text:
Evolution of the LEGO part catalog over time
I have downloaded the Bricklink catalog four or five times in the past, but the interval was very irregular. I would like to look at the evolution of the LEGO part list over the years. However, I didn't find an option on Bricklink, or elsewhere on the Internet, to download past versions.
Are you aware of any archive of Bricklink catalogs? I haven't looked at other platforms with LEGO catalogs. Any other idea to get systematic information on the evolution of the part list is also welcome, of course.

Since bricklink was recently purchased by Lego Corp., that database may be evolving further soon.

Are you specifically interested in only the Bricklink catalog, or are you interested in the evolution of produced LEGO elements generally?

@jncraton It is general interest. I tried the Bricklink catalog because it comes in a format that can be analysed by scripts quite easily. Questions I have are e.g. "Did the number of Technic elements increase by more than the average over the past 20 years?". And other statistics that may have evolved over time.

@user3794648 Yes, the catalog is constantly updated by the community. That is why an annual (or otherwise regular) snapshot would be interesting to have. Plus, the BL catalog comes in text format which is easy to reformat and to analyse.

You might be able to get the information that you are after from the Rebrickable database dumps. This includes set inventories for many sets, along with the year that the sets were released. Here's the full schema diagram:

A query something like this should provide a count of the number of sets every element has appeared in by year:

SELECT year,
       Sum(1),
       colors.name,
       parts.name,
       parts.part_num,
       colors.id
FROM   sets
       JOIN inventories
         ON inventories.set_num = sets.set_num
            AND inventories.version = 1
       LEFT JOIN inventory_parts
              ON inventory_parts.inventory_id = inventories.id
       JOIN parts
         ON parts.part_num = inventory_parts.part_num
       JOIN colors
         ON colors.id = inventory_parts.color_id
GROUP  BY year,
          colors.name,
          parts.name,
          parts.part_num,
          colors.id
ORDER  BY year DESC,
          colors.name ASC

Here's that dataset:
https://gist.github.com/jncraton/b0641ce5f8bc28e10e761a5ce1bafd51
Note that this query includes part variations (mold updates, prints, etc) as unique elements, so you may need to filter it down quite a bit for your use case. If you'd like to run your own queries directly against the full Rebrickable dataset, I maintain some scripts that make this fairly easy to do.


text:
What internal electronics do Spike Prime and Mindstorms Robot Inventor use?
What electronics live inside the SPIKE Prime hub? How powerful is the hardware?

If we open the hub we can take a look at the main PCB inside. There's just one PCB in addition to a small speaker and the replaceable lithium ion battery. Here's the top of the PCB:

And the bottom:

We see that the main CPU is an STM32F413. It includes 1M of flash and 320k of RAM and the ARM Cortex M4 core can be clocked up to 100MHz.
In addition to the 1M of embedded flash, there's a Winbond W25Q256JV providing an additional 32MB for program and data storage.
Bluetooth connectivity is provided by the TI CC2564C.
The 25 LED grid is driven by a TI TLC5955 (48 channel PWM LED driver). This part also drives the other 4 surface mount LEDs on the board.
The 6 motor outputs are driven by a trio of LB1836 dual motor drivers.
There's also an MPS 2639A to manage the lithium ion battery.
There are many other supporting components on the board, but that covers the majority of it.
Overall, this is similar in architecture (ARM-based, identical output drivers, etc) to the other Powered Up hubs. It is significantly more powerful in terms of horsepower and storage thanks to the 32MB flash chip and higher clock frequency (100MHz here vs 48MHz for Boost for example).

Is there any specific driver IC for the RGB LED under the central button?

@g.p.daniels The other surface-mount LEDs on the board are also driven by the TLC5955.

Can you identify which is the accelerometer and gyroscope chip?

Any idea what chip is the IMU and where it is on the board?

At Pybricks, we have confirmed that the IMU is a STMicroelectronics LSM6DS3TR-C by reading the chip ID over the I2C bus. I think it is U26 in the middle of the second picture.

Thanks @DavidLechner. Some teams (ours inclcuded) have observed that SOMEtimes it seems that the gyro has some of the same issues the EV3 gyro did, which can cause real problems for FLL teams. Do we know any other details about the gyro and how it is used? Is the a calibration during bootup? Can we manually (through code, especially python) trigger a recal? Is there a way (in code) to determine if the gyro has failed?

source: Stack Exchange

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

sort: votes


text:
Is this online shop legit?
I am wondering if this site is legit or no because I want to buy this LEGO set.
Here is the screenshot:

You can see the URL in the image.

That's a scam. I was going to write reasons why it is so, but there are so much red flags all over this website, I don't know where to begin.. Even Chinese copy cost more.

thanks a lot you saved me 50 euro

Just look at the "reviews". Half of them aren't even about this set. Parts of the web-page are rip-offs of the official Lego site or link through to the original Lego sources. This has all the hallmarks of a rip-off site and the prices are just too good to be true.

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


text:
How can I make church bells with a pull cord?
I would like to allow the viewer to pull on some strings or chains and let that ring my church bells (I know it won't make much sound, that's fine).  I'm thinking I'll need a pulley and some string, right? Then, do I just thread the axle through the pulley and attach the axle to the bell somehow? Are there any other parts I might need? Is there a good tutorial you can recommend for LEGO pulleys?

There's no real need to stick with LEGO strings. Any other, similar thickness, string would work the same way and will be cheaper and easier to obtain. This allows you to go with longer strings too.

Is there something I do to attach the string to the pulley?

I don't quite imagine the model/setup you are looking to implement, so cannot really advise anything reasonable.

It sounds like you're trying to implement a fairly simple bell mechanism such as this one:

You can certainly do this using some string and the pulley element that you mentioned.
I'd recommend tying the string to one of the holes in the pulley. Something like this worked reasonably well for me:

Here it is in action:

You'll likely want to do something to limit the range of motion so that the bell can't flip all the way around when the string is pulled too far. You should obviously make everything a lot prettier, too.

and maybe add a secret latch or something just in case it messes up


text:
Suitable arched bricks for building a bridge
I'm working on a LEGO project with my son and we want to include a bridge. However, I cannot find individual arch pieces that would work for a bridge.

Could you be more specific about what kind of bridge you want to build ?

This sounds like a fun project! There are lots of options available for arches. It might be helpful to know a bit more about what you are looking for. If you are trying to build an arch bridge such as this:

The 18838 arch or similar might be a good fit. These can be purchased on Bricklink or directly from LEGO fairly inexpensively.

If you don't have an easy way to get that piece or a regular arch piece doesn't meet your needs, you can get pretty good results emulating arches of any shape using inverted slopes (or regular slopes if you get clever). Here's an example brick-built arch by Tom Alphin:

You can find arched bricks produced by LEGO on Bricklink. You can also find available colors for each item as well as purchase if you need extra.


text:
Which resistor value is used for which motor in Power Functions 2.0?
Based on the answer here it seems that resistors are used to detect what is plugged in with LEGO Power Functions 2.0.  So which resistor values (or ranges) apply to which motors or other devices?  Are there any values of resistance that lead to "unknown device" errors or something like that?

M Motor (Powered Up/WeDo 2.0)
The M motor has a 2.2kΩ resistor between pins 5 and 6. Pin 6 is connected directly to pin 3.

LED Lights
I don't own any lights yet, but according to this post, they also use a 2.2kΩ resistor, but in this case it is between pins 5 and 3. This pulls ID 1 to ground. Here's the full circuit diagram:

Train motor
The measured resistance between pins 5 and 6 shows an open circuit. Pin 5 is connected directly to VCC, and pin 6 is connected directly to ground.

Other components
I wasn't able to determine any sort of passive identification on any other components (Boost motor and sensors, etc). My guess is that these have an onboard microcontroller and use an active handshake before establishing a data connection.
Summary
M Motor
3 (GND) ─────┐
4 (VCC)      │
5 (ID1) ─2.2k┤
6 (ID2) ─────┘

LED Lights
3 (GND) ─────┐
4 (VCC)      │
5 (ID1) ─2.2k┘
6 (ID2)

Train Motor
3 (GND) ───┐
4 (VCC) ─┐ │
5 (ID1) ─┘ │
6 (ID2) ───┘

Thanks Still wondering if the WeDo 2.0 motor works on 3v or 9v. Not sure what would happen if you plugged a WeDo motor into the Train or Boost Controller. Possibly the WeDo has a DC-DC converter to up the 3v to 9 v for the motors. This may also explain why the batteries on the WeDo 2.0 do not last very long, about 2 - 3 class room use.

I believe WeDo 2.0 steps up the voltage to 5v (http://www.philohome.com/wedo2reverse/cont.htm). Motor power scales with voltage, so the exact voltage used is variable. You can use the WeDo 2.0 motors with the Powered Up hub. This is what powers the Batmobile.


text:
Please help identify this LEGO set with large black curved elements with orange stickers
Can you please help me identify this set.

These are parts from 8058-1: Guardian of the Deep

except the Black Aircraft Fuselage Curved Forward 6 x 10 Bottom with 3 Holes.


text:
Help to identify a small tube part
I'd like some help identifying the black parts circled in the photo.

It's a piece of 3mm rigid hose. It looks something like this:

That particular piece must have been cut from a larger piece, as the smallest it has ever come is 3L (3 studs) and never black at that size.
It's debated if cutting tube pieces is a purist thing to do or not.

Cutting rigid hose is allowed in my opinion as The Sears Tower Architecture model (21003) had it as an actual step in the instructions.

It was the Space Needle set I believe, 21003-1


text:
Is it expected that LEGO will produce small (S or XS) PF motors?
The existing LEGO PF motors are the M, L, and XL, making builders suspect that the S and even the XS names were left out and reserved intentionally for later designs. However, the M motor was released ten years ago, and we have not seen any smaller motors.
Are there any (pro or con) signs suggesting that those motors will or will not be released in the future?

