# Question
Title: What glue should I use for permanent LEGO construction?
The incredible precision of LEGO parts makes them attractive for building precise jigs, but the fact that they can come apart fairly easily isn't so helpful for this application. Can anyone recommend methods and materials for gluing LEGO bricks together to create permanent assemblies?

I'd prefer to avoid thick adhesives like epoxy or hot melt glue, as I suspect that those might make it difficult to get the bricks to snap together completely. I think most bricks are made of ABS plastic, so I'd guess that a solvent like acetone might work to weld them together, but I've never tried it. Does anyone have experience gluing bricks together?

# Answer
The LEGO Group have recently started using solvents to "weld" elements together (notably the Minifigure legs to the magnet blocks), which are fairly heavily controlled in pure forms in most countries under drug legislation.

> **I have discovered that LEGO is not using glue at all, but a solvent, that actually loosens the surface of the ABS plastic and allows the molecules to combine.** Once the solvent evaporates, it leaves behind a cleanly fused surface with no residue at all.
>
> Reading further on the subject, I found that LEGO has been using two types of solvents. One is called MEK (methyl-ethyl-ketone) and at some point they switched to GBL (gamma-butyrolactone). I’m no chemist, so I had no idea what these are, but **I read that both of them are water soluble at certain temperatures. So, I thought to try loosening the seal between the minifig and the magnet by hot water.**

However, as the opaque LEGO bricks are made from a styrene based plastic (ABS), most "Plastic Cement" or "Polystyrene Cement" glues should work to fix your parts together permanently (as these typically contain the same solvents as TLG use, i.e. MEK/Butanone). As with most other plastic gluing projects, care should be taken around transparent elements, as well as ensuring you don't use too much and have it leak over the exterior of your model.
> 58 votes

# Answer
To summarize from the thread that Major Stackings linked, sounds like **Acetone** is the best general solution, as it melts the pieces together until they are permanently bonded together as one bit of plastic.

> You only need acetone, no need for other products or ABS chips. Just brush acetone on both pieces, join them and wait 5 minutes. You will find that your two pieces now are literally one piece. There is not anything stronger for abs plastic.

For the record grocery store nail polish remover is Acetone, at about 70% concentration (see material safety data sheet citation).

> Cutex Regular Nail Polish Remover
> Product code: PN 679 (VIJ)
> Date Prepared: January 14, 2000
>
> Hazardous Components: Acetone, Percent content: 70.0
> CAS number 67-64-1

You can get 100% concetrated acetone at the hardware store, or at beauty supply stores.

> If you don't mind a little extra work, using melted ABS is probably your best bet, you just need to chop up some scrap ABS into shavings (I used a big drill bit on some ABS and it made shavings very quickly), and then put them in some acetone. Play with the mixture until it comes out to your desired consistency. Make it in a squirt bottle, use it just like epoxy or whatever. This way, the entire work piece is made of ABS plastic so you shouldn't have problems with thermal expansion leading to cracks or separation like you can have with other materials.

If there isn't a tight fit though, Acetone alone might not be enough, and you can either melt a little plastic in Acetone solution to generate filler, or try other plastic-friendly glues that can both fit gaps and bond:

> Right, assuming the parts that need to be glued are already a nice snug fit. Plastic welder and/or ABS sludge come in handy when you need to fill a gap though, as is so often the case in carPC-related fabrication.

I'll be experimenting with a few of these soon and will update with my results. Science!
> 30 votes

# Answer
My Son and I were at the Legoland Discovery Center in Grapevine, TX yesterday. We spoke with a LEGO® Certified Master Builder. We asked him and he says that LEGO® uses MEK to permanently adhere their large Lego sets together (lifesize etc). We just finished putting together the Volkswagen T1 Camper Van. It is notorious for the roof coming apart, as is the usual lego problem of the walls around doors often come apart. Well, the MEK we got from Lowes today TOTALLY fixed it. In less than 3 minutes a part was VERY secure and won't come apart. You have to work fast as it is immediately affecting the plastic. Honestly, at less than a minute it won't come apart, and if you don't seat them securely, they will fuse out of place, so be careful. It didn't take more than a VERY light glaze with a paintbrush. I am SOLD and wish we had this years ago!
> 16 votes

# Answer
Recently had to glue *a lot* of LEGO together for work.

* Acetone was too time consuming and did not offer a solid bond.
* Cyanoacrylate-based hobby glues with thick viscosity seemed the most effective. The only problem was, when immersed in water the clear LEGO windows fogged up. (No solution to that so far.) Zap a Gap hobby glue offered best results.
* ABS plumbing glue worked but was difficult to apply. And if too much was applied, plastic disfigured from the inside out.
* Cheap hobby glues all failed for strength, and many disfigured the pieces and were often not thick enough to offer piece manipulation before gluing your hands to it or running down your arm.
* Hot melt glue was messy beyond all hell. But worked better than silicone for sealing roofs.
* Selley's advanced quick grip (water based) worked, was strong but failed under water. Was also far too time consuming and messy.
* Also tried Parfix contact glue. Disfigured the pieces.
* Epoxy resin in self-mixing and hand-mixing varieties offered good strength, but was too costly for the job.

That's all I have tested so far, going back to Bunnings and Auto pro.

Last one I tried was a plastic welding glue for sheet plastic and acrylics. Melted pieces from the inside out. But once set, it was indestructible.
> 12 votes

# Answer
MEK is the way to go - it's what the Masterbuilders at the LEGOLAND parks use. I once brought a miniland sized model from London to the US in my main suitcase that had been glued with MEK and the model was fully intact when I got to the other end!

As others have said, it is VERY nasty when breathed in. Do not even think about using it in confined spaces without a proper extraction system (seriously) and if you get any on your skin wash it off immediately. If you ever spill a bottle of it inside, evacuate the building immediately - believe me, even the LEGOLAND masterbuilders do this if they ever spill it.

Cheapest way to get MEK I have found is go to home depot or somewhere similar and buy some PVC pipe glue - that is MEK (and will say it on the 'ingredients' label).

When gluing - you only need a little brushed onto the brick - easiest to use a syringe of some similar device to put the glue between the studs - then apply the second brick. Wait a few minutes, and it's pretty well welded together. If gluing a large amount of bricks, do one row at a time and wait a few minutes between rows. Don't rush it or apply too much glue as the bricks will melt.
> 11 votes

# Answer
I use a small bottle of Gorilla super glue for my lego parts. It only squirts a tiny amount to be sure super glue doesn't get all over your parts, and also dries at a mid-range pace. I use it a lot to glue my Tiny Tactical parts to the guns after they come in the mail (which are insanely small parts) and the glue work like a charm.
> 7 votes

# Answer
We tried all kinds. Solvents just didn't cut it and only made the bricks stick tighter. The best we found is actually found at the hardware store in the plumbing aisle.

Oatey all purpose cement is the best we found so far. It contains all the above solvents including MEK (which by the way is either a carcinogen or causes brain damage when absorbed into the body excessively I can't recall) which works well. It is designed specifically for gluing ABS.

We apply it with a small craft paint brush and so far the bond is permanent and allows for plenty of working time without fear of gluing YOURSELF to the bricks.

And it cleans up easily with 100% acetone (hardware store stuf...not nail polish remover as its not concentrated enough).
> 5 votes

# Answer
So I've been referring to this post for a long time and I figured it is time to put in my experiences. One thing that many answers don't talk about is that different glues are good for different purposes so my input will revolve around that.

A little background. I've been building Lego for multiple decades though only recently started using glue as I've started making art and design for other people through my side business and almost unanimously they want something permanent. I make small delicate designs (I am being intentionally vague here since I don't want to look like I am advertising), mosaics, and large company logos.

The mosaics are made by taking the large grey baseplate and putting a single layer of plates on it (studs out). For this application I use 100% pure acetone. I take a small brush, dip it in the acetone and brush it on a small section of the baseplate and put the mosaic plates on before it dries. Stays together great and if you don't use too much it won't bleed out and mar the look of the mosaic.

For the logos and the small designs, which are built studs up (showing a smooth surface - like building a brick wall), acetone is terrible. Since it melts ABS plastic and is not viscous, it runs along the edges of the bricks creating smudges that don't come out. The end result looks bad especially in those areas where there is a connection between 2 contrasting color bricks. I also tried hobby glue (Testor's Cement Glue) and the results were not great but for different reasons. This glue is very viscous but what happens is when you apply it, it trails thin strands of glue that you need to clean up before it dries. When you squeeze the bricks together (a very tight fit), the glue squirts out and if you wipe it away it mars the glossy surface of the brick. That and that stuff smells so bad it makes you sick. What I have settled on is what Jay mentioned above: **Zap-A-Gap**. It is viscous enough to not run, does not thin out to strands, doesn't smell nearly as bad as the other glues, and dries really, really strong. I put on a small amount on the back of the brick so that the front surface looks untouched. I just finished a 30" square logo with a Lego frame and I can pick up the piece from its frame without any give. Still looking for a better solution, but Zap-A-Gap is the best for this.

Sorry for the long post, hope this helps!
> 5 votes

# Answer
MEK is significantly more aggressive than acetone. It shouldn't be used in a poorly ventilated area over a prolonged period.

Any of these suggestions should work, but choose carefully according to your working conditions.
> 4 votes

# Answer
I use Kragle for putting together the Lego kits, but not any of the removeable pieces or the lego figures. I use a medium viscosity kind of Cyanoacrylate hobby glue. Just have to be careful to not get it on your fingers and your eyes.
> 4 votes

# Answer
I've had some good luck using the Gel Super Glue. It's really controlled, and doesn't dry to fast.
> 3 votes

# Answer
Krazy Glue works but I would never glue my lego together unless it was minifigures to keep them good :)
> 1 votes

# Answer
I wonder if E6000 (available at any craft store) would work. They use it a lot in very expensive reborn dolls to indefinitely secure the eyes, etc..
> 1 votes

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Tags: building, glue
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# Question
Title: 1998 World Cup limited edition soccer figure
I bought a limited edition World Cup soccer figure in Paris during the games in 1998, #3005. It does not have the shell logo on the package -but does say limited edition on the right lower corner. The package also says collect both teams. Does anyone know anything about this lego figure?

# Answer
> 3 votes
Is this the figure in question?

He's the limited edition English or Scottish team player. The other limited edition figure was a Dutch (Netherlands) player. Lego released an entire soccer theme in 1998 in conjunction with the World Cup, which you can see here on Brickset.

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Tags: minifigures
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title: Connection between two NXT bricks

text:
# Question
Title: Connection between two NXT bricks
Is it possible send information from BrickNXT\_A to BrickNXTB\_B?

For example I have a touch sensor connected to IN\_1 of Brick\_A and I want send the result of the sensor status (1 or 0) to Brick\_B. If the touch sensor status on IN\_1 of brick\_A is 1, then the motor connected with OUT\_A in brick\_B, turn for 1 rotation.

