need to remove the cover from your EV3. This requires a Phillips screwdriver. Remove the 4 screws in the battery compartment and gently pull the top half of the plastic housing off.
The image below shows a couple buttons that I have already fixed and one button (the right button) where the adhesive has failed. You can see that the plastic covering is coming loose.

Use a sharp knife to cut away the plastic that has come loose. Since the adhesive is no longer sticky, it is not doing any good.

Use clear tape to fix the button back into place.

Then reassemble the EV3.

I doubt this will solve the user's problem... she is no longer active on Stack Exchange.

@mindstormsboi - but by editing this old question, you've brought it back to peoples attention, and they will then try and answer it. David's answer is very detailed, and was answered around the time of the question, and hopefully it will help someone who comes along later with the same problem.
Further to that, while tidying up odds and ends of grammar is commendable, ideally you would be making substantive edits/corrections to these posts, rather than fixing up the odd typo here and there, especially on older, unanswered posts :)

Try to restart the brick by keeping the center button and the exit(return) button pressed at the same time for about 5 seconds.

Thank you very much for answering my question . This didn't solve our problem. The brick turns on, we can walk around the menu, but 'ok' button doesn't work. I think button is good because if the button isn't good, it would not turn on.

Have you tried reloading the firmware?

I updated my software to brick and I wanted to restore the brick foundation, but it failed. Because when I pressed the  button then the brick started. It’s all right. After I pressed the  + <Center(or OK)> +  and the brick beeps. I think that brick doesn’t detect the  button. By this time  button doesn’t work.

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


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High resolution flat view box cover images
Where can I find high-resolution, manufacturer quality LEGO box cover image files with flat view, i.e. without perspective view?

Is there a set database somewhere that collects them? I have tried searching but so far without success.

this is only a guess but Lego would probably do what it can to make them not appear on the Internet. Making them available would make it easier to manufacturers of fakes... and Google is american company, so DMCA applies.

No, according to their fair use policy here: https://www.lego.com/en-us/legal/legal-notice/fair-play they currently don't mind scans of box-art under certain conditions... Unfortunately, no-one has currently done the effort to start a large repository of high-quality box-art scans...

Lego does not release them for most sets so you might have to do what we at Brickset do when we want them and use software to correct the 'distortion'.

I've been using Paint.NET and the quadrilateral reshape plugin to achieve this, but it takes a lot of time and the result is not optimal. (Amusingly, using the result in a Google image search can sometimes locate manufacturer quality flat-view images!) What tool do you recommend?


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Sensor usage during manual control
I created a design challenge where students will use their touch sensor and ev3 brick to play a game of freeze tag.  Is it possible to have a program where they can manually control their robot via smart phone app, and when another robot presses another robots' touch sensor, they become disabled and play a noise warning they are turning off and done playing, being "Frozen".

The EV3-G programming language has mailbox blocks where it can receive bluetooth messages. You could write a program that until the touch sensor is pressed keeps processing the messages to control the robot.
The hard part here will be writing an app for the smartphone that sends the messages, however the BT protocol EV3 uses is documented and apps are already available implementing the messaging system, e.g. in C# here: https://github.com/jovabel/EV3Messenger
There's also the lego commander app, but I think the instructions sent by it bypass any program running on the EV3 brick, or rather they run in parallel so I'm inclined to think that the only solution is to write your own smartphone app...


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Please identify this black 2x2 tile with sticker, sunset with 2 palm trees and boat
Can someone identify the set origin of this sticker on a black 2x2 tile?

This is part #  3068bpb0183 : Tile 2 x 2 with Hovercraft Sunset Pattern (Sticker)
From 8485-1: Control Centre II


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Could not open serial port or USB device, RCX on Linux
I am trying to use my old RCX 2.0 set on Linux (Xubuntu). The problem is that when I try to download the (official) firmware into the RCX via the command:
nqc -Susb:/dev/usb/legousbtower1 -firmware ./firm0332.lgo

I get the error "Could not open serial port or USB device". Note that:

There is a module for the USB tower corresponding to my Linux kernel,
The USB tower is recognized as /dev/usb/leogusbtower1,
I changed the permissions with sudo chmod 666 /dev/usb/leogusbtower1,
When I do echo "Hello!" > /dev/usb/legousbtower1 the tower blinks,
My version of NQC is 3.1 r6 from the Ubuntu repositories,
The tower works like a charm in a Windows XP virtual machine.

Because of the list above, I don't understand why I can't communicate with the RCX yet. Can somebody help me? Thank you.

what happens if you leave off the usb: prefix?

@David Lechner: Thanks, I still get the error with the prefix removed, I don't understand.

I use sudo chmod 666 /dev/usb/legousbtower0 and nqc -Susb -firmware firm0332.lgo. What about to try -Susb only

@TomasKulhanek: Thanks, but still not working :( I really don't understand.

New here but I just had the exact same problem you did, I can't be 100% sure this solution will work for you, but given that I also used the ubuntu repo version of the software I imagine it will.
Around the web I found the syntax you use -Susb:/dev/usb/legousbtower1...but I don't think this actually works (beyond the -Susb part).
What I ended up doing was simply using -Susb, but the important part is that you not have legousbtower1 at all, but rather legousbtower0. To achieve this you can remove any usb device that gets enumerated before the usb tower from its slot, then reconnect the usb tower before reconnecting the other device. (it's probably a keyboard or a mouse, and it will be shown in the /dev/usb/ directory, possibly as a usbhid or human interface device). If this is not possible then you can probably find another way to enumerate it first, but that is beyond the scope of my answer.
The following is untested:
My guess would be that the patch applied in the article here https://pbrick.info/2013/10/configuring-the-lego-usb-tower-on-linux/ does allow for the syntax you tried, but the version built for the repo simply hardcodes the path to /dev/usb/legousbtower0.

Just as an aside you can also do the following:
sudo ln -s /dev/usb/legousbtower1 /dev/usb/legousbtower0
That worked for me, and my challenge now is that there is no firmware :-)

All this above wasn't working for me. A short analysis with strace command showed that nqc called with -Susb:/dev/usb/legousbtower0 wants to open
/dev/legousbtower0. Though a symbolic link solved the problem.
I'm using fedora30, nqc version 3.1 r6.
PS: try to use -S/dev/usb/legousbtower0 wasn't successfull because then nqc
seems to believe that device is a normal serial device.


text:
EV3 low battery communicate right after startup
I just bought an EV3 and started having battery problems. I am using 6 NiMH 1.5V batteries for my EV3. They lasted for around 10 minutes of work and went flat (that's what the EV3 kept saying but the voltmeter was showing still ~1.5V each).
I ordered 6 rechargeable NiMH batteries. After installing them the brick started and after 2 seconds showed "low battery" status and shut down.
When I measure the voltage on the turned off brick it shows 9.1V and during startup it drops to 8.5V (still reasonably high, eh?). Two seconds later the brick dies and the voltage goes back to 9.1V.
Has anyone had similar problem? What may be causing this?

I would suggest contacting LEGO customer support. The brick should not shut down until the batteries are around 5V (or 6V for the official Li-on battery pack). If you have a way to measure current on the batteries, it would be interesting to see what that is. It should be < 200mA if no motors or sensors are attached.

Thanks! That's what I eventually did. LEGO support asked me to return my brick for a check and are sending me a new one.


text:
Which Lego Set Is This, large white and tan walls, blue base plates?
I picked up a few loose sets. No instructions. Any help appreciated.

Taj Mahal, definitely worth your time trying to get it completed/rebuilt ... Many collectors would be very thrilled to find this in a bulk lot, even though the set has recently been re-released.

That looks like the Taj Mahal (10189):

The instructions from Lego.com are easily found on Brickset under the instructions tab. It's a beautiful set if you have all of the pieces. Good luck!


text:
What part is this 2x2 curved slope?
This is the piece I'm looking for:

I need the part number.

Welcome to Bricks.SE!

The part number is in the picture.

That is 15068 PLATE W. BOW 2X2X2/3:

Or as Bricklink calls it: Slope, Curved 2x2 No Studs.


text:
Help regarding importing into LDraw
I just have a quick question regarding importing an .obj file into LDraw. I originally put a an .obj file through Brickr and exported as an .obj. Now, I want to import into LDraw in order to visualize it better. I am just wondering if this is possible and if not if there are any solutions?
Thanks for the help!

I know this is quite old question, but... LDraw is not an application, but rather a digital standard for LEGO parts used by created by community. It might help to get you an answer if you specify application you are using to import your *.obj file.


text:
Why do LEGO parts break?
I disassembled the Airplane set 7893 with normal pressure on the bricks and it happened that some parts broke like dry brittle leaves, see picture. The storage conditions have been in the open and some of the blue bricks show a bit of discoloration. I bought the set online and do not know what happened to it in last 10 years or so. The set is not that old, made 2006 or later and I wonder what can cause this weakness of the bricks?

In my experience, this happens when the lego has been washed with a too strong detergent or too high temperature...

Happened to me with unwashed LEGO, although I live in a hot climate with not much air conditioning.


text:
LEGO family identification
I found this little guy here, I remember I already had it in my childhood (~30 years ago).

Could somebody tell me what LEGO family it is?
The grid size is 2x2 LEGO studs, it just fits right onto one Duplo stud.
On the inside I see the LEGO logo and the following indication "4 01".

The most common term for the "cams" you refer to is studs.

Seems to be 4224c01: Basic Figure Finger Puppet Female (bfp001)

It appeared in two sets:
1050-1 Basic Pack (1986) and 1089-1 Lego Basic Figures (1985)
Edit (thanks to @Mark comment):
While Brickset list only 2 sets with this figurine, BrickLink lists 25.

BrickLink lists 28 sets:https://www.bricklink.com/catalogItemIn.asp?M=4224c01&in=S

@Mark Nicely found, I edited my answer.


text:
Alternate builds for classic space sets
I'm looking for a full list of the alternate builds on the boxes of Classic Space.  Any ideas?