Generally, speculative questions are considered off-topic, but in this case very little speculation is required to answer the question.
The clear answer is that S or XS PF motors will never be released.
The entire PF system is on its way out and is being replaced by the newer Powered Up system. For this reason, I would expect production on existing PF components to stop soon, and it seems highly unlikely that TLG would introduce new elements for PF at this point.
It is of course possible that they will include smaller motors as part of the Powered Up system at some point.


text:
Does my child need a smart device to control LEGO Powered Up train sets?
The first two Powered Up train sets can be controlled with smart devices (phone, tablet, etc). Is this required to control the trains?

No, a smart device is not required to control train sets 60197 and 60198. These include a standalone Powered Up remote control:

This provides much of the same functionality as a smart device. From the FAQ:

The LEGO® Powered Up remote control works a lot like how you would use your smart device (mobile phone or tablet for example) to control any other electronic device via Bluetooth technology. If you connect the remote control to the Smarthub in the train, you can control the speed or stop the train.

However, there are some features that are only available from a smart device:

The app does provide you with additional features, such as sounds, and the ability to see how fast the train is travelling from 0-10 increments.


text:
How many motors can be controlled using the Powered Up system?
I'm wondering how many motors I can control at the same time using the LEGO Powered Up system? What components are required to make this work?

With current hardware, the answer is 10. From the trains FAQ:

You can run up to 10 trains at the same time from one remote control. There are 5 channels on the remote control (you can tell them apart by their different colors), and with each channel you can control 2 Smarthubs in separate trains with motors plugged in – as long as on one train the motor is in port A of the Smarthub, and on the other train, port B.

Each Smarthub provides two ports:

There are 5 channels available on current remotes, so you can pair up to 5 remotes with Smarthubs and control 5×2=10 outputs at the same time.


text:
Why can't I reproduce this SD card box in LDD?
I've built an SD card box a few years ago. Now I am trying to reproduce it in Lego Digital Designer.

However when I tried to reproduce the closed version, LDD refuses to snap it in place.

In real-life, my box just snap very nicely. Why am I not allowed to do that in LDD?
Here is the WIP .lxf file

The issue here is that the hole in a Technic brick isn't at exactly the same height as the stud on the side of a System brick. Here's a slide from a great presentation which explains the details:

This difference is barely noticable when building, especially in your scenario because the hinge adds some additional play, but I believe that LDD won't allow these to connect because they are actually off by .12mm.
I tried to take a few pictures to demonstrate what I mean, but they didn't turn out very well. Here's a System brick (tan) connected to a Technic brick (blue). You can just barely see the .12mm difference at the top:

The difference becomes more obvious when more bricks are added so that the error is allowed to compound:

Seems legit (seeing the headlight brick example in the presentation slides). Just one question: is .12mm equal to 3/10LDU? That seems odd (I'm still a beginner in technical LEGO stuff)

You are correct that .12mm is the same as .3 LDU, and this does seem like a strange offset. My guess is that this decision was made in order to create the absolute minimum difference between these parts. I'm guessing that most children who build with these parts have never noticed this minor inconsistency.

Great answer. I never knew about that offset. Thanks!

LDD uses exact numbers, where as in real life ABS and polycarbonate have some give or flexibility that a computer program can't factor in. There are many documents about LEGO part stress that explain what a "legal" vs "illegal" build is. Any illegal build will not work in LDD. I break the rules all the time too, but LDD is looking at it from a pure math sense, which you can't cheat. Try and create a curved wall made of stressed 1x2 in LDD. You can do it in real life, but not in the program.

Try de-attaching the black piece and then attach it to the 2x2 and plate and attach all the pieces at the same time

Interesting... I just tried this myself (with real bricks) and the two parts definitely snap together nicely. No stress or anything. I'm wondering if the issue is the 1x2 plate. Maybe LDD can't deal with a hinged part having to snap into two places at once. What about if you remove the bottom 1x2 yellow plate? Would it snap in then? In that case perhaps first attach the 1x2 to the healight bricks, then attach the hinge-plate to the hinge, then rotate it towards the plate and see if it would snap on the 1x2 plate.

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


text:
Technic 8071 assembly problem
I am busy attempting to assemble Technic 8071, and have encountered a problem.
On page 83 of the first manual, a yellow gear (4203493) together with a grey splined rod (4211815) is added to the sub-assembly in diagram 13.
A little later, in book 2 page 4, diagram 14, two sub-assemblies are being joined, but the yellow gear is in the way. If you remove the yellow gear, everything goes together just fine.
I have backtracked through the instructions and re-assembled everything carefully, but there remains the possibility that I have made a mistake. Right now, it looks to me as though the documentation is incorrect. Can anyone confirm either that they have encountered the same problem, or that on the contrary, they have assembled the kit successfully? Is it just that I'm looking the wrong way at the diagram?
Edit: Added a couple of pictures

I have now realised my error. the smaller sub-assembly was incorrectly put together. The manual is correct. Thanks to all for your help.

Well that's actually a nice concept for a contest (I mean, we're all tired from build-in-the-bag, right?): mirror building!

Seeing the manuals, I'm fairly confident the instructions are correct.
The 11L beam from the second part (introduced in book 2, p 2, #1) looks like it should slide right next to the yellow gear (thus, not right on top of the right 7L beam (introduced in book 1, p 79, # 4) but one stud to the right, which shouldn't be a problem). To clarify, the 11L beam should be exactly in the middle, at equal distance of both yellow gears, right on top of the part with three holes protruding from the turntable on the right.
I'l admit I didn't build it myself yet though, so maybe I overlooked something.
Moreover, I don't really see what could go wrong, especially in book 2. Even in book 1 I can only imagine swapping the right 7L beam with the other part in #3 of page 79, thus having the two 7L beams next one to another, but that kind of mistake should be easier to spot than to make. Could you perhaps post pictures of the two parts as they are before you attempt to assemble them together?

I've added pictures. I hope this makes my problem clearer.

Indeed it does. Your small part (the one with the white beam) looks like it's mirrored from what it should be. The 11L beam should be on the right side, not the left one.

This is the image from the Book 2, Section 14, Page 4 on the instructions from the Lego Website - source. Does yours look like this?
To me it does look like it's not quite right - if you lift the yellow gear out, move the second part into position and then put the gear back it in it looks like it might fit, although the yellow gear wouldn't turn.
I'd advise contacting Lego support, or see if you can pick out the way the person put it together in this YouTube timelapse video.

The timelapse is interesting but goes way too fast... However, considering no-one posted a comment about a mistake, I find it hard to believe there is one.

I have this set and didn't encounter any problems. Not at this step, not at any other. (Unlike with easily a dozen other sets, where the instructions were wrong, in point of fact, in all kinds of ways and for all kinds of reasons, so I know LEGO aren't impeccable.) And everything was functioning properly when it was assembled. Sadly I've long disassembled it, so I don't even know what all these gears did anymore. And of course I don't remember by heart if my instructions actually looked the same as in the image above, so I guess I will have to check that to be completely sure.

Yes - that's pretty much the same image. Lifting the gear out doesn't help. It's really in the way! :-)

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


text:
Average price per weight of new bricks in sets purchased for retail price?
What would be a reasonable estimate for the price per pound of pieces purchased for the retail price in sets?  If the weight of a good sample of sets (not including the packaging or instructions) were known then a range of prices could be calculated.
The only number I can come up with now is to take the average price per new brick divided the weight of a brick- if a 2x4 brick were representative (I suspect it weighs more than average), then the price per pound would be around $0.10/2.5g * 453.6 g/lb = $18/lb, or using 2x2 as an average weight maybe around $40 per pound.  The numbers are interesting to compare to used bulk prices, or the cost of new bricks from pick-a-brick/brick wall cups (the cost of those is well documented elsewhere).

The short answer is that for retail sets, anything under $20 USD per pound of actual parts is a great value. $50 USD per pound appears to be fairly common overall.

I calculated this based on the actual part weights of all parts in a set. I only explored recent Classic, Creator, and City sets as these tend to be a good value and use System bricks almost exclusively. I used recommended retail price and didn't account for sales or other deals that can be found on retail sets.
Here's a graph of recent Classic, Creator, and City sets showing that $50 USD is a reasonable median price per pound:

The best value are the Classic bulk brick boxes, and the worst value per pound are the City minifig sets.


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

Currently, RobotC does not support Bluetooth messaging[1] or USB daisy chaining[2] LEGO MINDSTORMS EV3 programmable bricks.

It seems to be working for two NXT bricks


text:
MOC planning and design
What tools do you use when planning and designing a new MOC? Pen and paper? Or there is something more advanced?
I had the insane idea to try LDD to design my MOC and it was a nightmare.
Since my MOC uses sets from castle fantasy, there are maybe 3D models ready to use for LDraw or other kind of software suitable for this task?
EDIT: I will go into further details to explain my issues better.
This is the list of sets I want to place in my MOC:
Fantasy Era:

7036 Dwarves' Mine
7094 King's Castle Siege
7079 Drawbridge Defense
10193 Medieval Market Village
7037 Tower Raid
7029 Skeleton Ship Attack
7048 Troll Warship
7097 Trolls' Mountain Fortress
A lot of smaller sets like 5614 The Good Wizard that do not take space.