How to do this with NXC? My difficult is the connection and sending information between the Bricks.

# Answer
> 3 votes
Yes, it is possible. Have a look at the "Comm module functions" section of the NXT help file. For example, since the touch sensor status is a boolean value, you could use the SendRemoteBool and ReceiveRemoteBool functions. You can communicate wirelessly using the Bluetooth functions (BT\*) or you can have a wired connection using RS485 by connecting input port 4 on each brick to each other.

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Tags: nxt, nxc
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# Question
Title: What is the biggest LEGO-compatible one piece wheel?
I am wondering what the biggest LEGO one piece wheel is? (the inside part and the rubber part counts as one piece in my world)

# Answer
Pretty sure it's Hailfire Droid Wheel.
> 5 votes

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Tags: wheel
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title: Alternative flowers

text:
# Question
Title: Alternative flowers
I'm compiling a list of elements that are compatible with the Plant Flower Stem. In addition to the Plant Flower Small, I'm aware of at least two alternatives —

Are there any others?

# Answer
> 4 votes
The LEGO Scala flowers and butterflies also fit. You can see them on this page: http://www.bricklink.com/catalogList.asp?catType=P&catString=102

Also the LEGO Belville, flower, butterfly (same as Scala) and ladybug. You can see those here: http://www.bricklink.com/catalogList.asp?catType=P&catString=48

And from LEGO Friends all the other flowers with hole in the middle fit as well: http://www.bricklink.com/catalogList.asp?catType=P&catString=771

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Tags: compatibility
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# Question
Title: What is the best system for lifting things without pistons?
I am building a big walker thing. It has a mining laser at the bottom that can be lifted on one half, and the other is attached to the vehicle.

However, I can't seem to find a way, because the hooks attached to the strings come off to easily. The studs are also facing down and I am not using Mindstorms.

I'm looking for a purely LEGO solution.

# Answer
> 5 votes
Screwjacks!

Key components would be Technic, Gear Rack 1 x 4 and Technic, Gear Worm Screw

Application of said parts are left as an exercise for the reader, though since OP says they're not using Technic, this might be a moot answer.

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Tags: building, technic, pneumatic
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# Question
Title: Programming The Lego Mindstorms T-Rex from EV3 Laboratory
I bought the book The Lego Mindstorms EV3 Laboratory fron Daniele Benedettelli. I buid the T-Rex chapter 15 and when I tried to programming the T-Rex (chapter 16) I have a problem. I'm not able to make the last connection when I build the MoveAbsolute block. I send a picture. Do you know why?

# Answer
According the book the last input of the MyBlock is a Logic input, instead of a Number (default setting).

Make sure you changed it to Logic and try it again.
> 2 votes

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Tags: mindstorms, ev3
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# Question
Title: Any elements that can be connected to the cavity under a stud?
Are there any elements that can be connected to the 'cavity' (i.e. the space) under a stud (e.g. on a regular plate or a regular brick)? The cavity measures about 2.4mm in diameter.

So far I've only tried a minifig hand peg (not the clip side, the other side) but unfortunately it is just a bit smaller, it has a diameter of about 2.3mm.

**\[Edit\]** I'm talking about the cylindrical cavity with a diameter of 1.5 LU as indicated in the overview posted here -- What are the dimensions of a LEGO brick?.

# Answer
> 3 votes
If I'm understanding you correctly, you're talking about the molding cavity directly underneath the stud (that actually goes up into the stud), and not the main tube cavities under plates/bricks (that are actually offset from the studs).

If that's the case, no, I'm not aware of any element that "intentionally" fits that space.

First off, I don't think that space is made with a high tolerance. Looking at some of my bricks, the dimensions of that cavity are not nearly as uniform as the other features of the brick.

Secondly, I don't know how many System bricks have components that are not integer multiples of LUs.

You might get lucky and get a minifigure piece that has a detail that is 1.5 LUs, but you'd have to try a lot of them.

# Answer
> 1 votes
Without further specification, unless I read your question wrong, ANY normal brick-type element can be connected to the cavity under a stud - the whole principle that LEGO was based on, basically. Anything that has a stud on it will fit.

If you rather meant "non-stud" elements such as hands, signs, rods, etc., please update the question to make it more specific.

# Answer
> 0 votes
For base plates you can connect the light sabre pieces underneath the base plate but I don't think it was an intentional feature

# Answer
> 0 votes
*(Edit: after re-reading your question I realized I misinterpreted the stud with the bar. Leaving the answer for posterity.)*

There is. The size in the small holes beneath newer plates is the same size as a connector that doesn't have a fixed name. Bricklink calls it pin, others call it mini pin or stub. It is used in minifig headgears and a few other places, like the old dragon flame. It's not a connection people often use, but it can be done:

This picture is taken from a small writeup by Brian D'Agostine which documents other uses of it. You can also use the same pin (stub, mini pin, teensy tiny peg) to create fire strands:

Once you're aware of the connection you can find many fun fits for it.

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Tags: compatibility
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# Question
Title: How long does official Lego monorail track last?
Given the high cost of official Lego monorail track, I was wondering how long it tends to last/if there are any maintenance tips or tricks? I'm planning on using power functions to reduce the start/stop strain, but is there anything else to increase longevity?

# Answer
> 3 votes
Try to keep the track in mint condition. For example, don't expose it to extreme heat or cold. Keep it away from any pets or children who don't know better. Looking at some pictures, it seems that the vehicle on the monorail runs on a gear. Try interchanging gears every so often so that the gears don't wear and the teeth don't get bent or break.

# Answer
> 2 votes
The track is pretty durable. I have several pieces of old track that the motor runs on well. With the 3D printers now available I am hoping to be able to "print" some of the track with ABS filament. Getting the gear teeth just right will be the tricky part and the end connectors.

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Tags: durability, monorail
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# Question
Title: Is there a way to set a flat plane at an angle to horizontal of less than 22.5 degrees, but more than 0?
I am building an airplane with a wing dihedral (the wings angle upwards from the fuselage), but I am using parts 44302 and 44301 interlocked as designed:

Unfortunately, one click up is about 22.5 degrees, and horizontal is, of course, 0 degrees. Ideally, I need something almost exactly in the middle of the two degrees.

Are there any pieces or techniques that would let me do this?

# Answer
> 6 votes
Using a cut-pipe into a clip-with-tube will let you build a secure and precise angle.

If you have a solid brick behind the headlight bricks you can fix the angle by cutting the pipe at the right length.

# Answer
> 0 votes
I'm not sure how sturdy your design needs to be, but using bar and clip parts could do what you want. There aren't any fixed angles when using those, so you have complete freedom, but a less rigid connection.

If strength is an issue, you could try using multiple clips or the double wide variety:

# Answer
> 0 votes
You could put a sturdy (Technic?) structure inside the fuselage that provides the wing connectors with the required angles.

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Tags: building, piece-usage, disassembly
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# Question
Title: Mindstorm EV3 no longer recognises SD card
I followed the instructions to install leJOS on an SD card, to get Java support for the Mindstorms EV3 brio. The brick detected the leJOS files and processed the whole installation procedure successfully. However, at the end of the installation process the brick rebooted. Since then the SD card is no longer recognised by the brick.

I tried to format the SD card again to repeat the installation procedure, but the brick boots into the standard menu without recognising the SD card.

Any idea to get the SD card working again?

# Answer
> 1 votes
From the leJOS forum posts, I think your best bet is to try another SD card and use the officially recommended SD card creator tools to format and populate your new card.

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Tags: mindstorms, ev3
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# Question
Title: Where did "LL 928" and "LL 929" come from?
Just finished putting Benny's Spaceship set together, and the Number printed on the side is "LL 929" which appears to be an increment from a much older set the Galaxy Explorer, which had "LL 928".

My question is whether there is any known source for this ID? Is it just something random that someone came up with or does it actually refer to something (real or made-up)?

# Answer
928 was the original set number of the Galaxy Explorer \- so the numbering of that one is following the LEGO tradition of using the set number. As Joubarc points out, at that time the sets were branded LegoLand, which is where the LL comes from (in recent years LEGO often uses the Designer's initials).

I'd say that as Benny is a rather well used Classic Spaceman and his Spaceship is clearly a throw back to that style, his ship is numbered in homage to the Galaxy Explorer.
> 5 votes

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Tags: sets, space, the-lego-movie
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# Question
Title: Is it possible to make inverted slopes with solid studs
Many(all?) of the inverted slope pieces have solid studs and hollow studs( e.g. 3665) and a void around the stud. This(void & hollow) looks very inelegant, is it really that difficult to make solid studs with finished surfaces on these pieces? What's the material/cost/grip/aesthetic trade-off?

If lego decided to fill the stud and void of 3665 (i.e solid piece except for anti-stud), what would be the downside (apart from plastic, which is trivial)

# Answer
> 7 votes
Because of the way ABS plastic injection molding works, it is important that parts have a uniform thickness throughout, and don't just have a large section completely filled with solid plastic. This page explains a little about that:

> As the plastic solidifies in the mold, it freezes from the outside (near the mold surface) toward the inside. In thick sections, this results in inward pulling stresses (due to contraction) that can cause sink marks in the outer surfaces of the part. In addition, because thinner sections will freeze faster than thicker sections, there is also the possibility of stresses building up between thick and thin sections, resulting in part warpage.

The reason that the stud is open is because that area of the part couldn't be reached from the bottom as usual due to the closed slope underneath. The constraint of uniform thickness forces either the top or bottom of a stud to be open. This is the same basic reason that the studs on Technic beams are open as well.

# Answer
> 4 votes
Cost of the brick would raise by 10-20% of the extra material needed, I don't expect the mould to be more expensive.

But I think the main reason is the production proces itself. ABS is processed at around 200C (don't know temp used at LEGO). After filling the mould the whole brick must cool down again. To keep the brick shape stable, this process must happen at the same rate through the brick. If parts of the brick are thicker than others this takes more time to cool, which can cause the brick to deform during production, so it doesn't meet its tight tolerance spec.

I can't really come up with a Lego brick shape that is locally much thicker than the rest of the part.

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Tags: manufacturing
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# Question
Title: What is the quickest way to weed out compatible bricks from loose LEGO?
When I buy LEGO in bulk, I often find that there are at least a few clone brand bricks mixed in with them. What is the quickest way to weed out these non-LEGO parts?

# Answer
> 3 votes
My puny brain can only come up with one method: One Piece At A Time.

Check for the LEGO logo somewhere. Sometimes it's hard to find. On the Brick, Round 1 x 1 with Fins it's on the bottom of one of the fins.

Seems that most of the time there are minor, yet obvious, mold differences. Some brands, like Kre-O have an indent on one or more studs.