Since the alternate builds have only been printed on the boxes, this question seems to go in the same direction. There was no success, so far, with scans of LEGO boxes, but maybe some collector did this for Classic Space sets. It is a pity, that there are no alternate builds any more on the boxes.

It looks like someone has 'reverse engineered' them from the box images in this eurobricks thread.
Hope that helped.

those are not official alternates but rather people using their imagination to think up their own alternates. Which was how it was intended at the time, and how I spent many evenings after school work building contraptions.

@jwenting oh ok.


text:
When did LEGO stop using perforated plastic bags and switched to simple ones?
I'm talking about those sophisticated bags used to pack the contents of the sets in 90's.
Here is an illustration of such bag:

Could anyone tell when LEGO started to pack the majority of their sets into simple bags instead of perforated ones?

AFAIK TLG still uses these bags, and they are not unique to the 90ies. They are used for accessory bags, such as the one in your picture, or other various accessories such as these that came in the 2013 Friends Advent Calendar:
https://store.bricklink.com/v2/catalog/catalogitem.page?S=41016-11

Thank you for your reply! I didn't know that. However, I shall probably update my question because I implied usual sets, vast majority of which used to be packed in those perforated bags.

Now they are about to get rid of plastic bags altogether in favor of paper. https://www.bbc.com/news/business-54169686


text:
Can you extract a program from the EV3 brick to the computer?
As part of an assignment, I made a program for my EV3, but however my computer automatically restarted, so I lost that program. I need to show the program!  However, the program is still in my brick. So, I was wondering, is there any way to extract a program from a brick to my computer? And if there is, what would I need? (extra software, Bluetooth, connection cable)? Thanks

Update:
There is a tool at http://ev3treevis.azurewebsites.net/ that can be use to create a new .ev3 file from a .rbf file recovered from an EV3 brick. Some information will be lost, but at least simple programs should be able to be recovered.
Original answer:
You can extract the compiled program from the EV3. Compiled programs have a .rbf file extension. However, these files only contain EV3 VM bytecodes and cannot be converted back to the EV3-G project file format (.ev3p file extension).
Details about extracting the program from the brick and what you can do with it has already been answered here.


text:
Can you help me identify the set this dark grey pedestal sub-assembly belongs to?
Can anyone help me identify the set this sub-assembly belongs to?

Are you positive this is a sub-assembly from an actual LEGO set, or is it just someone's custom built? I have looked at some of the combinations, and I wasn't able to find a set that has all the parts in this assembly.

Are you sure it is Lego?
The lettering on the studs doesn't look like the word "Lego" to me.

Zooming in on the first image shows the logo pretty clearly. May well not be a single set though

This is from 70114-1: Sky Joust


text:
Two separate functions of 5282 RC remote?
Given the RC set of 5282 and 6272c01 below:

Is there a solution to use the two paddles that command the auxiliary output of the receiver for different functions?
For reference, see this at 1:45.
I'm trying to light two different 8870 led lights, one with the left paddle, the other with the right paddle.

Since the lights turn on for both directions, you would need a way to only pass current to them if the current is running in one direction. I'm not sure if there is a way to do that.

I hoped there are two circuits there, one for each paddle, but the new cables weren't wired to support that.

With only using existing non-modified LEGO parts a mechanical solution with a servo motor, two polarization switches and cluch gears is thinkable, but this is all really cumbersome...
It's a bit ironic really, there's a bit of (trivial) circuitry in the 2x2 black brick before the wires of the LED lights split that causes the LEDs to work no-matter the polarization, because LEDs by their nature only work when the correct polarization is applied...
One solution would be to modify the circuitry in the 2x2 plate.
Schematics are here:
http://www.philohome.com/pf/pflights.htm
What basically needs to happen is that the diode bridge is removed and the C1 wire is soldered through to the + side of the leds (to the resistors) and the C2 wire to - side ...
Same for the other pair of leds but switching C1 and C2...

Do you mean that 6272c01 does output differently depending on the pressed paddle?

Yes, I believe that is the case. Don't have one to test myself but you could test yourself by attaching a motor. I believe the motor will turn in different directions when pressing the different paddles.

Indeed, the motor turns as you expect.

I think it would be fun to modify a pf LED set so the diode bridge is short-circuited and switch the cables of one of the LEDs. Only one of the pair of LEDs would light up depending on which paddle is pressed...

Would be fun if I had any knowledge on the field, but I haven't. I understand the technical reason, though.

I've planned to have one led set per side, meaning one set for right, other for left... still, not mandatory this way.

Besides the mechanical solution (PF switches driven by a motor) there are no lego components I'm aware of that can do what you want without modifying them.
If you are willing to modify them, anything is possible and the modifications are straightforward for anyone with an electronics background...

Any third party then?

Can't imagine a third party offering this off the shelf.
However, shouldn't be to hard to find a person with an electronics background in your vicinity that would be willing to do the modifications to the LEDs for a bit of spending money...
I could do this for you, but I don't know where you from and hence if it's worth the shipping costs...

Another thing to note, if you modify the leds to short-circuit the diode bridge, the leds would burn a bit brighter as the diode bridge also has some resistance...


text:
Will my mighty white rocket yellow in direct sunlight?
I recently bought the Saturn V and placed it on my windowsill where the rocket is exposed to the direct impact of sunbeams every day. Having encountered several yellowing effects on older white parts I wonder if this will speed up this unwanted process of discoloring?

Possible duplicate of What causes certain LEGO parts to yellow over time, and how can this be prevented?

Absolutely it will. The yellowing is caused by exposure to UV light, which it will get more of with direct sunlight shining on it. If it has to be in the window you could look at some glass coverings that block some of the UV, or find a home for it else where under electric light.

you were so right Craig, it yellowed in months on a lot and lots of parts, annoying. now i painstakingly try to reduce the damage with hydrogen peroxide which is working more or less


text:
Can I convert my train 9V 4563 to the Power Functions motor?
The motor of my locomotive is dead.
I have two choices : repurchase it or buy a Power Functions replacement.

It is possible of customize my train 4563 to use the Power Functions motor?
If yes, what set to buy ? (88002, 8879, 8878 another?)

To expand on Michael's link-only answer: Older train motors were powered by the track and the speed of the train is controlled by a track-side switch.
Newer PF trains are powered by the battery box on the train and controlled by the remote which sends IR signals to the IR receiver.
This means your train needs room for

the wire from the motor to the IR sensor,
the IR sensor and its wire to the battery box, and
the battery box

Fitting these into an older train or a modern train not designed for PF (such as the Constitution Train Chase) requires some rebuilding and some compromises. For the Constitution Train Chase I had to modify the coal tender to hold the battery box and the motor, and I had to put the IR sensor in the cab of the locomotive. This means unsightly wires slung between cars. However, when the train is in motion you don't really see that.
For a locomotive that already is designed to accommodate the old motor, there may be room inside it to fit the battery box and the IR sensor. You will have to sacrifice some of the interior.
Note that for summer 2018 there is a new train Power Functions system coming out, which is going to use a different system: a new motor connection, a new battery box, a new remote. The battery box will have Bluetooth or some other radio-frequency controller in it and thus you won't need the IR sensor anymore. This will save a lot of room in builds and eliminate the need for line of sight.

Here's LEGO's official answer to this:

Motorizing older trains using Power Functions
We introduced LEGO® Power Functions in 2009 as the new electric building system to replace the 9V, 12V and RC systems. What’s great about Power Functions is that they can still power your favorite trains from years ago!
You might have to make some slight changes to the design to fit the Power Functions elements, but here’s what you’ll need to get you trains updated:

Either 88000 LEGO® Power Functions AAA Battery Box or 8878 LEGO® Power Functions Rechargeable Battery Box and 45517 Transformer 10V DC
8884 LEGO® Power Functions IR Receiver
8879 LEGO® Power Functions IR Speed Remote Control
88002 LEGO® Power Functions Train Motor with 8886 LEGO® Power Functions Extension Wire

Perhaps you'll need an extra wagon to hold the battery box.


text:
Looking for ideas to make wire connectors compatible with Lego Functions
I like to make custom battery packs for Lego Power Functions. Is there any simple way to make wire connectors?
The only option that comes to my mind is to buy LEGO Power Functions Extension Wire # 8886, cut the wire, and connect it to my custom battery pack. Would that work? Is there a better idea?

The only option comes to my mind is to buy LEGO Power Functions Extension Wire # 8886, cut the wire, and connect it to my custom battery pack. Would that work?

Yes it would work, and people have done it.
Here's a YouTube video someone has made on their own custom Power Functions batteries.

Is there a better idea?

I don't think it would really be possible to produce a Power Functions compatible connector for less that the $3 LEGO charges for their cable at a small scale, so that's probably your cheapest option.

The video is helpful. When I searched youtube, I could not find anything. May I ask how did you find the video?

@AllanXu I had searched custom lego power function battery on YouTube, and it was one of the results.

Yes, I have done so. Wanted to motorize the Wall-E set. Initially did so with a AAA lego battery box in his belly, but with the wires and everything, not really enough room.
So I indeed cut up an 8886 extension wire and connected the wires to a clip you can get in any electronics store on which fits a 9V block battery.
When powering an SBrick or IR-receiver, only the outer wires need to be connected to the clip. When connecting immediately to motor or PF switch, only the inner wires need to be connected.

I made a battery holder following these instructions:
www.instructables.com/id/Lego-AA-Battery-Holder

It works great even without glue. It requires only Lego and 4 clips.

Welcome to Bricks! That looks like a nice way to make a custom battery box. Unfortunately, this doesn't appear to answer the question about how to make connectors for a custom battery box. We're really looking for answers that directly answer questions rather than those that might add to a conversation.

Thank you for your suggestion. This triggers so many other good ideas as well. The idea can be done with simpler bricks as well. Perforated bricks are harder to find.

