Pole direction on electric chuck
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  1. #1
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    Default Pole direction on electric chuck

    In looking at electronic chucks today I noticed that the standard chuck comes with longitudinal poles and the fine pole chuck comes with transverse poles.

    I think I understand the benefits of going with a finer pole spacing, but I don't really understand the tradeoffs of pole orientation, and I wasn't able to find much searching "longitudinal vs transverse" on here.

    Is this just an issue that transverse pole orientation requires more total laminations and is therefore only an acceptable cost on fine pole chucks that already carry a premium or is there more to it than that?

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    The pole orientation will be a factor on the thickness and shape of your parts.

    If you are running thick parts, lets say 1/4" and thicker- I don't think you will have any issues. Say you are doing die blocks.

    Thin narrow parts require special attention when you are looking at magnetic chucks. Like custom knife blanks.

    Your vendor should be able to help you to decide.

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    ^ Generally speaking the more poles your part crosses the better it sticks, equally steel can only "transmit" a certain amount of magnetism, hence why coarse poles don't grip thin parts well at all despite having larger stronger magnetic fields. Finer poles, less magnetism is one way around that.

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    In order to (over)simplify the concept and to make it clearer with a graphic representation, imagine to cut a section of the chuck on a plane perpendicular to the surface and lamination.
    You can roughly represent the magnetic fields between adjacent poles like semicircles with the center on the surface of the chuck in the middle of the brass/copper/aluminum strip and circumference passing in the middle of the magnetized strip.
    Obviously, the fine pole chuck has many small semicircles, whereas chucks with coarser poles have fewer, but larger semicircles.
    The semicircles are an approximation of where the strongest magnetic field is located. If you have a thick object on a fine pole chuck, the magnetic field will penetrate only partially the object and, as adama mentioned, the overall magnetic field of a fine pole chuck is less than a regular chuck. On the other side, if you're placing a thin part on a regular chuck, most of the magnetic field passes through the chuck and doesn't contribute to holding it down.
    As Cash has pointed out, especially with poles running lengthwise, you could have challenges when dealing with narrow parts spanning very few poles.
    For the construction point of view, I believe that it is cheaper and easier to build a chuck with poles running lengthwise, since you have fewer laminations to deal with.

    Paolo

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    ^ worth adding a fine pole chuck also does not have as many poles as it first seams, oftern more than a few of the surface poles are more akin to jumpers - shorts - just a shallow bar put in the non magnetic separator so the pole jumps into the part, down into the separator and then back into the part before finally returning to a pole.

    Also worth adding a fine pole chuck works better on small parts too, not just thin ones, sure the per inch grip is less, but it can readily outperform a coarse pole chuck on parts of just a couple of square inches in practice. I currently have a 6x18" fine pole chuck on my J&S 540 a 6x18" capacity 1hp grinder and i really like it, sure on big grinders like Chuck has its a different story, but for small tool room grinding jobs the fine poles a nicer option IMHO.

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    Quote Originally Posted by adama View Post
    ^ worth adding a fine pole chuck also does not have as many poles as it first seams, oftern more than a few of the surface poles are more akin to jumpers - shorts - just a shallow bar put in the non magnetic separator so the pole jumps into the part, down into the separator and then back into the part before finally returning to a pole.

    Also worth adding a fine pole chuck works better on small parts too, not just thin ones, sure the per inch grip is less, but it can readily outperform a coarse pole chuck on parts of just a couple of square inches in practice. I currently have a 6x18" fine pole chuck on my J&S 540 a 6x18" capacity 1hp grinder and i really like it, sure on big grinders like Chuck has its a different story, but for small tool room grinding jobs the fine poles a nicer option IMHO.
    I assume the B&S Micropole chuck would be in that category. How well would it work with "magnetic" parallels or V blocks?

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    Don't know is the honest answer, i have never ever used magnetic parallels with what i have needed to grind sorry.

    I would expect them to probably work better with a coarser pole chuck. but if you got them to match the pole pitch presumably they would work, just would expect more flux leakage.


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