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Re: 11112 magnet progress

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  • Matt Rock
    More work: I made a housing for the Hall Sensor, out of plexy glass. Glued the sensor and made a notch on the other plexy glass piece. Sandwiched the sensor
    Message 1 of 5 , Jun 15, 2004
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      More work:

      I made a housing for the Hall Sensor, out of plexy glass. Glued the
      sensor and made a notch on the other plexy glass piece. Sandwiched
      the sensor and extended wiring out of the the package. Now I was
      able to take consistent flux readings for every magnet. I went
      through all the magnets, and determined various grades of magnets
      for the project. I have set aside the most powerful out of the bunch
      to be used for the middle cone to compensate for the weaker North
      pole on the cone/rim. Mid range for the ramaining cones and rims.
      Some weaker magnets were determined with this methodology. I had
      found that worst case, some were about 216 gauss units under the
      most powerful. Mid range were about 126 gauss units.

      This might be a worthwhile approach to try for others interested, as
      the sensor does work! 5 millivolts per single (1) gauss reading.
      Hall sensor was $20 Canadian from Electrosonic (Gordon Baker/404).

      Made another cone stand, so now I have three to protect the cones
      while working on them.

      Going to recheck my proportions on the cones, I have neglected a few
      things that I should check, so that the 1:1.6182 ratio is present.
      This would be diameter of cone to length of side. Although, all the
      drawings that were done ahead of time do reflect the ratio, I'd
      better be sure it's in there on the hardware. I have been keeping
      very strict to my drawings, so I don't think this will be an issue.

      If I have time, after checking the remaining 100 magnets, I will
      begin to locktite my cone fasteners.

      Anticipation............

      Matt





      --- In hameltech@yahoogroups.com, "Matt Rock" <mattihorn@i...> wrote:
      >
      > Tonight's work:
      >
      > I got the Hall sensor (honeywell--SS94A1). It works great. Save
      for
      > the fact that the 9VDC battery should be replaced with a constant
      > voltage supply, as the voltage drops about 1/10th a volt over 10
      > minutes. Definitely works though and I am able to discern between
      my
      > magnets for strength. I am finding that they all hover from 0.11
      > volts to about 0.75 volts in the measures. That is about 1 to 130
      > gauss between the lowest and up to the highest so far.
      > I did about 200 magnets, but the battery was not maintaining
      > accuracy, so I'll be doing this with a voltage supply set for
      about
      > 9VDC and 30 mA. 9VDC seems to be ideal. This should be a quick
      > exercise, as all I need are numbers for levels. I am using a
      > measured distance of about 1 cm from the hall sensor. Measuring
      only
      > south fields, primarily.
      >
      > I got my middle ring dismantled and I have tripled the steel
      banding
      > to compensate for the width (for the North rejection magnets).
      > Going to plan for time, to dismantle and locktite a cone tommorrow
      > night and keep the inner cone out for magnet mounting, of course
      > after I get better readings on the magnets. If I can keep the
      > magnets relatively the same on a per cone basis and rims too, then
      I
      > increase the chances for better balancing.
      >
      > Choi,
      >
      > Matt
      >
      >
      > --- In hameltech@yahoogroups.com, "Matt Rock" <mattihorn@i...>
      wrote:
      > > Hi all:
      > >
      > > On with the next phase of my work.
      > >
      > > The epoxy is in my possession and I have tested it for fastening
      > on
      > > aluminum (un-oxidized and scored). It appears to have very good
      > > adhesion. The aliminum epoxy fills up the crevices on the magnet
      > > adding to the holding power. Cure time is about 24 hours.
      > >
      > > Now, since I don't have magnetic film in a large size, I have
      > > decided to test my magnets Maximum Energy Product(s) (BHmax)
      using
      > a
      > > Hall Effect sensor circuit. I was thinking about building a
      > > Helmholtz coil setup to do this, and yet the Hall effect is much
      > > easier.
      > > Of course, it has to be a measuring device capable of measuring
      a
      > > static magnetic field. I have a trifield meter that only works
      > with
      > > oscillating magnetic fields. No good, unless of course I build a
      > > device that spins the magnets individually to cut the axis of
      the
      > > internal coils sensing magnetic fields.
      > > I want and need to do this so that I have an idear of an
      > imbalanced
      > > magnets I should know about.
      > >
      > > I have built 2 wooden stand with padding, that hold my cones
      while
      > I
      > > work on them. They are angled in direct proportion to the cones.
      > > Padding is for protection from dents etc.
      > > I had bought about 30 mini clamps, plastic kind, so that I can
      > > completely mount all magnets in one go per cone.
      > >
      > > Before I do any mounting, I will be going around to lock-tite
      all
      > > the fasteners. Partially, disassembling the cones to do this and
      > to
      > > mount the magnets.
      > >
      > > If anyone has any better ideas to test the magnet's fields
      without
      > > film, I'm all ears :)
      > >
      > > Choi,
      > >
      > > Matt
    • Trent George
      Hi Matt, I have just been reading about your progress. I have a couple of comments / questions. a/ I think that the cermaic magnets loose most of their
      Message 2 of 5 , Jun 15, 2004
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        Hi Matt,