This is just an alternative way =) Do not use (and try to somehow connect) the original holder, but make everything from simple parts...


text:
Is there a current source for the LGEO parts library?
I'm working on a povray render of a model. I've seen the LGEO (not a typo) part library referenced in various places, but I haven't been able to find a working download link.
Is there a current source for an updated version of this part library?

Perhaps this Eurobricks thread is helpful: https://www.eurobricks.com/forum/index.php?/forums/topic/108739-new-parts-for-lgeo-library/
It seems that the lgeo library itself is no longer maintained but this person maintains his own version. The download links are on the first page...

The library you linked to does not include the original LGEO parts by Lutz Uhlmann, nor the updated parts by Owen Burgoyne.

As stated in your "various places" link, the LDraw.org web site maintains an All-In-One-Installer (AIOI) which contains and installs LGEO and is updated in January every year so I assume they use the latest version of LGEO.
BTW, I found an LGEO quirk when launching POV-Ray from within LPub3D which I use for generating building instructions.  I kept the screenshot below highlighting how you have to tell LPub3D that LGEO is not available, even though the AIOI installed it:

Thanks for that. I was aware of the AIOI, but I don't use Windows, so it's not super helpful. In addition, the LGEO link on the AIOI page 404s, so it wasn't clear if this is updated or not.

Sadly the AIOI download doesn't allow easy extraction of it's contents. You'd need to install it on a Windows instance and then grab the LGEO stuff. However I think Michael's link to the forum is your best bet for up to date parts.

This is now available on Github.
I was able to find a working download of just the original LGEO library on Eurobricks thanks to some help from the other answerers. I trimmed that down a bit, as that download required integrating some other files in order to work properly. This repo should now work perfectly on its own, but it only includes parts up through 2008 that were created by Lars Uhlmann.
If you are looking for a more complete and cutting edge set of elements, Darats' version (from the accepted answer) seems to be the most current and high quality.

This wiki page describes how to get all the LGEO parts.
https://wiki.ldraw.org/wiki/LGEO


text:
Problem with "warping" of LEGO water
I was trying to imitate the cool water technique of Legopard on MOCpages.

Sadly, I found that when I did it on a large scale (about 46x46 pegs), the water tends to warp upward in the transverse direction, curling the edges.  I cannot get my lake to sit flat.  I get the standing wave in the longitudinal direction, as shown in the picture, but the entire sheet warps in the transverse direction.
I first thought that perhaps mold type played a role, but building it in either clip type gave the same results.
Next, I tried putting in longer 1x plates below to hold the longitudinal wave as shown in the picture, while hopefully straightening the transverse curl, but the problem is that the 1x1 clips hold the water/tiles too tight in the transverse direction, thus pulling the pieces too close together, so the plates end up making the warp worse as they push the bases apart further (due to the normal tolerance or piece spacing).
I would love any ideas people can offer.  I am not sure how Legopard got his to sit so flat.  I am finding that even 6 tiles wide gets a noticeable warp and his picture is many times that.

Have you tried putting anything longer underneath? Maybe a 1x10 plate for example.

Yes, as described above, putting in a transverse plate was great for the standing wave in the longitudinal direction, but it made the transverse curl worse as it forced the 1x1 clips underneath even further apart.

ah, I didn't understand the "putting in 1x plates below" was talking about long plates, I read that as just 1x1. Could you edit the question so it's clear.

Fantastic question! Welcome to Bricks!

This image of the same model shows that the whole set sits on a frame of bricks. In the inside, you could place bricks underneath wherever necessary to attach the water plates (not only 1x... but maybe 2x10, or several 2x4 in a row). They are invisible, so color and type don't matter. If this row of bricks reaches from one side of the frame to the other, it can shift to allow the longitudinal waves but it cannot curl up transversal(ly?).

I just tried that out, just a preliminary attempt, using two 2x10 bricks running transversely.  Believe it or not, it causes the curl to concentrate itself at the joint, creating a strong "V" between the two bricks with a full 1-2 mm gap.  Thus, this method would require a lot of large bricks.  I will have to look at it more to see if I can afford the extreme depth. My project is 16' x 6.5' (5 m x 2 m)!  It sits on a masonite board, so any depth requires special work in creating a hole and deepening the masonite board in that area (as mentioned, the bean-shaped lake is 46x46 pegs).

I admittedly don't have the 46x46 = 2116(!) 1x1 clips to properly build this, but I was able to build a small sample to replicate the problem.
Because this construction technique eliminates the natural tiny gap between elements, you can't easily reinforce it just by attaching plates and bricks to the underside. This construction is essentially "out of system". When you attach bricks underneath, you are forcing an error between this and standard system construction. This is why you see the "strong v" when bracing this with plates or bricks underneath.
One way that you might be able to brace it is by using a continuous offset of some sort. Here's an example:

You could also try building it without any reinforcement and then try to flatten it out (e.g. you could leave it under a pile of books overnight). I'm honestly not sure if this is likely to work, and it may permanently deform your bricks if it does, so I can't strongly recommend it. Realistically, this technique is already putting these parts under a lot of stress and may permanently harm them anyway.

I agree it is definitely stressing them.  I have a large metal bowl, and I considered putting the lake on the upside down bowl and weighting the edges a little.  I don't think it will work, however, as I have a few pieces that are falling out all the time and I think it is because their grips are a little looser; I will need to verify that.  If I loosen the hole batch, I think the whole thing will just fall apart.

There seems to be a fundamental flaw here.  When I line up a dozen 1x1 clips, 1x1 tiles, and 1x1 plates, it appears that the clips are a little wider than the others, the plates next and the tiles least.  Thus, straightening the warp demands the creation of gaps between the tiles, again pointing to a problem if I try to stretch the grips out with weight.

I will play with your technic idea and let you know what I find.

That certainly seems to be the core of the issue. If you wanted to turn to the dark side, you might be able to fix it by sanding down the 1x1 clips. :)

To help share ideas, in case somebody else runs into this someday, I will post another idea I have been playing with.  I don't know which solution I will go with yet, but I add this idea to help others.
The idea is basically to create some fault lines through the lake where I can hinge the water and avoid the accummulation of stress.  I have started playing with it on one end.
Basically, I remove all of the 1x1 clips across the entire width of the lake, but using some pattern that allows a somewhat natural look to remain.
Next, I put a collection of 1x plates beneath that area, so that the colors don't look too bad.
Finally, at my high points in the wave, I use some 1x hinge plates to connect the two pieces.  Thus we keep a single top surface, but cause the accummulative warp to remain minimal.
I will try to get a picture of the underside and top to help people see what I am doing.


text:
Lego train magnet strength
Some questions about these train magnets:
https://www.bricklink.com/v2/catalog/catalogitem.page?P=73092

I'd like to know roughly how much weight two of those could lift or what force is needed to separate two of these...
According to BrickLink, the magnet was produced from 1980-2009, would there be a considerable loss of strength between magnets produced in the early days and later?
I suppose how they were stored or how much they were played or dropped would also influence heavily their remaining strength...
I suppose I could re-magnetize them with a neodymium magnet, anyone care to guess or experiment about how strong such rejuvenated LEGO magnet would be?

Temperature also plays a role. Magnets lose their strength faster in warmer environment. Heat neodymium one to 80 degrees Celsius and it's gone.

Test setup

Take 20 magnets from my collection
Build a test stand with a magnetically attached bucket containing an adjustable weight:
Designate one of the magnets a reference (#0)
Repeat for each one of the 19 other magnets:

Attach the magnet to the bucket
Carefully add Technic beams to the bucket until the combined weight of the bucket, batteries, beams and the magnet reaches the limit and the assembly falls onto the rug below:
Measure the weight of the assembly and note it:

Measure the two strongest magnets against each other to get an estimate for the upper bound
Measure the two weakest magnets against each other to get an estimate for the lower bound

Limitations
The magnets were mostly purchased between 1990 and 2000 and were stored for several years in a sunny attic room and then for a few additional years in a cold basement in various states of assembly (separated, joined in pairs or assembled into a column of several magnets).
The weight of the bucket was increased by adding Technic beams, which weigh 2-4 grams each, thus limiting the precision of the breaking point (but see the next paragraph for a more serious limitation).
The kitchen scale has a precision of about 10-20 grams.
All pairs were measured only once.
Care was taken to construct the bucket in a way that results in the center of mass being as close to the symmetry axis as possible, but the amount of deviation was not measured.
Results
The 19 pairs have resulted in the following measurements (all values in grams):
220 (#1)
240
220
220
220
240
250 (#7)
240
240
230
210 (#11)
240
240
230
240
240
240
250 (#18)
240

This results in an average value of 234 grams of force required to pull the magnets apart (including the weight of the lower magnet)
The two strongest (#7 and #18) together: 260 grams
The two weakest (#1 and #11) together: 200 grams

I'm aware of the inherent imperfection in this test method, but in my opinion, it represents a reasonable compromise between time investment and attained precision. I would welcome any critique aiming to improve it though.

Brilliant answer


text:
How do I connect a LEGO wheel to axles so it can be powered?
I have a growing LEGO collection, which started with a lot of parts from the generic 10697-1 'LEGO Classic Large Creative Box' set. Sometime later, I bought a bunch of wheels, part numbers being: 55981 and 6014.
My question is, how do I connect these wheels to axles (e.g., 3706) in such a way that the wheel can be driven by power functions (e.g., by a LEGO motor/servo)?

I do not think this wheels are meant to be powered and I don't see a practical way. However wheel 55982 is entirely similar to wheel 55981 except it has a technic axle hole, so you could reuse any 55981 tires you have...

@MichaelVerschaeve You should post that as an answer!

