Peppermint_M

How tall can a Lego tower get?

17 posts in this topic

Thanks, Peppermint_M. That was a fascinating read.

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I'm having a tower building competition at my daughter's birthday party this weekend - i'm thinking of asking this as a question for the 8 year olds for a bonus mark.

Of course the supplementary question (for the BBC) should be "How much would the Lego cost to build that tower?"

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Given the way the brick pancaked, I wonder if building with plates would be better or worse. Plates should take a lot more to crush because the voids between interlocking plates are much smaller and the shorter side walls should only translate about 1/6 as much torque to the corners. On the other hand, you'd need three times as many plates to build to the same height as you would with bricks, so although you're able to support more weight, you also need to add a lot more weight to get the height.

It's an interesting problem. If I had to guess, I'd suspect that the tallest possible tower wound consist of stacked plates at the base, giving way to stacked bricks further up once the remaining height of the tower dropped below the crush load of the bricks. I'd test it out but I seem to have left my hydraulic press in my other pants...

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Using plates seems like a good idea, but you also stand to triple the area-loss ratio from stud/tube clutch. Clutch works by microscopic difference in space under the brick to space taken up by the studs.

Not a problem with an average sized build, a massive issue when spread or stretched over a greater expanse.

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According to the article, the brick was placed between 2 metal plates, one below, one above. So the load was on the studs. A metal plate with stud-size holes placed atop the brick, so it would rest directly on top of the brick, not on the studs, would make a more accurate test, as the load would be more directly transferred to the outer walls and center tube of the brick.

Look at the bottom of a 2xN brick; you'll see ridges where it grips the studs of the brick below. Older bricks have full-thickness walls. Plates still do to this day.

Plates may be stronger because of their greater wall thickness, though their greater weight per unit volume has to be considered, as mentioned already. Another way plates my win out, is that a wall 1/3 the height (and same thickness) is less likely to buckle. The biggest strike against plates, is that they add material horizontally. The key is to add material vertically. 1x2 bricks may be perfect for this. That, however, would mean building double-tier walls, with rowlock courses every few courses, to unify the 2 tiers.

Check this website for what I mean by "rowlock course" (enlarge first step image).

To those of you that have access to a hydraulic press and a load cell:

Probably the best way to test, is to build a small tower out of a bunch of 1x2 bricks you don't mind mushing together.

Maybe 12x12 studs, 9 courses, rowlock on the 2nd and 8th courses, and an additional course of 1x2 tiles, to eliminate the need for a custom metal plate. Or nix the tiles and shave the studs off the top course.

Then get out the camera and notepad, and document the whole experiment from start to finish.

Edited by splatman

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Question: when using plates, do the studs of a plate touch the horizontal wall of the plate above?

If so, I'd go for 16x16 plates :D

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I did a similar test today at work. I have attached data and pictures.

As you can see the studs are pressed in to the brick and then i collapses.

Tomorrow I´ll retest with a tile on top and a plate on the bottom.

(I had to make the images really small due to the 100kb attachment limit)

post-16650-0-14142100-1354743456_thumb.jpg

post-16650-0-32154700-1354743462_thumb.jpg

post-16650-0-20108300-1354743474_thumb.jpg

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I did a similar test today at work. I have attached data and pictures.

A real LEGO-nerd would be able to tell which bricks was tested, looking only at the force/deformation graph :sweet:

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I am impressed! (Both that you carried out that experiment and that I could read the graphs despite not doing materials testing in about three years...) I wonder what other brands end up lokoing like/ failing at.

Oh and Hrw, only Brits can listen to the BBC radio on i-Player but the BBC online magazine is golbal access and more succinct with photographs etc...

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Ah that is frakking beautiful. Love all it takes is a few AFOLs to blast some holes into hours of research. :laugh:

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Here are the results from test 2.

I think that test point 3 in the first graph is a non-LEGO brand brick.

One interesting reflection is that its not that easy to calculate the maximum height of the tower. Although the maximum force the brick can withstand is ~4400N it has deformed ~2,2mm at that time. That's almost 20% of the bricks height.For an accurate height you have to look at each individual brick and determine how much weight its subjected to and subtract the corresponding deformation,

1x2.jpg

2x2.jpg

Edited by Swe_Mckvack

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Very interesting graphs. Have you tried just a plate-tile combination to see the effect (if any) of short (plate) side walls v. tall (brick) ones?

I suppose the next questions would be whether particular color dyes impact material strength and whether long term UV exposure degrades plasticity.

Another interesting test would be to see what trans-clear parts do, I _think_ those are polycarb elements rather than ABS. If you test that though, keep your distance. From my ( limited and unintended ) experience, clear parts tend to snap/shatter rather than deform when over stressed.

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I did a test with 2x2 plate modified and after the initial deformation of the top stud, nothing happened to the actual plate. So the plate configuration will tolerate above 5000N with is the limit of our current load cell.

Regarding the UV-testing I actually have access to one :classic: .

The problem is that its running a outdoor test at the moment but sometime next year we will run a indoor simulation and then I can do a complete test of different colors and materials if there is any demand for it.

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