I have recently sorted some headlight bricks and 1x1 bricks with one stud on the side and found that there are many variations on those, including whether or not the stud has a through hole, or whether or not the 'back' of the brick is solid or open.

Often enough, the plastic will simply feel wrong.

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Tags: organisation, clone-brands
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title: Old sets, new bricks

text:
# Question
Title: Old sets, new bricks
Are there sellers out there that compile old discontinued Lego sets with new bricks? In other words they source new bricks and instructions to put together old discontinued sets. Thanks

# Answer
> 12 votes
I am not aware of any sellers that do this, but if you like to assemble discontinued sets, bricklink has a feature that allows you to do this using bricklink seller inventories. Just look up the set on bricklink, add the Inventory to your wishlist and review which sellers have the pieces you need, then order them.

Go to the "Wanted" tab on Bricklink: http://www.bricklink.com/wantedAdd.asp Then select the "Part Set" tab and fill out the item number of the set you are looking for (you might need to do a Catalog search to find out this number). Pick the options you want, check the "Set Minimum Qty" option, and "Submit for Edit". You will now have a broken down list of parts that you can edit (for example, replace original parts with proposed substitutions, this is useful when your set is really old and the original part is difficult to get, but a more current part exists that likely has better availability). Add this to your Wanted List and you're ready to go.

Alternatively, many old, discontinued sets can be bought, in box, on ebay and bricklink, but depending on the rarity and popularity of the set you might be paying a significant premium.

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Tags: sets, shopping
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title: Lego Escher structures

text:
# Question
Title: Lego Escher structures
How are these done? Is it trick photography? With some kind of giveaway background it should be obvious, but I notice they are not us telling that.

# Answer
> 9 votes
The first photo on this page shows the model Andrew Lipson made.

The photo is taken under a such angle in respect that the different parts line up in the photo, to get the desired effect.

"Waterfall" used a combination of specifically angled photographs, coupled with some post processing to remove the overlapping elements:

> OK, let's come clean. We actually resorted to photographic manipulation for this one. \[...\] The final image was constructed by very carefully overlaying portions of the left image with the corresponding portions from the right. Yes, it's dirty. We couldn't see how else to do it. Sorry.

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Tags: building, design
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# Question
Title: Is there a guide that has the number and kinds of pieces per set?
Is there a guide that has the number and kinds of pieces per set - for example 8 pieces of this and 14 pieces of that? I am trying to sort out a large container of multiple sets. I have thousands of pieces, and would like to put them back into sets.

# Answer
> 2 votes
As mentioned by @gev, Bricklink is a great place to go. It is, however, not the most intuitive site to use. Here is how you can easily get the item counts:

1. Start with the Search box at the top of the page. Before typing in the name of the set, make sure the selector is set to search the Catalog.
2. Enter a term from the name of the set (e.g. "Millenium" or "Falcon").
3. The Catalog results will pop up. You might find sets or individual pieces listed, or even several (regional) variations on the set.
4. Go to the entry that best describes the set you (think you) have. The entry will start with a number (e.g. 10179-1 for the Millenium Falcon UCS) and after the number, in parenthesis, you will find a link to the inventory (labeled "(Inv)"). Clicking on this link gets you to a detailed inventory with item counts for the particular set.

Rinse and repeat for other sets you have ... good luck!

Alternatively if the set is from 2002 or later, you can go to http://service.lego.com/en-us/buildinginstructions to download the building instructions, which contain a detailed inventory at the end. Unfortunately, the resolution and color palette of these instructions is not the greatest (at least on the ones I've tried) so it might require some sleuthing to decipher the different pieces (studs are not showing very well, and it is difficult to tell the different color shades apart, like light grey, dark grey and black).

# Answer
> 1 votes
Best one out there: BrickLink!

Brickset is OK, too, but Bricklink has tons of people willing to sell you nearly any missing part you may need. :)

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Tags: piece-information, sets
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# Question
Title: EV3 controlled by 8879 speed control through IR sensor
Is it possible to send commands to an EV3 brick from the Power Functions Speed Control remote?

Would I have to interpret the raw sensor values to do this? Are there any references that would help?

# Answer
> 3 votes
It is possible, but not with the LEGO EV3 IR Sensor.

The LEGO 45509 EV3 Infrared Sensor does not respond to the 8879 remote. There is actually a "hidden" mode that is not accessible from the standard LEGO software called IR-REM-A that is essentially this "raw" mode that you have conjectured. However even in this mode, it does not respond to the 8879 remote (unless you press both brake buttons at the same time, which is not very useful).

Instead, you could use the HiTechnic IR Receiver sensor which does work with the 8879 remote. There is not an EV3 block for it, so you will need to use a 3rd party development platform that supports it, such as ev3dev.

Or, you could also use LIRC. There are lots of options for IR Receivers included homebrew (if you are a hardware hacker). Although not exactly what you need, here is an example of someone who make an IR Transmitter for the EV3 to control Power Functions motors (using ev3dev).

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Tags: ev3, power-functions
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# Question
Title: How to fix a broken LEGO Star Wars Corellian Defender set
I was playing with my Corellian Defender which took me up to 4 days to build. It broke unfortunately and I am very sad since I love it very much.

I need some tips to rebuild it back.

# Answer
> 6 votes
How to fix it depends on how broken it is - if you've got a few large sections that need to go back in it might be easier than if they have been broken down to the individual elements.

The first step is to ensure you still have the instructions - if not, they should be available on LEGO's site: Building Instructions and search for "75025" (there are two books so make sure you get both 1/2 and 2/2).

With the instructions to hand, you should then be able to work out what you need to remove to re-attach the parts that have come off - I find that taking a few additional elements off is often enough to add back the parts and I can then rebuild the additional elements.

In the worse case scenario you need to establish which step in the instructions best represents the bulk of the remaining model and then disassemble everything else back to that point.

Alternatively, invent a new ship with the pieces ;)

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Tags: building, star-wars
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title: Buy an specific set of bricks

text:
# Question
Title: Buy an specific set of bricks
I have a specific list of bricks for building a LEGO set that I found online, with approximately 300 pieces and around 70 different blocks.

I have seen that one of the best ways for buying LEGOs seems to be Bricklink web page. However, there are hundreds if not thousands of sellers, and the webpage does not seem to be designed to add a list and search for sellers or something like that.

Has anyone been in my situation? How would you buy an specific set of bricks without going comparing one by one all the shops to see wich one has the mos amount of bricks etc?

If you have curiosity, I want to build the mini LHC

# Answer
> 4 votes
Please see my response to this post. Using the Wanted List feature you can upload your own list of bricks and then see which vendors have these items - you would still need to fill a shopping cart at each vendor to see their price, but that is not so difficult by using the "add Minimum quantity" link at the top of the individual shop page.

---
Tags: shopping, pick-a-brick, bricklink
---


# Question
Title: How to upload an XML file to wishlist in bricklink
I am trying to upload an XML file with my brick wishlist to BrickLink. However, even if I follow the instructions on the webpage, it never seems to find the product in the catalogue. If I manually use the search bar to search it in the catalogue however, it will always find it.

I have no idea what is wrong.

The help says:

```
<INVENTORY>
    <ITEM>
        <ITEMTYPE>P</ITEMTYPE>
        <ITEMID>3622</ITEMID>
        <COLOR>11</COLOR>
    </ITEM>
</INVENTORY>

```

If I change that to:

```
<INVENTORY>
    <ITEM>
        <ITEMTYPE>P</ITEMTYPE>
        <ITEMID>3062</ITEMID>
        <COLOR>23</COLOR>
    </ITEM>
</INVENTORY>

```

It doesn't work. However it does exist: http://www.bricklink.com/catalogItem.asp?P=3062b&ccName=306223

and that with the 6 Digit IDs. What about the other ID types, the ones that can not be broken into colour/ID? e.g.: 4211425

How can I upload my list to Bricklink?

# Answer
> 3 votes
Bricklink is correct - 3062 does not exist. Your link shows 3062b, which DOES exist (Don't ask me why the base number does not exist though :) ). So if you change your XML to

```
    <INVENTORY>
        <ITEM>
            <ITEMTYPE>P</ITEMTYPE>
            <ITEMID>3062b</ITEMID>
            <COLOR>23</COLOR>
        </ITEM>
    </INVENTORY>

```

It should load.

I do not know the answer to the second part of your question: 4211425 translates to ITEMID 3460 in color White, and the Catalog knows this, but the wanted list does not :(.

---
Tags: bricklink
---


# Question
Title: Way to build LEGO spaceship with regular bricks
How do I build a spaceship without buying a spaceship set?

With a limited amount of bricks, like, say 300 2x4, 100 2x2, and about 20 2x1 bricks.

I'm looking for instructions.

# Answer
> 5 votes
Yes.
Long answer: Yes. Your imagination is the limit. Wondering however what the intent of your question is .... are you looking for instructions on how to do this?

---
Tags: building
---


title: How to put LEGO together upside down

text:
# Question
Title: How to put LEGO together upside down
I'm building a truck. For the transmission, I want to make it all even and symmetrical.

To do that I need the pieces to stay together but they have no studs connecting so they will just fall apart.

Does anybody have any suggestions to keep them together besides using the light saber shaft?

This is the main chassis for the truck.

This is what I want the transmission to look like, but it's quite big so I want it smaller. As you can see, the arch bricks won't go together this way so I need an idea to keep them together.

# Answer
I attempt to create a searchable index of SNOT techniques, as this is called. Of those, the strongest 180 degree stud reversal are probably one of these:

If you want to connect the two curves together bottom to bottom, you should be able to do it with an axle, sort of like these two techniques:

If that doesn't work I once had luck playing around with a lever and a rubber band. It was tricky, but it did work:
> 14 votes

# Answer
I think this is how we did it as kids. However, it was 1970s. Probably too primitive, clumsy, or against the rules now.
> 8 votes

# Answer
Generally, the lampholder plate does the job:

http://www.bricklink.com/catalogItem.asp?P=4081b

but some idea of the scale you are working in will help get a better answer, or if you can post a picture of the model you might get a specific answer.
> 5 votes

# Answer
While Windfire's suggestion is valid, there are several elements with opposing studs.

Many of the parts listed on that link don't apply, but several do, including the first five.

If you're not clone-averse, Cobi makes some great plates with studs on both sides, though I have no idea where you can get them aside from buying entire sets known to contain them.
> 2 votes

---
Tags: building, snot
---


# Question
Title: Is this a real Duplo Train Base or fake?
I'm new to LEGO, so forgive me if this is a simple question. I purchased a lot of 30 Duplo Train Base from eBay.

Below is the picture that accompanied the listing. There is a disclaimer stating: `(Stock Pictures colors of trains may be different)`

What I received aside from the 20 that fit the Duplo Train Base plus 10 of these train bases:

The LEGO DUPLO Creative Suitcase 10565 shows the train base with a pincher tip and not a closed loop:

Not sure, what the other 10 train bases I received are. The 10 cars do seem to say DUPLO inside the circle if I look closely.