Kingdoms:

6918 Blacksmith Attack
7187 Escape from Dragon's Prison
7188 King's Carriage Ambush
7189 Mill Village Raid
7946 King's Castle

I want to build a nice terrain where to place all those sets together. for example, a mountain where to place the Mine, and a hill to put the Blue Castle on top. The a river for the Drawbridge, a plain for the medieval village and the the mill, a coast for the harbor, a sea for the two ships, and another coast for the Troll fortress. I have yet to decide where to put the Red castle.
The whole MOC would require 10-14 big baseplates (my estimate). So planning the whole thing is very hard and I got lost with LDD very soon. To make things easier, it would help a lot if the software has the "size box" for the sets, so I have a way to understand how to place each set on the scene without having to build them from scratch, so I can concentrate on the terrain.
I have no clue on how to go forward on this, to design all the terrain and then get the component list (and it's cost) to build everything.

Hi Terix, this question is probably not a great fit here on LEGO Answers as it's really only answerable with Opinions. As TheBrickBlogger points out if you post about the specific issues you're having we can give you some better answers.

I've added more details to narrow down my issue, hope it makes a better question.

Design stage

decide roughly where everything should go
use various boxes to place them at the right position and height
build the bits in the middle once you are happy with the layout
if you don't mind cheating and are good with a ruler, you could build a multi-level base-plate out of wood and just build the very top level of ground.

Buying pieces
(Duplo is relatively cheap and builds big to lay down hills/mountains, use Lego bricks on top to provide a building surface.)
Find a lego store that you can get to easily and often.
The Pick-a-Brick wall will often have useful grass / slope / tile / transparent pieces that can make large and cheap filling areas (pour lots of clear blue 1x1 round plates into a tray for water).
If there is a really useful piece on the PaB wall you can ask for a box full of pieces, (which I believe is known as a K2), this is probably the cheapest way to buy 1000s of bricks at a time, (if they have a box available).
inventories for local Pick a brick walls: http://wallofbricks.com/

There is any way to know all the sizes of built sets either in cm or knobs? I have all the sets stored away because lack of space and would be easier to avoid opening everything to check sizes.

Official Lego website has all instructions for download as PDF, Brickset.com has a database of most sets that can be used to find pictures and instructions from other sites.

Some of the more popular programs used when designing MOCs are:

LEGO Digital Designer
MLCAD
SR 3D Builder

There are some other ones available but those three seem to be most preferred editors. They all have quite similar set of features but their user interfaces are very different. I encourage you to try each of them out. If you wish to find most extensible software, MLCAD seems to be rather old and stable platform to build upon.
I myself use pen & paper for concepts and ideas and LEGO Digital Designer for designing.

I'm not sure why are you saying that using LDD to design your MOC was an "insane idea" that turned into an "obvious nightmare". LDD is meant exactly for that; designing MOCs. You don't mention what issue you ran into, but you should be able to build any kind of castle in LDD just fine. If you specify what problems you encountered others could probably help you with solving them. Although LDD was originally intended for children to be able to design their own MOCs and order them directly from LEGO (a feature that has been discontinued), it is very powerful and you can design pretty much anything.
I myself use a combination of planning on paper, real LEGO bricks, and LDD to design MOCs. Paper to get the initial concept, real bricks to work out scale and some details, and LDD to finish the MOC and get the bill of materials so I can order the pieces I don't have from BrickLink.

I added more details of what I'm trying to accomplish, maybe my question now is more clear :)

I looked at your updates to the question. Yes, that is going to be a challenge because unless you virtually build all those sets it is going to be hard to work around them in LDD. May I ask why you want to create this project virtually? Usually for very large projects like this people just build them in real life. Landscaping is not that difficult to tie buildings together; some grass, some trees, a river, a couple of roads... you don't really need LDD for any of that.

As far as your question in regards to each of those sets, you should be able to figure out the size by looking at the picture of each set and counting the studs of the foundation.

Here is a link to an article I wrote some time back about building a Medieval Village, including landscaping. You might find it helpful: http://thebrickblogger.com/2012/08/guide-to-building-a-lego-castl-village/

I need to know the size of the MOC because before building it, I need to build the furniture that will hold it in place :) Now I don't have the space to keep it, maybe I will build it when I'm almost ready to go with the project, but now I need to still figure it out. I downloaded all the manual pdf and counted all the studs. I need glasses now, but this step is done :)

Since your project is going to be very large, I would suggest that you work with contstruction paper. You can draw out the outlines of the castles and other various buildings, and you can also plan out the baseplates. This should help you build the furniture that will hold it all.

Also, I might suggest that you may want to make that furniture modular. In otherwords, instead of making one large table, make i.e. 4 smaller ones that can be configured in different ways. This way you can always expand our layout, or make it smaller, or configure it differenently, depending on your needs.

I know this is an older question but, for anyone else who might be looking for a good way to plan/design/refine a MOC idea, I wanted to throw in my 2¢. For the past week or so I've been working on refining my own MOC idea using Mecabricks. It's taken me a little while to get familiarized with the toolset available and there are probably some features I haven't even looked into yet, but it's a pretty great, online LEGO CAD (computer-aided design) tool for putting together MOC's. If you just want to "jump in" and start building, their Workshop is accessible without any signup, although to save your designs you'll need to register (free) an account.
I've not tried their import functionality, so I can't speak to that at this time. I'm not sure how it works or if it would be a way to bring in the information for existing sets. I couldn't say if there are any bricks "missing" from their available list but you can use pretty much any color, including transparent, metallic, etc. It does not (currently) offer the feature for producing instructions, although that appears to be in the works. It does, however, offer a way to export the parts list when you're done to a CSV file or an XML file that can be used on BrickLink to add the parts used in your MOC to a wanted list.
Just for reference, I hadn't used this site until this week, and I've already been able to use it to create several variations of a pretty simple MOC idea I had (my designs use bricks that apparently aren't available in the colors I've chosen, but this has at least given me an idea of the direction I want to take it).


text:
How to unplug black friction pin connectors
Black friction pin without slots connectors are common in older Technic sets. Note that these were quickly replaced by the current version with slots that is much easier to remove.
 vs
Especially in older sets, it is not uncommon for these connectors to get completely stuck (as if glued) in bricks with holes. I have to resort to pincers and brute force. This typically results in the connector being damaged.
The orange brick separator is often not tough enough to do the job.
So, how can you separate these things?

It depends in what type of beams the pin are mounted.

For studless Nicael's methode is the easiest. Otherwise you can use method 3
For studded beams you can use variation on this methode. take a axle of 6 or 8 long, 5 or 7 other beams and some plates. Stack the beam side by side and lock them together with the plates. Place the beam with the pin on top pin sticking out. Place the axle in the hole under which the pin is located. The axle will stick out 1 stud. Puch this on a hard surface that is allowed to be scratch / dented. This will remove also pins that are deformed.
If the pins are in other parts you often can move them to a studded beam by pushing the other end in a studded beam and putting in a minifig tool, like a broom, shovel or light saber blade.

Loose parts:

Half assembled:

Axle placed:

Pushing pin out on table:

Switching to a beam:

My preferred method is the last one, but instead of using a Technic brick, I use a half width beam. The stick blocks the pin as it does with the full width brick, but once the stick is removed, the pin is very easy to pull out from the beam.

Take your cross axle:

And push it into the hole where your pin connector had stuck

Thanks, it's a method I've tried. I've found it usually works better if you don't push the cross axle perpendicularly (into the empty centre of the connector) as in the image. Rather aim for the black connector's outer edge from an angle (about 20 degrees). I agree that using cross axles is better than the orange brick separator.

@Gruber Looks like you are right! So it suits you or not?

This method is good, but it doesn't solve the hardest cases. One thing I'm going to try is to see if heating up the plastic in hot water is going to make things easier. Once separated, perhaps washing these black connectors can remove residues or filth that increase friction?

Indeed, LEGO used to recommend building a tool with two axles, an angle element and two bushes for just this event.

Here is an alternative 'pin-pusher' that I put together using as few pieces as I could (except for a few tiles to make it a bit more intersting).

The blue pin near the centre pushes pins out half way, just enough to remove the pins by hand and not to far for it to pop up out in the air.

The two tan axles help to align the Technic beam you are using, I find they are most useful when you are trying to remove a long row of pins on a single beam.

It is also quite good at removing double pins with axle holes.
You could use some blue-tac to keep in in place but I don't think it's necessary.

I originally wanted to build a motorised version that would pins out of the holes almost like a drill press but I settled for something simpler and more functional.

I have resorted to brute force in the past. By which I mean destructive removal of the pins. I use a Dremel tool with a 2mm drill bit or 3mm router bit to carve away at the pin until it disintegrates.
The new style pins sell for about 0.3c each on Bricklink, so if you're assembling a model it makes sense to just buy a pile of new pins and and use those instead. I use the pins as "stuff" for my construction models to work with, so I bought 10,000 pins in one hit for about $50 including delivery. It's just not worth putting the old pins into newly assembled models when it's so cheap to avoid the problem.
To actually remove the pins when they are stuck I use the approaches other people have given. When they fail I use olive oil as a lubricant (soak Lego in oil, wait). That's much easier if you can keep the end you're going to be pulling on out of the oil. Then use the "jam a bar into the end" technique to lock the pin into another Lego beam and pull it out. Usually twisting is required.
But I have to admit that I don't bother any more. I pull models apart, and pins that I can't get out with my fingers I just drill out. If I really have to I'll buy more old-style pins on Bricklink, but I have enough friends who buy second hand Lego and hate those pins that my supply is adequate. And I'm happy to give away the new style pins in exchange. Again, they cost me 0.5c/pin...
The old pins are brilliant if you're exhibiting a model and it has parts that tend to fall apart. Use the "stuck forever" pins and things don't fall off nearly as easily. It's legal, so you can still put the "Model is 100% unmodified Lego" sign on it whereas if you use glue you can't do that.

Do you have a link to the page on Bricklink where these new-style pins are sold? Thanks.