Normally when wheels are powered using an axle they have an axle hole, whereas your wheels have a pin hole, and a 3mm mini pin hole.
So you should probably buy some wheels with axle holes anyhow, for future building.
However, in the meantime, there are tricks to driving parts which use a pin hole, for example, a lego 55981.
You simply use either this, or this and this
There is also a 2L pin version here or a 2L axle version here
There are other clever ways to do it too but this should be enough to get you started. I am not familiar with a way to drive the other wheels you mentioned
unless I have forgotten a way, these are not really designed to be driven at all nor easy to be driven because they have a 3mm 'mini' pin hole, which fits into a 3mm 'mini' pin.
The reason I say 'clever' is because these friction pins act as clutches, if there is not enough torque required to drive the wheels then they will slip and rotate independently of the wheel.
If there is sufficient torque then they will grip the wheels pinhole and drive it.
This has both positive and negative effects depending on what you're doing.


text:
How to protect my LEGO city from the dust?
I have a LEGO city with all the modular LEGO in my bedroom. But the dust is killing me at nights. How can I protect them? Where can I get those display domes?

How big of a city are we talking about?  Adding a picture of your set-up might help people come up with more ideas for you.

Where I'm from it's called Plexiglas. Other tradenames are Crylux, Acrylite, Lucite or Perspex...
Anyway, you can get sheets of it cut to size in D.I.Y-shops or hardware stores to build your own domes.
If you are less handy, you can find lots of shops offering standard or custom solutions.
If I google "plexiglas", I find dozens of solutions near where I live.
I know of one person who had a custom pyramid shaped Plexiglas dome made for the 10181 set (Eiffel tower)

I know it is a bit simplistic, but you might try just using a light sheet.  If it is a light, tight fabric, it probably will go on and off pretty easily.
If you have lots of delicate parts on your buildings, you could get some small stilts of some sort to hold the sheet up over those areas.  That will give you the circus tent look, I imagine.


text:
Is there a list of the most common Lego Technic parts?
I searched the internet for this and I found a list of complete sets. But I am looking for a list of the most common (and in some sense the most important or most helpful) individual Lego Technic parts. Is this available somewhere?

I'm guessing that this would probably be the Technic Pegs (with or without the friction nubs), as most Technic sets include a fair number of them to join things together, followed by axles and cogs.

On Brickset, you can browse parts in the technic subcategory and you can  sort by "Set count", i.e. the number of sets the element appears in.
https://brickset.com/parts/category-Technic
So that would take care of your "most common" requirement. I'm afraid that "most important" or "helpful" is rather subjective and hence difficult to quantify and have lists sorted by those measures...

Big +1 for solution that works for "most common" anything and likely will not get outdated.

And then you also need to click through to sort by "number in each set" - for example the "Connector Peg with Friction" not only comes in the most sets (almost 1900 at the time of writing), but it's also in very large quantities, the first 30 or so results contain at least 200 of them.

724 in the bucket wheel excavator, you can use bricklink for an accurate part count, it doesn't source its inventories from the lego replacement pages, they're done manually.
We should take into account the nature of this element though; it's THE pin, it's how you connect things with technic, basically having the same function as studs in system lego...


text:
Can you identify this piece of non-LEGO submarine from a sketch?
This is from a submarine set I bought on aliexpress. It's not LEGO but usually the pieces are the same. I'm missing this piece and cannot identify it.  Can you guys help me?

If you are looking for the LEGO equivalent of it, it's a Slope, Curved 2 x 2 No Studs, 3 Side Ports Recessed: https://www.bricklink.com/v2/catalog/catalogitem.page?P=44675#T=P


text:
Which set does this bag belong to? Blue and clear orange pieces
Hi can you please help identify which product this belongs to? Bought this from second hand shop.
The spiked flail is part of a smaller bag - no number however it was in a larger bag with a large number 2 on it, below which are the numbers 304R7:

Hope this helps in identifying it.

You mean this: https://brickset.com/sets/containing-part-4613938 ?

Can you post a picture of the bag?

Updated my answer with set identification based on the picture.

Based on the title of the post and Larme’s clarifying comment, you are looking at 59232 Minifig, Weapon Spiked Flail/Mace in a bag with date code 304R7 (which indicates this bag was produced in 2017).

Looking at BrickLink, there are several sets made in 2017 that have this element in Flat Silver (no other color was produced recently). There is one set from 2016 but that set did not come with bags AFAIK. Most are from the Nexo Knights range, but one is from the Super Hero Girls line. If the bag has no large number on it, it must have come from a small set, for example 70361 Macy’s Dropbot Dragon. If the bag does have a large number on it (1, 2, 3 etc) it will be from a larger set. Without more information on what is in the bag besides the Flail, it is impossible to narrow the set down further.
UPDATE: Now that a bag picture has been provided, it is clear this bag belongs to set 70351 Clay’s Falcon Fighter Blaster from the Nexo Knights theme. The Technic connector with hole in the middle in Orange is only in this set (out of all the sets on the list containing the Flail).

Bags without large numbers on them are also found inside of bags with large numbers on them in some larger sets, when the only knowledge of where it comes from is "second hand shop", we can't really rule out that it's a larger set where a numbered bag was opened, but the smaller unnumbered bags inside weren't.

Now that a picture of the bag has been supplied it should hopefully be possible to narrow the set down by inspecting the other parts in the bag.

Yes, posted the other answer on an account that asked me to register. Thank you for pointing me to the merge account. Thank you all for your help. I found the instructions online and successfully assembled clay's falcon fighter blaster. However, I am missing bag #1 and had a few extra pieces left.


text:
Power Function Converter Cable for LEGO MINDSTORMS
This is a follow up to this question:
How to use Power Functions with Mindstorms EV3?
The question was asked in 2013 (5 years ago). Fast forward to 2018, the product that was suggested in the answer is retired:
https://shop.lego.com/en-US/Converter-Cables-for-LEGO-MINDSTORMS-NXT-8528
Is there a replacement for the retired product?
Is there any better option, other than what is shown in this video?
https://www.youtube.com/watch?v=Ns3TODgRlCE

If cost is not a concern, there are a few for sale on BrickLink: https://www.bricklink.com/v2/catalog/catalogitem.page?S=8528-1 (starting at a 400% markup).

No, there is no replacement yet except soldering your own cable or using third party products. Basically the answers in that question of 5 years ago are all still valid.
Mind that LEGO is transitioning to a new power functions system (with motors and sensors as in the boost and WeDo 2.0 products), perhaps we'll see solutions for that quite soon.

Would you be able to share a link to the article shows the new power function system? I invested in the existing function family, so I guess I will need to create converters for them as well.

LEGO hasn't officially announced anything yet. But, articles like this make it sound like we should know more sometime in 2018.

Products already available:
WeDo 2.0:
https://education.lego.com/en-us/products/lego-education-wedo-2-0-core-set/45300
Boost:
https://www.lego.com/en-us/boost
Also an upcoming train set will have Power Functions 2.0:
https://brickshow.com/2018/01/power-functions-2-0-to-be-featured-first-in-upcoming-lego-city-train-sets/
Perhaps also check out the WeDo 2.0 faq, it clearly states that the new system is intended to replace the old Power functions, although no timeline has yet been set
https://education.lego.com/en-us/support/wedo-2/faqs#core


text:
Quality of Brick, Modified 1 x 1 with Headlight over time
I have a problem with my 4070 Brick, Modified 1 x 1 with Headlight .
I packed my Lego and put in the basement at the end of previous century. Now I see my "headlight" bricks are broken at the bottom, or, if not visibly broken, they lost gripping strength. It applies to white, red, gray and blue. Actually, it applies to every color I have.
Are ones currently made more sturdy? Do they survive better? Or is replacing them only a temporary solution?

According to bricklink, some of these have a slot below the sideways stud. It's considered a defect rather than a design decision. Do your headlights have this slot? I think the general consensus is that the element has design flaws, but the element is considered to useful to retire it.

@MichaelVerschaeve Either they does not, or I just don't understand what you (and bricklink) are talking about. I'll try to find a photo of this defect to see. If you can share a link to photo, I'll be grateful. Edit: you mean this? If so, then no, they do not have it.

Yes, I meant that. Bricklink currently considers it as a different mold, but it's marked for deletion: https://www.bricklink.com/v2/catalog/catalogitem.page?P=4070a

You can go on to LEGO.com for replacement pieces, or you can fix it with a little superglue

I just got a call from LEGO Support. I can't repeat it word for word, but (translating to English) it was like:

Over the last decade manufacturing process of this brick has undergone many improvements that have improved its durability. You shouldn't encounter any problems with new ones if you will buy them, and if you will have problems in two years after buy, we will replace them free of charge. Sadly, we can't replace parts older than 2 years for you for free.

Two years of play is quite a long time, so it seems they are pretty confident about quality now.


text:
Is there a drop-in replacement for 4275 + 4276 hinge?
Both parts are not in production since 2008.
Hinges in my sets are in various conditions, some of them are way too loose to my liking. No ones fault, I was active kid who built a lot. But now it's like 10 years too late to replace them with new ones. Or is it? I'd prefer original Lego brand replacement that can be used without changing anything else in building instructions, but other ways to replace them are welcome, too. Restoring the ones I have is another question (that probably was already asked).

If their replacements are not to your liking, you can buy these pieces after market on BrickLink. They are not terribly popular, and were produced for a while, so prices are fairly reasonable.

@AlexanderO'Mara I'm thinking of building my own Blacktron cockpits, so I'm open for replacements, but if I can't find them, I'll buy the ones from BrickLink. I hope i still have all my old ones for old sets, but I'm not sure anymore.

Not exactly drop in replacements, this particular modified plate has no protrusions around the hinge, it's entirely flat.
I see two possible replacements:
44301 and 44302. However they "click" in angles of 22.5 degrees and have protrusions...
60478 in combination with 63868 (clip and bar connection) is freely rotating but ofcourse again protrusions...

