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Bending a Scaffold Pole

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  • Bending a Scaffold Pole

    Looking for some "how-to" suggestions here...

    I am building a shade for a patio. It'll consist of standard diameter (48.3mm) scaffold poles up to 5m in length used to keep shade netting panels stretched tight. The panels have eyes every 15cm or so, and these are attached to the scaffold poles by hefty rubber rings and S hooks. There's a fair tension in each of the rubber rings, enough to keep the panels taut. Maybe 5 or 10Kg.

    I have seen similar arrangements, and in many cases, the scaffold poles get bent inwards by the rubber rings. Although this doesn't matter from a structural point of view, it doesn't look nice (my OCD kicking in again).

    So I would like to pre-bend the scaffold poles outwards, such that when the rings are in place, they pull the scaffold poles nice and straight. The amount of bend isn't much - about a diameter, a diameter and a half over the entire length. I only need to bend one pole of 5m length - the others are all clamped to walls and can't go anywhere.

    Any thoughts on how to do this? I thought of running a bead of weld down the length and *hoping* it bends the right amount, not sure. The hard part is getting an even bend along the entire length.

    Ideas?

    Ian
    All of the gear, no idea...

  • #2
    How about an oxy/fuel torch? Look up heat straightening. Such a gentle curve should be easily done I think.

    Is the material galvanized? Might need to clean off the zinc before heating or welding.

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    • #3
      Set the poles at a slight angle to begin with. No need to bend. I assume you are not going beyond yield point.

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      • #4
        Weld straight beads along the length. The more you weld, the more it bends. The weld doesn't have to be continuous. If you make clean and low welds, it will just look like part of the pipe. Paint for weather resistance.

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        • #5
          The material is indeed galvanized; they're standard scaffold pipes.

          If the poles were cantilevered from the wall, I'd indeed set them at an angle. In this case, however, they're effectively pin jointed at their ends. To bend them, I think I'd need to go just past yield point, or they'll spring back straight again. Scaffold pipe is remarkably resilient when you don't want it to be!

          I was thinking about grinding the zinc off a narrow strip along one side and running a bead along the poles with my MIG. Doing short stitches is a good idea, that way I can build up more of a curve by filling the gaps in.

          Ian
          All of the gear, no idea...

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          • #6
            The short stitches with spaces between will give you your curve through a series of small kinks. But the eye will never see that. And as mentioned after the first set of these cools off and shrinks if it's not enough just do a second series of short stitches between the others.

            Maybe start out with one inch stitches ever 6 inches? Or even 1in every 8 inches? If that's not enough of a curve fill in additional 1inch long stitches between those? It shouldn't take much to get what you're after.
            Chilliwack BC, Canada

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            • #7
              Just support the ends with blocks and step on the middle with your feet. If you aren’t heavy enough find a friend or two. The block height can be adjusted so you don’t overbend. I done all kinds of pipe straightening this way.

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              • #8
                Originally posted by garyhlucas View Post
                Just support the ends with blocks and step on the middle with your feet. If you aren’t heavy enough find a friend or two. The block height can be adjusted so you don’t overbend. I done all kinds of pipe straightening this way.
                I use this same method to straighten or bend steel, but use my truck and a floor jack to supply the weight.
                The truck tires don't mar the steel.
                Larry

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                • #9
                  Originally posted by garyhlucas View Post
                  Just support the ends with blocks and step on the middle with your feet.
                  But by application of a point load midspan, you are likely to get a pronounced bend at that point rather than a more graceful curve the full length of the pole.

                  If you have the kit, imagine making a 5m long longbow.

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                  • #10
                    I am doubtful that prebending will give the result you desire. I think the pipe will need to be stiffened but putting something inside it.

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                    • #11
                      I would try heat straightening with a oxy fuel torch before welding. More controllable and don't need to clean up after.

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                      • #12
                        Originally posted by The Artful Bodger View Post
                        I am doubtful that prebending will give the result you desire. I think the pipe will need to be stiffened by putting something inside it.
                        Why do think this? In buildings, the beams are very often precambered upwards so that as the dead and live loads are applied, the precamber drops out and they become level.

                        Even if stiffened, the pipe will still deflect, just less than an unstiffened one.

                        His idea is the correct one, to precamber the member so that when the working load is applied, it becomes straight.

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                        • #13
                          Don't weld, or apply heat to a galvanized pole - not because of the zinc fumes (although that is a concern), but because you don't want to compromise the coating. Find a tree with a V shaped crotch and put the pole in the V and bend away. Doing it manually like this helps you control the amount of bend and where the bend is. You can make a series of small adjustments until you get the deflection you desire.

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                          • #14
                            Originally posted by djc View Post
                            Why do think this?
                            The difficulty of getting the exact prebend.

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