@Gruber I edited it into your question but the edit hasn't been approved yet. Sorry I didn't realise that: http://www.bricklink.com/catalogItem.asp?P=2780  and click "lots for sale"

I used to use the longest Technic axle I could find. The axle would be uncomfortable to use for dismantling large LEGO sets with hundreds of Technic pins as it would always dig into my palm when I forced the pins out.

If you push one or more 2x2 Round Bricks into one end with a 2x2 Round Plate (with or without a rounded bottom) you have a nice handle which is a bit more comfortable to use.

When you place it down on a table it will never roll off onto the floor.
You can also change the colour of the handle to make it easier to find.

Everyone has come up with a solution, but I do not understand whether I am missing something or if I actually know something others do not.
There is a LEGO piece made precisely for this. It is the Technic separator.

Never seen this screwdriver-like thing before. I could only find it for sale on Amazon.co.uk. Does it even work?

Yeah I have one myself and J have taken apart that green tractor 2jn1 technic from the early 2010s faster than you can imagine.

I've used tweezers since I don't have an axle rod in hand.

Did they leave scuff marks on the pin?


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Can I build UCS Death Star by buying bricks separately?
I'd like to get the UCS Death Star, but it's too expensive :(
I got the build manual, and I see what bricks I need. I am thinking of buying them separately via Bricklink.
Has anyone tried doing that?

There is a whole site dedicated to working out how you can build a particular model using parts from other sets - Rebrickable. A combination of that and Bricklink would be cheaper as you'd end up with fewer extra parts.
There's also a thread on EuroBricks where someone has done what you're doing and there are some useful tips (mostly about buying as much as you can from a small number of sellers to avoid huge postage costs). Brickset's "links" tab is handy for more information on the set.


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Cheap Lego sets for Kindergarten classroom?
I am wondering what is the best way to get a set of Lego bricks for my kindergarten classroom?  The children love playing with them and I no longer own them due to a transfer of grade levels.

Are you looking for Duplo or regular Lego?

You have a lot of resources at hand as a teacher in your community.  Have you considered sending home a request for gently used LEGO Bricks in your student's folders at the start of the year?
The parents of your kids may not have any on hand, but will certainly know someone who does!
-Brian

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

If this answer was useful to you, please consider marking it as accepted. Thank you!

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


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

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


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How does cleaning yellowed Lego bricks affect their clutch power?
Will cleaning yellowed bricks (via the retr0brite solution) decrease the clutch power of lego bricks?
I've also heard that certain colors of embellishments on the minifigs or bricks do not hold up well to this solution, is there any definitive list of colors that do/don't hold up well? I have some old white bricks with red and black printing on them that I'd love to unfade if it won't wipe out the lettering.

The retr0brite method only affects the surface of the brick and does not affect the clutch power.
I have used the method on several printed bricks. I have noticed the black printing will start to fade if the bricks are left in the solution for a long time. I have not noticed that it affects other colors as much as black, but this may be because the fading of black ink on a white or yellow background is more obvious. I have never seen the treatment completely erase any printing.
The length of time it takes the solution to start breaking down the ink is going to vary with the strength of the solution, the time in the solution and the amount of UV light. You can control the first two variables, but if you are using sunlight to provide the UV it is difficult to gauge or control.
The easiest variable to control is time. I would leave the bricks in the solution for perhaps an hour at a time, then take them out, rinse them off in water and dry them. Keep one of the yellowed bricks as a "control" against which you can compare the treated brick to get an idea of how much color has changed. Repeat as necessary until the brick is back to the color you want or you notice the ink beginning to fade.
Check the color of the bricks indoors. I use the sun on my front porch to provide the UV light when I'm soaking bricks, and I have noticed that bricks that look nice and white when I'm out in the bright sun will still appear yellowed when I get them inside.


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Where can I get threads compatible with LEGO pulleys?
Have LEGO threads ever been produced? Even the biggest LEGO rubber band is too short to meet my requirements.
I need them for this year's WRO challenge. Note that the challenge only allows Lego products, so I can't just buy the rubber band I need elsewhere.

Roughly how big of a rubber band do you need?

Do you need rubber bands, string, or both? If you need long rubber bands you may have to either loop them together and use wheels instead of pulleys, or use Lego chain links or tread links to make arbitrarily long loops

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

Many office supply/stationary stores will sell rubber bands large enough to do a similar job.
I've managed to find a large rubber band 200mm long and 12.5mm in width. It would be too wide to fit on a standard TECHNIC pulley, but you can attach it to any TECHNIC wheel rim wide enough such as 56145. The grooves on either side of the wheel rim should keep the band from slipping.
I don't know exactly what you plan to build, but you might want to also consider other ways of ways of transmitting power, could you perform the same function as efficiently using a drive shaft.

WRO only allows LEGO PRODUCTS... :(


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Cheapest and Simplest way to build a LEGO Technic car?
Having no LEGO Technic parts at all, I'm looking for the cheapest and simplest way to build a LEGO Technic car which can be combined with two Lego Technic motors to drive forward and backward (phase 1) and to steer to left and right (phase 2).
I see two possibilities:

Buy a complete LEGO Technic product (which one can you recommend?)
Get all the parts needed online (which parts do I need?)

I would like to combine the two motors with my Raspberry Pi.

I think your best bet is to start with 42048 Technic Race Kart and a 8293 Power Functions bundle. This gives you just one motor, but that's enough for propulsion (going back and forth).

You would need to look into a motor driver board (for example the DRV8835) for the motor, and look at schematics for a power functions cable mod to be able to drive the motor directly from the RPi - see this question for several suggestions on how to do this..

For steering you can look into a 88004 Servo Motor, or use a normal Medium motor with extremely fine control or a good set of gears to be able to make small steering adjustments.

Note that you will end up with a big set of power functions parts on a small chassis - the go cart is big enough to carry them, but not by a large margin. The two photos are not at the same scale.

Thank you. Very helpful. Having read some tutorials I'm now thinking about getting the "BrickPi", which will help connecting Lego motors and sensors to my RaspberryPi. In this case I wouldn't need the motor driver board. This is not the cheapest solution but it looks very simple to me.

Yes, the BrickPi is a great solution as well. And to @Móż point: yes, it becomes quite cramped but if you remove the seat and the fake engine, there is enough space to place the motor and the battery box. I have done this in my classroom program.

Oh, you might want to add the BrickPi details as an answer to this post as well - could be helpful. @mosquito87


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Non-working technic system
Recently I've been working on a car which when going forward is fast, and when going backward automatically goes slowly.
Here are two photos of it:

(Just replace the text by "input") As you can see, it uses a switch to change of speed.

Above view.
To make the system work, the motor not only turns the most visible circular gears but also the worm gears. And then these worm gears move the switch and the speed is automatically changed.
Here is my problem: Once the 8-tooth gear between the worm gears  gets to one end, it won't go back. Plus, when it is going from left to right, the motor has a big difficulty turning the worm gears. I want to avoid using a rubber band, so can someone help me?

I would suggest another solution. On the 9396 helicopter the blades can only rotate in one direction, because when a backwards rotation is input, a gear in the transmission line is lifted away from its neighbor automatically. In the instructions it's here (the yellow L-beam lifts up):

Where the gear is lifted away, place another gear for it to interact with there, which would be the transmission for your backwards drive.

I would try to action the switch with a rotating motion directly applied to it; on your picture it seems you're just holding it in place with an idle grey axle and trying to move it with a somewhat clever, but complex, mechanism.
You can use a torque gear to prevent the movement from going too far; but there's probably a more elegant solution using a differential to split the output to both your gear train and the switch. Assuming the load on your gear train is important enough, the power should first go to actuating the switch; and when that is blocked, it should revert to your gears and wheels.
This means you have to make sure moving the switch is always the easiest thing to do even when it's in the middle; as such you may also want to make sure to use a smooth axle joiner instead of a ribbed one; and you'll want to have some basic load on the gears even when the switch is in the neutral position.
On the other hand, I'm confident there should be a way to achieve a similar effect (different speeds according to the direction) using other means, such as multiple differentials and maybe some wheel only able to rotate in one direction.

authors: 金匙室內設計工程有限公司


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LEGO controller 8879
How does the LEGO Technic 8879 controller work? When you make it go forwards/backwards and let go does it stay at that speed like the more recent helicopters or does it go back around? And how does it go forwards and backwards, is it like the 8885 controller where you have to have a motor for each of the front wheels to turn?

It is not spring loaded, meaning if you set a dial to a specific value it will stay there. There are two channels that can be controlled with the two dials, and either can be set in one direction ("forward") or the other ("reverse"). I put these terms in quotes because their exact function depends on your model, but in the simplest scenarios (like controlling two separate train engines) they act so.
A single channel (dial) can control one or more motors, but in the latter case all motors will receive the same signal which means they will rotate in the same direction with the same percentage of their maximum speed - different motors can have different maximum speeds.


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Which LEGO AT-RT is this?
I made a LEGO AT-RT with the help of a video but I can't find it now. It looks like a clone scout walker but green and a bit different in design. I loved that AT-RT. I hope someone can help me find it. The legs look like the legs on the LEGO 75002 Walker:

If you watched this on youtube, how about digging through your history?  https://www.youtube.com/feed/history

A quick search found these two video's of AT-RT's in green
https://www.youtube.com/watch?v=c0sFAreiaPc
and
https://www.youtube.com/watch?v=Cbc_k_GwfRw
this AT-RT is also very nice and greenish (no video)
https://www.flickr.com/photos/legoarts/4917477074/in/photostream/

What i seen is bigger but thx for the help :D

This may be the clone trooper you are searching for...