"It's good when it's good enough" I guess. 44301 and 44302 would work most of the time.


text:
Compare part lists between Stud.io models?
I've created a MOC using Stud.io, bought the pieces and built it. Since it was unstable I've changed the model in Stud.io, and now I would like to buy just the pieces I've added. I could compare both version of the model manually to get the differences, but that would be somewhat cumbersome and error prone, so I'm wondering if there is some tool to compare two models, or two parts lists?
I'm thinking about something that could for example take two BrickLink XML files, and produces a new XML containing only the parts (and amount) not present in the older version.

You could try and import both XML files into Excel, then sort and compare. Probably the fastest way to do this.

Thanks, but I would consider that finding the differences manually, too.

Since there doesn't seem to be a tool, I've written my own one. In case anyone else want to use it, check it out here: https://github.com/ChrZae/bricklink-xml-diff
Take care tho, it can only really process the XML generated by Stud.io, the XML-format itself has more fields which I didn't care about (also no guarantees it will always work correctly).

Thanks for automating this.  It'd be great if your README explained how to use it, what the requirements were, and whether filing github issues is the preferred support venue.  https://gist.github.com/PurpleBooth/109311bb0361f32d87a2

I would use the winmerge tool:
http://winmerge.org/downloads/
XML files are text files. You can compare two text files with Winmerge and extract the differences...
some manual labor would be involved if the same part is present in both lists but with different amounts, but I would expect this to be all rather straight forward...

Thanks, but I would consider that finding the differences manually, too.

@Christian all solutions are in some part manual. Of course, making this part smaller can be desirable. On the other hand, WinMerge is tried and true, deals really well with whitespaces etc, and using it allows user to correct mistakes on the fly. Your program may be all nice and fine, but it didn't have all that many testers.

@Molot, on the other hand, parsing and writing XML is not that hard, there are tried and tested libraries...

@Mołot true, its bareley tested, but then again I trust myself even less when it comes to comparing 2K parts and finding the 200 differences and writing them up without making a single mistake, however good the diff-tool is ;)

@Christian winmerge can generate pretty good diff files. Then you'll have just a list of xml blocks added and removed. Rather straightforward, and I did it on things much more "important" (in the terms of $) than something like 200 bricks

@Mołot how do you deal with parts that are out of order? The XML generated by Stud.io is not sorted, so the same part may turn up at totally different positions in the file. So unless winmerge knows how to sort the xml, you would have to find these all yourself?

@Christian there is an option to detect moved blocks. See this screenshot: https://i.stack.imgur.com/90Whq.png

I usually use Rebrickable to compare whatever I need.
First, you need to create two custom lists (My LEGO > My Custom Lists). Import tool supports "BrickLink Stud.IO files" so no conversion is required.
Once you got your lists sorted you need to compare them using "Compare sets" feature (Sets > Compare Sets). While the name suggest only sets could be compared in reality functionality is broader - you can compare custom lists as well. You will then be presented with the result, where "unique" parts are the ones that does not exist in compared model. You can also export this list for further use.

A little bit late to the party but I made this notebook to compare your brick:
https://github.com/mhoangvslev/bricklink_tool_suites/blob/main/Bricklink_Compare_Parts.ipynb
I simply use 2 part lists downloaded from Bricklink.
Feel free to modify it to your need.


text:
How to use the ultrasonic sensor on mindstorm NXT
I've been struggling for some time on this. I'm trying to code the robot to move when the distance is above a certain integer and stop when the distance becomes lower than the certain integer. I'm coding in Eclipse Helios. My code is below:
import lejos.nxt.Button;
import lejos.nxt.Motor;
import lejos.nxt.SensorPort;
import lejos.nxt.UltrasonicSensor;

public class robot {
    public static void main(String[] args) {
        UltrasonicSensor us1 = new UltrasonicSensor(SensorPort.S4);

        System.out.print(us1.getDistance());

        if (us1.getDistance() >= 25);
            Motor.A.setSpeed(50);
            Motor.C.setSpeed(50);
            Motor.A.forward();
            Motor.C.forward();

        if (us1.getDistance() < 25);
            Motor.A.backward();
            Motor.C.backward();
            Button.waitForAnyPress();
    }
}

Welcome to Bricks.SE! How does this behave currently? What changes to your program have you tried?

It's a little unclear from your question where this is currently failing, but I do see a couple issues with your code.
1. Your if blocks are probably not doing what you expect. You should include braces to conditionally run the block following an if statement. As written, all of your code executes all of the time. This is a tricky bug to spot, as it looks correct, but isn't. You probably want to change this:
if (us1.getDistance() >= 25);
    Motor.A.setSpeed(50);
    Motor.C.setSpeed(50);
    Motor.A.forward();
    Motor.C.forward();

To this:
if (us1.getDistance() >= 25) {
    Motor.A.setSpeed(50);
    Motor.C.setSpeed(50);
    Motor.A.forward();
    Motor.C.forward();
}

2. You say that you want the motors to stop, but it looks like you are actually reversing them. You'll likely want to change this:
Motor.A.backward();
Motor.C.backward();

To this:
Motor.A.stop();
Motor.C.stop();

Your code may still need some tweaking, but hopefully those two fixes get you back on track.

I suspect the OP is more familiar with Python, hence the mistakes in the if-syntax.....

Second if needs to be replaced by a loop... Very unlikely that the distance will be immediately less then 25 cm after starting the motors, you need to continuously check...
And stopping the motors can then be done unconditionally (i.e. outside the while loop)
Something like
while (us1.getDistance() >= 25 && !Button.ESCAPE.IsDown())
{
   Thread.sleep (1000);
}
Motor.A.stop();
Motor.C.stop();


text:
What about Power Functions motor, S size?
LEGO Power Functions has motors in M, L and XL sizes. Usually, if someone uses this size designations, the smallest one is S. It would make sense to have them named S, M and L if there were meant to be only 3.
Now, for my personal "rebuild, restore" project, I'd need something a bit smaller than M, to go with my old sets. Is there any S size power function motor? Was there? Was planned, but cancelled? Any official or semi-official info on it?

There's also E (https://www.bricklink.com/v2/catalog/catalogitem.page?P=87577c01&idColor=86#T=C&C=86) and the servo motor (https://www.bricklink.com/v2/catalog/catalogitem.page?id=110903#T=C), and I think there's at least one more variant that I can't remember, but at least the two varaiants that I do remeber aren't smaller than M.

@Henrik E is the same size as M (6 x 4 x 3) and servo is, well, servo.

The E motor is better used as a generator than an actual motor. No benefits compared to a M motor...

Only in 2012 the L-motor was released. The M and XL motors where released in 2007. That is a gap of 5 years where people were even more confused about the size options...
Anyway, no smaller motor with power functions
However if you are willing to go with the 9V system (possibly with conversion cables), there's the mini and micro motor, standard motor is also a bit smaller in length.
More info here:
http://www.philohome.com/motors/motorcomp.htm

As far as we know, no other motor sizes were planned. It's possible they were named this way to allow for future expansions, like when the L motor was added.
It's worth noting that it's unlikely we will see any new motors come out for the current Power Function system, as Power Functions 2.0 was just recently announced at the Nuremberg Toy Fair and features the Boost connectors.


text:
Can someone identify this brick?
I'm looking for a kind of brick, the brand or the model, which has this specifications: The top has studs. The bottom doesn't have tubes. However, the bottom has support walls in the middle. Here is the picture:

What is the brand for this brickset (definitely not LEGO)? Is there a term for this kind of interlocking system?

How does this compare scale-wise with LEGO? Is that the same dimensions as a 2x4 plate?

I don't have a LEGO for scale. Here's the measurements: length: 3.75 cm. width: 1.85 cm. height: 1 cm.

Adding onto Zhaph, how is the quality and compatibility compared to LEGO bricks? Check this pdf for reference:http://uploads.brickset.com/docs/clonebrands_v1.6.pdf

I would say it it cold come from a brand from China, I can’t identify this system, but it is the opposite of that of a normal LEGO brick. It is still a normal 2x4 plate.

A good clue, but still not enough information to find where to purchase new ones or know whether it's still produced.


text:
Using the unregulated motor block and conversion cable to light LEDs
I have the following setup:

It consists out of

An EV3 brick
A nxt to 9v conversion cable (https://www.bricklink.com/v2/catalog/catalogitem.page?P=x1676)
A 20 cm 9v to Power Functions conversion cable
Power functions LED's

This is my program:

It works fine if I provide a negative power to the unregulated motor (i.e. the LEDs light up for 5 seconds), however with a positive power, it flashes just shortly.
This does not seem to depend on the orientation of the connectors between the conversion cables.
Also the motor test pane on the EV3 brick behaves similarly, the LEDs flash when pressing the button to move 'forward' and lights up continuously when pressing the 'reverse' button.
So I have an acceptable workaround, but I would like to know why this is.

The light turning off happens because of the Device Connection Manager in the EV3 firmware. The algorithm used to detect when a motor is connected relies on there being a load on pins 5 and 6 of the output ports to determine if the motor is a Large or Medium motor. The 8528 adapter cable only has wires on pins 1 and 2.
When you use a VM command (via a programming block or by using the on-brick app) to tell a motor to run, it forces the motor to run, but then the device connection manager immediately resets everything because it doesn't think that a motor is connected.
Also see How to use Power Functions with Mindstorms EV3?
The fact that setting a power of -100 keeps the power on continuously, though, is new to me. I'm at a bit of a loss to explain that observation.
UPDATE:
I've done some digging and now I better understand what is going on.
Output port pin 2 is connected to pin 6 via a 100k resistor as seen in the schematic diagrams below.

When the EV3 is instructed to run a motor in the forward direction pin 1 will have battery voltage and pin 2 will be at 0V. When running in reverse, however, pin 1 will be at 0V and pin 2 will be at battery voltage.
When using the converter cable, nothing is connected to pin 6 externally, so it will also be at battery voltage (pulled down slightly by R216 to +5V). This triggers an event in the device connection manager. Most of the time (but not 100% of the time) the EV3 will think that it has a motor attached because of this and so the LED will stay on.


text:
Is there any software for designing and testing Technic mechanisms?
I'm finding Technic parts can be challenging sometimes, and the costs can be high.
Is there any 3d design software that can help with designing before I decide to buy the parts?

