Construction Machinery Jenga

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7 Responses:

    • ardgedee says:

      Could be but not necessarily. Most of those trucks are doing exactly what they're designed to do, but with freshly-felled trees or tall pallet racks or bridge abutments, rather than giant probably-hollow Jenga blocks.

      My problem with the video is "Built For IT Trials" means something totally different in my professional sphere. The closest these trucks will get to an IT trial is severing buried network cables.

      • Jeremy Leader says:

        I don't think they're hollow. The video claims the blocks are 600lbs each, which seems only a little light for what looks like roughly 8 foot long blocks, glued up out of 3 by about 20 2x6 planks.

        • Richard says:

          The blocks are 22 planks wide by 3 tall (@0m28s)
          The block length is triple the block width (@0m00s)
          The planks are about 4x as tall as they are wide.

          If the planks are "2x6" (which in crazy USAian means 1.5 inches by 5.5 inches, ie 0.04m x 0.14m), the volume of the blocks is 0.88 m^3.

          Douglas fir (semi-arbitrary choice) wood has a density of ~ 550 kg m^-3, which would give a block mass of ~ 486 kg, or far over (+78%) the 272 kg claimed @0m28s.

          However your "2x6" plank dimension does seem on the money, given that the tine width of Caterpillar pallet forks is 4 inches and eyeballing @0m36s.

          Constructing hollow blocks seems beyond the call of duty for this application.

          So it must be some low density wood, on the order of 300 kg m^-3.

          http://www.engineeringtoolbox.com/wood-density-d_40.html suggests cheap white pine could almost be the ballpark, at its fluffiest end.

          You're welcome.

          • jwz says:

            Slow Clap.

            Absolutely sincere.

          • nooj says:

            Neat video.

            Yeah, I think you're right on the size. There are only two actual planks across, though; they alternated 2x6s and 2x12s for overlap (0m45s, 0m51s).

            There are no visible nail heads, hammer strike marks, or screws/bolts holding the wood together. So it's surely glued, face-to-face, which would be very easy to do by machine. Individual boards were spliced pre-gluing to make the full length (1m36s, look for the glitch in the grain pattern in the top 2x12, but not to bottom 2x6). Splicing for length is cheaper than finding so many long boards, especially with a constructed beam.

            The sides and faces of the blocks are very smooth, with an accurate width and depth. They were probably jointed and planed to size after gluing. I think you can see the jointer/planer marks at 0m54s; there is a "fuzziness" along the entire depth of the block, that crosses all 22 slabs. This indicates an effect after gluing, not due to the slabs. But don't quote me on the jointer marks; it may be a trick of the lighting.

            In addition to being jointed, it was probably made in a compression jig. That's a big goddamn wooden beam, but nothing a bunch of plywood and clamps couldn't handle. If not compressed in a jig, I would expect to be able to see thinner boards on the top and bottom from where the planer cut a noticeable amount of wood in some places. But I didn't see evidence of that.

            I would be surprised if they used anything but the cheapest, easiest pine available, which would be low density, untreated, uncolored, etc. Hollow blocks would be a big surprise. Much higher construction cost to save a few pennies on trash wood.

            A low density wood you would expect to be easy to score (ie, mar, scratch). Scoring visible on both top layer blocks at 0m50s, and no hammer strike marks visible anywhere.

            So they bought a shitload of 20' (6m) boards, 600 each of 2x6s and 2x12s, at a cost of maybe $10-20K ($35-40K retail without a volume discount). They were stacked in some kind of makeshift jig with spray glue between layers. After the glue dried and the clamps were removed, they hummed off the sides to exact specs with a garden-variety industrial planer and cut to length with a chop saw. The corners were rounded last.

            After the video was shot, the wood was reused for some other purpose, I'll bet. That's a lot of nice wood to just turn into particle board.

            I suppose the use of the ever-irritating backup beep as a "tasteful" closing tone was an unavoidable propaganda freebie.

            And I gotta say, that excavator wasn't even trying to win at the end! It's like he was being deliberately risky for entertainment value.

  1. nooj says:

    There's a making-of, though it doesn't add much: html

    One thing they say is they waxed the shit out of the blocks with shuffleboard wax so they would actually slide, which I should have realized right away.

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