Are you thinking of the 20th Anniversary AT-RT?  The legs are very similar but the head looks fairly different.  It is grey with sand green and tan accents.  The set number is 75261.

authors: اسلام الكمبيل


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Where will the World First Lego League be held in 2015?
Every year First Lego League (FLL) is held in 3 different countries. I know that the world festival will be held in St. Louis, but where will the other two be?
Last year it was held in Germany and Canada.

Sorry there is no tag for FLL so I chose the lego group because its the closest to my question, if someone can create a tag for FLL that will be great.

I fear that this is likely to be considered "too localised" as it's only going to be a valid question for the next few months :(

Will be repeated every year right?

Yes, but this question is specifically asking about 2015 - you've already pointed out that it was in different locations last year.

Hmm, just remembered that we removed Too Localised last year. This may well be closed as Off Topic at some future point when it's no longer relevant though.

The FLL World Festival is going to be held in St. Louis, MO, USA, on April 22-25, 2015 (http://www.firstlegoleague.org/event/worldfestival).  This is the only official championship event held by the FLL.
Before the World Festival, various qualifying events are held all over the world.  You can learn more about those events by searching on this page: http://www3.usfirst.org/whats-going-on
Unofficially, FLL partners hold Open Championships around the world.  These events generally take place in the United States (in addition to the official World Festival), Canada, Asia, and Europe.  For more information, visit this Wikipedia page:  http://en.wikipedia.org/wiki/FIRST_Lego_League_Open_Championships


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

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

If you later buy a retail kit, however, you should be able to use the software which comes with it to control both kits.

...but retail version - as of this writing - has not blocks to use ultrasonic or gyro sensors that come with EDU version.

You may also want to check What is different between the EV3 Home and Educational sets? (Philo, since what you just said isn't mentionned in that particular Q/A, you may want to go there as well and add what you know)

You may now download and add gyro and ultrasonic sensors blocks for retail software. See eg. http://www.lego.com/en-us/mindstorms/downloads/ev3-blocks/gyro/

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

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

@Zhaph-BenDuguid http://shop.lego.com/en-US/LEGO-MINDSTORMS-EV3-31313

The retail edition of the NXT kit doesn't include software in the box, and provides only limited printed building instructions (presumably to save on costs).
However, as indicated on the box, you can to download it from LEGO.com/mindstorms directly, and for free.
Currently, the software is on the download page.
The instructions can be found on the products page, under "EV3 Starter Robots" and "EV3 Bonus Robots". You can download them as PDF or view them interactively online. You can also install a mobile application to view them easily while building.


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EV3 digital interface with sensors?
The EV3 Brick is noted as having both analog and a higher speed digital I/O with auto ID up to 460.8 Kbit/s (UART), and 4 motor port with encoders.
The NXT Brick has 4 sensor ports both Analog and Digital: 9600 bit/s (IIC), and 3 motor ports with encoders.
I know the EV3 brick can use NXT sensors and motors, but I cannot find info on the difference in the communication protocol. Are the NXT sensors and motors less precise then the EV3 sensors and motors? Will the EV3 Brick support more sophisticated sensors and motors in the future?
Thanks,
John

I can't tell much about sensors since the EV3 Hardware Development Kit has not yet been released, but the existing motors have the same precision specifications and are completely interchangeable between NXT and EV3. And yes, hopefully, with the better bandwidth we can expect more sophisticated sensors!
See also http://robotsquare.com/2013/07/16/ev3-nxt-compatibility/


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What is the largest number of pieces in a set for LEGO, Nanoblock, or any other brand?
What is the largest number of pieces in a set for LEGO, Nanoblock, or any other brand?
I recently bought a 6800-piece LOZ Block set (Chinese Nanoblock knockoff).  I was wondering if there are sets in any block size or brand that have more pieces than that.

The LEGO World Map set has 11695 pieces.

"Are we updating all the questions that ask this? I'm confident there's more than one." – If there is more than one question asking the same thing, most of them should probably be closed as duplicates. (If they're similar but not the same, they should probably not be closed, but perhaps edited to differentiate them from one another.) In any case, such meta-commentary probably should be left out of your answer itself.

While this is true for now I suggest to include this link to Brickset that would always list sets with the most pieces. It would make this answer always relevant.

Brickset has a query for sets with most pieces: brickset.com/sets/query-45
Top of the list is Taj Mahal with 5922 pieces.

The obvious update for this question is the LEGO 75192 Millenium Falcon with 7,541 pieces.
I wonder whether LEGO has plans for a 10k-piece set, maybe also the Millenium Falcon :)

Largest Lego set apart from the world map is the 10,000 piece Eiffel Tower (technically 10,001 but that includes a brick separator). Followed by 9090 (Inc 3 brick separators) for the Titanic and 9036 (Inc 1 brick separator) for the Colosseum.

TIWI Fantasy Castle = 6850 nano blocks. (Amazon)
Magic School, Nano Brick Harry Potter style castle - 6369. (eBay)
I found Swan Stone Castle on eBay = 11810.

Is 6850 the set number or the piece count? Adding a photo or a link to the set would help this post enormously.

Certainly not from the Lego camp, in terms of commercially released consumer sets. As far as I can remember, the Taj Mahal from 2008/9 had something around 5900 pieces, and is no longer available to buy new.

I was asking about any size or brand as the one i just bought from loz blocks  already has more pieces than that (6800)

Here is Koyae European Castle (Amazon URL) set that supposedly has 11,810 pieces. There are many clone sets that are advertised with many more pieces than they have, this one might be real according to the size of the build.

There is a 11,800 nanoblock building Neuschwanstein Castle.

A picture or URL to official source would greatly befit this answer.

The box for Kawada Nanoblock Schloss Neuschwanstein says "over 5800 pieces" and does not support the 11,800 figure given in this answer. https://imgur.com/tZvN1f1

My googling was also unable to find such a set.

Careful with numbers on clone sets, there are quite a few around that claim 6,000+ pieces and reviewers say it’s only 600. No idea if it’s fraud or just cluelessness. I found one with downloadable instruction booklet that was clearly 2,000 parts according to the instructions instead of 6,000.

And try googling for “New Swan Stone” as well. :-( Seriously.


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Where can I get the rest of the bags for the Helm's Deep set?
I have the Helm's Deep LEGO set from The Lord of the Rings. It is supposed to have 9 bags total, but I only have 4 of those bags. Does anyone know where I can buy the remaining bags?

I don't know of anywhere that sells bags of parts for sets, but you could try BrickLink - you might be able to pick up a second incomplete set for a bargain - or more realistically, you can "Part Out" every component piece to a wishlist, remove those that you do have, and then look to buy the missing parts. It sounds daunting, but you can sort according to which sellers have the most parts from your wishlist, and hopefully get the bulk of them in one hit.
Your mileage may vary on prices. Like anything, rarity and availability dictates asking prices. Common blocks should only cost a few cents each, but anything unique to this set is likely to be hard to find and/or expensive.

Be aware that such larger sets often also contains pieces that are not in bags or are in un-numbered bags.
I'm not aware of anywhere where such bags are sold in any structured way. In the RLUG (Registered LEGO User Group) that I'm a member of (Byggepladen in Denmark), some members occasional get (or get the chance to buy) a box that contains a number of random bags from various sets, but it's rare that people bother identifying which set a bag is from, they are just opened are the parts sorted and put into the collection. If you are a member of an RLUG you might ask there, but it will probably require a lot of luck, but I don't see other possibilities.


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How to fix the Lego Technic RC Stunt Racer (42095) set's turning drift?
I just finished the Lego 42095 Stunt Racer and noticed that there is a slight drift to the right when it drives forward. It works fine in reverse mode - reverses in a straight line.
Any suggestions, solutions please?

The best way to do this is that the motors are running at a slightly different RPM If both left and right motors run at exactly the same RPM they make us a straight line. PF L motors don't have rotation sensors to drive in straigth by default.


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Which part is this round window frame?
Please identify the round white semi-circle piece in this window.  It kind of looks like a mudflap, but I think it's bigger.

It looks like a Wheel Arch (mudguard) piece, #50745

The confusion may come from its age; newer sets seem to use a smaller one (part 98282) https://www.bricklink.com/v2/catalog/catalogitem.page?P=98282#T=C

@RSchulz Out of 11 sets using 50745 element in 2021, 6 sets have it in White. I'd say this wheel arch (50745) is still pretty common these days.

Huh. Only 10 of the smaller one in 2021. I just assumed when they changed the mold, they'd go all in.


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Is there any way of knowing how many bags came with a set?
I have just acquired 9474 Battle of Helm's deep and have some others where the box is open and I don't know if all the bags are in there. For example this set it looks like bag one has been opened, and I have three bags each of 2 and 3.

I have reworded your question title slightly so that hopefully other people with a similar problem can find a solution. (We also have had similar questions before but they tend to have the same answer)

Instructions
If you cannot find a review, most sets detail which bags you will be using for each stage within the included instructions. LEGO provide a easy lookup for most instructions included in sets if you do not have a physical copy.
Online reviews
An easy way to find out these sort of things is to find a review online, for sets of this size there are often quite lengthy details.

A total of 9 bags, each with 1 or 2 smaller bags inside.

Weight
To be sure you could also weigh all the bags, add them up and deduct it from the known weight (subtracting the box and instruction weight). Physical information of sets including dimensions and weights can be found on LEGO set databases like Brickset.com

thanks for the link, not a site I have found before.

The instructions in two recent large sets I had easy access to check (Colosseum, and Lamborghini Sian) only indicate which numbered stage you're on, they don't indicate how many numbered bags the stage consists of.  For the Sian each stage is in its own sub-box so that shouldn't be a major headache when I start building it. For the Colosseum though, with 40 stages and 2-5 (typically 3) numbered bags per stage I had to pre-sort everything to be able to build with any confidence.  In neither case would the manual be of help to the OP.