        I have just been reading about your progress.

        I have a couple of comments / questions.

        a/ I think that the cermaic magnets loose most of their magnetic
        strength ~ 350 F (over 55%) and at around 850 F they are dead (until
        you re-magnetize them - expensive and difficult and you have to
        remove them all) check out following link

        http://www.bunting-magnetics.com/magnets/ceramic.cfm

        so I think the adhesive temperature is a mute issue if the magnets
        die....

        b/ I can loan you a fancy gauss meter and sensitve probe if you like.
        I have two. it give fancy digital readout of magnetic strength with
        polarity indication.

        c/ I hopefull pick up some aluminum cones this week. I have had them
        spun. 24" x 20" (outer) and 24" x 10" (inner) have made 6 of each.
        wooden molds where expensive :-( using aluminum 090

        d/ am making 4 experimental "drums" from steel and copper....

        I am planning on using 1.875" x .875" x .385" magnets with two holes
        so I can attach with rivits around drum and cones.

        I hope to get vibration and heat....
        I should have pictures in next couple of weeks.

        I think that too much heat > 350 F will kill magnet strength and kill
        devices operation. I don't think enough airflow will reduce "plasma"
        type heat.

        lets hope both / either of us get some impressive results / success.

        your photos show some impressive construction skills, I am envious :-)

        I worry your tall cone ratio may be very ambitious. a real non-
        conformist :-)

        I hope to make another prototype with 24" x 10" and 24" x 5" cones to
        see if they are more / less effetive than the 20" and 10" high cone
        ratio. I think you have around a 12" x 20" ratio for outer cone. it
        will be interesting to compare results.

        How did you construct your beautiful cones....

        Trent
      • Matt Rock
        Hi Trent, You are right about this case of demagnetization that could occur. I have kept this in mind from the start of the project. That is why I went
        Message 3 of 5 , Jun 16, 2004
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          Hi Trent,

          You are right about this case of demagnetization that could occur. I
          have kept this in mind from the start of the project. That is why I
          went straight for the Ceramic #8 type magnets with a 450F curie temp
          rating. Of course, the adhesive I got is 450F rated as well, so both
          will basically last until if that temp point is surpassed.
          I won't be putting my device inside a shell, as per David Hamel's
          suggestion, that the device can run as a heater. That is my hope,
          anyways, that I can run it as a heater. So it will be getting full
          air, no shell to reduce air flow or create a larger vacuum. In time,
          I might consider trying the shell. Hopefully, the excess air contact
          will prevent such high heating.

