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Re: [GrizHFMinimill] Re: Converting the MiniMill to belt drive

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  • Rick Kruger
    Klaus, That site only allows members to view anything. If you want other folks to see your mods, you may need to post them elsewhere, such as Ty Hoeffer s web
    Message 1 of 20 , Jun 1, 2002
      Klaus,

      That site only allows members to view anything. If you want other folks to
      see your mods, you may need to post them elsewhere, such as Ty Hoeffer's
      web site:
      http://warhammer.mcc.virginia.edu/ty/7x10/vault/Mills/G8689-MiniMill/

      Yes, an interested person could join the group, but that means having to
      monitory marketing preferences for yet another.

      Rick K.
      Portland, OR

      At 06:55 AM 6/1/02 +0000, you wrote:

      >The one advantage of Brett's conversion that I could see is that you
      >still have the hi/low speed selector. I don't know which gears brake
      >most often. In my case (as it was for Bratt) it was the gear that was
      >driven by the small metal motor gear.
      >However I decided to go without any gears in my conversion which can
      >be seen in the photo section of the mini_cnc_mill group:
      >http://photos.groups.yahoo.com/group/mini_cnc_mill/lst
      >You might have to join to see them.
      >I also changed the motor to the famous treadmill motor and used 2-
      >step pulleys. I used a flat belt with a spring loaded tensioner.
      >This setup has a great range of speeds and huge torque compared to
      >the original mini-mill. Because of the spring tensioner the head can
      >only run in one direction. This is only a small part of the
      >modifications I have made to the mill. It's very easy to get carried
      >away, which is what happened to me.
      >Klaus
    • nplaks
      I should have pointed out the the Machinists Workshop MiniMill belt- drive modification uses double pulleys on both the motor shaft and spindle. The diameter
      Message 2 of 20 , Jun 1, 2002
        I should have pointed out the the Machinists Workshop MiniMill belt-
        drive modification uses double pulleys on both the motor shaft and
        spindle. The diameter of the both sections of the double pulley on
        the motor shaft are the same diameter. The pulley sections on the
        spindle are of different diameters or in other words a two-step
        pulley. With this arrangement, the author of the MW modification
        article uses two different sized belts to retain the two-speed
        feature of the original MiniMill gear drive. The MW modification has
        the the two double pulleys and belt out located in a manner that
        appears to provide easy belt changing capability. Furthermore the MW
        modification does not do anything to the MiniMill that would prevent
        it from being restored to its original gear drive arrangement if one
        so desires.

        However, before I move ahead I am going to try to determine if by
        using a two step, two-diameter, pulley on the motor shaft it is
        possible to use a single belt for the two speeds.

        Norman Plaks
        Raleigh, NC




        --- In GrizHFMinimill@y..., "klauszietlow" <klauszietlow@y...> wrote:
        > --- In GrizHFMinimill@y..., "nplaks" <nplaks@n...> wrote:
        > > One of my `to do projects' is to change the gear drive in my
        > Grizzly
        > > MiniMill.
        > >
        > > Brett Flemming's MiniMill belt drive modification is on Ty
        > Hoeffer's
        > > site at:
        > >
        > > http://warhammer.mcc.virginia.edu/ty/7x10/vault/Mills/G8689-
        > > MiniMill/Projects-Mods/DriveBeltMod/MillBeltMod.html
        > >
        > > Brett Fleming's description indicated the need for an electrical
        > > reversing switch for the motor to restore proper spindle
        direction
        > > required after his modification.
        > >
        > > As noted previously on this list, the June/July 2002 issue of
        > > Machinists Workshop included an article for a belt drive
        > modification
        > > of the MiniMill. The MW modification uses two pulleys and a
        belt.
        > > One pulley is on the motor shaft and the other pulley is mounted
        on
        > > the spindle. With this arrangement, the spindle will rotate in
        the
        > > same direction as the motor.
        > >
        > > On My MiniMill, the spindle rotates in the same direction as the
        > > motor. This means that for the MW modification, the motor will
        not
        > > have to be reversed for proper operation of the mill.
        > >
        > > I went back and carefully checked out the Brett Fleming
        > > modification. It also uses two pulleys and a belt. The first
        > pulley
        > > is mounted onto the motor shaft. It is not clear onto what the
        > > second pulley is mounted. It is not mounted onto the spindle!
        It
        > > appears to possibly be mounted onto the transmission shaft, which
        > if
        > > so suggests that there still is a pair of gears between the
        > > transmission shaft and the spindle. This in-turn would explain
        the
        > > spindle reversing that results from this modification.
        > >
        > > Have I missed something? Would there be any advantage of the
        > Fleming
        > > modification over that of the MW modification, even with the loss
        > of
        > > motor torque that results from reversing direction?
        > >
        > > Norman Plaks
        > > Raleigh, NC
        >
        > The one advantage of Brett's conversion that I could see is that
        you
        > still have the hi/low speed selector. I don't know which gears
        brake
        > most often. In my case (as it was for Bratt) it was the gear that
        was
        > driven by the small metal motor gear.
        > However I decided to go without any gears in my conversion which
        can
        > be seen in the photo section of the mini_cnc_mill group:
        > http://photos.groups.yahoo.com/group/mini_cnc_mill/lst
        > You might have to join to see them.
        > I also changed the motor to the famous treadmill motor and used 2-
        > step pulleys. I used a flat belt with a spring loaded tensioner.
        > This setup has a great range of speeds and huge torque compared to
        > the original mini-mill. Because of the spring tensioner the head
        can
        > only run in one direction. This is only a small part of the
        > modifications I have made to the mill. It's very easy to get
        carried
        > away, which is what happened to me.
        > Klaus
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