# Answer
These 10 are Duplo Vehicle Car Base 2 x 6 with Hitches and Red Wheels (Old)' (4883cx2) and came in Red, Blue and Yellow
> 11 votes

# Answer
A legitimate duplo train part will have the word Duplo imprinted inside each round stud, like you see in the image here, sorry for the fuzzy pic.

-Brian from brickablocks.
> 6 votes

---
Tags: trains, duplo
---


# Question
Title: Where are the electric pieces for 42029?
I was building LEGO 42029 Customized Pickup Truck, when I got to a page where I needed electrical parts, such as the battery box and the wires. I checked and these pieces were NOT included. Should they have been included? If not, where can I buy them?

# Answer
> 8 votes
These pieces are not included in the set. Motorizing this set requires the addition of a Power Functions motor as shown here:

You'll need the Power Functions Motor Set (8293) if you'd like to motorize your truck. This can be ordered from shop.lego.com or other online retailers. It's usually hard to find in stores, but if you have a LEGO store nearby, they will likely carry it.

---
Tags: piece-information
---


# Question
Title: How much are large retail LEGO Minifigures worth?
I have an extra large LEGO figure *(approximately 19 inches/48 cm tall)* that I wish to sell. This is an item which has only been available to retailers as part of merchandising the stores.

Any ideas how much these are worth?

# Answer
> 5 votes
These typically go for several hundred USD at the low end, and can be up to several thousand for the rarer display figures.

One way to get an idea of the current market price is to check out the items currently for sale on Bricklink. A search for 'display figure' in the gear category should give you a pretty good idea.

# Answer
> 2 votes
I have been making a list of these over the past few months. I have about 43 and I think that another 50 or so exists. You can see the full list here. http://www.minifigpriceguide.com/MAXIFIGS.0.html

I think that these figures generally go for between 400 - 1500 depending on the character. The last Spiderman Doc Ock combo that I saw went for around 3000.

---
Tags: minifigures, shopping, value
---


title: Quick way to inventory parts

text:
# Question
Title: Quick way to inventory parts
I have a rather large collection of LEGO elements that are not sorted in any way, and I'd like to keep track of them. There are a few other posts about ways to keep track of elements, and I've looked at them. I've downloaded about three different programs that are for LEGO inventory keeping, but I'm kind of picky.

I'd want something that I can input bricks into rather quickly, and though these programs are cool, I don't need to look up current prices or keep track of sets or whatever, as I have loads of loose pieces. Does anyone know anything that would meet those conditions? Even some sort of scanner build would be great.

# Answer
As you have probably guessed by now, there is no easy solution to your question. It all comes down to computer vision.

In this solution, Akiyuki built a massive machine out of LEGO bricks, a camera, a scale, 2 Mindstorm NXT and, which he fails to mention in is parts list, a computer and some electronics.

Computer vision is complex, and making a working prototype is still an impressive task. Even though the software component of this project is most probably the reuse of an existing solution like OpenCV, there are many other problems to overcome. For example; Mechanically bringing the parts to the camera one by one in a controlled fashion. Also if the part is not laying down from a recognisable angle, you would probably have to flip it or take pictures with multiple cameras in order to get a good look at it.

Still, being a software developer myself, this is not the part that worries me. Even if you manage to build the whole machine, you still need to compare the pictures with a library of all the known LEGO bricks. Even more, they need to be imaged from all possible sides (when laying down). Building this knowledge base is a big endeavour on its own.

Here is a video of the working machine.

---

If you can reduce the complexity of parts to sort it can really help. Akiyuki has also made sorters for Technic beams and axles (both of which work on the same very simple principles).

If you do decide to build a brick sorter you probably would be better off designing one for the parts you use the most/have the most of and hand sorting the rest.
> 8 votes

---
Tags: piece-information, organisation, inventory
---


# Question
Title: What does "No Friction" mean in Parts "Gear with 8 Teeth Wide, Notched and No Friction"
http://www.brickowl.com/catalog/lego-gear-with-8-teeth-wide-notched-and-no-friction-11955

As title, what does "No Friction" mean in the part "Gear with 8 Teeth Wide, Notched and No Friction" ?

# Answer
In the case of this item, it means that the gear will slide freely along the axle it rotates around.
> 5 votes

---
Tags: piece-information, gears
---


# Question
Title: Can I change the Bluetooth identifier for an EV3 brick?
I'm coaching a number of FIRST Lego League teams and wish to set up our lab so that each computer could potentially be paired with each brick, but I want to uniquely identify the bricks (EV3-Team1, EV3-Team2, etc). Is there a way to change the brick's Bluetooth name?

# Answer
I'm teaching an after school robotics program and the kids are using the LEGO MindStorms Education Core Set #45544. I was dealing with the same situation when I had to connect 10 EV3s to Bluetooth or Wi-Fi and I couldn't distinguish from one EV3 to the next. Anyhow, I figured out how easy it was to give each brick it's own unique identifying name. You want to make sure that the EV3 is connected to the computers via USB cable and that the LEGO MindStorms program is opened. In the bottom right corner of the screen, you'll see the hardware page. Click on the brick info and then just change the name. See image below.
> 6 votes

# Answer
You can change it in the NXT 3.0 software itself. Connect the robot to your PC, and in the software itself you can change it in the bottom right hand corner, above the firmware number and the connection type. Hope that helped.
> 1 votes

---
Tags: ev3, bluetooth
---


title: Issues with set 10234 book 3 pg 43

text:
# Question
Title: Issues with set 10234 book 3 pg 43
The white wing-like piece continues to pop off when placed. Has anyone figured out a fix for this or am I doing something wrong

Instructions 3 & 4:

src: http://lego.brickinstructions.com/10000/10234/163.jpg

# Answer
Sometimes, the piece connecting your two white plates in Step 2 might be bent or not completely flat. An rounded LEGO piece can have other pieces that it connects falling off because it can't hold on to the studs as usual. This could happen to the white wing piece itself.

Two, they can be a hassle. Normal pieces can sometimes just be a pain in the back. I got a set with pieces in perfect condition and they still come off. Make sure you squeeze those pieces really tight to each other to prevent and pieces from falling off.
> 2 votes

---
Tags: building, instructions
---


# Question
Title: Why doesn't lego make many 2x2x4 Pieces?
I'm just wondering if anybody here knows where I can get some 2x2x4 pieces ... It seems that Lego doesn't make many just standard bricks that are 4 high ... I've found a few singles here and there on Ebay, but these don't exit in the pick a brick store and they are reeeally hard to find. Looking for about 16 Dark Stone Gray 2x2x4 pieces ... any leads? Or any idea why they don't make standard bricks that are 4 high? I assume it's because you can easily stack to 2 highs, but for cosmetic reasons I can't do this in my build. Thanks!

# Answer
I can't find any evidence that a 2x2x4 piece has ever existed. Bricklink identifies a 2x2x3 brick, and there are many sellers around the world that will happily sell you 16 dark stone grey pieces for pennies/piece.
> 6 votes

# Answer
Another option you might want to consider is looking at 1x2x2 DUPLO pieces. They correspond to 4x2x4 lego pieces (slightly bigger than you are asking for, but not knowing the details of your build you might be able to incorporate these) and they interconnect (a 2x2 lego piece fits on a single DUPLO stud.) If you mount them sideways you get a 2x4 surface (but it would be 4 deep, not 2 deep as you requested). EDIT: This post shows how DUPLO and LEGO play together :)
> 4 votes

# Answer
As odd Todd mentioned LEGO never made 2x2x4 pieces. The largest brick of similar size is 2x2x3 and 2x4x3. For larger smooth surfaces LEGO usually uses panels. You can find all the panels LEGO ever made here: http://www.bricklink.com/catalogList.asp?catType=P&catString=91
> 1 votes

---
Tags: piece-information
---


# Question
Title: Which brands (fictional and non-fictional) have appeared in the Town/City theme?
A few years ago I wrote an article about the fictional organisation logos found in the City theme.

I'd quite like to revisit this, as I'm sure I must have missed some. I also only focused on the fictional brands, but I know some licensed brands have appeared too.

My current list is:

**Fictional**

* Police
* Fire
* Hospital (Star of Life logo)
* Postal service (envelope and bugle icon)
* Railway (double arrow logo)
* Refuse / recycling agency (eg 4206)
* Highway maintenance agency (motorway icon) - eg 6653 and 6521)
* 'Octan' (oil/energy company)
* 'AirLine' (now uses the bird logo)
* 'International Transport' (eg 161 and 6367)
* Cargo company (yellow box on blue world logo) - eg 4551

**Real**

Are there any others?

# Answer
I can't believe that nobody else else has posted the most important *real* company that appears within the LEGO City theme... the LEGO company itself!

---

There is a good list of promotional sets on Brickipedia, that includes the set theme. Many of the town / city sets include logos or brand names of real-world companies.

Other sets that include real-world brands (some of which don't count as Town / City, according to the Brikipedia themes list) include:

* Esso appeared on some very early sets.
* DB (Deutsche Bahn) appears on various trains, including 7725.
* Sports sets such as, 3432 which has NBA logos on the player's chests, or 65221 that included a Spalding basketball.
* 1656 Viking Line cruise ship.
* Interfrigo, set 147.
> 7 votes

# Answer
Here are some additional non-fictional brands and their set(s) under the Town theme:

**Chocomel (Nutricia), Holland**

Chocolate Factory

**Canada Post**

Mail Van

Mail Truck

**ANWB (Breakdown service), Holland**

Breakdown Assistance

Roadside Recovery Van and Tow Truck

**UNICEF**

UNICEF Van

**Touring Club Schweiz**

Breakdown Assistance

**Air Canada**

Air Canada Jet Plane

**MD Foods (Denmark)**

Milk Truck

**Emirates**

Emirates Airliner

**Arla (milk supply company, Sweden)**

Milk Delivery Truck

**Renault**

Racing Car

**Velux**

House with Roof-Windows

**Color Line**

Container Lorry

**Tine Dairies (Norway)**

Milk Delivery Truck

**McDonalds**

McDonalds Restaurant

Also there is the 'Houses' set from Weetabix. This doesn't actually include the brand in the Town set itself, but includes the pieces to build a Weetabix figure in the set and is part of the Town theme.

Under the City theme:

**Vestas**

Vestas Wind Turbine
> 5 votes

# Answer
Real brands include:

Mostly it's the three early Maersk Trucks - 1552, 1831 and 1651 that are usually listed under the Town theme.

