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Consistent gauss across all rod magnets/slugs

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  • #16
    Thanks for sharing!

    I was a bit imprecise plus I measured when the PU was on the bass. Now, when the PU taken out I get A 1340 Gs.
    Yeah, the presence of the strings increases flux.
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    • #17
      Originally posted by Helmholtz View Post
      Here is a simple and effective method:

      [ATTACH=CONFIG]53642[/ATTACH]
      You don't have to have the stack of neo bottons that long, since the neo's have no permeability of their own, their strength diminishes with distance as though each preceding button was empty space, and so I suspect by about the 4th or 5th button there's no longer any practical increase in strength.

      I'd still favor using a single long bar, since the neighboring pole pieces are in the return path of the stack of neo's, although I've charged some pole pieces with the stack of neo buttons and not had trouble, not nearly as much as with the vice pass-through method.

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      • #18
        My method for partial demagnetization is to use another AlNiCo 5 pole piece as a foil. If you press two AlNiCo magnets together, face to face, they will mutually and partially demagnetize, so you can take one AlNiCo 5 rod, charge it with a neo, and then press that rod down onto the rod you want to demagnetize, and if it's Gauss is initially around 1100, it should drop down to around 500. It's an imperfect science, but you can repeat the process as many times as needed until you end up with the strength reading you're going for.

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        • #19
          My method for partial demagnetization is to use another AlNiCo 5 pole piece
          This is also my preferred method for partial demagnetizing of individual poles as it allows for more control than with neos. Nevertheless I recommend the use of shims if only slight weakening is required.
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          • #20
            You don't have to have the stack of neo bottons that long, since the neo's have no permeability of their own, their strength diminishes with distance as though each preceding button was empty space, and so I suspect by about the 4th or 5th button there's no longer any practical increase in strength.
            Well, yes and no. While the flux density directly at the poles does not increase when increasing the number of buttons from 5 to 25, the measured B at a distance of 10mm above the poles is 25% stronger with 25 buttons. The reason is that generally a wider pole spacing of a dipole produces a more focused axial field, decreasing less with distance. This helps the field to penetrate the alnico poles and gives better magnetizing results.
            (Apart from that I am more comfortable if the demagnetizing neo pole is further away from the alnicos.)

            Concerning potential demagnetization of neighboring poles by "returning flux" (of course all the magnet flux must return eventually): My measurements show that the net axial flux density within and above the pole plane does not change polarity. This means that at least level and lower neighboring magnets won't be demagnetized by any inverse axial field using my method. (There might still be some small effect by the radial field component produced by the pole edge of the neo, but it seems to be insignificant.)
            If longer neighboring magnets get slightly demagnetized, I wouldn't mind because they tend to be stronger anyway. And those could be easily remagnetized without weakening their neighbors.

            I'd still favor using a single long bar, since the neighboring pole pieces are in the return path of the stack of neo's, although I've charged some pole pieces with the stack of neo buttons and not had trouble, not nearly as much as with the vice pass-through method.
            A long neo bar won't touch the shorter alnico rods in a staggered pole PU and thus may fail to saturate them.
            Last edited by Helmholtz; 06-05-2019, 02:27 PM.
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            • #21
              Originally posted by Helmholtz View Post
              I never got consistent results with the neo/vice method. The problem is that moving the PU out of the vice/field distorts the magnetic patterns and often partially demagnetizes the poles.

              Here is a simple and effective method:

              [ATTACH=CONFIG]53642[/ATTACH]

              Each rod consists of 25 neos measuring 8mm diameter x 3mm thickness.
              It is essential to approach and withdraw the neo rods exactly on the magnetic axis of the individual pole to be magnetized. Never tilt or move them sideways when within a distance of 1 inch (or even more depending on neo strength) from the poles.

              From magnet theory, a longer magnet can hold a somewhat higher charge. I typically find up to 25% difference between the longer and the shortest magnets in a vintage staggering and fully charged magnets.

              BTW, the best way to find out if your magnetizing field is strong enough and the magnets are full charged is to reverse the magnetic polarity and see if you get the same Gauss values as before.
              My charging jig consists of a couple of good sized N42's installed in a couple of handles to make using those Neo's possible. I have a number of spacers that I use to regulate the gauss level of the rod magnets. Works great! Beauty is, there is no right or wrong on any of this stuff if the pickups your winds create the tone you are looking for.

              Click image for larger version

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              I use disc's similar to your pic if I want to tweak the charge or am doing something like a 5/2 split pickup and want a specific charge relationship between the A2's and A5's.
              Take Care,

              Jim. . .
              VA3DEF
              ____________________________________________________
              In the immortal words of Dr. Johnny Fever, “When everyone is out to get you, paranoid is just good thinking.”