@DanIsFiddlingByFirelight You are absolutely right. Building instructions don't say how many bags of a given number are needed. And some of the larger sets don't have any bag information at all in the instructions (e.g the 2012 Sopwith Camel plane I just build a few weeks ago). You can also have some unnumbered bags (PF motors and/or large/oddly shaped/transparant pieces). A review or "unboxing" video on YouTube is the only way to be sure, if it shows enough detail.

@Tonny For small sets it is rare and I suppose you can also try following along with the instructions whilst visually inspecting the bags.

@Ambo100 At 1368 pieces I wouldn't call Battle of Helms Deep a small set. I would call it medium. (Opinions will differ on what is "small", but I think of small as build-time less than about 2 hours. With my usual build-speed that amounts to 500-800 pieces depending on complexity of the build.) Visually inspecting closed bags is not easy. It is doable I suppose to determine if you have all bags, if you can match the larger bricks and specialty pieces in each stage with the bags.

@Tonny. I am not saying it is small by any means, I meant to be speaking as a general rule. For smaller sets (let's say less than 500) pieces, basically most sets that you might buy (sets in the CITY line for example).


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Interfacing Mindstorms NXT 2.0 with webcam
I very recently started playing with Mindstorms and have used the sensors that was provided along with the NXT 2.0 set. I'm planning to work on something on the lines of image processing and I need a camera for this. Is there a way I can interface the NXT Brick with a webcam so that the Brick can send instructions to the webcam as to when to capture the image? Are there other better methods of using webcams and Mindstorms together?
Anything along those lines would be helpful. Any pointers to good reading materials would also be helpful.

The original Mindstorm's had the "Vision Command" extension that enabled you to use a LEGO-ised webcam with your RCX brink - however the USB cam needed to be attached to the PC, which rather limited the movement, and then the VC software interfaced with the RCX for you.

What do you want to do? The NXT processing power and memory is limited after all. Do you want to have the webcam connected directly to the NXT, or will it be connected to a computer? If you go with the latter it is highly language specific, as you need libraries to interact with the NXT and the webcam. If you need the first I think NXTCam is the only option currently.

The latter, most probably. While I haven't thought through it, I was thinking if I could use a phone to capture an image. For example, the brick will trigger an app on the phone via Bluetooth (or something else?). The app will switch on the camera, take the picture and do something with it. Or if I use a webcam, it may just stream a video to my computer or something. This maybe just one of the things that can be done. I don't know.

I would go and give a try to leJOS http://lejos.org/ if you can write Java.

Yeah, I ended up using leJOS. Thanks anyway.

IMHO your best bet is to use Mindsensors' NXTCam

Yeah. But the communication can only be between the brick and NXTCam right? I can't do complex processing on the brick. I need a computer to do that.

@PrateekKulkarni Use Bluetooth and Java.

If you could use a PC as intelligent robot brick, I would suggest you:

standard web-cam
OpenCV (for image processing)
nxt-python


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Compatibility EV3 software with NXT brick - known limits?
Lego says I can I use the new software to program old NXT bricks:

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

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

You can try the iPad version NXT-G.
More stable than osx version.

iPad has no USB and doesn't support bluetooth. Even if NXT-G was available, how would it connect to a NXT brick?

EV3 has no support for the Light Sensor, just the Color sensor.  There is a Raw Sensor that can be used to create a Light Sensor MyBlock.  That MyBlock can then be used to create the various WaitFor, Loop, and Switch blocks using the Logic form of those blocks.
Then there is the calibration problem.  The Color Sensor block in calibration mode does not work on the NXT brick.  The EV3 can also program around that using file operations.
Finally, there is the memory problem. The new firmware leaves a bit less memory available on the NXT. The programs still need to be managed carefully to avoid using up all the memory.
Yes, you can use EV3 software on NXT bricks.  In general it is very easy.  There are some issues.

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


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Why was 4265 redesigned?
According to Bricklink, there are three versions of the part 4265:

4265a with teeth and tight-fit axle hole
4265b with teeth and loose axle hole
4265c without teeth and loose axle hole

Looking at the release dates it seems like B superseded A and C superseded B, although there were long overlap periods. My guess is B was introduced to reduce the amount of plastic used per-part and possibly to make it easier to slide it on an axle.
Then C removed teeth because they're fragile and tend to break off.
Is my theory correct? If not, then why was that part redesigned?

I suppose that you're right about the teeth being fragile, but it's also worth pointing out that they are quite useless. I bet they were intended to prevent the part from unintentionally spinning on the axle, but the way that they designed the hole in the part already did the job. Also, I think they are called "bushes."

Also, they might have made the clutch tighter since it was quite pointless and annoying for the bushes to occasionally slip off.

If you check sets each version was available in, you'll spot there isn't much of an overlap. Yeah, some sets still had older version, while newer one was already introduced, but is more of an exception (or error while inventorying a set) rather than a rule. A version had its end in 1993, B version began to appear in 1992 and ended in 1997 (with few odd sets released afterward), just where newest, C version, was introduced.

Part A & B were fragile, to the point where enough teeth fell off you ended up with your own version of Part C.  :-)

I'll speak from my experience with these items as I don't have any formation backed by TLG.
The teeth themselves, found on A and B version of the 4265, while looking fragile, weren't the cause of the redesign I think. These could bend or deform but still be gripping with Technic plates with toothed ends as well as toothed pin axle connectors (which I think was the primary reason teeth existed on half bushes at first).
First two versions seem to be quite weak since they tend to crack quite often. Especially with aging, when clutch strength increases (perhaps parts shrink a little over time?). Don't know the reason behind designing version B, but it looks like the issue with cracking was observed and TLG tried to remediate this.
As for version C, I cannot really tell if supplemental sets released in 1993 really had this version included. It looks like the actual year C version was used is 1997, being part of several sets. You'll also notice this is also the year modern Technic connectors (like 32016) were introduced. These new connectors have the same angles you could construct from toothed pin axle connectors with busing of A or B type and are much stronger. Due to this there's no need for half-bushing to have teeth, thus it can have a little more plastic to make it stronger. In fact, I cannot really remember if any of modern 1/2 bushing I have got cracked or broken.
As seen on this picture from Rebrickable C version (represented here as 32123a and 32123b) had minor mould change over its production as well. Bricklink doesn't distinguish these variations and use 4265c part number for both.

Oh! I knew the teeth could be interlocked with another bush but I completely forgot about those plates with toothed ends - even though just yesterday I assembled an old Technic set that had those. And I think I still have one of those axle connectors.
As a side note I remember quite a few of the old bushes breaking or losing single teeth but I indeed can't remember any modern being damaged. But that could have something to do with the fact the old ones were used by me and my brothers, while the new ones only by me.

Since those teeth pin axle connectors caused so many teeth to fail, I assumed they just replaced them with angled version, which also made the bush version less necessary.  Big improvement, in my opinion.

I never had a tooth break on one of the old-style bushings, but more than half of the ones in my collection, including nearly all of the "a"-style ones, have split down the body of the bushing.

Indeed the interlocking of the teeth with plates or toothed pin axle connectors was rarely used, but it did happen: it is for example used in set 8480 (Space Shuttle) to give the cockpit ceiling the right angle. Without the teeth, the cockpit ceiling will move around its axes and never take a nice position.
The angled connectors are much more robust, but also take up much more space, so I have trouble considering them as a straight replacement for the old system.


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EV3 additional build instructions - PDF download or print possible?
The EV3 retail edition comes with printed instructions to build only one of the possible robots and it appears you have to use the software to view the build instructions of the other models.
My question is: is it possible to download or export/print these additional model instructions?
I have attempted to find both downloads (Lego's PDF search function returns nothing) and an export/print option to no avail.

Edit to add:
PDF downloads are now available from the LEGO Site:

3D Building Instructions

The images used for building instructions are available (jpeg images) in folder C:\Program Files\LEGO Software\LEGO MINDSTORMS EV3 Home Edition\Resources\ContentPacks\Retail\nonlocalized\LEGO\pack0\projects (more or less, depends on OS and installation choices). Take care not to modify anything there, as you might need to reinstall the software!
It's a bit more complex for .ev3 project files containing building instructions (eg. downloadable bonus models):

Open the ev3 project file as if it is a zip archive.
Inside you'll find a file named ActivityAssets.laz. Open this one as
a zip archive too,
it contains all the images for building instructions. You can
extract those images to a separate location
then you can print those images or build a PDFfile, you can put that on your tablet...
take care not to modify the project files!

Remember that these images are the property of their owner (LEGO or model builder), use them for you own personal needs only!

Thanks - seems like the only option until/if Lego release the manuals as PDF downloads.

Building instructions of 31313 retail set official models are now available: http://www.us.lego.com/en-us/mindstorms/community/bi/


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

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


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How can EV3 Gyro sensor drift be handled?
EV3 robots can use a Gyro sensor to determine the direction the robot is heading.
The initial conditions are important.  The sensor needs to be still and then the sensor reset.
However, once in a while the Gyro returns values that drift over time.
What can be done to handle Gyro drift?
Step one would be to remove the drift using the

Hardware fix:  unplug the gyro sensor, make sure the robot is still, and then plug in the sensor.
Software fix: Gyro Drift Simple Fix which should only need to be run once.

However, I'm aware of several FLL teams using this fix and even then, once in a while the robot goes crazy, because the Gyro sensor has acquired a drift.
Applying the Simple Fix at the start of every run does not seem to fix it every time.
Is there a way to handle this?

There are two options that I can think of.