Toys R Us also appeared on one City themed truck

Outside of the Town/City themes but still minifig scale you then have:

* Maersk Train \- under Trains.
* SNCF - In it's old orange livery is the basis for the Horizon Express train under Creator.
* Ferrari - Is usually listed under the "Racers" theme rather than Town/City
* Porsche - In the 2015 LEGO Speed Champions line
* McLaren - In the 2015 LEGO Speed Champions line

Other brands have also appeared in other more advanced/non-minifig scale themes, such as:
> 2 votes

# Answer
I wouldn't consider "hospital" as fictional.

At first, LEGO did seem to use the Red Cross logo, but they have since then had to stop (presumably because of the Red Cross being very protective about their logo). Note that the logo they have been using since isn't fictional either.

12v era trains provided stickers for a lot of different train companies, I'm not sure if what they use now is fictionnal or not (I think so)
> 2 votes

# Answer
Lego also collaborated with several airline companies to release a standard plane but with stickers denoting the airline name. I remember excitedly purchasing them back in the day. They were only available through their in-flight shopping if I recall correctly. I have two. One is El-Al and the other one is for a Japanese carrier (need to check either ANA or Japan Airlines). Here is the link to the "generic set" although it is labelled El-Al. http://www.brickset.com/detail/?set=4032-3

You can actually see the whole set of airlines here: http://www.brickset.com/browse/themes/?theme=World%20City
> 2 votes

# Answer
Depending on how you classify "Town/City", you might want to consider these:

**Real**

**Fictional**

* Ghostbusters 21108
* Gringotts and other Harry Potter brands 4714, 10127
* The smiling minifig coffee cup part
> 0 votes

---
Tags: city, theme
---


# Question
Title: How can I use bluetooth on my phone to run a program on the EV3 brick?
I tried the Commander app but it seems to just let you control individual motors.

I would like to run the various programs I have made using an input on the phone through Bluetooth

Is this possible and if so, how?

# Answer
> 2 votes
There is an Android app called EV3 mailbox that can send messages to the EV3 brick. You can trigger your program to run in different ways by sending out different mailbox messages.

---
Tags: ev3, bluetooth
---


# Question
Title: Bluetooth communication between computer and nxt using RobotC
I'm thinking starting a project involving controlling the movement of a NXT robot from the PC using RobotC.

Is it possible? Does anyone have a simple code solution?

# Answer
> -2 votes
It's possible. simply make a BT connection and then use the control interface from your computer

---
Tags: nxt, bluetooth, robotc
---


# Question
Title: The most amount of pieces [ever] per set
Which set number had the most

* Standard LEGO elements to date?
* Technic LEGO elements to date?

# Answer
The largest LEGO set by piece count is :

31203: World Map (2021)

Piece count : 11695

Second:

10294: RMS Titanic

Piece count : 9090

Followed by :

10276-1: Colosseum (2020)

Piece count : 9035

---

Largest Techic set :

42100-1: Liebherr R 9800 (2019)

Piece count : 4108

Second :

42082-1: Rough Terrain Crane (2018)

Piece count : 4057
> 17 votes

---
Tags: sets, records
---


title: Bluetooth Conection PC-NXT1-NXT2

text:
# Question
Title: Bluetooth Conection PC-NXT1-NXT2
I want to connect, via Bluetooth, one PC with a NXT brick and then have that NXT communicate with another NXT.

So I send a message from the PC to NXT1 and have NXT1 send a message to NXT2. Is this possible?

# Answer
> 2 votes
https://bitbucket.org/Thad\_Hughes/cortex/src

Here's something in NXC and python that routes from NXT1 to NXT2 through the PC; emulating a non-master/slave config between all three devices. Has the added benefit of a seamless pairing method.

It could be helpful to give a little more detail (what languages you are using, what direction(s) of communication you desire)...

# Answer
> 1 votes
Yes it is possible. You just need to write a program for NXT1 that forwards the messages from the PC to NXT2.

---
Tags: nxt, bluetooth
---


# Question
Title: Remove decals from LEGO Friends mini-dolls
I am trying to remove the decals from my LEGO Friends mini-dolls. Does anyone have any suggestions for doing this? I tried rubbing alcohol on a minifigure once, and it made it all gross looking, so I know that probably won't work.

A rubber eraser is working, but it takes an awful lot of work, and is very difficult to get the sides of the torso done. (And I am dreading the feet and skirt...)

Thanks!

# Answer
> 5 votes
Pure eucalyptus oil works excellent, won't damage your minifigs, (and it smells good too!). You can get it in small bottles at health-food stores, pharmacies, and Asian stores. You don't need much, so a small bottle can last you a long time.

Just pour a little of the oil on a piece of cotton or soft towel, and rub over the printed area you want to remove. It gets wiped off almost right away. If it is a small area you want to remove, use a Q-tip. Just be careful not to touch areas you want to leave intact as the oil works pretty fast. Wash off the minifigs with pure water afterwards.

You can also use Brasso (the metal polish), but it takes a bit more rubbing and it smells really bad. But it does a good job in general and won't damage your minifig. It is also easier to control than the oil on small surfaces as it is more like a paste and won't run like the oil could. Make sure you rinse the minifigs off really well once you are done.

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Tags: cleaning, customization, friends
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# Question
Title: How to switch an NXT sensor port by a motor port?
Me and my partner are finishing up our robot for the RobotCup and we desperately need one more motor port. We will only use 3 sensor ports, so my question was if there was even the slight chance that we could switch one for the other.

# Answer
That's not possible - sensor ports don't have the hardware to drive motors. That said, you can buy a motor multiplexer like this one to do the job for you, if competition rules allow this.
> 2 votes

---
Tags: nxt
---


# Question
Title: EV3 motor TACHO signal connection. Hardware schematic questions
I'm trying to understand EV3 motor TACHO signals circuit on the EV3 hardware schematic.

Please look at the image below.

There are two things I can't understand:

1. On the left side, the TACHOA0 input is connected to the ADC and Schmitt trigger inputs via RC circuit. I can understand that the 4.7K resistors and 100pF, 47pF capacitors are used to filter the signal. But I can't understand why those two 100K resistors are used.
2. On the right side, TACHOA1 input is connected to the ADC and Schmitt trigger inputs via RC filter. Here I don't understand the role of MA1 signal.

# Answer
1. The EV3 detects when motors are connected and disconnected using the ADC (and gpios). The two 100k resistors are basically a voltage divider, so when the motor is disconnected, the ADC will read 2.5V. If a motor is connected, the motor encoder will either pull the signal high (above 3.7V) or low (between 0.1 and 0.65V). The detection algorithm is actually a bit more involved than this, but this is the general idea.

For the full details, see the Device Connection Manager Driver and the actual source code. The documentation is not quite exactly correct, so when in doubt, trust the actual source code and not the comments (documentation is generated from comments).

And even though you didn't ask about it, I should point out that the transistor (Q10A) is also used as part of the detection.
2. You don't show it, but MA1 is connected to pin 2 on the output port, which is one of the motor driver signals, so MA1 could either be battery voltage, floating or ground depending on the state of the motor driver chip (via 1OUTB2). Additionally, the voltage could be steady or PWM depending on the speed and direction the motor is running. Or, MA1 could also be something else if there is no motor plugged in (or something besides a motor is plugged in).

On NXT sensors, pin 2 is connected to ground (pin 3). In the source code, it looks like this is just used to detect if a NXT sensor is plugged into the output port.
> 5 votes

---
Tags: ev3
---


# Question
Title: How to turn the NXT at an angle with NXC
How can I program, with NXC, a Lego NXT to turn a specific angle?

I've tried using `wait()` but the problem isn't solved.

Can I use `RotateMotor()`? What parameters should I use? For example if I want it to move in a square, what kind of parameters.

# Answer
This depends on the exact configuration of your robot, including but not limited to the distance between the wheels (if it's a differential drive robot), the diameters of the wheels, the gearing (if any is used) between the motors and the wheels.

A simple solution would be to experiment with various parameters and making corrections based on the direction and magnitude of the observed error. For example, if you send an order of `RotateMotor(100)` and see that your robot turns about 30°, you would try again with `RotateMotor(300)`.

Another possible solution is to write a program that displays the values read from the motors' encoders, perform the required maneuvers by pushing the robot by hand, and noting the displayed values. In theory, those values would be the ideal parameters.

Of course, the most sound and correct solution is to whip out your geometry skills and calculate the exact angle the motors need to turn, but this approach tends to fail when reality does not behave perfectly (as in skidding, measurement errors, friction, etc.)

All in all, I'd recommend picking a starting value, trying it on your robot, observing the results, making adjustments based on the observations and starting over the loop.

For reference (if you hadn't already found it): NXC RotateMotor command
> 1 votes

# Answer
Control loops. The builtin RotateMotor commands are very imprecise. Have a look at this file for a nice library that makes skid steer vehicles turn very precisely:

https://www.dropbox.com/s/o31qaxx0glx4m3x/Instacode.h?dl=0

You'll need to adjust the constants at the top of the file.
> 1 votes

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Tags: nxt, nxc
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# Question
Title: How can I attach a Technic Linear Actuator to a EV3 Medium Motor?
I'm pretty new to serious LEGO building (never got past very blocky houses as a kid but got into Technic a couple of months ago) and need to connect a Technic large linear actuator (61927) to a Mindstorms EV3 medium motor for a piece of lab equipment I'm making.

Does anyone have any hints on how to do this? The mounting thing on the linear actuator keeps getting in the way and I'm having trouble getting things to line up.

# Answer
First of all, let's identify the parts you are trying to attach.

The EV3 medium motor is a pretty accurate description, I'll assume it means this.

The linear actuator is more ambiguous, it can mean both the smaller and the larger variant.

For the smaller one, I'd use two 3 x 3 technic beams or two technic triangles, one on each side of the motor, attached by technic pins in the first case or half-pins in the second. The axle can be connected via an axle joiner.

For the larger actuator, I'd use two quarter brackets and two hybrid beams for spacing.
> 4 votes

# Answer
Try this on for size:

Here's an exploded view.

This should be compact, robust, let you change gear ratios (so you can get more speed or more torque; the linear actuators are very slow for most applications.), and mount to your system quite well.

Cheers!
> 2 votes

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Tags: ev3, technic
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title: What's the circle piece in this MOC?

text:
# Question
Title: What's the circle piece in this MOC?
I saw a moc from here.

But have no idea what the piece it use on the arms of the robot, and on the guns.

# Answer
It is a Tile 1 x 1 Round, with groove

Edit after clarification in the question:

The arms have something that looks like a bit of Hose, Ribbed cut to the required size.

The gun is, as gev pointed out, based on a standalone ray gun piece that has the ribbed section molded in originally.
> 2 votes

# Answer
The bit held in the mech hand is a Ray gun.

The bit on the forearms is almost certainly a short bit of Hose, Ribbed 7mm D. 2L like zovits said.
> 5 votes

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Tags: part-identification, moc
---


title: Identifying Lego set from 1980's

text:
# Question
Title: Identifying Lego set from 1980's
Can someone please help me identify this Lego set from the 1980's?

