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Hall Sensor Magnet info

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    Hall Sensor Magnet info

    So My Buddy rode all winter, and the water got in through the hall port. split the casing off the sensor, and cracked the magnet, on one of the sub zero nights. The sensor we have a replacement for, also have the motor apart and it looks fine other than the magnet ring.. Anyone have any idea on the pole count of that ring? here is a link to some possible replacements if we know more about it...

    Our Face Multi-Pole Magnet Rings provides tight tolerance control, precise pole location & very consistent magnetic performance make these target wheels suited for speed, counting, commutation, tachometry and encoding applications. Shop our full inventory of Face Multi-Pole Magnet Rings today!

    Any Insight?

    Last edited by Jimwildman; 2 weeks ago.

    Alot of reasearching and ive found out the magnet ring, wheel or whatever its called has 10 seperate magnetic poles, alternating in polarity.

    I have designed one using 10 of the 12 magnets in an old ebike pedal assist pickup ring. Prototyped in pla, and once the fit is perfect, and bench tested, ill print it in abs, hopefully that will hold up to any heat in the motor.

    If it works out ill share it on thingiverse and post up a link here..


      Click image for larger version  Name:	image.jpg Views:	0 Size:	1.42 MB ID:	167067
      here is my prototype, the 10 magnets are alternating pole faces, north south, etc.

      testing it with a scope, there is a change every 2 motor cogs. If you consider 0=off, and 1=on, and y, g, b, being the 3 hall sensors corresponding to the motor phases, then this is what ive got..
      starting measurment.
      y g b
      0 0 1
      2 cogs later
      0 1 1
      2 cogs later
      0 1 0
      2 cogs later
      1 1 0
      2 cogs later
      1 0 0
      2 cogs later
      1 0 1
      then it repeats, 360% has been reached.

      Click image for larger version  Name:	IMG_2290.jpg Views:	0 Size:	267.2 KB ID:	167068
      didnt bother to test in reverse.
      here is a decent way of understanding the relationship;
      Click image for larger version  Name:	IMG_2291.png Views:	0 Size:	555.8 KB ID:	167069

      Now what I did was to place one magnet, into the hole with the keyway lined up with it, and checked it against the old magnet. To insure that the pole face is right, if wrong it will not line up with the key on the old mag, the magnets will fight it to the side.

      My testing says its good to go.. will install next nice day and report back..

      I will upload the stl and scad files to thingiverse and add a link here once done.

      If you have a studdering, quitting, running backward, bike and have replaced the hall with no effect, you might have a bad magnet.

      you can place a sheet of paper on it and dump some iron powder to see the issue…

      Click image for larger version  Name:	2022-03-29 12.08.07.jpg Views:	0 Size:	155.2 KB ID:	167070
      you can see the one magnet has split its poles, at this point, all three phases would receive power at the same time, literally slamming the motor full stop for a split second.. it would usually not spin at all just humm and throw a code 3, over current.. makes sense now that I can see it.

      Watch this spot for a link to the files… ill also try making a floating compass to see if that first mag is north or south, some of you may not have enough magnet to do that linup test..
      Last edited by Jimwildman; 3 days ago.


        tested for north and the first magnet in, at the keyway has the north face out.

        As Promised.. Link to My Thingiverse page

        Last edited by Jimwildman; 3 days ago.


          The motor is on the bike and running smooth again.. it looks to me like the plastic on the hall sensor is also abs, so as long as you print in abs, and superglue in the magnets , followed by gluing the magnet assembly to the shaft, its good.. I set the timing screw right in the center like stock.. the part in abs is stronger than the original ceramic magnet. Im feeling pretty good about its chances. I hope this saves some good motors from being junked.
          Last edited by Jimwildman; 1 day ago.