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Help to make a eliptical DD coil design.

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  • #1

    Help to make a eliptical DD coil design.

    Hi all.
    Donald Bowers (DB Shells) and I would like to hear your opinion, how a eliptical DD coil (Shell) shall look like.
    There is many different designs of smaller eliptical DD coil out there and the pictures shows some.
    The reason to ask this, is that I ask Donald If he could make some 5x7" Shells, and he ask naturly "how shall they look"
    Then I remembered som Very diffirent opinions in here, when it comes to coil designs.
    Personaly I like the eliptical type, with not to much Heel and toe problems.. Like 5x7 / 6x8 sizes, but it could easy Be made like 5.5 x7 or what you would prefer.
    another matter is where to make the cable output, and the tab placement for the rod Clovis and total thickness.

    Any ideas and help would Be great.

    Thanks.
    Henrik.
    Attached Files
    Tags: None
  • #2
    Personally, I don't think there's much difference between the different 'elliptic' variants. So any of these shapes will be OK. What I would prefer to see is NO voids in the coil case - I want a solid shape. Smaller coils are often used for detecting tough terrain, with vegetation, or crop stubble, and a smooth bottom is needed to avoid it fouling. A solid shape also allows easy fitment of nulling loops etc. And if a coil cover is also available, that would be good.

    Comment

    • #3
      Because I have used metal detectors for thousands hours I can only tell: I NEED A COIL AS LIGHTWEIGHT AS POSSIBLE !!!
      (Not a heavy brick filled with epoxy.)
      But I am sure guys who making detectors and buying shells probably wanted something absolutely different.

      Comment

      • #4
        If that was a reference to my comment: I was talking very specifically about small coils, like the 5 x 7 mentioned, which will naturally be lighter, and can stand being proportionally heavier. Besides, just because it's a solid case doesn't mean you have to fill it with epoxy.

        Comment

        • #5
          Sorry, it was not a reference to your comment and not about small coils at all.
          I just want to bring as much attention as I can to the problem of coils weight because 90% of energy detectorists spending is moving heavy coils.
          Try to swing coil from Garrett AT PRO or especially Fisher CZ 10" for several hours.
          (It was a 600 gram brick of epoxy I owned so I build my own 50% lighter and 70% bigger using fiberglass.)
          I am sure guys who build it never used it.

          From my point of view coil shells are build wrong. They protecting top of coil and for bottom you need additional coil cover.
          To make it much lighter it is possible to create a "bottom shell" from fiberglass which will keep a shape and protect bottom
          and fill it with epoxy mixed with air bubbles once windings are set inside.

          No more bricks on sticks.

          Comment

          • #6
            The weight can feel different, If the Detector is good balanced.
            I'm more interested in a design DB can make, with so many votes a possible. Then ist up to the coilmaker to make it light, If he/she want that.

            Comment

            • #7
              Originally posted by Henrikras View Post
              The weight can feel different, If the Detector is good balanced.
              I'm more interested in a design DB can make, with so many votes a possible. Then ist up to the coilmaker to make it light, If he/she want that.
              Even if it is good balanced you have to move that mass on the end of pole so every gram counts.

              I vote for first picture because it looks like less volume to fill with epoxy.

              I hope to save peoples money they will spend on arthritis treatment after using brand name coils from most manufacturers.

              Comment

              • #8
                Originally posted by Henrikras View Post
                Hi all.
                Donald Bowers (DB Shells) and I would like to hear your opinion, how a eliptical DD coil (Shell) shall look like.
                There is many different designs of smaller eliptical DD coil out there and the pictures shows some.
                The reason to ask this, is that I ask Donald If he could make some 5x7" Shells, and he ask naturly "how shall they look"
                Then I remembered som Very diffirent opinions in here, when it comes to coil designs.
                Personaly I like the eliptical type, with not to much Heel and toe problems.. Like 5x7 / 6x8 sizes, but it could easy Be made like 5.5 x7 or what you would prefer.
                another matter is where to make the cable output, and the tab placement for the rod Clovis and total thickness.

                Any ideas and help would Be great.

                Thanks.
                Henrik.
                Henrik,
                See attached. Here are the first impressions. If there is any interest I can make a bottom section.
                Don..
                Attached Files

                Comment

                • #9
                  Great work Don

                  Comment

                  • #10
                    It did raise the bar a little on trimming though.
                    Attached Files

                    Comment

                    • #11
                      Hi Don. Sorry the late answer but it was nighttime here.
                      IT looks VERY nice - perfect job you did.
                      If any fine adjustments - its the tabs ! I'm not sure my self, Maybee they should Be 1-2 cm more back or they should Be some smaller model. NO Big deal just an idea.

                      maybee others Wiewers could come up with a comments.

                      Henrik.

                      Comment

                      • #12
                        Some small adjustment.. Look how nice this Shell is. Its top class DB work.
                        Attached Files

                        Comment

                        • #13
                          I think I'm ready to make a run on these if anyone might be interested. Rough dimensions are 5 1/4" wide by 7" long, 2 sided, 1/16" ABS plastic.
                          NOT perfect by commercial standards but close..
                          Don
                          Attached Files

                          Comment

                          • #14
                            Look at this nice 5,5" x 7" DB shell... It Just arrived from Donald Bowers. Very nice work you made Don.
                            Now my coil work can start and it will Be AWESOME. Deus with this eliptical coil at iron infeasted areas.. Whau.
                            Attached Files

                            Comment

                            • #15
                              Hi all....
                              My new DB Shell 5.5" x 7" got now a good working TX / RX combination.
                              Utube http://www.youtube.com/watch?v=msz4D9YAdcI&sns=em
                              It seems that my stroggle with the 7" Deus coil is pay Back time. No problems so fare.. (Knock knock under the table)

                              Now the BIG issue. Shielding ! What to do ? Paint with Graphite Spray, or mix some with powder / binder and do it with a brush ?
                              Do it inside the shell like the 7" coil or make a foam case and paint this like a closed shield case ?

                              I'll will sleep to that. But no quenstretion, I will make a low resistance like 3-500 ohm like my 7" coil. That worked so why not do the same.

                              Henrik

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