Have you taken a look as SR 3D Builder as recommended in this answer?

@Zhaph-BenDuguid, I know a few 3d logo rendering tools, but I did not know that one. I think there is no simulation tool for testing the mechanisms. Perhaps the answer to this question is : "No there is no such tool"

Yeah, the testing part is the tricky one. Microsoft Robot Design Studio does have some simulation tools in it, but as I note the current version only supports one LEGO robot. I think earlier versions were a bit more flexible, but had a fairly limited set of parts.

I searched for more than a month and I found Lego Digital Designer (LDD) is the balance between simplicity and functionality.
You can learn LDD in a few hours. Very good videos available on youtube
LDD is not just 3d rendering tool. It understands the connectivity between technic beams and pegs. Very impressive.
The most impressive feature in LDD is that it can simulate the technic gears. Take a look at this video and see it for yourself: https://www.youtube.com/watch?v=13wietMv0g8
These two videos will save lots of time:
Lego Digital Designer Tips and Tricks - 1/2
Lego Digital Designer Tips and Tricks - 2/2
Update:
This post helped me to import so many existing Lego lits in LDD. I learned a lot form existing designs. Also, I can find the part numbers that I am looking for, or just copy them from the model.
Can I import existing Lego kits into Lego Digital Designer?


text:
Angular resolution of NXT motor
I am sure that I read somewhere that the resolution of the motor sensor was 2 degrees, but I can find no mention of this in the NXT Help file. What's more, the motor control block allows the Duration to be set to an odd number of degrees. Can anyone please clarify this for me?

I found the resolution of the EV3 motors by attaching a 90° connection to the motor, and a long axle with a pointer at the end so I could see changes in small angles.  By running a loop a large number of times with settings of 360°, then with 360.5°, then 360.75°, and watching for when the changes trigger actual accumulation of ending point, I found that there was no difference between a rotation of 360° and 360.75°, but at 361° the difference appeared.
I'll try the same setup with an NXT motor and let you know the results.
So it's like a step function with an interval of 1°.
I have building instructions and the program that I'll but on Rebrickable sometime this week.
Hope this helps.

I found a partial answer myself in the Mindstorm Education NXT User Guide, page 31.
It says the rotation sensor has an accuracy of +/- 1 degree. Not quite the same thing, but good enough to work with. If it turns out that I don't get the results I'm looking for, I will have to use some gear wheels.


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What is this long spiked black piece with rubbery orange tip piece used for?
Missing instructions but it should stand out if you’ve ever seen it

Welcome to Bricks.  Do you see LEGO logos on it anywhere?  Can we get a picture of the other side?

This is part 61406pb04 Plate, Modified 1x2 with Angular Extension and Flexible Orange Tip, which comes in 2 sets:
8076 Deep Sea Striker

70135 Cragger’s Fire Striker

It sounds like you're going through a large collection, so may have this question again.
In general, if you have a LEGO part you don't recognize, the best thing to do is to search for the four or five digit design number on the underside.  (It's small on many parts, molded into the plastic in the recesses.)  In this case, the design number is 61406.  There are several websites you can use to find it based on the design number; Brick Owl is one I'm fond of.
From there, you can look at the sets that used (and others with the same design but different colors) to get a sense of its usual use.


text:
How to safely straighten 2569 Lego Antenna Whip 8H?
I have one of those, in trans-neon green, that's slightly bent. I don't want to break it or make it opaque. Is there a way to make it straight again without risk? Preferably universal way, but way specific to 2569 piece would suffice.

It's not a particular rare part, easily replaced with bricklink for a couple of cents, so I wouldn't worry about damaging it. If it's bent it's damaged anyway.
For standard lego made out of ABS the procedure is to submerge it in hot water (hot to the touch but not scalding or boiling) for about a minute and then straighten it with your fingers or pliers in cold water...
However, this is a transparent piece so made out of PC instead of ABS. The melting point of PC is is about 50 degrees Celsius higher. So I guess the hot water will need to be near boiling...


text:
LEGO servo (88004) controlled by Raspberry Pi using python pigpio
I'm trying to control a LEGO servo (88004) using a Raspberry pi.
I would like to use pigpio to get a more precise control (no shaking, like with gpio PWM).
It's work with a regular servo (3 wires). It kinda works with the 88004, it buzz when I test it (both with c1 and c2), but I can't make it move :-( (see code below).
Anyone have a suggestions to this problem?
"Kinda" working python code.
import time
import pigpio

pi = pigpio.pi()

if not pi.connected:
   exit()

#sudo pigpiod -s8
c1 = 23
c2 = 24
pi.set_PWM_frequency(c1,1250)
pi.set_PWM_frequency(c2,1250)
print(pi.get_PWM_frequency(c1))

#use NAME (GPIO02 = 2)

while True:
   pi.set_servo_pulsewidth(c1, 0)
   pi.set_servo_pulsewidth(c2, 0)
   print "reset"

   try:

      pi.set_servo_pulsewidth(c1,2000)
      pi.set_servo_pulsewidth(c2,2500)
      print "c1"
      time.sleep(3)
      pi.set_servo_pulsewidth(c1,0)
      pi.set_servo_pulsewidth(c2,2500)
      print "c2"
      time.sleep(3)

   except KeyboardInterrupt:
      break

print("\nTidying up")

pi.set_servo_pulsewidth(c1, 0)
pi.set_servo_pulsewidth(c2, 0)

pi.stop()

I figured it out :-)
Using pi.set_PWM_dutycycle(c1, 128) # PWM 1/2 on makes it move.
In hindsight kinda obvious :)

Interesting to learn that power functions are controlled by PWM. I thought they were controlled analogously with a proportional voltage on the C1 and C2 pins


text:
Are there any LEGO "MacGyvering kits" for the on-the-go LEGO fan?
I keep a small box of electronic parts in the car, for times when I get an idea I want to try out, or have a quick gizmo that I need to solve a problem.  I also have a box of mechanical parts, like strings and pulleys and weights, that I'll use sometimes.  When I hang out with my engineering friends, we'll often come up with ideas that we can quickly build and test.  It seems that I should put together a similar set of LEGO parts.
I'm looking at a target volume about 3200 cm³ (200 cubic inches, 3.4 quarts), including space for organization.  No individual element should be larger than 140mm×230mm (17×23 studs).  The most important goal is versatility.  I'm mostly orienting this towards engineering tasks, but may also throw in a few minifigs for decorative builds.
The best idea I currently have is to use the Creative Suitcase, and augment it with parts from one of the smaller Technic kits that's almost entirely general-purpose Technic parts, like the Compact Tracked Loader.
It seems likely that people have built similar "on-the-go" kits, or have their "hotlist" of LEGO parts that are always at hand when prototyping.  Any thoughts on the matter?

It seems like you have the parts in mind, but really just need a case.
I have used fishing tackle boxes and artist supply boxes, but the compartments were too narrow.
Pros: Versatile, cheap, stackable, configurable.
You can use the removable compartments as parts trays during builds. You can find them in various colors at the major discount retailers in the U.S.
Cons: No handle. Not durable. If you drop or step on them, the hinges will crack.
Dimensions

13 3/8" L x 10 3/4" W x 2 1/2" H
34 cm x 27.3cm x 7.9cm

Listing at the Sterlite website


text:
How many 2x4 Lego bricks would it take to build a real skyscraper?
As an exercise designed to communicate the scale of plastic waste in the oceans, which was estimated at 268,940 tons in 2014, I'm trying to describe how many life-size buildings one could construct with your basic 2x4 lego pieces of the same weight. A believe a 2x4 piece is 31.8mm long, 15.8mm wide, and 9.6 mm tall, not including the studs, and 2.32g.
Naturally, I don't aspire to simulate skyscrapers that anyone could actually live in, but I'm trying to come up with a defensible estimate for the number of bricks in, say, a Lego Empire State Building (1,250' tall, not including the spire).
One idea is to imagine building a solid structure that is completely enclosed. Another is to make a hollow one with double-layered floors and a solid base.
Forgive me for the open-ended question, but is anyone familiar with the mechanics of how one builds a extremely large structure with Lego pieces that, while not necessarily structuring sound for human consumption, and least holds together?

I would have thought that the bricks would collapse under their own weight, but alas, you could build up to a couple of kilometres high! http://www.dailymail.co.uk/sciencetech/article-2242973/How-Lego-bricks-stacked-the-breaks.html

Apparently you could build a tower of 2x2 bricks 3.5km tall before it starts to collapse under it's own weight (2x4 bricks would probably collapse sooner). See also What's the Largest LEGO Construction Ever for an example of a (full size, albeit around a metal frame) house made from 3.3 million bricks.

Great question. Others may have better answers for a more "realistic" design, but the math for a solid structure is actually pretty quick. Take the Empire State Building for example:
Height: 381m
Base: 129m x 57m
Volume: 381m × 129m × 57m = 2 801 493m³

And a basic 2x4 brick:
Volume: 31.8mm × 15.8mm × 9.6mm = 4.823424e-6 m³

The number of bricks needed to simply fill the volume is total volume over brick volume, so:
Number of bricks: 2 801 493 / 4.823424e-6 = 580 810 022 092 bricks
Weight: 580 810 022 092 bricks * 2.32g = 1 347 479 metric tons

Basically, you're looking at 580 billion bricks weighing in at ~1.3 million metric tons for a solid structure the size of the Empire State Building.
This puts you at about a fifth of an Empire State Building's worth of bricks dumped in the ocean in 2014.

Yeah, a quick back of the envelop estimate for building a double layer shell, along with 102 double thick floors only comes to about 4,000,000,000 bricks. However, you'd use less if you modelled windows and doors, more for interior walls and stair cases ;)


text:
Is this from a Lego set?
Can anyone tell me which set this partial build is from?  Any help to identify it is greatly appreciated!

