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IS everything ok ?

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  • berstrong
    I build my first Vdg and drew a picture of it is everything ok ? http://www.berstrong.republika.pl/vdg.jpg And I have a question, Does asbestos is good
    Message 1 of 6 , Oct 1, 2005
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      I build my first Vdg and drew a picture of it is everything ok ?
      http://www.berstrong.republika.pl/vdg.jpg

      And I have a question,
      Does asbestos is good material for upper roller and teflon tape for
      lower roller ?
    • BoB
      ... Hi Yes it looks like you have the basis for a VDG, a couple of things that might need a little tweaking though, what metal are you planning to use for the
      Message 2 of 6 , Oct 1, 2005
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        --- In VanDeGraaffGenerator@yahoogroups.com, "berstrong"
        <berstrong@y...> wrote:
        > I build my first Vdg and drew a picture of it is everything ok ?
        > http://www.berstrong.republika.pl/vdg.jpg
        >
        > And I have a question,
        > Does asbestos is good material for upper roller and teflon tape for
        > lower roller ?

        Hi
        Yes it looks like you have the basis for a VDG, a couple of things
        that might need a little tweaking though, what metal are you planning
        to use for the top roller? personally I would try and steer clear of
        metal rollers, just use another material from the positive end of the
        triboelectric series, nylon is a strong favourite.
        I would also swap the rollers around so you have nylon on the
        bottom and polythene on the top, this will give you a negative
        generating machine.
        Asbestos would be a bad choice for a roller for several reasons,
        It is not smooth enough to give a good contact to the belt, It
        would cause a fair bit of dust which would contaminate both the
        other roller and the belt and of course the obvious health hazard.
        I use a Teflon (PTFE) roller in my machine, it works a treat.
        Hope this helps you a little

        Bob
      • Craig Fuller
        I agree with Bob, metal rollers have proven in long term to dust up the inside of the machine, causing a range of problems, including drastically reduced
        Message 3 of 6 , Oct 3, 2005
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          I agree with Bob, metal rollers have proven in long term to dust up
          the inside of the machine, causing a range of problems, including
          drastically reduced charging current (eventually zero), as well as
          internal arcs that flash all the way from the top of the machine to
          the bottom. If someone has their hand on it at the time, you usually
          get a frown because the sudden drain of charge is painful.

          Asbestos gets a big fat check minus. From my experience, asbestos
          should only be used where the risk of generating small particulates
          is
          negligible. Im metal rollers will generate dust, it's reasonable to
          assume that asbestos will too.

          I would like to add that my machine is set up to charge the top
          positive and it works beautifully. I suspect that reversing polarity
          involves more that just a simple roller swap. This subject has not
          been researched in enough detail by any of us to explain why.

          --- In VanDeGraaffGenerator@yahoogroups.com, "berstrong"
          <berstrong@y...> wrote:
          > I build my first Vdg and drew a picture of it is everything ok ?
          > http://www.berstrong.republika.pl/vdg.jpg
          >
          > And I have a question,
          > Does asbestos is good material for upper roller and teflon tape for
          > lower roller ?
        • BoB
          ... Hi Craig Although I havent tried it, im sure you only need to swap the top and bottom rollers over to reverse the polarity of a VDG. So long as the 2
          Message 4 of 6 , Oct 3, 2005
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            > I would like to add that my machine is set up to charge the top
            > positive and it works beautifully. I suspect that reversing polarity
            > involves more that just a simple roller swap. This subject has not
            > been researched in enough detail by any of us to explain why.
            >

            Hi Craig
            Although I havent tried it, im sure you only need to swap the top
            and bottom rollers over to reverse the polarity of a VDG. So long
            as the 2 roller materials are at either end on the tribo series
            and the belt material is reasonably neutral. I have found
            this web site the explains it much clearer than I
            could, it is also very interesting for anyone setting out on
            a VDG building adventure, interesting enough, its called
            "how to build a Vandegraff"
            http://www.gocs1.com/gocs1/Psionics/Vandegraff%20Generator.htm

            if you scroll down about half way, the is a section titled
            "Positive or Negative Potential's (Checking The Polarity)"

            Although I cant remember why I think negative charging VDGs are
            "better" than positives, back to google....

            Bob
          • Craig Fuller
            Hi Bob, Thanks for the link. While swapping top and bottom rollers definitely IS the way to change the polarity, I was referring to others actual results.
            Message 5 of 6 , Oct 4, 2005
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              Hi Bob,

              Thanks for the link. While swapping top and bottom rollers
              definitely IS the way to change the polarity, I was referring to
              others actual results. The polarity DOES change, but so far I
              haven't found anyone who has had satisfactory results after doing
              this. They always seem to end up with much less charging current.
              Dick has experienced this strange result, so maybe he could shed
              some light on it, but I think he just swapped them back and got his
              full charging current back. I haven't tried this with mine, so I
              can say for sure. It's a little bit mysterious, that's all.