I remember building a house, work shed/garage and some type of vehicle. The base plate is light gray. It came with 2 minifigures, male and female, a broom and shovel, and slanted windows that were used for a skylight.

# Answer
> 2 votes
My closest bet would be the Car Repair Shop. However, there are lots of other sets that could match the description.

Edit #1:

The other potential candidates:

In case none on these is what you are looking for, you could take a look at Bricklink and browse the results.

Edit #2:

Based on the picture you added, the 730-2 BASIC Building Set seems the most likely choice (it has both minifigs, the broom, the shovel, the faucet, the slanted windows). There are also many pieces from other sets: both the blue and the red-yellow propeller, the yellow spaceship engine besides the male figure, etc.

---
Tags: set-identification
---


title: Raw RGB data to Color?

text:
# Question
Title: Raw RGB data to Color?
I'm trying to convert the raw RGB values from a Colour Sensor into HSL but it doesn't seem to be working:

```
R = rgbn[INPUT_RED];
G = rgbn[INPUT_GREEN];
B = rgbn[INPUT_BLUE];

var_R = ( R/255 );
var_G = ( G/255 );
var_B = ( B/255 );

float H = 0;
float S = 0;
float V = 0;

float var_Max = var_R;
if (var_G > var_Max) var_Max = var_G;
if (var_B > var_Max) var_Max = var_B;

float var_Min = var_R;
if (var_G > var_Min) var_Min = var_G;
if (var_B > var_Min) var_Min = var_B;

del_Max = var_Max - var_Min;

// Calculating H
if (del_Max == 0) {H=0;}
else if (var_Max = var_R) {H=(60*((var_G-var_B)/del_Max))%6;}
else if (var_Max = var_G) {H=(60*((var_B-var_R)/del_Max))+2;}
else if (var_Max = var_B) {H=(60*((var_R-var_G)/del_Max))+4;}

// Calculating S
if (var_Max == 0) {S=0;}
else if (var_Max != 0) {S=del_Max/var_Max;}

// Calculating V
V=var_Max;

NumOut(0,LCD_LINE6, H);
NumOut(0,LCD_LINE7, S);
NumOut(0,LCD_LINE8, V);

```

And once I've converted it to HSL how can I recognize the colour?

Here is my code that gets raw RGB data:

```
#define       COLORSENSOR SENSOR_3
#define       S_CLR     IN_3
#define       FLT_MAX
#define       FLT_MIN

unsigned int rgbn[4];

void color_sensor_on() {
  SetSensorColorFull(S_CLR);
  ResetSensor(S_CLR);
}

task main(){
  color_sensor_on();

  while(true)
  {
    ReadSensorColorRaw(S_CLR, rgbn);       //Raw data
    RGBToHSL();
  }
}

```

# Answer
> 2 votes
Not sure what language you are using, or calls you are making before this, but:

```
float var_Min = var_R; if (var_G > var_Min) var_Min = var_G; if (var_B > var_Min) var_Min = var_B;

```

Should be (note the use of \< rather than \>)

```
float var_Min = var_R; if (var_G < var_Min) var_Min = var_G; if (var_B < var_Min) var_Min = var_B;

```

Your posted code is putting the maximum value into the minimum variable, messing up things down the line...

Another thing that will help is to not use the RawColorSensor call. Change your main task to this:

```
ColorSensorReadType csr;

task main(){
   csr.Port=S3;
   SetSensorColorFull(csr.Port);
   while(true){
       SysColorSensorRead(csr);
       RGBToHSL();
   }
}

```

And the first few lines of your RGBToHSL call to this:

```
R = csr.NormalizedArray[0];
G = csr.NormalizedArray[1];
B = csr.NormalizedArray[2];

```

This will normalize the values between the values of 0,255 (or at least roughly). I've had more luck with this call since it also tries to calibrate the values.

After this, you'll need to find the color values you're using with a tool like http://www.colorpicker.com/ . For example, orange would have HSV (HSB on that site) of (40,100,100). (The scaling on these values may differ). So, to detect orange, check if: Hue\>30 AND Hue\<50 AND saturation\>90 AND value\>90. Make sure there is play with your thresholds, otherwise the check will work once in a hundred tries.

---
Tags: nxt, programming, nxc, sensor-colour
---


# Question
Title: Accessing ARM Processor Memory Registers through NXC
Specific to the NXC (Not eXactly C) programming language. Is it possible to access the memory registers on the ARM AT91SAM7S256 processor? I'm trying to investigate the use of Timer Interrupts to schedule a sampling routine.

I do know it's possible with nxt-gcc, but I don't know enough about NXC to understand if it would work. Would it not be possible to run with interrupts since the firmware uses the blocking I2C to communicate with sensors?

# Answer
NXC creates bytecode for the standard (or NXC upgraded) NXT virtual machine. The idea of this virtual machine is to create an abstraction layer to prevent malicious low level calls such as accessing memory registers on the processor.

So, without a low level compiler, such access would not be possible.
> 3 votes

---
Tags: nxc
---


title: Old LEGO movies

text:
# Question
Title: Old LEGO movies
As I remember, it was about 1990 maybe some years earlier, there were movies, made by LEGO, they were about 3 minutes long, maybe longer.

It was of course not computer-generated videos but normal, animated movies created with bricks and photographs were made every single frame. It was very fluent and smooth (maybe some animation tricks were used), much much better than those what people make now, but the idea was the same as here.

It was not from minifigures, but each person (character) was made by many bricks.

I only remember a movie of some soccer players, but there were more of them.

I can't find them on YouTube, I only get present computer animated videos or just amateur movies like the one above.

# Answer
> 2 votes
Yesss!

I've finally found it.

They were called "LEGO Sport Champions".

Here is the link to watch them on YouTube:

https://www.youtube.com/user/LEGOsports/videos

# Answer
> 3 votes
What you're talking about are often referred to as "brickfilms".

Reddit even has a subreddit for them: /r/brickfilms. (Honestly, I wouldn't even have remembered about them had I not just stumbled upon the subreddit yesterday.)

Searching YouTube for the term "brickfilm" also gives you a number of results, some tutorials and many actual brickfilms.

(I'm pretty sure Lego itself did not make or sanction any brickfilms. Like any medium or sub-medium, 90% of brickfilms are probably not very well-made.)

---
Tags: history
---


title: LEGO RCX hardware schematic

text:
# Question
Title: LEGO RCX hardware schematic
Where can I find the hardware schematic for the LEGO RCX brick? I spend a lot of time but unfortunately didn't find any useful information.

# Answer
> 3 votes
There are partial reverse engineered schematics done by Mark Bellis here

---
Tags: rcx
---


# Question
Title: Is there a Technique or Algorithm for Building Spheres?
There are times when I would like to build a sphere or a dome like this one:

From Small Lego Sphere Project

While this example is great, I find it difficult to scale it to another size, whether smaller or larger, without it...not looking roundish anymore.

Is there a tool available that can design a sphere or dome based on a size?

# Answer
> 13 votes
This website generates a sphere in LDraw format: http://lego.bldesign.org/sphere/

Here's a link if you want to learn how it can be done: http://groups.csail.mit.edu/graphics/classes/6.837/F04/assignments/assignment5/ (there are other ways too)

# Answer
> 11 votes
Here is my less popular but earlier Spheroid Generator

http://olson.pair.com/moc/spheroid/

It let's you generate simple sphereres or ellipsoids as well as parabolic "tent" shapes.

The principle is to divide space into 1x1 brick or plate cells, and any cell that falls mostly within an ideal geometric shape becomes a brick (or plate).

Output is LDRAW model format using 1x1 bricks and divided into step numbers.

Alternate approaches divide the sphere into facets for SNOT building; my program can't do that.

I could be persuaded to pick up the project again after 10 years...

# Answer
> 4 votes
I have done it see this video.

I have updated the spreadsheet so that it can give you a visual indication of the cross-section at each layer (in quarters) and uploaded it onto Google drive for public access

---
Tags: building, shapes
---


title: What Lego set does this belong to?

text:
# Question
Title: What Lego set does this belong to?
I want to find which LEGO set this unusual piece belongs to. I have 10? I have a few sets from the late 1980's and the rest are from the 1990's. I have looked and looked. Hope you can help!

It looks like a 1 x 1 square brick with six studs extended 1/4". The studs have a square lip around it. The brick base has two studs and then there is a square with four studs that fits around it to make six!

The color seems to be closest to Medium Blue or Medium Azure

# Answer
> 13 votes
That isn't Lego, it's Construx by Fisher-Price. I had some of those :)

http://www.thisoldtoy.com/fisher-price/dept-7-playsets/f-construx/nuts.html

---
Tags: part-identification
---


# Question
Title: How large is the face of a 2x2 45º brick?
I am attempting to make a decal for a roof tile, sort of like the computer face on certain bricks of the type. However, as there appears to be no template, how large is the face of a 2x2 45º brick?

# Answer
The sloped face of the 2x2 brick is 16mm across by about 11.3mm tall.
> 5 votes

---
Tags: piece-information, size, slope
---


title: NXT Motors curving to the right

text:
# Question
Title: NXT Motors curving to the right
The NXT motors have been curving to the right by about 10-20 degrees. We have checked the program, no curves. We have checked the wiring, but it is also plugged in fine.

# Answer
It could be that one wheel slips more than the other. This happens when the tires get dirty. Also, you can adjust your center of balance so that more weight is on the drive wheels and they will slip less.

You can also use the gyro sensor to compensate for any slippage of the wheels.
> 2 votes

# Answer
Check your motors.

I had the same problem due to one motor being older than the other.

Try to match motors which have a similar age or usage.

If this is not possible, use a gyro sensor.

Also, check the center of gravity. This can cause wheel slippages.
> 0 votes

---
Tags: nxt, motor
---


# Question
Title: How to import an unofficial parts archive into LDraw?
I recently created a basic EV3 robot in Lego Digital Designer and exported it as a LDraw file. When I opened the LDView file, the EV3 elements were missing. I then proceeded to download an unofficial parts archive from here: http://www.eurobricks.com/forum/index.php?showtopic=85317

The ZIP contains the folders "parts" and "p". How do I import this into LDraw?

# Answer
> 2 votes
You have no need to use these unofficial parts, all EV3 parts (except for the stickers) are now LDraw official parts, and should already be in your library if it is up to date (otherwise, download and install complete.zip from here). The problem you most probably have is that the file LDraw.xml that directs conversion between LDD and LDraw doesn't support EV3 parts. For more details on this file, see here.

---
Tags: ldraw
---


# Question
Title: How would I make a decal for a 2x2 dome brick or a 2x2 round slope brick?
I am looking to make a decal for a custom droid using either the R5-series head or the regular dome R2/R3/R6/R7/R8 head. However, I do not know the process for creating droids. Does anybody know how?

