Interesting color choices

[meeotch]

I have noticed with many of the larger sets that there tend to be some strange choices for colors on some of the interior elements. This is especially true when the set is built on a techinic frame. So I guess there will probably be a few different reasons to be given as to why the color of some of the internal elements to be so arbitrary. Specifically:

Are the pieces that are designed to couple 2 axles together different colors for different sizes to aid in not puting the wrong angled piece on while building? (I'm sure it is, so I'm knocking this one out of the way first.)

Does the above question also explain the different colors used for the axle pins?

Why are some technic beams included that are such arbitrary colors like red, blue and yellow on a set that doesn't otherwise include those colors and doesn't seem to be terribly necessary at least as far as easy identification of the piece while building goes?

and the reason I decided to finally ask the question:

I'm currently building the Death Star II and I sorted out the pieces pre-build. I saw while sorting that 4 green 2x2 plates were included along with quite a few of the light bley 2x2 plates. Why would green ones be included, instead of just four more light bley pieces?

[Athos]

I think the reason has been previously given as: (1) surplus of parts in that color; and (2) it gives kids more colors, which they like.

Steve

[Draykov]

I think Steve has also mentioned in the past that brighter colors stand out better on instruction sheets, so overall, this method can contribute to a less frustrating build process for youngsters.

[meeotch]

I understand the above reasons, but in this case, I'm talking about building the UCS Death Star II. While there isn't anything explicitly against youngsters building it, the originally 300 dollar MSRP and sheer size of the set means very few will actually get it, meaning that at least for this particular set, the two largest groups of people buying it are those looking to display it (meaning the internal pieces won't be seen) or people looking to up their collection of bley, meaning the 4 green plates wouldn't really be a selling point.

[theJudeAbides]

Are the pieces that are designed to couple 2 axles together different colors for different sizes to aid in not puting the wrong angled piece on while building?

This doesn't answer your question, but...
I'm assuming you're talking about pieces like this and this. Here's a fun fact that I recently discovered: each of these types of elements has a number on them that corresponds to their given angle:
1 - 0 degrees
2 - 180 degrees (PI radians)
3 - 157.5 degrees( 7/8 PI radians)
4 - 135 degrees (3/4 PI radians)
5 - 112.5 degrees (5/8 PI radians)
6 - 90 degrees (1/2 PI radians)
You can use these numbers to determine which type of angle you should use.

Does the above question also explain the different colors used for the axle pins?

To determine an axles length, place it alongside a brick or plate and see how many studs it spans. For example, if it spans 4 studs, it is a 4-length axle. LEGO's method of coloring axles is actually quite simple: even-length axles are black while odd-length axles are light-grey. (Also, axles with stoppers or other weird things are usually dark grey.) The only exception to this is 2-length axles which are increasingly being made in red (I suspect this is to help differentiate them from black technic pins). This is actually a nice way to help differentiate similarily sized axles. For example, while it's fairly easy to differentiate a 4-length axle from a 6-length axle, it isn't as easy to differentiate a 4-length from a 5-length without examining them closely side by side. Making them different colors makes sense.

If you've ever wondered why some technic pins are light grey while others are black, there is a reason: black technic pins have something called "friction ridges" on them while grey ones do not. What does this mean for you as a builder? If you connect a tire using a grey pin, it will rotate freely and quickly, but if you connect it using a black pin, it won't spin nearly as easily, due to the increased friction due to, you guessed it, the "friction ridges."

The moral of the story here: LEGO likes to use different colors for pieces that look very similar but function differently. This helps us, the builders, differentiate between pieces when we're assembling the set.

[Walter Kovacs]

To answer the specific question about the green 2 x 2 plates in the DS II, theose plates are specifically usd during the construction of the superlaser. In a subsequent step they are removed, similar to the yellow technic beam in the V-19 set. The plates are green for easy identification on the removal step, likely.

[meeotch]

Yeah, I saw that as I was finishing up that set a couple days ago, I thought it was really weird. I have never seen parts removed during the build before, and the thing I found really weird is that it didn't seem necessary to add them in the first place to hold anything. But I'm not complaining, I'll take 4 free 2x2 plates!

[huck to flat]

Using these different coloured pecies does this mean it saves money, or is it that it means you get more colours in a set or is it just that they show up better in instructions?

[Flynn]

LEGO's method of coloring axles is actually quite simple: even-length axles are black while odd-length axles are light-grey. (Also, axles with stoppers or other weird things are usually dark grey.) The only exception to this is 2-length axles which are increasingly being made in red (I suspect this is to help differentiate them from black technic pins). This is actually a nice way to help differentiate similarily sized axles. For example, while it's fairly easy to differentiate a 4-length axle from a 6-length axle, it isn't as easy to differentiate a 4-length from a 5-length without examining them closely side by side. Making them different colors makes sense.

If this is true, than it must be a recent change, since many older odd-length axles are in black (Which becomes increasingly annoying with my 3-length axles...).

[speaknspell]

its all about having points of reference. a model that is just a sea of gray or worse yet...black is impossible to build without something to go off of. Also on some of the more complex elements like technic elements its proven that younger children really can't tell the difference between them without color coding.

Steve