The 4 x 4 corner plate does not appear to come in purple in any official LEGO sets. Do the pieces say "LEGO" on the stud?

I don't have the lego with me. I saw it in a charity shop. In the past I've bought bags from charity and managed to work out what they are but i'm having difficulty with this one.

The yellow brick on top looks like a bootleg, are you sure that is a legit LEGO piece?

Can you take it apart? Lego Bricks always come in only one color (unless you consider the printing on some of them.

Whoops, never considered that you didn't have em with you. Sorry

It's most likely that this is not an official Lego set. There has been such a piece (the purple ones) but it never came in that color, therefore it must have been manufactured from a clone brand. There could be that 00.1% chance of it being a piece from an official Lego set, but based on the poor quality of the build in the image and the fact that Bricklink couldn't find it, I still think it's from a clone brand. Also, if any of the plates have only specific studs with holes in them that aren't in a reasonable pattern (such as outline of house walls), then there's a big chance that the plate came from Mega Blocks and not Lego™.

I did some zooming out. It is hard to tell due to the low resolution but I'm 99% certain that none of the visible nobs on the green pieces have the Lego logo. So it almost has to be a clone brand.

Indeed.  None of the studs have holes in them either, but still likely to be  a clone brand.


text:
EV3 Unregulated Motor - different plus/minus power behavior
I'm helping some fellow Bay Area LEGO User Group builders who want to use an EV3 to power a 9V train.
I'm using the NXT to 9V conversion cable (https://www.bricklink.com/v2/catalog/catalogitem.page?P=x1676)
with the old 9V metal train track connectors (https://www.bricklink.com/v2/catalog/catalogitem.page?P=5306c01&C=0#T=C&C=0) and the Unregulated Motor (UM) block in EV3=G.
My first test was to have the train travel one second in one direction then one second in the opposite direction in an infinite loop.  The results were fine with the train going in the direction that used a negative power in the UM block, but either no motion or shaky motion in the direction that used positive power values.
I tested the track with a multi-meter and verified that the power was only consistent and steady when using the negative power.
On this site I found an interesting answer describing what is probably happening:
Using the unregulated motor block and conversion cable to light LEDs
But that answer is only partly applicable -- I found that if I put a one second Wait block between power changes, then the power is consistent.  But different!
So a power setting of +40% for one second moves the train one track segment, while a power setting of -40% for one second moves the train three track segments.  It looks like I can generate a workable program, but I'm curious about why this behavior is happening, and if there will be other surprises.

Also see https://bricks.stackexchange.com/q/2325/3498

The answer is basically the same as the LED question that you linked. On the EV3 output ports, pin 2 is internally connected to pin 6. So, when you tell a motor to go in reverse (negative power value), pin 2 is powered, which in turn raises the voltage on pin 6. Both pins 5 and 6 are used for automatically detecting when a motor is connected.
So, when you use a negative power setting, most of the time (but not 100% of the time), it it will trick the EV3 into thinking there is a motor connected and the motor will stay powered. However, when you use a positive power setting, pin 1 is powered instead of pin 2, so the EV3 thinks that there is no motor connected (because nothing happens to pin 5 or pin 6). So, in this case, the device connection manager in the EV3 software takes over and resets the motor port, which causes it to stop sending power to the motor.
I attached an oscilloscope to pins 1 and 2, to see what is going on.

As you can see, the output is only turned on for 380ms, then it turns itself off. The motor was instructed to run indefinitely, but in reality, this is not what happens.
Since your test involved running the motor for 1s but it really only runs for 380ms, one would expect the car to run 38% of the distance as in the reverse case. You observation was 33% (one track length vs. 3), so that is quite close to what is expected.
As a workaround, you can Use the Unregulated motor block in a loop like this...

It is important to use two different "power" values. Each time you change the value, it turns on the output port again. If you use the same value, the software won't update the motor port and the device connection manager will take over and turn off the output.

Appreciate the thorough analysis and solution.  I've forwarded this info to the MOC designers.  You can see their work starting on page 34 of the 50th issue of BrickJournal.  I've got the digital version; the hardcopy version hasn't arrived yet.  Your help will be incorporated into whatever they've got planned for Bricks By the Bay 2018.  I'll try to post a video after the convention in July 2018.  Thank you!


text:
EV3 touch sensor specs relevant for a brick-built MOC
I want to integrate the following EV3 touch sensors (45507) into a MOC:

For aesthetic reasons, I want the MOC to be mainly built out of system bricks and plates, with only some internal stuff in Technic (basically just connectors and beams to hold the EV3 parts).
I'd like to know what offset in plate height or stud width I'm looking at when the button is pressed or not pressed.
Also I'd like to know how much weight there can be on the button before the EV3 will consider it pressed or bumped.

The first question is easy. The full travel of the button is 1/2 stud. The second question (about weight) probably depends somewhat on the individual sensor. Maybe I will get out my scales and see what it is later.

This paper has information on NXT touch sensors: https://bibliotecadigital.ipb.pt/bitstream/10198/2262/1/Proceedings_10thConferenceMobileRobotsCompetitions.pdf

Not sure how accurate my rig is, but I get something like 2 millimeters of travel before the touch sensor is "pressed". The HiTechnic Force sensor doesn't seem to give an accurate measurement, but according to my kitchen scales, it takes about 80g force (0.8N) to trigger the sensor.

Incredible dedication to anwer this question!


text:
What LEGO set are these decorated tiles from?
I have a box of LEGO from when my husband was younger and I have been going through and putting them in their sets for my son. I have now run out of the instruction books and still have some sets left.
Can anyone identify what set these pieces pictures may have come from? It seems like his sets are all from the 90’s.

Oh wow nostalgia kicked in. I had this when I was a kid

I still have some Spyrius sets. Not complete, but the printed parts are all there.

These came from a number of sets, including a handy "Decorated Elements" set that covered most of the printed parts from the mid-90s space theme.
However, Recon Robot appears to be the only one that contains two of the 2x2 tiles and only one of the 2x1 tiles.
Instructions can be found in a number of places, including on Let's Build It Again.

Those old-school sets made my young me drool looking at those product catalogs that came with the Lego sets back them. Recon Robot was on my wishlist until a couple months ago, when I managed to buy it used in a garage sale. It is a very nice set overall with lots of fun parts to play with, and it was part of the "Spyrius" collection.


text:
Steer with the LEGO Mindstorms EV3
In my workshops I get asked regularly, what the turn option of the default steering block means (see the image).

Obviously, if the turn option is set to 0, the robot is moving forward. A positive value is turning right, a negative is turning left. So far, so good.
I looked in the source code and found a programming scheme I tried to visualize. A large comment within the code describes the process as follows:

Speed [-100 .. +100] is move forward or move backwards  Turn ratio
  [-200 .. +200] is how tight you turn and to  what direction you turn

0 value is moving straight forward
Negative values turns to the left
Positive values turns to the right
Value -100 stops the left motor
Value +100 stops the right motor
Values less than -100 makes the left motor run the opposite
  direction of the right motor (Spin)
Values greater than +100 makes the right motor run the opposite
  direction of the left motor (Spin)

So the turn ration is multiplied by 2, because as a user we can just put -100 <-> 100 in there. I then used this code to calculate some values:
for (var i = -100; i == 100; i++) {
  turn = i * 2;
  if (turn >= 0) {
    motorB = speed;
    motorD = speed - turn;
  } else {
    motorB = turn + speed;
    motorD = speed;
  }
}

If I visualize those values, I get the following image for speed 100:

That's fine. You can see the real turn value (the ones we as a user can set) and the calculated speeds for two (virtual) motors B and D. I tried this with the educator model and it works perfectly well.
But when I use the same code for another speed value (33), I get motor outputs that are too high in my opinion:

The Motors will have values over +100/-100. Is there a threshold in the code and the motor outputs will be cropped?
Did someone else dig into this? Did I made a mistake?
P.S.: I love such things. If someone is interested in doing more if this, just ping me. :)

In addition to scaling the speed, the number of rotations of the motor is also scaled. For example, if the steering value is set to 50, one motor will turn the full number of rotations and the other motor will turn 0 rotations. If steering is set to 0, both motors turn the full number of rotations. If steering is set to 25, one motor will turn the full number of rotations and the other motor will turn half as many rotations. If steering is set to 100, one motor will turn the full number of rotations and the other motor will turn the same number of rotations in the opposite direction.

I can't say that I understand your problem, but maybe this link will help EV3 Move Steering Block Explained
If you are asking about how the steering parameters relate to how much the machine will turn, then that is going to depend very much on the geometry of the machine: wheel diameter and wheel separation.

I believe that it is the intention that the ratio between the speeds of the two motors is entirely determined by the turn parameter, not the speed parameter.
I think the following code better represents how the turn block behaves:
for (var i = -100; i == 100; i++) {
  turnfactor = 2*i/100;
  if (turnfactor >= 0) {
    motorB = speed;
    motorD = speed * (1-turnfactor);
  } else {
    motorB = speed*(1+turnfactor);
    motorD = speed;
  }
}

This is correct. Also seen in practice (with the number rearranged a bit) here and here.


text:
Loop interrupt stops all loops, not just the one designated
I have been using loop interrupts for a while, and not had an issue... until now. And it is driving me nuts.
My program has 2 main loops, titled "touch" and "end" with two more nested in the "touch" loop, both titled "01"- these are just for turning with the gyro. I've attached pics so you can see this in detail.
The problem loop is the "touch" loop - the main nested one. I have a separate thread running to check the state of a switch. When it is pressed, I have a loop interrupt for the "touch" loop only. Since it is nested, and I only have one loop interrupt, I would expect it to pick up with the "end" loop and start over... but instead it ends the program, as if I interrupted both "touch" and "end".
I'm obviously missing something here... anyone with ideas, please speak up.