# Answer
> 1 votes
The problem of creating a flat sheet that could be fitted onto a (semi)spherical surface (a dome head) is known to be impossible to solve perfectly, but there are viable approximations of varying precision. This matehmatical paper details one such approximation (for spheres, but the process can be modified for domes) using petal shaped pieces. By varying the number (and so the width) of the petals the approximation gets closer to ideal, but even with three petals a reasonable quality can be reached. Of course, much trial-and-error can be expected.

AFAIK The LEGO Group uses pad printing, this can be quite expensive to set up but produces the best quality prints.

For the R5 heads the process is much easier since the surface of this head piece can be flattened into a shape called an Annular Sector. With some measuring and calculation (and maybe some trial-and-error) it should be possible to design a sticker that fits this kind of head.

---
Tags: size
---


# Question
Title: Need help identifying extra large Lego figure from 2003
I came across these LEGO figures at an estate sale and have had no luck trying to find out what they are called.

They are much larger than a regular minifig but have a shaped foot plate to attach to regular sized Legos. They can be squeezed down and compressed and then pop back up.

Top and bottom are two different pieces and inside there are screws visible. Only markings are "LEGO" on front shirt and "48379" and "2003" on bottom of foot plate. Thinking they were not part of a set but a promo item or accessory.

# Answer
> 9 votes
48379 is the part number for the torso piece. 2003 would be the copyright date for the LEGO trademark.

They are both promotional items which were distributed with McDonald's Happy Meals.

**Bricklink:** 7923-1 (White Soccer Player #4)

**Bricklink:** 7917-1 (Blue Basketball Player #22)

---
Tags: minifigures, minifigure-identification
---


# Question
Title: How can I rotate an EV3 motor an exact number of degrees using RobotC?
I'm trying to rotate the motor of an EV3 by an angle of 50°. I can't. How I can rotate a NXT/EV3 motor by a given angle using RobotC?

# Answer
> 3 votes
The command that you are looking for is setMotorTarget as shown in the documentation here.

Essentially, you need to set the target rotation for the motor in degrees and then wait for the movement to take place:

```
//Sets motorA target to 50 degrees at a speed of 100
setMotorTarget(motorA, 50, 100);
// Waits for movement to complete
waitUntilMotorStop(motorA);

```

---
Tags: ev3, programming, motor, robotc
---


# Question
Title: How to find out which set contains a higher plate percentage?
I want to gather various types/colors of plates to do some mini model MOCs. How can I find out which set has the best plate percentage or price per plate pieces?

I know there are a lot of ways to find out which set has what kind of parts, and brickset.com also has a statistic for each kind of part including plate percentage of every single set. For a single type of plate there are also a lot of ways (bricklink, rebrickable, brickset, etc.) to find out how many of them are available in which sets.

But I wonder if there is there a quick way to get a list of the plate number/percentage for all the recent years' sets? To check out each set for this information is really painful.

Or if there is no quick way, which sets could be the best candidate to gather various plates? I know a few sets have many plates (e.g. 10230), but their current prices are also very expensive thus potentially making them poor candidates.

# Answer
Almost any set I can think of will have many many non-plate parts, even if it also has lots of plates in it. Plus you run into the problem of determining what constitutes a "plate". Does this count? or this? or this? If I were you I'd just go down the list of sets you can purchase on shop.lego.com, visually inspect the set to see if it looks like it has lots of plates, then check the inventory on rebrickable.com or bricklink.com. The architecture, Minecraft, and creator sets are probably your best bet.

You might be better off buying plates individually from Bricklink or the Lego website. You can also visit a Lego retail store that has a pick-a-brick wall; they usually have plates available in a few sizes and colours and you can get as many as you want. Otherwise, most sets will have lots of pieces you won't need.
> 2 votes

# Answer
The best set from 2014 is Furry Creatures (31021) at $0.20 per plate.

Here's one possible way to do this:

1. Download the listing of all parts in all sets from Rebrickable.
2. Join this data up with pricing data (perhaps from the Brickset API) to get yourself some pricing information for each set.
3. Define which parts count as plates.
4. Write yourself a little program to count the number of plates in each set and divide by the price.

If I use the plates in the plates service pack from 1999 as my plate list, here's what I get for the best price per plate for sets containing at least 150 parts released in 2014:

```
 id          price_per_plate  plates           us_price
 31021-1     0.201919         99               19.99
 21020-1     0.235802         212              49.99
 31020-1     0.246438         73               17.99
 40182-1     0.249875         80               19.99
 40090-1     0.262895         38               9.99
 40183-1     0.277639         72               19.99
 21107-1     0.286803         122              34.99
 31025-1     0.302955         132              39.99
 40180-1     0.307538         65               19.99
 31024-1     0.319043         94               29.99
 10243-1     0.323866         494              159.99
 31023-1     0.336966         89               29.99
 10242-1     0.352077         284              99.99
 31026-1     0.354291         254              89.99
 60058-1     0.356964         56               19.99
 31019-1     0.356964         56               19.99
 79116-1     0.372287         188              69.99
 75038-1     0.384462         65               24.99
 21117-1     0.402241         174              69.99
 41056-1     0.403065         62               24.99

```

This is quite expensive if you aren't interested in the other parts as well. You'd be better off buying these on a secondary market like Bricklink or perhaps even directly from Pick-a-Brick.
> 3 votes

---
Tags: piece-information
---


# Question
Title: Custom EV3 Block: "Unable to compile..." ("string subsection")
I am attempting to make a custom block according to the EV3 Block Developer kit (found here). I was able to create a simple block that returns the length of a string. This is what it looks like: (The above program would correctly display a value of "2" on the screen.)

However, I am running into problems when I try to use the "string subset" block in the dev kit. The following program will not even compile (the text says "GOODBYE CRUEL WORLD"):

I've hunted down the problem as residing in the "string subsection" block: Whenever this block is left out, the code will compile. Is this block not supported in EV3-G?

---

**Edit**: Here's the program along with the error:

# Answer
> 1 votes
A temporary fix I found that works: using the provided "gray blobs", there is one named "PBRStringAtIndex" (or something like that) which will indeed compile (EV3 only). This does not address the similar "write at index" issue, and the output is a "byte" (presumably ASCII), not text.

*(I will update this answer as I find out more.)*

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


# Question
Title: How to get good color readings from the color sensor?
What type of setup is needed to get good color readings from the Mindstorms EV3 color sensor:

* Shape of object?
* Size of object?
* Distance to object?
* Color of background?

# Answer
The color sensor works pretty well as long as the object is about **1 1/2- 2 modules** from the object.

The sensing is best when the **object is flat**.

The object is large enough to be **fully contained within the "spotlight"** that the sensor emits. As long as this is true, it doesn't really matter what the background color is.

Another thing to consider is that the color sensor has different modes (active vs. passive). In **"active"** mode the sensing is affected much less by the ambient lighting conditions.

Pro tip: if you are using EV3-G or RobotC without Xander's drivers, the color detection works best on LEGO's colors (the color the bricks are in). This is especially noticeable for the "green" color.
> 7 votes

---
Tags: ev3, sensor-colour
---


title: Creating a native EV3B block

text:
# Question
Title: Creating a native EV3B block
I'm trying to create a native block for a hardware sensor. I've got it working pretty well, but can't get it to show up in the "port view" as anything but a sound sensor. I really need the live view of the data the sensor is seeing. Is there an example of how this is done that I could follow?

# Answer
> 4 votes
The answer is: you can't.

The EV3 brick detects which type of sensor is plugged in to the ports by examining the electrical characteristics of the sensor. Electrically, all NXT Analog sensors look pretty much the same, so they will all be detected at the LEGO NXT Sound sensor (or possibly the LEGO NXT Light sensor - or a very, very small chance as the LEGO NXT Touch sensor).

So, take @momrobo's advice and write a small program that simulates the built-in port view.

Or, if you are really ambitious you can create an adapter so that the sensor will look like an EV3 type analog sensor instead of an NXT type analog sensor. How do to this would be better suited to a blog post.

# Answer
> 1 votes
instead of the live data on the port view you can make a small program which contain you sensor block and a display block and make you sensor block send its data to the text display block so you've made your own port view.

# Answer
> 1 votes
***You Can't***

EV3 Port view is a simple program 'downloaded as application. It can only use certain original sensors.

You would have to make your own program. If you want it in the same section, you can use an option called 'download as application'.

---
Tags: ev3
---


# Question
Title: What is this Lego piece - Yellow with handles and an octagonal section?
It clearly says Lego on it, but I have no idea what it is. The only number inside is 4-01.

# Answer
This is a "Underwater Scooter". It's a handheld device to propel a diver forward.

Similar devices can be seen in the James Bond movie "Thunderball".
> 21 votes

# Answer
This is part is commonly found in the Divers theme back in the late 90's (http://brickset.com/sets/theme-Town/subtheme-Divers) The part in question is a minifigure accessory:

http://www.bricklink.com/catalogItem.asp?P=30092
> 6 votes

---
Tags: part-identification
---


# Question
Title: Can I identify the colour of objects 5mm in diamater with an EV3 Colour sensor?
My plan was to make a simple robot to sort beads like this:. Its the Hama Medium size beads, they have a diameter of 5mm so they are fairly small. After some testing, reading and asking here I figured out that it would be impossible for me to get any color reading at all from objects that small with the default sensor setup (8 distinct colors).

Is there some *trick* I can use to get the sensor to see the beads and get at least some of the color?

# Answer
> 2 votes
You may try to use the color sensor in RGB mode using a 3rd party block found here: http://mindcuber.com/mindcub3r/mindcub3r.html#ColorSensorRGBBlock With this block you get a set of three 0-255 values, one for each R G B color. It will still be tricky to correctly classify the color of your objects as the readings are noisy - you can try to set ranges to each RGB value with or w/o normalization - but at least you have some data to work with.

---
Tags: ev3, sensor-colour
---


title: What is NXT-G number format?

text:
# Question
Title: What is NXT-G number format?
We've been following this tutorial to connect a NXT 1.0 brick to a PC via Bluetooth.

We've been able to set up the communication, send and receive data in ASCII format.

However, whenever we try to send an integer and use it for calculations, it returns the wrong result.

For example, sending 60000:

```
TX: 00 09 00 05 60 EA 00 00 00

RX: 02 09 00

```

After adding 1, it returns the following:

```
TX: 00 13 0A 00 01

RX: 02 13 00 00 05 00 00 80 3F 00 ... (zeroes)

```

We've tried sending different numbers, but they all return the same value.

The NXT-G software is identical to that in the tutorial.

How does NXT-G handle the integer data type?

# Answer
> 5 votes
The NXT actually uses IEEE 794 32-bit floating point number format in little endian byte order. I like using this site for conversions.

