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A great technique for bending tubing.

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  • gplynas
    In our business (building large radio transmitters), we have to wind some large coils of tubing, some tubing as large as one-to-two inches diameter. To
    Message 1 of 3 , Jan 7, 2005
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      In our business (building large radio transmitters), we have to wind
      some large coils of tubing, some tubing as large as one-to-two
      inches diameter. To prevent the tubing from collapsing or buckling,
      pack the tubing full of dry sand first. With the tubing filled with
      sand, I've even made coils at field sites by wraping a 1 inch copper
      pipe around a 55 gallon drum. That is without using a tubing
      bender. A mandrel or tubing bender will help, but the sand will
      help make it a better coil. When you are finished, tap the tubing
      to release the sand.

      Best regards,
      WA5LFY
      Paul
    • Jim Dunstan
      ... Hi Paul: Sounds like fun. Many years ago I was in Arctic servicing a low frequency beacon xmtr and had a couple of young University Students with me ....
      Message 2 of 3 , Jan 8, 2005
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        At 01:42 AM 1/8/05 +0000, you wrote:

        In our business (building large radio transmitters), we have to wind
        some large coils of tubing, some tubing as large as one-to-two
        inches diameter.  To prevent the tubing from collapsing or buckling,
        pack the tubing full of dry sand first.  With the tubing filled with
        sand, I've even made coils at field sites by wraping a 1 inch copper
        pipe around a 55 gallon drum.  That is without using a tubing
        bender.  A mandrel or tubing bender will help, but the sand will
        help make it a better coil.  When you are finished, tap the tubing
        to release the sand.

        Best regards,
        WA5LFY
        Paul              

        Hi Paul:

        Sounds like fun.  Many years ago I was in Arctic servicing a low frequency beacon xmtr and had a couple of young University Students with me .... I remember one of them found a frozen rabbit carcass and for some crazy reason tossed it into a large copper coil in the antenna shack at the base of the tower.  The rabbit fired up and the xmtr went off the air .... prematurely hi hi ..

        We also had other uses for coiled copper tubing .... attached to threaded fittings on a pressure cooker hi hi ..


        Jim Dunstan, VE3CI
        Thunder Bay, ON

      • gplynas
        Jim, For 18 years I worked for a company designing low frequency navigation beacons and shipping them to places like the Alaska pipeline route, so that might
        Message 3 of 3 , Jan 8, 2005
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          Jim,
          For 18 years I worked for a company designing low frequency
          navigation beacons and shipping them to places like the Alaska
          pipeline route, so that might have been one of mine that cooked the
          rabbit, although most were no more than 100 Watts. The coils that
          we make now are for transmitters in the 100,000 to 600,000 watts
          range and we pump water through the coils to keep them cook. The
          guys that bend those coils are artists, but the general technique is
          as described except that they have some very large lathes to slowly
          roll the coils. For home construction, creating a wooden frame to
          act as a mandrel, packing the tube with dry sand, sealing the ends,
          and then bending around the mandrel is a straightforward way to get
          a smooth loop. No scrap copper.
          Regards,
          Paul Lynas



          --- In loopantennas@yahoogroups.com, Jim Dunstan <jimdunstan@r...>
          wrote:
          > At 01:42 AM 1/8/05 +0000, you wrote:
          >
          > >In our business (building large radio transmitters), we have to
          wind
          > >some large coils of tubing, some tubing as large as one-to-two
          > >inches diameter. To prevent the tubing from collapsing or
          buckling,
          > >pack the tubing full of dry sand first. With the tubing filled
          with
          > >sand, I've even made coils at field sites by wraping a 1 inch
          copper
          > >pipe around a 55 gallon drum. That is without using a tubing
          > >bender. A mandrel or tubing bender will help, but the sand will
          > >help make it a better coil. When you are finished, tap the tubing
          > >to release the sand.
          > >
          > >Best regards,
          > >WA5LFY
          > >Paul
          >
          > Hi Paul:
          >
          > Sounds like fun. Many years ago I was in Arctic servicing a low
          frequency
          > beacon xmtr and had a couple of young University Students with
          me .... I
          > remember one of them found a frozen rabbit carcass and for some
          crazy
          > reason tossed it into a large copper coil in the antenna shack at
          the base
          > of the tower. The rabbit fired up and the xmtr went off the
          air ....
          > prematurely hi hi ..
          >
          > We also had other uses for coiled copper tubing .... attached to
          threaded
          > fittings on a pressure cooker hi hi ..
          >
          >
          >
          > Jim Dunstan, VE3CI
          > Thunder Bay, ON
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