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Re: [mill_drill] Re: new article available: An Experimental Way toStatically Balance a Bench Grinder

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  • Mark Cason
    ... Rick, there is something else that needs to checked... the shaft. I had a cheap 8 grinder I got off of one of those traveling tool trucks, and no
    Message 1 of 12 , Jul 31, 2011
      On 07/31/2011 09:12 AM, Rick Sparber wrote:
      > Denis,
      >
      > Yup, that was where I started. To me, their product is a proof of
      > concept. There is no way I would pay that kind of money for something
      > that is easy to make.
      >
      > In the end I came to realize that I did not need to add an external
      > weight in order to balance my grinder. The problem was in a defective
      > wheel. It must have a non-uniform distribution of grains in the wheel.
      > It looks OK but when mounted and trued, still causes a lot of
      > vibration. Its replacement runs much smoother. I did try to improve
      > the balance of the new wheel but could not by simply adding a weight.
      > My guess is that the static balance is good but the dynamic balance is
      > a little off. In order to correct for dynamic balance, I need to be
      > able to place a weight at a given distance from the center of rotation
      > at a given angle plus a given point along the center of rotation. Not
      > so easy to do on a grinder.
      >
      > So in the end I pulled the article you read from my site and left a
      > more traditional one.
      >
      > Rick
      > Rick.Sparber.org <http://Rick.Sparber.org>

      Rick, there is something else that needs to checked... the shaft. I
      had a cheap 8" grinder I got off of one of those traveling tool trucks,
      and no matter what I did, I could never get it to balance.

      I took the wheels off, and found that they weren't even the same
      thickness all around. I threw them away, and bought some good ones, but
      I still couldn't get it to run smooth, so I started measuring the
      grinder itself.

      The shaft measured fairly round on both sides, when using a micrometer,
      but when I measured to see how concentric the bearings were, they were
      out so far, that my DTI couldn't measure them. My dial indicator showed
      that the shaft wobbled over .100" on one side, and nearly .060" on the
      other.

      After that, I looked around, and found a nice 10" Wilton, for a price I
      couldn't refuse, that runs really, really smooth. Now, the 8" one is in
      the scrap pile, awaiting resurrection.

      --
      -Mark

      Ne M'oubliez ---Family Motto
      Hope for the best, plan for the worst ---Personal Motto
    • Rick
      Mark, Good point about the shaft. I ll add it to the article. Rick rick.sparber.org
      Message 2 of 12 , Aug 1, 2011
        Mark,

        Good point about the shaft. I'll add it to the article.

        Rick
        rick.sparber.org

        >
        > Rick, there is something else that needs to checked... the shaft. I
        > had a cheap 8" grinder I got off of one of those traveling tool trucks,
        > and no matter what I did, I could never get it to balance.
        >
        > I took the wheels off, and found that they weren't even the same
        > thickness all around. I threw them away, and bought some good ones, but
        > I still couldn't get it to run smooth, so I started measuring the
        > grinder itself.
        >
        > The shaft measured fairly round on both sides, when using a micrometer,
        > but when I measured to see how concentric the bearings were, they were
        > out so far, that my DTI couldn't measure them. My dial indicator showed
        > that the shaft wobbled over .100" on one side, and nearly .060" on the
        > other.
        >
        > After that, I looked around, and found a nice 10" Wilton, for a price I
        > couldn't refuse, that runs really, really smooth. Now, the 8" one is in
        > the scrap pile, awaiting resurrection.
        >
        > --
        > -Mark
        >
        > Ne M'oubliez ---Family Motto
        > Hope for the best, plan for the worst ---Personal Motto
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