Do the "hardware" fix before every run of the robot to reboot the sensor along with the "software" fix to zero it.
Don't use the Angle reading at all. To calibrate the sensor, sample the rate (d/s) 10 times or so and take the average to get the "at rest" rate offset and store it in a variable. Subtract this variable from the rate returned by the sensor to get the actual rate. Integrate the rate over time to calculate the angle. (I haven't actually attempted this myself, but this is how you use, for example, the HiTechnic Gyro sensor since it does not provide an angle).

At least 1. can be done by FLL teams.  2. can also be done, but . . . wow is that complicated.  How many samples per second?  Does it fix the problem? It is better than "Don't use the Gyro sensor." which is my current recommendation.  I was hoping for something less complicated.  I'm going to give this a day to see if there is another option.

My team put their software fix in a loop with a small wait that cycles until the d/s = 0, then reset it to 0. Here's a simplified version:

It works like a charm. We don't mess with the hardware reset anymore. Combined with a heading variable, a turn my block, and a few drive my blocks they can program a maze run in minutes.
FWIW: They output their angle and rate to the display so they can monitor it even when not connected to a computer. They're working on checking the number of loops and total time it takes to optimize. Your team may need to play with the wait time a bit to get the best results.

The Gyro is a tricky sensor to use, but at yesterday's FLL competition in Elk River, at least 5 teams had worked out the issues to their satisfaction.  I'm revealing their answers here.  It is unfair to those teams, since their research does represent a significant advantage over other teams.  That said, none of their solutions were complete.  Each team had some part of the answer, but none had everything.
One team, not one of the 5, had given up on using the gyro in the belief that it could not be place close to the rechargeable battery pack because the gyro sensor would get too hot.  I hadn't heard that before and have no idea if it has any basis in fact.
Almost all of the teams used the "Simple Gyro Fix" mentioned in the original question.  They varied in whether they paused before, during, and after each step.
Two teams had tests to avoid leaving home base with a "drifting" gyro.  One waited 10 seconds to see if the drift was still less than 2 degrees.  Another ran the robot through a routine that cause the robot to twitch if it was drifting.  No twitching meant it was ok.
A different set of two teams added a double reset of the gyro.  This reset being the reset of the Gyro angle to 0.  One of those teams said they had followed the advice of some site on the internet.  That team also added a 1 second wait before and after the double reset.  The first to "still" the robot; the second to ensure the zeroing of the gyro angle had been taken.
One team had a set of MyBlocks that turned based on either the rotation sensors or the gyro sensor.  It allowed them to retreat from using the gyro sensor if they needed to.  They had gone to the trouble because of the bad reputation of the Gyro sensor.  In front of the judges, they used the gyro.  It worked.  Clearly, they had worried a lot and then figured out how to use it.
The teams differed in how they turned.  Some pivoted, some spinned, and some accepted any motion.
One team used the gyro to go straight, sort of a proportional line follower with a gyro sensor instead of light sensor.  They did not use it for turns.
None of the teams did the work of recording the drifting episodes to a file.  None of the teams displayed a warning as a sound, a blinking light, or a message on the LCD panel before the robot left the home base.
None of the teams switch automagically to the rotation sensors when the gyro is known to be drifting.
None of the teams used #2 of the accepted answer.

An additional suggestion from a team judged a couple weeks ago.  They did their best to isolate the robot from vibration during the brick's boot up time.  They started by demanding everyone keep their hands off the table, but found that less effective than placing the robot on the floor.

The most reliable way I've found to quickly reset the gyro is simply unplug it & plug it into a different input port, then unplug it & plug it back into it's port.  Just unplugging & plugging it into the same port doesn't always work for me.
My software always has a 1 sec delay as the first step, and then software reset of the gyro.  This is so after pressing the button on the brick to run the program I have a sec to remove my hand & the bot settles perfectly still, then the gyro resets itself to zero before any motors start to run.
Just this last weekend I started using the gyro to run perfectly forward & it works like a charm, but I haven't experimented how long until it's off by a degree, etc.


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What strategy should FLL teams use to pick their next robot mission?
FLL teams compete by running their robot on missions.  The robot leaves the base, does a task, and then returns to base.  Each mission is worth a few points.  The goal is to collect the most points in a 2 and 1/2 minute run.
The tasks are at different positions across a 4' x 8' obstacle course.
Some missions are easy, others very difficult.
Some missions require intricate Lego constructions.  Some require difficult programming.  More than one task can be accomplished before returning to base.
What strategy should an FLL team use to pick the missions to attempt?
Given there are about 15 missions that each take somewhere from 10 to 30 seconds to run and the team has 5 missions that work most of the time and the 5 missions consume the 150 seconds available, what should the team work on next?

This is a bit too abstract for me. Can you somehow illustrate what the missions are and what the course looks like? I think I have seen a course you describe in a school project. However, it is difficult to tell at the moment.

First off, that website is horrible, so much clicking on expandable things, a terrible UI.
The PDF download of the rules is better.
Looking through the missions I notice a few things:

None of the missions have significantly bigger point values to make them obvious choices over other missions.
The missions are all based on end state and cannot be repeated for multiple points

So it appears you should simply try to maximize the number of successful missions accomplished in the limited time period.
Some missions should obviously be combined since they are handling similar pieces and would be easily doable with the same robotic manipulators.
Such as:

Moving pipe sections for: pipe removal, pipe install, pipe construction
Moving Big Water pieces for: fountain, flower, and water collection
Manipulation of levers or handles: flow, water treatment, faucet
Picking up, moving, and aligning pieces in the field: pump addition, rain, manhole covers, sludge, water well
Moving objects from the base onto the field: tripod, water well, slingshot

Also some missions must be done before other missions:

Manhole covers removed before a tripod is placed
Pipe removal before pipe install

The best bet is to pick a group of tasks that a single robot build is likely to be able to do well and go from there.
Some thought might be given to completing the furthest missions first, so that traveling past already completed missions doesn't mess something up.
You might start by sorting the task into groups like I have done, try to judge the inherent difficulty of the mission, and rank them comparing with point totals.
On a final note: As this is a competition for children to learn about engineering and robotics, you should really just explain the rules/different objectives/point values and help the kids pick a strategy themselves.  The planning process itself is as much engineering as the programming and building of the robot.


text:
What is a better algorithm for wall following with an ultrasonic sensor?
This wall following algorithm uses the ultrasonic sensor.  It has a horrible worst case behavior.  Place the robot about 3 cm too far from the wall.  Instead of moving closer to the wall, the robot turns toward the wall and spins.
Place the robot too close to the wall and it works very well.
The sensor points out from the right side of the robot, in front of the powered wheels.

How should the algorithm be changed to handle the "too far away" case?

If a significant distance from the wall, you'll need to turn 90 degrees in place clockwise, drive up to the wall and turn 90 degrees in place counterclockwise.
I'd suggest mounting a touch sensor in front of the vehicle handle the part of driving up to the wall, if that is not possible, estimate from the scanned distance how far the vehicle should drive.
If close to the wall but not close enough to have the wall-following algorithm work correctly, I'd suggest "wiggling":
Repeat the following steps until close enough to the wall:

rotate left wheel forward by a small angle while blocking the right
wheel.
rotate right wheel forward by a small angle while blocking the
left wheel.
rotate left wheel backward by a small angle while
blocking the right wheel.
rotate right wheel backward by a small
angle while blocking the left wheel.

In each step use the same angle (determine an optimal angle by trial and error)

Also could set the target distance to +2 cm for a short time, then +1 cm, and then the actual target distance.  I was hoping that I had missed a trick in using the ultrasonic sensor.


text:
Programming RCX in 10.9 environment
My school has 15 RCX robot kits that this year has just been sitting because all the old computers with OS X 10.4 are now gone and we are using OS X 10.9.  I would like to run the original RoboLab Software (1-2.0) because it is for middle school kids.  The graphic programming interface works great with these students.
Is there anyway I can do this.  I would hate to toss the 15 sets as they are still very usable. We also have 6 NXTs.
What are my options here?

NXTs can jump to the latest version of EV3 software.  That version is downloadable from Lego.


text:
Technic beam centering for beam with even length
I design stereo camera housing for robotics (3d printing). I want the housing to be able to connect to both LEGO Classic and LEGO Technic blocks. I designed 2 groups of 4x4 holes/pins on the bottom/top of the case for LEGO Classic. This works fine using the camera as "intermediary" piece (connecting bricks both from bottom and top and incorporating the camera into a LEGO robot).
However I also want Technic to mate the camera. I came up with holes for Technic pins which make some of the "Classic" holes deeper. The problem is Technic uses odd number for beams so they can center with one hole. Is there a part (maybe 2-sided double-beam) that would connect even to odd and allowed me to center the camera on LEGO Technic properly?
Sure I could move the holes one step to sides (make beam 5 fit) but that would produce the same problem on the Classic side (centering, using 7x2 or 8x2 instead of 6x2).
Camera bottom side (hole in the center is for tripod screw):

Camera top side:

Hmm...  I don't know...  I personally, wouldn't try to reinvent pin placement of Technic holes and Studs. I'm not saying being creative that way is too challenging. What I am saying is that, we should work with examples, or in this case parts that already bridge Classic stud width with Technic holes.
Placing pins where the studs belong seems akin to reinventing the wheel, when we could be building off the long work history already put into the wheel's design, and spring board off that instead.
With that said, I'd point you to a Technic 2 x 4 plate with three holes.

Replicate it, split it in half (lengthwise), and embed the top on to the top of the camera housing.  Take the split bottom half and embed that into the bottom of the camera housing.
Visually, to me, the stud width of your design looks like a Technic 2x6, but there seems to be enough room to jam a Technic 2x8 in there.

For my brain to work, I like pictures.  So, for piece inspiration, I'd go to Bricklink's database and just type "pin", "pins" or "holes" and look at the pictures of parts that have a key word in them.  Doing this expands the possibilities of what could be done to make your design solid.

