Wood rack failure

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  • dlminehart
    Veteran Member
    • Jul 2003
    • 1829
    • San Jose, CA, USA.

    Wood rack failure

    Well, I can report that my rack, made with 3/4" galvanized pipe embedded in 2x4s, has its weight limitations. After piling on a half dozen 8' particle board shelves, along with about a dozen 2x4s, the ends of the pipe bent and also the wood at the bottom front of the holes compressed. Result: spilled the load of wood. Luckily, it was the bottom shelf, so it didn't have the effect of bringing everything down. I'll redo, but not sure how. Less weight, bigger pipe, whatever.
    - David

    “Be yourself; everyone else is already taken.” -- Oscar Wilde
  • gmack5
    Veteran Member
    • Dec 2002
    • 1973
    • Quapaw, Oklahoma, USA.
    • Ryobi BT3000SX & BT3100

    #2
    Try putting a reinforcing "gusset" under the shelf support pipes, maybe just on the bottom shelf (reserved for offcuts) and support your longer wood on the pipes only (no shelf as such), spaced, at the minimum, every 32".



    Stop thinking why you can't and Start thinking how you CAN!
    Remember, SUCCESS comes in CANS!
    George

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    • LCHIEN
      Internet Fact Checker
      • Dec 2002
      • 20913
      • Katy, TX, USA.
      • BT3000 vintage 1999

      #3
      quote:Originally posted by dlminehart

      Well, I can report that my rack, made with 3/4" galvanized pipe embedded in 2x4s, has its weight limitations. After piling on a half dozen 8' particle board shelves, along with about a dozen 2x4s, the ends of the pipe bent and also the wood at the bottom front of the holes compressed. Result: spilled the load of wood. Luckily, it was the bottom shelf, so it didn't have the effect of bringing everything down. I'll redo, but not sure how. Less weight, bigger pipe, whatever.
      You have a trmendous cantilever considering only 1-3/4" (I'm guessing here) is in the vertical 2x4.

      Two questions:
      How long was the portion of the pipe hanging out with load on it,
      and how sloppy was the hole (and did you use an angle on it).

      The load on the very edge of the hole is massive if the hole is oversize but the entire hole supports the pipe if the hole is close-fitting. Thats because the edge is the fulcrum for this lever.

      Obviously, the longer the arm the more force multiplication on the fulcrum.

      Using an angle doesn't help the strength any but if the pipe bends and the wood slides to the outside then the leverage increases creating a cascading failure. A slant will help keep the wood on even if it bends a little.
      Loring in Katy, TX USA
      If your only tool is a hammer, you tend to treat all problems as if they were nails.
      BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questions

      Comment

      • dlminehart
        Veteran Member
        • Jul 2003
        • 1829
        • San Jose, CA, USA.

        #4
        Gussets sound like a good idea. Maybe I'll try those metal guard plates used for protecting wiring going through studs, since they have built in "nailing" capability. Or those joist hangers, that use actual nails.

        I had about 16"-18" hanging out with load center of gravity about 40% of the way out from the wall. The holes were pretty tight, with a 5 degree upward angle. The other ones, without the heavy particle board shelving, still look pretty good.
        - David

        “Be yourself; everyone else is already taken.” -- Oscar Wilde

        Comment

        • Jim Boyd
          Veteran Member
          • Dec 2002
          • 1766
          • Montgomery, Texas, USA.
          • Delta Unisaw

          #5
          I went with 3/4 black pipe at 10 degrees and 3 1/2 inches in the stud with mine. They have been holding ALOT of weight for a couple of months now with no problem.
          Jim in Texas and Sicko Ryobi Cult Member ©

          Comment

          • dlminehart
            Veteran Member
            • Jul 2003
            • 1829
            • San Jose, CA, USA.

            #6
            Mine were in 2x4s bolted from the outside of my garage to the studs through my siding. Since there was no lateral bracing, I opted to use them with the wide side of the 2x4 against the wall, allowing only about 1-1/4" depth. Perhaps I should rethink that as well, using the narrow side of the 2x4 against the wall with some horizontal 2x4s between the vertical ones to keep them from twisting under load.

            If I'm doing the verticals oriented this way, I might as well just use protruding lengths of 2x4, supported with gussets on the sides, instead of the pipe.

            Back to the drawing board, in any case.
            - David

            “Be yourself; everyone else is already taken.” -- Oscar Wilde

            Comment

            • bmyers
              Veteran Member
              • Jun 2003
              • 1371
              • Fishkill, NY
              • bt 3100

              #7
              Loring, I was expecting you to have some math to support your opinion in there. Didn't see any.... I thought you would have estimated the 2x4's and particle board down to within a few pounds (only because the original post didn't include relative humidity)...



              Bill
              "Why are there Braille codes on drive-up ATM machines?"

              Comment

              • LCHIEN
                Internet Fact Checker
                • Dec 2002
                • 20913
                • Katy, TX, USA.
                • BT3000 vintage 1999

                #8
                quote:Originally posted by bmyers

                Loring, I was expecting you to have some math to support your opinion in there. Didn't see any.... I thought you would have estimated the 2x4's and particle board down to within a few pounds (only because the original post didn't include relative humidity)...



                Bill
                No numbers given, no math possible.
                Loring in Katy, TX USA
                If your only tool is a hammer, you tend to treat all problems as if they were nails.
                BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questions

                Comment

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