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How to roll spiral copper tubing?

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  • How to roll spiral copper tubing?

    I am want to build an Archimedes screw out of 3/4 or 1/2" copper tubing.
    A spiral about 8" diameter and fifteen to twenty feet long.

    I have a tubing roller and a hydraulic jack type bender.
    Just can't picture how to get a spiral.

    Any ideas?

    I am sure I will have to fill it with sand to keep it from crushing.

  • #2
    Go slow & at an angle. The spiral will occur & you can just keep rolling & rolling til your arm gets tired. Unless you have a powered roller.

    I would use the tubing roller, but that's what I have in my shop.
    Mark

    I haven't always been a nurse.........

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    • #3
      so you are going to make roughly 10 turns around a cylinder less than a foot tall. just one? if you want it to end up 8" you are going to have to wrap it tighter than that, experiment to figure out how much or wait for someone who knows off the top of their head.

      one way
      slide the end of the tube onto a mandrill fixed tangent to the outside of the cylinder and start walking around an assistant with a blow torch upstream of the bend does not hurt, don't go fast. you may need a cheater on the far end of the tube to finish.
      might be tricky if you do not have 40' of clear space in the middle of your shop an a way to anchor the fixture really well.

      another way is to have a really low back gear on your lathe.
      chuck up your fixture support the other end with the tail stock
      have an appropriately shaped block sliding on the
      ways with a gully to feed the tube in.
      (probably too want to feed the tube in below the carriage height)

      the fixture could be wood and could be "threaded"
      to better support the walls of the tube as it wraps around

      this has the advantage of only needing a narrow path in front of your lathe.

      sure there are plenty of other great methods as well
      --
      Tom C
      ... nice weather eh?

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      • #4
        Why not use clear plastic tubing? It's easier to work with, and you'll be able to see it working.
        Any products mentioned in my posts have been endorsed by their manufacturer.

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        • #5
          You just need to find someone with one of these:

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          • #6
            I assume this coil will not be self supporting and will need some sort of core support?

            I'd try to think of a method of winding it around the core, whatever that will be.

            Dave Cameron

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            • #7
              Wrap the tubing around some 8" pipe, you will of course have to figure out how to hold it and bend it as you go, but the pipe will make a good mandrel.

              rollin'

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              • #8
                shouldn't need to wind the spiral, just keep making circles (they'll self stack) till you have enough for the turns you intend to have. Then stretch it on your support like a spring.
                The loops need to be slightly larger than the core to start (experiment a bit) as they will 'shrink' a bit when stretched.

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                • #9
                  If you have to use copper, use refrigeration copper tubing. It's soft and should have no problem coiling. Besides that, all I gotta say is that is going to be one expensive coil unless it's spread out. Using 1/2" tubing, you'll need nearly 1000 feet of copper tubing for 20' coil. At around $2/ft, you do the math.
                  Last edited by CCWKen; 05-15-2012, 03:36 PM.

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                  • #10
                    I can't even do the math to figure the length required. Not without knowing what the pitch of the coil is supposed to be.

                    Dave Cameron

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                    • #11
                      Copper Coil

                      Do you want a Spiral or a Helix? Get the terminology correct.

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                      • #12
                        Sorry,helix is the right word.
                        I like the refrigeration copper,had not thought of that.
                        The mandrel idea should work .Wrap a hundred feet of copper around a six inch pipe,then stretch the coil to twenty feet and slip it inside an eight inch.
                        Using the six as a center support and drive shaft.I will have to design some type of bearings for the drive shaft.

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                        • #13
                          I think I would go looking for an auger of the correct diameter and then just follow the blade part (at the very least, taking a look at an auger would give you an idea of how tight you want to make the helix). Auger for fence post holes or, what sprung to my mind, auger for moving grain.

                          Somewhere on this site, there was someone (Evan?) who made a rig for turning pickets (wrought iron) and a version of that (with a mandrel as a core) may also work.

                          Got to admit, unless that tubing is carrying something inside it or copper is needed for another reason, seems a bit of a shame to spend the money on copper if an outer casing is just going to cover it up.

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                          • #14
                            While at a friends the other day, I saw that the neighbor had tossed some flexible 2 inch tubing into her yard. It looked like vacuum cleaner hose, except for the bore was smoother and it wasn't spiral, just ridged. The first thing I thought of was Archimedes screw. It might have been just the stuff to make one.

                            Copper certainly has the potential to last, but I think you'd have to make sure it's drained if the temperature would go below freezing. Something else I've wondered about, but not done the math, is the torque requirement for the screw. If you turned it very slowly you could ignore any water friction effects, and if you ignore bearing friction, you're left with trying to calculate based on how much water is in the tube at any one time, and the height to which it has to be lifted before it exits at the top.

                            I suppose there's going to be some ideals involved, which would include size of pipe, number of coils, angle of the assembly, and the height to which the water needs to be lifted. I have not researched any of this.
                            I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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                            • #15
                              Please tell us what you're going to do with this.

                              The cost of the copper tubing plus the inner and outer support tubing will exceed the cost of a decent pump, motor, and electricity to run it for the rest of your life.

                              Filling one hundred feet of tubing with sand is going to be quite a task. Getting it out is going to be next to impossible.
                              Any products mentioned in my posts have been endorsed by their manufacturer.

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