1×6 arches: direct comparison

The new-style raised arch (to the left, 92950) got introduced in 2009, and has been gradually replacing the old-style arch (to the right, 3455) across the board. However, after four years, not only haven't I run into a single set where it was structurally a necessity, but it also actually looks worse in all the sets I own. So I find myself constantly replacing new-style arches with old-style arches.

Wheel well VW bus

Just one of many examples: the wheel well of the VW Camper Van. The raised arch introduces a questionable corner on the back side, and an utterly hideous bump on the front side, both of which are completely uncalled for. Replace the new arch with an old-style one, and suddenly the curve is perfectly smooth on the back side all by itself, and on the front side you can easily make it smooth as well by putting that cheese slope onto a headlight brick with a 1×1 plate, thus effectively moving it ½ plate back.

Now, I understand that in the Tower Bridge, say, the old arch wouldn't work for the middle windows, as it is just a bit too low the way they are designed. However, here's the punchline: the new arch is a bit too high, introducing a gap that doesn't look right. In fact I only got rid of it by raising the middle windows by ½ plate, using some SNOT magic. That can hardly be the point.

So, has there been any kind of official statement explaining the redesign of this part? Or, failing that, do you own any sets that absolutely require the new-style arch for structural reasons?

  • If I remember correctly, the old arch (the right one) is empty inside, so if it's placed on another brick the studs would go inside. Is the new one also empty?
    – Voitcus
    Commented May 9, 2013 at 12:03
  • @Voitcus: yes, it is empty as well. In fact if you look at them from the bottom at a straight angle, the two parts look absolutely identical.
    – RegDwight
    Commented May 9, 2013 at 12:06

3 Answers 3


Although I can't think of any sets that make use of this technique, I have found that the Slope, Curved 4×1 Double No Studs fits perfectly under the new-style arches.

Slope, Curved 4×1 Double No Studs

  • 1
    That's very interesting, I wonder if LEGO did actually think about it when they redesigned the part. Considering they usually try to consider as much parts interactions as possible, it's not impossible, but we have yet to see a set where they use it.
    – Joubarc
    Commented May 10, 2013 at 6:24
  • 1
    This is fascinating. It never occurred to me to even check this combination. Unlike with 6091 and 6005, which form a useful structure together, this combo here is obviously useless other than for a wall pattern. Most importantly, I first got the slope in Flo’s V8 Cafe, which was introduced only last year where I live, or in 2011 according to BrickLink. In other words, TLG held back the complement to the new raised arch a whopping two or three years. Why that would be, escapes me.
    – RegDwight
    Commented May 10, 2013 at 11:34
  • Ah, but of course we also have the Slope, Curved 2×4×2/3 No Studs, with and without bottom tubes, which got introduced in 2009 and 2008, respectively. Still not a combination that I have seen used anywhere, but at least that's now a whole system of (at least) four parts, and the years start to make sense now. And of course TLG can always build upon this to introduce more parts in the future. Really interesting. Still, going by the year, the 2×4×2/3 slopes must be the actual answer.
    – RegDwight
    Commented May 10, 2013 at 12:08
  • The key word in your last comment is "system" - LEGO likes that all its parts play nicely with each other, regardless of whether they actually use the combinations or not.
    – Joubarc
    Commented May 11, 2013 at 10:51
  • So yeah. If you can add the 2×4×2/3 slopes to the answer, mentioning that they were released at the same time as the arch, I will accept. In fact I can edit that info in myself, if that's too much hassle for you.
    – RegDwight
    Commented May 17, 2013 at 11:23

With a lot of part redesigns, there's usually a factor which is considered very highly by LEGO: cost reduction, and more precisely the amount of plastic moulded.

Another example of this is the way posts under 1 x n bricks are now hollow. I've heard a more subtle one recently: the sides of the Arch 1 x 5 x 4 are thinner than before, which doesn't seem to matter except when you try to attach studs underneath - they don't hold. I tried with some brown arches from Medieval Market Village and I can confirm it. Funnily enough, the part seems to have been redesigned again since then.

Of course, LEGO probably won't redesign a part just for that reason alone, since creating a new mould is very expensive, so they will most likely do it only when they want to redesign the part anyway or when a mould has to be replaced.

I have no way to know which reason is behind the 1x6 arch change, but it's likely they felt the new design fitted more with the system as a whole - seeing donutsftw's answer, I can't help feeling he may be right. Not only is the interaction between these two parts nothing short of perfect now, but it's possible LEGO has thought of something else that makes more sense with the new arch too.

  • If you mean "cost reduction" by using less plastic, I can't agree with you. I suppose this brick is not very often and less material here seems nothing. However, perhaps RegDwight could compare weights of the two bricks? I'm pretty sure it's not more than 1-2 grams, and as I asked in another question it seems there are larger possibilities to reduce production costs.
    – Voitcus
    Commented May 10, 2013 at 6:39
  • Well maybe that's not the main reason, maybe it never is, but I still believe that if and when LEGO redesigns a part, then they'll usually considers all ways to use less plastic in the part. But yes, I agree that it's unlikely it's the only motive to redesign, especially given the cost of moulds.
    – Joubarc
    Commented May 10, 2013 at 8:35
  • About the 1x5x4 arch, according to comments on this photo LEGO may revert to the old version somewhere in the future
    – Joubarc
    Commented Jun 22, 2013 at 10:21

I don't know, I can't test it, but for me it seems, that in the new arch it is possible to insert a 1/3-high brick (length 4 studs) in the hole, so the studs of the piece would not touch the arch itself.

In the old one it is almost surely not possible (haven't tested). There is of course a question what this should be achieved for.

  • Nope, that's the joke. The recess is only 2/3 of a plate high (or 2/9 of a brick). So the plate sticks out. And you are right that the studs don't touch the arch, so the plate sticks out and doesn't stay in place.
    – RegDwight
    Commented May 9, 2013 at 12:01

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