So, to decode your messages:

> TX: 00 09 00 05 60 EA 00 00 00

Byte 0: 0x00 - response required

Byte 1: 0x09 - write message command

Byte 2: 0x00 - Mailbox 1

Byte 3: 0x05 - Message size of 5 bytes

Bytes 4-7: 0x60 0xEA 0x00 0x00 - since this is little endian, reverse the bytes, 0x0000EA60, which plugged into the conversion site gives us 8.4078E-41

Byte 8: 0x00 - null terminator

Then you add 1.0 on the NXT and return the result.

> RX: 02 13 00 00 05 00 00 80 3F 00 ... (zeroes)

Byte 0: 0x02 - return packet

Byte 1: 0x13 - message read command

Byte 2: 0x00 - success

Byte 3: 0x00 - Mailbox 1

Byte 4: 0x05 - message size of 5 bytes

Bytes 5-8: 0x00 0x00 0x80 0x3F - again, little endian, so reversing bytes gives 0x3F800000 and plugging in to the calculator gives 1.0

Bytes 9-63: 0x00... - padding

---

So, it looks like the NXT is doing exactly what you actually told it (8.4078E-41 + 1.0 = 1.0) rather than what you thought you told it (60000 + 1 = 60001).

---

Plugging 60000.0 into the calculator, it looks like your message should be

```
TX: 00 09 00 05 00 60 6a 47 00

```

---
Tags: nxt, software, bluetooth, nxt-g
---


# Question
Title: Is there a list of giveaway sets from Toys R Us or other events?
Toys R Us frequently has giveaway sets called "Make and Take", where kids are invited to come in, build a set and then take it home for free. This is similar to the Lego Brand Retail store Monthly Mini Model Build events. The MMMB kits are typically very similar to Lego polybag sets: they come in plastic bags, they have a set number, they have high-quality instructions. (Some months one of those things might not be true, but in general all three are true). The MaT kits, however, seem to be a little more ad-hoc, but at the end you still end up with a build that has a full instruction sheet and a decent handful of parts.

An example of a MMMB set is 40127, a space shuttle., which was February 2015's MMMB.

An example of a MaT is Emmet's Car which was available at Toys R Us at different times depending on your country (the events are not coordinated like the Lego Store events are).

As you may surmise from my use of Rebrickable links, I like to keep a detailed list of all the kits I and my kids own. However, Emmet's car is the only example of a MaT kit I've found. Is there a detailed list of the kits that have been given away, with instructions, inventory, etc?

I'm primarily interested in finding the MaT kits on Rebrickable, but if they're not there I'll accept info from other sources. I'm mostly interested in MaT kits given away at Toys R Us in Canada, but for other people's benefit would like to know about kits like this from other retailers, or in other countries.

# Answer
> 3 votes
Try Brickset.com (I'm the founder of the site). We list all that we are told about.

You can also record your collection there, and keep it in sync at Rebrickable.

# Answer
> 0 votes
Since I started working there (this past year) on the days I was there we had a sponge Bob one and LEGO Ninjago. If you're interested in getting future ones let me know and I'll grab a few for you. At the end of the event we usually have at least a box full that they put in the break room for employees to take.

---
Tags: shopping
---


# Question
Title: Which wheels are suitable for Power Functions M-Motor
I'm attempting to build a small self-propelled LEGO robot. Initially I was attempting to use some cheap DC hobby motors but I spent a lot of time trying to attach LEGO wheels to the motor's 3mm spindle and could never get enough torque to make the robot move.

I have now purchased two official Lego M-Motors. Unfortunately I don't have any wheels with a large enough diameter so I'm now looking around to get some matching wheels for the motors. The wheels will need to have a diameter of at least 40mm (the motor's height is 24mm).

I have had a look around but am a bit bamboozled by all the options. Has anyone use one of these motors in a robot and have any suggestions for a wheel type?

# Answer
> 1 votes
Sariel has a comprehensive list here: http://wheels.sariel.pl/

Your can also use his gear calculator to determine the output drive parameters (Torque Speed etc).

# Answer
> 2 votes
The M-motor is directly compatible with almost all the wheels that LEGO has produced, and, with a little building, compatible with every wheel imaginable, even brick-built wheels.

If your problem is that the wheel is smaller than the diameter of the M motor, perhaps you want to attach the wheels to an axle, and then drive the axle with the motor. There are many different gearing solutions variations that would accomplish this.

If you need to purchase one or more wheels, Bricklink is a great site to buy individual bricks.

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Tags: power-functions, wheel
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# Question
Title: Microsoft Robotics Developer Studio & RCX Support?
What is the last version of the Microsoft Robotics Developer Studio that supports the RCX?

The Wikipedia link (http://en.wikipedia.org/wiki/Microsoft\_Robotics\_Developer\_Studio) indicates RCX was dropped in the "latest" version but doesn't indicate what version.

# Answer
I'm not an expert on Robotics Developer Studio, but the phrase indicating that support was dropped in the latest version was added in July 2008, so you'll need to go back to version 1.5 in order to have RCX support.
> 1 votes

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Tags: rcx
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# Question
Title: How do you eliminate the gap between castle doors?
I'm building a MOC castle and want to use a pair of 1x5x7 and 1/2 stockade doors. My problem: I can't get the doors to fit flush. Either there's a 1/8 to 1/4 inch gap between them, or they overlap. Are there published instructions from a castle Set which show how to set them flush? Or, can someone please explain how to solve my problem? Thanks so much.

# Answer
> 9 votes
I'm assuming that you are referring to this door:

These doors are designed for the hinge to attach from the back of the door and not the side, which might be what is tripping you up. There are ways to get these to line up with the hinge on the side, but the easiest fix is to just have them hinge from the back.

This part is used in many sets including 7036-1 Dwarves' Mine. Here's an example of this part in use from the instructions for that set:

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Tags: building
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# Question
Title: Is my Lego Star Wars "Jabba's Sail Barge" set a one of a kind?
Back in 2006 or 2007 I bought a Lego Star Wars "Jabba's Sail Barge" set. When I opened it and took out the instructions, it had an additional piece of paper. It showed that the piece 4299023 had been replaced with a normal solid piece. I am writing to ask if this makes the set I own worth more, as it is rarer, and is it desirable ?

# Answer
> 6 votes
The short answer is **no**, this does not make your set more valuable.

You have recieved a set that contains what Bricklink calls an "Alternate Item". These are alternate pieces/stickers/colors/etc. that are packaged into normal sets by LEGO in order to ship out the sets in the event of a part shortage. They are perfectly normal. And, usually, they are more common pieces than the pieces they replace, so there is no added value for the part.

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Tags: piece-information, star-wars
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title: Absolute Turning Motor in NXC

text:
# Question
Title: Absolute Turning Motor in NXC
How can I turn my motor **to** 123 degrees, not **for** 123 degrees?

I tried the `PosRegSetAngle("output", "angle")` command and didn't work.

Documentation for PosRegSetAngle

# Answer
> 2 votes
PosRegSetAngle should set the position of the motor relative to the position the motor was in when regulation was enabled. In what way didn't it work when you tried this?

It sounds like you may be asking how to wait for the rotation to finish. I'm not sure if there is a built-in way to do this in NXC or not, but I think that something along these lines should get you there:

```
# Enable regulation
PosRegEnable(OUT_A);

# Set target angle
PosRegSetAngle(OUT_A, 123);

# Busy loop while the motor turns
while (GetOutput(OUT_A, ActualSpeedField) != 0) {}

```

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Tags: nxt, programming, motor, nxc
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# Question
Title: What RGB-values do I get from the colorsensor
I have the extra colorsensorblock used by mindcuber \- ColorSensorRGB - installed. Now I'm trying to use it in my own projct. But what values does it produce?

It seems like it has a **min**-value of 0 (as expected), but some testing gave me a **max**-value of 395 (I was expecting 255).

What is the range of values delivered?

# Answer
The returned values are the reflected light intensities for each of the three LED colors (red/green/blue).

The scale is actually 0-1023. Basically, this is the raw value returned by a 10-bit analog to digital converter in the color sensor (2 ^ 10 = 1024).

The LEDs themselves may not put out enough light that you could ever reach the maximum value, so you will have to calibrate the sensor accordingly. For example, your calibration could consist of holding the sensor close to a white sheet of paper and finding the maximum value for each color, then use those maximum values to normalize the actual sensor values to a scale of 0 to 100%.
> 3 votes

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Tags: ev3, sensor-colour
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title: Where is this turban headpiece from?

text:
# Question
Title: Where is this turban headpiece from?
Where is this turban headpiece from?

# Answer
> 4 votes
I believe that this is a non-LEGO custom turban piece:

It is manufactured by BrickForge and is available for purchase directly from them. It's currently not available in Sand Green though, so if you're hoping to get your hands on this exact piece, you'll need to check BrickForge resellers or secondary markets such as Ebay.

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Tags: part-identification, minifigures
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# Question
Title: What is the best way to create an authentic weatherboard wall?
I am working on a house where I want to create a weatherboard look for the outside walls. I'm not certain the best way to go about this.

Currently I'm using the horizontal side of a 1x2 profile brick:

Which gives the following appearance:

I am wondering though if there are any better techniques to create the weatherboard look:

It seems that the 1x2 profile brick has its ridges roughly twice as dense as a true weatherboard exterior.

One advantage of these profile bricks is that their reverse side gives the interior a VJ (tongue and groove) look, which is the interior look of the house that I am trying to model.

However, the lack of anything larger than 1x2 and the overly dense ridges means that I'm leaning towards looking for other options.

# Answer
One option would be to use the relatively new bricks with masonry profile:

If you aren't aware, the reverse side of these bricks includes the horizontal lines but leaves out the vertical ones. This allows you to create something like this:

This solutions provides the advantage of less dense horizontal lines, but being that this is a newer part, it also really limits your color selection.

Your pictures make it look like you are trying to build a white house, which is currently impossible using this part as it isn't available in white. The best that you could do is light gray, which is what I used in my example.

There is a 1x4 version of this part that would make construction much easier and sturdier, but it's only available in medium dark flesh at the moment:

This construction also leaves you with a brick pattern on the inside of your wall. It doesn't sound like this is what you want. One solution would be to create a double wide wall, but that may not be feasible in your case.
> 2 votes

# Answer
There are a number of brick-intensive approaches to this. Here's a few:

This flickr user (Andrew) has an example, but the "how to" image on the next slide is hard to figure out: https://www.flickr.com/photos/8215600@N03/5223554342/in/photostream/

This is one for a roof, but the same technique could be used for a wall: https://flic.kr/p/a3PcXk

Also, I suggest taking a look at the Lego Techniques Flickr group for different wall techniques: https://www.flickr.com/groups/788191@N24/
> 1 votes

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Tags: building, design
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