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              • #22
                HI
                I remagnetize the other magnets, but the A string magnet was still too strong. I read on some forum that you can demagnetize a magnet pole a bit by closing the neomag at 45º angle to a few cm distance. Closing the magnet from bridge or neck side. (Not up-down direction). I managed to get the B down some 200 Gs. The Tele Bass now much more balanced than before.
                I also set the PU height. And found 4 mm or 5/32" to be the most pleasing. I use thick flat wound La Bellas which may cause the bigger distance than the normal 3,2 mm or 1/8".
                Last edited by okabass; 06-05-2019, 08:31 PM.

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                • #23
                  Originally posted by okabass View Post
                  HI
                  I remagnetize the other magnets, but the A string magnet was still too strong. I read on some forum that you can demagnetize a magnet pole a bit by closing the neomag at 45º angle to a few cm distance. Closing the magnet from bridge or neck side. (Not up-down direction). I managed to get the B down some 200 Gs. The Tele Bass now much more balanced than before.
                  I also set the PU height. And found 4 mm or 5/32" to be the most pleasing. I use thick flat wound La Bellas which may cause the bigger distance than the normal 3,2 mm or 1/8".
                  A slanted magnetizing/demagnetizing field will result in a more or less slanted magnetization pattern of the alnico pole (more so with isotropic alnicos like A2, A3, A4 than with anisotropic A5) probably resulting in uneven pole surface B. This is likely to influence to magnetic aperture of the respective string. May not be audible, though.

                  What was wrong with demagnetization using the neo rod(s) and shims/spacers? Reduce spacer thickness until you measure some effect and then repeat approaching the neo rod with the same spacer until you get the desired result.
                  Last edited by Helmholtz; 06-05-2019, 08:59 PM.
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                  • #24
                    Originally posted by Helmholtz View Post
                    A slanted magnetizing/demagnetizing field will result in a more or less slanted magnetization pattern of the alnico pole (more so with isotropic alnicos like A2, A3, A4 than with anisotropic A5) probably resulting in uneven pole surface B. This is likely to influence to magnetic aperture of the respective string. May not be audible, though.

                    What was wrong with demagnetization using the neo rod(s) and shims/spacers? Reduce spacer thickness until you measure some effect and then repeat approaching the neo rod with the same spacer until you get the desired result.
                    HI
                    Ok.
                    I first tried remagnetize the other weaker mags. But the A was still too strong. I tried the "shim" method with an other "practice" PU and tried several times but not succeeded . Then I remember that 45 degree method. If the pole is is uneven magnetized didn't notice it (AKG headphones). But must listen with an amp and playing with my band.
                    Thank you all good advice. I managed to get my Tele Bass much more balanced than before.
                    Last edited by okabass; 06-06-2019, 07:03 AM.

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                    • #25
                      Originally posted by Helmholtz View Post
                      I never got consistent results with the neo/vice method. The problem is that moving the PU out of the vice/field distorts the magnetic patterns and often partially demagnetizes the poles.

                      Here is a simple and effective method:

                      [ATTACH=CONFIG]53642[/ATTACH]

                      Each rod consists of 25 neos measuring 8mm diameter x 3mm thickness.
                      It is essential to approach and withdraw the neo rods exactly on the magnetic axis of the individual pole to be magnetized. Never tilt or move them sideways when within a distance of 1 inch (or even more depending on neo strength) from the poles.

                      From magnet theory, a longer magnet can hold a somewhat higher charge. I typically find up to 25% difference between the longer and the shortest magnets in a vintage staggering and fully charged magnets.

                      BTW, the best way to find out if your magnetizing field is strong enough and the magnets are full charged is to reverse the magnetic polarity and see if you get the same Gauss values as before.
                      What kind of gauss reading do you usually get on Strat single coils with this method? What is the gauss reading on the neo mags you are using?

                      Thanks in advance

                      Glaze

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                      • #26
                        what is the gauss reading on the neo mags you are using?
                        A single neo measures 2700G, the stacked rod is 4600G.


                        What kind of gauss reading do you usually get on Strat single coils with this method?
                        If applied as described the method achieves full saturation of A5 (and all lower grade) poles, meaning 1000G to 1250G (depending on A5 quality) for the longer poles in a staggered Strat PU. Generally the shorter poles can't hold as much charge and thus will be up to 25% weaker.
                        Last edited by Helmholtz; 12-26-2019, 05:06 PM.
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                        • #27
                          Originally posted by Helmholtz View Post
                          A single neo measures 2700G, the stacked rod is 4600G.




                          If applied as described the method achieves full saturation of A5 (and all lower grade) poles, meaning 1000G to 1250G (depending on A5 quality) for the longer poles in a staggered Strat PU. Generally the shorter poles can't hold as much charge and thus will be up to 25% weaker.
                          Very cool information. Thank you.

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                          • #28
                            The magnetism of N52 is too strong. I personally suggest you use N48 or .
                            Last edited by big_teee; 02-28-2020, 06:14 PM. Reason: No Ads allowed in the Tech Forums!

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