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Movable Crane out of Wood?

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  • #16
    i made a tripod of three 12' 4x4 pieces of pressure treated lumber. i welded up metal cages about 10" long to fit over the ends of the 4x4s, and they each have a tab sticking out. the tabs all come together in the center at the peak and i put a 5/8" bolt through them to hold them together. i've used it to lift a bit over 1000# and i back my truck under it. it just clears the sides of the bed.

    i've never noticed any flexing or problems, but i wouldn't stand under the thing, that's for sure.

    i was just thinking about it a day or so ago and i think i am going to weld the three 10" cages into a single unit, and just stick the 4x4s into it when i need to set it up. that removes one failure point (the 5/8" bolt) and makes setup a bit easier (you don't have to find a friend to help hold the three pieces together while you try to stick the bolt through the three tabs).

    use this idea at your own risk. i can't be responsible if it collapses on you or your vehicle.

    andy b.
    The danger is not that computers will come to think like men - but that men will come to think like computers. - some guy on another forum not dedicated to machining

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    • #17
      <font face="Verdana, Arial" size="2"> i made a tripod of three 12' 4x4 pieces of pressure treated lumber....................... i've used it to lift a bit over 1000# and i back my truck under it. it just clears the sides of the bed. </font>
      Andy B. ,that's a hell of a good idea. Maybe some simple 1" flat bar strapping the bottom of the tripod would guarantee that the legs wouldn't spread out and give an extra safety margin.
      Anybody got an idea of the load capacity of Andy's contraption? I have to move a bunch of machinery out of my garage and bring it to my other house and to my shop. Building 3 of these gizmos would save a lot of time and some $$$ .
      I like that idea..........elegant and simple..

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      • #18
        gin poles used to be the same, in a barn a piece of hickory or good wood with a iron end on it. Makes the end much stronger. IN my old shop I had 12"x 1/8" wraps around 4x4 posts to support a 12" ibeam in the ceiling. I welded them around the posts. Nailed them with a hundred nails.

        Wood that is structurally sound will hold enourmous weight for it's given weight per strength. Unfortunatly, there is not a true consistiency. Metal is uniform. It is not allowed to deflect much strengh can be had. even a 24" I beam will deflect.

        THE URL Forrest posted I printed the page out. Having the measurements can help make your own.

        OUR aframe at the shop like I said is made of boiler tube, thicker than exhaust tubing but thinner than waterpipe. A double rail top with sheetmetal zig-zags. WHen it was outside it was much stronger, the legs buried up in the ground anchoring themselves. Inside the legs on the "rollers" skate around making themselves much weaker. With a proper legs design, a thin pipe or double 2x12's would hold much. I have lifted engines with 2x4's. A good one or a bad one will show itself thou.

        The boiler tube aframe weighs less than 200 pounds. You can Mig the thin tubing and get proper penetration. If I worked a job where I had ready access to the boiler tube I'd come up with a good design. It was made to lift a electric motor where a crane has no access.

        Even with a Ibeam in the ceiling you worry. I keep expecting to pull the ceiling down in my shop. I have the Ibeam sitting on the double 2x12's over the shop double door with a foot cut in it and bolted to the wall, going across the bay it is too short to go to other wall but has a 2x4 rect tubing legs that go out to interior walls and rest on them. One of the interior walls was tore out when the big lathe fell over as I was moving it by myself. It didn't fall then.. so? Am I lucky or a good engineer? Sometimes that is the question.

        Large diameter tubing is much stronger per weight than ibeam. Ibeam is designed to accept a directional load against the web, turn a long one sideways and you bend it.

        Whatever you build, perodically test it before trusting it.

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        • #19
          Dig around and see if you can come up with a website(I have their printed material)on the American Plywood Assoc......you're looking for plywood beams.Much usefull info.You'll be shocked at some of the impressive engineering data.

          One redneck trick we use for temporary supports is Safeway metal scaffolding.You can practically pick up a small car with them.They also have wheels and can be rented fairly cheaply.We even use them for form supports for suspended concrete applications.

          Just be dang carefull with whatever you decide(am sure you will),don't get hurt trying to save a cpl. hundred bucks.Best of luck,BW

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          • #20

            So this is American progress.

            The Romans did it- and if I can vaguely remember the Good Old Days, the Greeks did it to turn invading warships over.

            Wow!!!!!!!!!

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