Also for me, it's easier to reverse engineer things I see.  So, for ideas I would BL search these parts, look up the sets that they were in, and watch a Youtube * speed build of one of these Technic sets to see how the part was used, and maybe come across an ingenious way someone mated Classic studs with Technic pinage.
(* When dealing with Youtube. Time is precious and limited, so remember we can reclaim some time by speeding up YT playback with the settings "gear".)
EDIT
Another design compatibility suggestion:
There are no pictures showing the total height of your camera rig.  I'm just imagining it inside a robot, or something, and the height of it doesn't conform to the standard bricks built around it.
Try to standardize your work, by making  sure the total height is equal to a pillar of bricks, and round the entire height to the nearest brick.

What if you had anti-studs where you want them, at stud-depth, but also overlaid technic holes at full technic pin depth where you want them? This would lead to a complicated, non-standard arrangement, but if you look at, eg, the new 2x1 jumper plates, they are designed to allow a stud in the middle between the two normal anti-studs. Since you have two different depths here, it might be possible to make the technic pins still click properly.
Failing that you could just not provide the full set of technic holes and instead spread them around outside the studs.

Thanks for great hint! I think the technic pins will make it and click, but the classic anti-studs may connect a bit looser since the technic holes will be just horizontally in the middle between the classic anti-studs and will interfere with them. But I could make the classic anti-stud diameter a bit smaller to fix that. I think it will work! I tried to have clean and "nice" design so this solution has not come to my mind. It will be a bit ugly but will work better! :)

Rin Rio-Oki's example of the 2x4 plate with technic holes shows the concept even better than what I imagined, because of course you can fit the technic holes betwen the studs if you offset them in that way. That is a proven design, I guess.


text:
Tips for hair loss problem in HeartLake world?
Is there anything to do to prevent the rubber hairs (or hats) from leaving Stephanie's head?
In my opinion, hairs and head stuffs for Friends don't stay in place as well as they do in the minifig's world.
My daughter is fed up with those girls with hair loss problems!
Any tips?!

Oof. The title sounds like you're trying to solve my hair loss problem. Is that intentional?

no Jan ! if I was talking about you, I would have set the 'Jan' tag, not 'friends' ! :)

Here I was, poised flag as spam...  but NOOOOOoooo...

My LEGO Friends minifigs are just fine. Their hair doesn't come off that easy. Perhaps there is some difference in the mould and you ended up with some loose ones? It happends to regular minifigs too where the hair/helmet fits very loose or very tight. You could put a little bit of tacky-glue (blu-tack) inside the hair pieces to keep them on while still being able to remove/change them.
Also, I have to ask; are these minifigs directly from LEGO? There has been some sellers on eBay selling knock-off Friends minifigs from China. At first glance they look just like the real thing, but they are of lesser quality.

None of the hair pieces for any of my authentic Friends set stay on during play.


text:
What set are these large quarter circle curved bricks from?
I got a random box of Lego!  I'm trying to figure out what set these bricks are from:

Welcome to Bricks.SE!

Few pieces to be certain, but I believe it's from the set Maula's Ice Mammoth Stomper (70145):

https://www.bricklink.com/v2/catalog/catalogitem.page?S=70145-1

You might want to mention that that part (https://www.bricklink.com/catalogItemIn.asp?P=87559&in=S) only appears in one set with this piece (https://www.bricklink.com/v2/catalog/catalogitem.page?P=98138&idColor=15#T=C&C=15) on it.

I find it very interesting that LEGO was so reluctant to add basic green pieces out of fear kids would build tanks with them, yet here they are adding a whole mobile weapons platform.

@MechMK1 Times do change, indeed. LEGO now* embraces the philosophy of teaching the concepts of good, evil and struggle by releasing conflict-based sets with clearly identifiable good and bad sides. Or, if you prefer cynicism, they see that there is market demand for such sets and are willing to compromise somewhat. *Note: there were such sets even in the '80s, see for example the 1989 Space Police theme.

@zovitssupportsGoFundMonica I personally am not opposed to the idea of teaching such concepts, given how popular games for kids are all based around cartoonified violence (with a distinct lack of identifiable good and evil) anyways. But the reason why I brought it up was that the lack of a basic color for such a specific reason seemed like it was very important for the company, and it seems weird to just throw that out of the window for profits.


text:
What are the torque limits of gears?
I am using Lego in the classroom to introduce students to geared machines.
As part of this I am asking them to design a winch, using a small 1.5V DC motor and a collection of the common Lego gears, i.e. the 8, 16, 24 and 40-tooth spur gears, and the special worm gear.
Based on rough back-of-the-envelope calculations, I will require about 5 N.cm of torque at the winch drum.

Do I have to worry about breaking any gears due to excessive torque?
Do I have to worry about gears slipping (skipping teeth) due to high torque?
Has anyone performed experimental (destructive) tests to quantify the
maximum torque these gears can withstand? Order of magnitude is OK - will the gears break at 1 N.cm, 10 N.cm, 100 N.cm, ... ?

One thing to bare in mind is that some LEGO gears exist in several variants, each of which may have different torque limits. The following tutorial cites some of these differences: http://sariel.pl/2009/09/gears-tutorial/

Do I have to worry about breaking any gears due to excessive torque?

LEGO Gears are one of the strongest LEGO components. When you apply great amounts of torque, they may slip or grind, but never break.

Do I have to worry about gears slipping (skipping teeth) due to high
  torque?

If you apply high amounts of torque, your gears will slip. This happens even with moderately high amounts. They may also slide down the axle and grind the side of the other gear, or the axle.

Has anyone performed experimental (destructive) tests to quantify the
  maximum torque these gears can withstand? Order of magnitude is OK -
  will the gears break at 1 N.cm, 10 N.cm, 100 N.cm, ... ?

Your gears will withstand the torque quite well - it's probably other components, like the axles and beams, that will give way first. Don't worry about breaking the gears - the worst situation might be that an axle or two might bend.

Actually it is quite possible to break gears when using very high gearing ratios. See http://www.firstroboticscanada.org/main/wp-content/uploads/LEGO-Gears.pdf . It gives some circumstances in which the author has broken gears, though it doesn't include any actual torque measurements.

There are more elements to breaking gears than torque, like pressure and speed.

Simply put, they won't break. I've put LEGO gears through everything I could and they were fine. That includes spinning an 8-tooth gear at around 80,000 RPM (sustained for only a second or two) via a flywheel-based stored-energy device. I've driven a 9lb vehicle with about 40 gears in the drivetrain, and none broke.
Slipping teeth is rather common. As a guide, if you sandwich spur gears between two beams or bricks with holes, you're not going to grind them. I would trust that for 100Ncm or more. If you are going to put the structural beams further away from the gears, the torque limit reduces. You can increase it by adding bushes (to stop gears from sliding along axles) or by adding short beams that span two axles - this stops the axles from bending and disengaging the gears.


text:
City scale connection for five-bladed helicopter rotors
I want to build a Super-Puma helicopter in city minifigure scale and form, I have the basic design planned, but I am not familiar with any five-sided technic connectors, which I will need for the rotors.
I have thought of a potential idea, but it is still a little too large for city scale helicopters:

Any better ideas out there?
Update - I had this idea, but it is quite loose, maybe I could tighten it up by using PC dishes on PC sticks (PolyCarbonate pieces used together bind to each other).

I tried wrapping string round the pegs and they still wobbled, this one's tricky.

5-fold symmetries are difficult to build in LEGO, especially at small scale. Here is an attempt, still a bit bulky...

LDraw file here.

I like this, replacing the 1x5 plates with technic connectors number 1 (http://www.bricklink.com/catalogItem.asp?P=32013) and putting  a rubber band round it makes it a serious possibility.

I think I have a valid semi-legal design, it is good for display models, although Philo's answer to this question provided an excellent design for playing-with models.

I now have to decide if I want playabiliy or good looks on the model.

If you mount your assembly on a 2x2 rotating tile (3679 & 3680) you have both - playability and good looks :)

It would rotate better, but there is still a poor connection because of the band as a primary component.  If I used the concept that stickers are 'legal' I could increase the diameter of the heads by applying layers until I have a perfect fit, but that doesn't seem fair somehow.

To that point, if I was building for a child, I would definately use Philo's design.  As it is, I should build two helicopters, one with each design, and see what I think.

I mounted the assembly on a technic peg in a 2x2 round brick on a turntable.  It spins very well, but the blades are at different angles every time it stops.

Use a tire instead of rubber band.

I am intrigued by mechanical problems like these and couldn't resist adding my own solutions in the hope of being helpful.  I threw together the first few ideas I had that were fairly compact and used contrasting colors to help the eyes figure out the building techniques.  They are all raw designs that are free of cosmetic pieces to expose their construction and welcome a builders tweaking for specific applications.  Lastly, if there is anything that needs clarification then please comment and I will add details.

Having such a tight middle, the top design requires a very thin axle, like part# 2569 antenna, or part# 93550 sword/foil.  If this is an issue, then adding pieces will open it up giving you more options.  Here is a photo of it pulled apart for clarity and an additional photo demonstrating one of many variations possible.

Those are all really rather neat - any chance you could expand on the top one a bit more? I can't quite see how that all holds together.

@Zhaph-BenDuguid - Info added, thank you for the interest :)

Cheers, very neat, and also cleverly adjustable too!

I know this is an older thread, but I think I've come up with a small improvement on WindFire's build using part# 33492 Cone 1 1/2 x 1 1/2 x 2/3 truncated.  Its slighty larger than a head so it's a tighter fit.

Also, using part# 85861 Plate, Round 1 x 1 with Open Stud allows it to have a bit better hold than the clip connection.  Now to somehow improve the elastic option.