              Some possibilities that come to mind:
              - Residual charge accumulated inside the machine (support column,
              rollers, belt...) could act to neutralize the charging current?
              - Subtle differences in roller dimensions, resulting in comb
              proximity change?

              Just some thoughts.

              Craig

              --- In VanDeGraaffGenerator@yahoogroups.com, "BoB" <bob@t...> wrote:
              >
              > > I would like to add that my machine is set up to charge the top
              > > positive and it works beautifully. I suspect that reversing
              polarity
              > > involves more that just a simple roller swap. This subject has
              not
              > > been researched in enough detail by any of us to explain why.
              > >
              >
              > Hi Craig
              > Although I havent tried it, im sure you only need to swap the top
              > and bottom rollers over to reverse the polarity of a VDG. So long
              > as the 2 roller materials are at either end on the tribo series
              > and the belt material is reasonably neutral. I have found
              > this web site the explains it much clearer than I
              > could, it is also very interesting for anyone setting out on
              > a VDG building adventure, interesting enough, its called
              > "how to build a Vandegraff"
              > http://www.gocs1.com/gocs1/Psionics/Vandegraff%20Generator.htm
              >
              > if you scroll down about half way, the is a section titled
              > "Positive or Negative Potential's (Checking The Polarity)"
              >
              > Although I cant remember why I think negative charging VDGs are
              > "better" than positives, back to google....
              >
              > Bob
            • Richard R. Linder
              Hi All: Right Craig, On my first VDG I used Teflon on top and Nylon on the bottom and the vinyl impregnated nylon belt material that I ve been crowing about.
              Message 6 of 6 , Oct 4, 2005
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                Hi All:
                 
                Right Craig, On my first VDG I used Teflon on top and Nylon on the bottom and the vinyl impregnated nylon belt material that I've been crowing about.
                 
                The reason I wanted to switch to  (+)  top  (-)  bottom was that I wanted a VDG that was charged opposite to the big VDG.  You guessed it!  I wanted to run them side by side and see how big the strike would be between them.
                 
                Swapping the rollers resulted in no charge at all.  Charging current was 0 uA !  To this day I have not resolved the issue but I would like to some day so I could try the side-by-side experiment.
                 
                DIck 
                 
                 
                ----- Original Message -----
                Sent: Tuesday, October 04, 2005 6:52 AM
                Subject: [VanDeGraaffGenerator] Re: IS everything ok ?

                Hi Bob,

                Thanks for the link.  While swapping top and bottom rollers
                definitely IS the way to change the polarity, I was referring to
                others actual results.  The polarity DOES change, but so far I
                haven't found anyone who has had satisfactory results after doing
                this.  They always seem to end up with much less charging current. 
                Dick has experienced this strange result, so maybe he could shed
                some light on it, but I think he just swapped them back and got his
                full charging current back.  I haven't tried this with mine, so I
                can say for sure.  It's a little bit mysterious, that's all.

                Some possibilities that come to mind:
                - Residual charge accumulated inside the machine (support column,
                rollers, belt...) could act to neutralize the charging current?
                - Subtle differences in roller dimensions, resulting in comb
                proximity change?

                Just some thoughts.

                Craig

                --- In VanDeGraaffGenerator@yahoogroups.com, "BoB" <bob@t...> wrote:
                >
                > > I would like to add that my machine is set up to charge the top
                > > positive and it works beautifully.  I suspect that reversing
                polarity
                > > involves more that just a simple roller swap.  This subject has
                not
                > > been researched in enough detail by any of us to explain why.
                > >
                >
                > Hi Craig
                > Although I havent tried it, im sure you only need to swap the top
                > and bottom rollers over to reverse the polarity of a VDG. So long
                > as the 2 roller materials are at either end on the tribo series
                > and the belt material is reasonably neutral. I have found
                > this web site the explains it much clearer than I
                > could, it is also very interesting for anyone setting out on
                > a VDG building adventure, interesting enough, its called
                > "how to build a Vandegraff"
                > http://www.gocs1.com/gocs1/Psionics/Vandegraff%20Generator.htm
                >
                > if you scroll down about half way, the is a section titled
                > "Positive or Negative Potential's (Checking The Polarity)"
                >
                > Although I cant remember why I think negative charging VDGs are
                > "better" than positives, back to google....
                >
                > Bob


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