Is the code after the "end" loop executed? The program could also terminate because of an error, is there an error icon or message on the EV3 display?

Also perhaps try renaming the outer loop. Perhaps "end" has a specific undocumented meaning...

I'm guessing that the interrupts in loop 03 are somehow being triggered.

@MichaelVerschaeve The sound at the very end does play, and there are no error messages. Changing the names of the loops does nothing different.


text:
What do the 'X' and 'K' codes mean for rubber bands?
I see that LEGO rubber bands/gaskets are often associated with a number preceded by an 'x,' such as 'x71' for the small/18 mm bands. A few bands also have a 'K' prefix, such as 'K4' for the large/30 mm units. This latter item is also known as and 'x89' rubber band.
I'd like to know what these prefixes mean and where they came from. Likewise, I'm curious what the actual numbers refer to.

The prefix 'x' means that the element design-ID used by LEGO is not known or was not known at the time it was entered into the Peeron database (www.Peeron.com).
If a design-ID is known, the people who maintain Peeron use that to identify the piece. Otherwise you get 'x' with some number...
This is indeed often the case with strings, rubber bands, gaskets as there is no room to print the design ID on the element.
I have no idea about your 'K' prefix, could you give a reference where 'x89' is refered to as K4 ?

If you look at the instruction page at the following EuroBricks post, you will see the white band described as ‘K4’: https://www.eurobricks.com/forum/index.php?/forums/topic/112647-rubber-band-sizes/&do=findComment&comment=2284212

So used in the instructions of a couple of sets, seems to indicade the diameter in studs more or less...
A bit confusing, as LEGO uses K prefixes for the sizes of boxes they ship elements in (K4,K6,K8)...


text:
What is this orange winged thing without studs?

It looks like some really old flying thing.

That piece is often used as a caterpillar track, or conveyor belt

It's hard to tell the colour in your photograph but it might be Medium Dark Flesh (a.k.a. medium nougat)
At the bottom of this page there are three sets which use this piece in that colour.
If you look carefully you should see the number "57518" shaped into the piece. Almost all Lego pieces have that a code on them that you can use to find them on sites like BrickSet or BrickLink.


text:
High Torque Subtractors
I would like to use a subtractor in my next RC LEGO tank, as it enables the vehicle to turn on the move, as opposed to stopping and then turning.
Unfortunately, the subtractors I have tested so far cannot withstand the torque of heavy vehicles, which either causes the subtractor to break apart, or the differentials/gears to grind.
Does anyone know any subtractor designs which are able to deal with high tension/torque/stress levels so that enormous vehicles can still use them? 3kg-5kg tolerance would be ideal.

It sounds like you need a stronger differential.
Might I suggest this design by Nazgarot:

If you make two, you can build a big and sturdy subtractor like this (probably customizing the gear ratios to your requirements, the right gearing could also remove the need for a PF switch):

Here's a video of it in action:

Very nice answer. You deserve to get the six-sided hat for this. :)

Excellent. I've come back to this question like 4 times hoping someone had finally figured out a decent answer.


text:
Function in EV3 Basic
I have been programming in basic for ~30 years. I want a translation of the following code into EV3 Basic:
function index( x , y )

  return x + y * ( maxx , + 1

end function

sub look

  for i = 0 to 5

    motor.start( "bc" , 75 , 75 , false )

    program.delay( .025 sec )

  next i

  motor.stop( "bc")

end sub

How do you do this in ev3basic?

I don't think this is something we can solve, shouldn't this be moved to SO?


text:
How to ship a LEGO sculpture to a contest?
I am planning to participate in an art contest that allows paintings, sculptures, or video clips. I have a LEGO sculpture in mind that would fit the idea of the contest, but it would have to be shipped to the jurors. The contest itself is not about LEGO at all, so I have no idea how they will react to a LEGO set. I just want to use it as a medium to convey my message.
The sculpture would be a diorama with a small figure (not a minifig) and some larger figures. The basic question is: How can the sculpture be delivered to the contest in one piece? I can think of some options:

Glue: Since the figures would stand in the diorama, the glueing area would be quite small, breaking is likely to happen.
Sturdy build, use Technic connections: Having the figures attached to the sculpture with lift arms would look weird and would probably decrease artistic value.
Partly disassemble the sculpture and give instructions for final assembly to the contest committee.

Number 3 is my favourite solution. However, is it acceptable for a contest to deliver a partly assembled sculpture?? I would wrap each figure separately and deliver also photographs/descriptions of the final arrangement.
Do you have experience with shipping sculptures and contests? What is the most feasible approach? Are there other considerations?
EDIT: After Mołot's comment I contacted the contest committee. They were very kind, and obviously, it is no problem to submit half-assembled work (in this case). Lesson learned: Ask!

"is it acceptable for a contest to deliver a partly assembled sculpture?" - No one here can know that. Only way to know that is to ask contest committee.

All 3 methods are necessary when shipping builds.

As @Mołot commented, first ask the contest committee whether they have specific rules. In general though, shipping in chunks is common, ideally few pieces that are simple and straightforward to attach.
Rigid, sturdy builds are obviously going to stand up better to the travails of shipping, so try to avoid spindly construction. Follow good mechanical engineering principles, and if you can use technics for internal support, it may be very useful.
Glue also helps - yes, it's a bit more permanent, but for this type of production, you want that.
Additionally, shipping with "popcorn" pieces densely packed really helps prevent damage. Be aware that whoever unpacks it may be less keen :-)


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How to glue a LEGO tree decoration in a way that's not permanent, to prevent accidental disassembling?
I have a sweet LEGO Santa Claus and few other builds that would look cool as decorations on Christmas Tree. Sadly, it would probably break if I would try to hang it. It can stand all right but is not sturdy enough to hang, or to survive much handling, really.
So I want to glue it together. But I don't want it to stay glued. I want to be able to disassemble it when I no longer use it as an ornament that hangs on something. Is there any way to glue LEGO bricks and still be able to wash away the glue without damaging them when I want to?
Note: this question has nothing to do with the safety of 4 years old kids, like this one, and strength of connection I'm asking about is way smaller (hanging on a tree vs kid potentially trying to take it apart).

As I said in this answer I think the best option would be to use a water soluble glue (such as PVA, White Glue, Elmer's Glue All, etc.). This dries clear, but can be washed off with warm water and a soft brush.

Possible duplicate of Removable glue for LEGO models

@chicks see my edit.

Thanks Molot.  That should help it be less confusing.  I'm going to tweak the title too.

@Molot - Still no answer? When you have them out next time could you please post a picture of them?  I have some ideas...

@JohnnyB it's long time to Xmass season. I hope I'll be tidying up my brick storage soon, then I'll post pictures.

You can increase the "clutch" power of bricks by sandwiching a piece of paper towel between each connection. Once the bricks are together, cut away the excess paper using a knife.
The effect of this is roughly the same as applying a weak glue. Your builds will not become impervious, but will hold up better to handling and hanging.

I'd like to note that this may only work for some bricks as there are cases where bricks without extra layer (like paper you mentioned) already tend to crack, thus loosing a clutch power.

If you need it to be glued but not permanent, I'd try paper-mache paste. It'll wash out. I've never tried it, but I think it should work.


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Is there a good place to find upcoming LEGO conventions?
Is there a continually-updated site that tracks LEGO conventions/gatherings around the country (USA) or world? Ideally there'd be a way to filter them by date/type/location.

There is the LEGO ambassadors network calendar:
https://lan.lego.com/calendar
This contains all events organized by RLUGS (LEGO communities recognized by LEGO), which are the largest events generally.
However, where I live, all sorts of communities and individuals organize events, it is quite a challenge to keep track of all of them.


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Where to find pictures of undersides of bricks? (possibly Lego clones about 25-30 yrs ago)
I am trying to identify which non-Lego bricks I might have played in the past. Don't recall the names but I can probably recognize them from photos if I see them again
For example, I remember some 2x4 bricks having two horizontal lines across the center (on the underside).

Related: https://bricks.stackexchange.com/q/9880/9417

@Molot that's pretty close. Is there some proper term to describe the design of the underside that allows blocks to fit together?

Nothing I know. I just remembered seeing what you described on this site. Luck.

Could it be BRIX BLOX?  Came across these on eBay and thought about you...


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Advanced LEGO set for my 5 yr 2 months old child
My Son is considerably talented in LEGO building. Till now, he has completed over 30 LEGO sets all by himself which includes this year completion sets - 42054, 42064, 42072, 42073, 31010, 3367 And 70625. His very first LEGO set was built when he was three years old - 40220.
Now looking for more challenging sets for him. Any suggestions?

As far as building experience, LEGO Technic sets are considered the most challenging. Looking at your list, it appears that your son already built some pretty large LEGO Technic sets, so if he enjoys the challenge, you can purchase him more of the larger Technic sets. Also, note that most large LEGO Technic sets will have alternate instructions, or the models can be combined with other sets. Additional instructions are available on the LEGO Technic website.
Compared to LEGO Technic, pretty much all other sets are going to be simpler, however some of the larger regular sets can still provide a good challenge. I would suggest browsing the paper catalog or LEGO's online shop together, and see what strikes his fancy. He might be into a particular theme to not just build but also play out stories. Or he may like vehicles, trains, motorized sets, or robotics.
Also, encourage him to free-build. There are alternate instructions available for many LEGO sets both online and in book form, or he can just build from his own imagination. That's really the next level for a talented LEGO fan; designing and building their own models.
You might also want to check if there is a LEGO club near you for young LEGO fans. They are usually well structured and focus on robotics and other educational aspects of LEGO, which may be a good fit for your child.

My daughter is also voracious with lego.  I like to just let her decide what she wants to build, within reason.  I think the Technic sets are the most challenging for her but at 8 she is doing sets labeled for teens, she has needed help occasionally.  I also like to make up challenges for her, "That is a great car you built, can you add the pull-back motor to it?".