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  • BroMikey
    replied
    Something like this would push those magnets right out. Made out of wood is better. BTW I was thinking wrong that a stainless rotor might shield some, so my indecision about the need for shielding has been removed.

    Last edited by BroMikey; 06-25-2022, 01:12 AM.

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  • BroMikey
    replied
    Taking out those magnets should be easy, almost to easy. The sleeves will keep them in best. if you ever get it done right your output is going to be massive. Send it back to have the holes shaved to match the new dia. plenty of room for a 20 thou wrap around

    You don't have to do the outside magnets just yet but providing a shield would probably reduce the sized needed. You are losing flux everywhere. The shields divert the flux out to front and center so double the flux in front. The old 2" were short but the 1" have a huge potential for magnifying flux thru the redirection of shielding. The distance is 4x as great going from .25-1.00. With double the pull I hope the rotor doesn't flex to badly being so limber

    Be sure the covers are as close to 1" long as possible. Texture for gluing is important, don't let them polish the surfaces. Or be sure to sand all surfaces roughly making it more porous. You don't need me to tell you that. You are almost home.

    Last edited by BroMikey; 06-25-2022, 04:38 AM.

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  • BroMikey
    replied
    Thin sheet metal cans or cylinders.

    Shim Stock cylinders

    https://www.metalshims.com/c-29-custom-shim-stock.aspx




    https://www.first4magnets.com/blog/w...ding-a-magnet/

    Which material will work?


    Any ferromagnetic metal. That is any metal containing iron, nickel or cobalt. Many steels are ferromagnetic metals and will work for redirecting magnetic shields.

    Steel is the commonly used metal because it is cost-effective and widely available, however some stainless steels are not ferromagnetic.

    Overall, many applications we come across and are asked about, a steel sheet-metal shield is usually the best solution.
    Last edited by BroMikey; 06-22-2022, 07:10 PM.

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  • BroMikey
    replied
    [QUOTE=Turion;n510390]Glue


    FALSE , they are thin tin simple cups that when driven in with a rubber mallet sometimes can become misshapen. I think he drove in one half on each side. See close up and see the shine. That is one pretty glue job

    https://www.youtube.com/watch?v=U3JhNA_0FKI&t=70s


    Last edited by BroMikey; 06-22-2022, 07:11 PM.

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  • Turion
    replied
    Glue
    image_24793.png

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  • BroMikey
    replied
    Stainless Steel


    No. It varies depending on the exact stainless steel. We only covered a few in this article. We found:
    • 430 Ferritic Stainless Steel – Magnetic
    • 304 Austenitic Stainless Steel – Not magnetic, or a little magnetic after cold work (bending, deforming, etc.)
    • 316 Austenitic Stainless Steel – Not magnetic.
    How do I know if my stainless steel is magnetic?



    Will stainless steel act as a magnetic shield?


    Magnetic “shields” don’t block magnetic fields, they redirect it. See our earlier article on Shielding Materials.

    All metals that act as good shields are also attractive to magnets. If you’re using a stainless steel like 316 that isn’t ferromagnetic, it’s not blocking any fields, at least not any more than an air gap.

    What material will work?


    The short answer is: Any ferromagnetic metal. That is, anything containing iron, nickel or cobalt. Most steels are ferromagnetic metals, and work well for a redirecting shield. Steel is commonly used because it's inexpensive and widely available. Note that some stainless steels, especially the 300 series varieties, are not ferromagnetic.


    Conclusion


    Which material is right for you depends on your specific shielding problem. For low field strength, sensitive electronics, MuMetal can provide better shielding than steel. For many applications involving large, powerful neodymium magnets, the higher saturation point of steel serves better. In many specific cases we're asked about, a steel sheet-metal shield is often the best solution.


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  • BroMikey
    replied
    mu metal shielding cans of thin sleeves

    https://www.emi-shielding.net/magnetic-shields-gallery/

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  • BroMikey
    replied
    Originally posted by Turion View Post
    Look at the output on the coils in this video. He has no shielding around his coils.
    https://www.youtube.com/watch?v=kfRxsC9yumQ&t=4s

    And the simplest thing to do to test that idea would to remove every other magnet, so I would be left with 10 on the rotor instead of twenty. That would remove the existing 10 of the same polarity, since they are in a N/S configuration right now and I would be taking out either all the N or all the S if I took out every other one. Once those 10 are removed, I would have to then remove every other one (of the 10 left) and reverse them so that the remaining magnets were all N/S. I may get to that point, but not there yet. Even if I get down to 10 on the rotor, that's four MORE than I had with the original rotor, and that rotor put out 130+ volts per coil.
    What are the rings then? Look closer


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  • Turion
    replied
    Look at the output on the coils in this video. He has no shielding around his coils.
    https://www.youtube.com/watch?v=kfRxsC9yumQ&t=4s

    And the simplest thing to do to test that idea would to remove every other magnet, so I would be left with 10 on the rotor instead of twenty. That would remove the existing 10 of the same polarity, since they are in a N/S configuration right now and I would be taking out either all the N or all the S if I took out every other one. Once those 10 are removed, I would have to then remove every other one (of the 10 left) and reverse them so that the remaining magnets were all N/S. I may get to that point, but not there yet. Even if I get down to 10 on the rotor, that's four MORE than I had with the original rotor, and that rotor put out 130+ volts per coil.
    Last edited by Turion; 06-21-2022, 09:37 PM.

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  • BroMikey
    replied
    Here is the classic illustration of adjacent magnetic fields overlapping and how the lines of force tank out. Your magnets are aligned in this way only closer. Do you understand now? Your findings support text book models.

    Last edited by BroMikey; 06-21-2022, 06:38 PM.

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  • BroMikey
    replied
    Poor man's machine shop using indicators. Close enough for horseshoes. Centering and gap adjustment.

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  • BroMikey
    replied
    Jordan's little machine shielding

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  • BroMikey
    replied
    And yet another build where magnets are crammed together tightly. What do you see?

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  • BroMikey
    replied
    Here is another example of the need for shielding on a dual rotor model. The fields this close together must be controlled and pushed of in front.

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  • BroMikey
    replied
    Thanes magnet shields when magnets are so close together the fields overlap.

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