          You're project sounds very interesting, spun cones and all. That can
          be expensive, raw material forming of cones, solid pieces. But if it
          works, that's all that matters. I'm curious to as what set of
          geometry you are following. Although I do see a ratio of 1:1.2 or a
          5:6 ratio. Interesting that this is in the cone only.
          I have incorporated my 5:6 ratio from cone to rim, in the magnetic
          nodal ratios instead.

          haha, yes the cone's are tall for my design, however I have seen the
          prototypes' behaviour and they looked very good. Well balanced and
          stable. Much of the designing is intuitive, as most of my work has
          been up to this point, so I am going to let it continue regardless
          of possible failure. My feeling tells me that failure is not in the
          picture.

          My cones are about 17" (side) to an 11" inch diameter, but the ratio
          is VERY important between the two, which is forming the Golden Mean
          or Ratio. Basically a cone design pulled right out of the pentagram.
          The inner cones are slightly under 11 inches and about 7 inches on a
          side.

          I constructed my cones using 11 thousands of an inch aluminum
          flashing (20Inch width by 10 feet long pieces). I made three 'inner
          cone mechanisms' to withstand downward pressures/force and also
          maintaining angles and proportions using these mechanisms. They are
          made out of solid aluminum spun on a lathe. Each comprise of a arrow
          tip, extension rod, and an inner cone mating component.
          Stainless steel fasteners throughout. I also made appropriately
          created rims (via latheing) that contain critical angles for the
          cone which are used to mate the cone skins (inner and outer)
          together but also providing very strong rigidity for lateral (side
          to side) forces.
          So basically, the cones incorporate downward and side to side
          pressure protection. No deformations are expected to occur while
          under vibration. It was my idea, to not have the cone skins feel and
          contact forces and to be sort of 'free' from this, only to vibrate.

          Yup, your's sound like a good go as well. Maintain that precision! I
          have been trying to keep as close as possible to the 1/1000ths of an
          inch. The closer to nature, the better.

          Good luck,

          Matt

          --- In hameltech@yahoogroups.com, "Trent George" <tgeorge@S...>
          wrote:
          > Hi Matt,
          >
          > I have just been reading about your progress.
          >
          > I have a couple of comments / questions.
          >
          > a/ I think that the cermaic magnets loose most of their magnetic
          > strength ~ 350 F (over 55%) and at around 850 F they are dead
          (until
          > you re-magnetize them - expensive and difficult and you have to
          > remove them all) check out following link
          >
          > http://www.bunting-magnetics.com/magnets/ceramic.cfm
          >
          > so I think the adhesive temperature is a mute issue if the magnets
          > die....
          >
          > b/ I can loan you a fancy gauss meter and sensitve probe if you
          like.
          > I have two. it give fancy digital readout of magnetic strength
          with
          > polarity indication.
          >
          > c/ I hopefull pick up some aluminum cones this week. I have had
          them
          > spun. 24" x 20" (outer) and 24" x 10" (inner) have made 6 of each.
          > wooden molds where expensive :-( using aluminum 090
          >
          > d/ am making 4 experimental "drums" from steel and copper....
          >
          > I am planning on using 1.875" x .875" x .385" magnets with two
          holes
          > so I can attach with rivits around drum and cones.
          >
          > I hope to get vibration and heat....
          > I should have pictures in next couple of weeks.
          >
          > I think that too much heat > 350 F will kill magnet strength and
          kill
          > devices operation. I don't think enough airflow will
          reduce "plasma"
          > type heat.
          >
          > lets hope both / either of us get some impressive results /
          success.
          >
          > your photos show some impressive construction skills, I am
          envious :-)
          >
          > I worry your tall cone ratio may be very ambitious. a real non-
          > conformist :-)
          >
          > I hope to make another prototype with 24" x 10" and 24" x 5" cones
          to
          > see if they are more / less effetive than the 20" and 10" high
          cone
          > ratio. I think you have around a 12" x 20" ratio for outer cone.
          it
          > will be interesting to compare results.
          >
          > How did you construct your beautiful cones....
          >
          > Trent
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