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Re: antibacklash nut concept....thoughts??

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  • j_t_wright
    dds6263, I have had problems with mild steel on the unlocked axis when cutting back and forth (climb milling in the back direction to speed things up). I have
    Message 1 of 12 , Oct 1, 2003
      dds6263,

      I have had problems with mild steel on the unlocked
      axis when cutting back and forth (climb milling in
      the back direction to speed things up). I have
      had to tighten up the gibs to where they are really
      quite stiff to avoid the table jumping in the "climb
      milling" direction :-(

      Do folks generally crank the table back between
      cuts to avoid this? I did this at first, but
      abandoned it as generally I got by ok while working
      aluminum. Hmmm, steel is a bit more demanding....

      Jim

      --- In GrizHFMinimill@yahoogroups.com, "dds6263" <jpb62@j...> wrote:
      > Jjfear, I half disagree. Not that the DRO will not end the problem
      > associated with cutter location, it will do that fine. However,
      > unless you eliminate the backlash, you always face the real
      > probability of the table jumping out of position as soon as you
      start
      > your cut. If your always cutting in a direction at right angles to
      > the "way" with the lash, it is not a problem, but if you must climb
      > mill in the same direction as the lash, the table will jump back
      and
      > forth as it reacts to the cutting forces. I have only about .002"
      > lash in my "x" table so I usually don't notice much of that on
      > that "way". But my "Y" table has about .020 lash and it drives me
      > crazy if I can't lock it into position.
      >
      >
      >
      >
      > > Jim,
      > >
      > > You mention installing a DRO system. If you do that, your concern
      > > over backlash will go away. The scales only measure actual
      movement
      > > of the slides, not the handle turning.
      > >
      > > You won't even notice it anymore.
      > >
      > > Just my 2 cents'
      > >
      > > Jerry F.
      > >
      > >
      > >
      > > --- In GrizHFMinimill@yahoogroups.com, "j_t_wright"
      <buildit@p...>
      > wrote:
      > > > Folks,
      > > >
      > > > Did anyone ever try Kayla's suggestion to modify
      > > > the Grizzly X and Y feed nuts to minimize backlash
      > > > (see photo section and message 1297)? Mine is currently
      > > > about 10 thou on both axis (and so not a burning
      > > > issue), but it would be nice to reduce it further.
      > > >
      > > > I am doing a bunch of mods (L-bracket on column,
      > > > lead shot in column, and DRO's), and thought that
      > > > I might as well look at this while I have things
      > > > torn down. Nuts are just $9.95 at LMS :-)
      > > >
      > > > Kayla's strategy is to cut the nut through 90%
      > > > of the way (going from bottom to top), adding
      > > > a set screw at the base of the cut, and applying
      > > > pressure against the back section of the nut using
      > > > the set screw.
      > > >
      > > > Thanks for any feedback.
      > > >
      > > > Jim
    • j_t_wright
      Jerry, I expect that you are right. Also, it seems that Kayla s mod is untried and perhaps problematic. Oh well, if it ain t broke, don t fix it :-) JIm
      Message 2 of 12 , Oct 1, 2003
        Jerry,

        I expect that you are right. Also, it seems
        that Kayla's mod is untried and perhaps problematic.
        Oh well, if it ain't broke, don't fix it :-)

        JIm

        --- In GrizHFMinimill@yahoogroups.com, "jjfear" <jjfear@i...> wrote:
        > Jim,
        >
        > You mention installing a DRO system. If you do that, your concern
        > over backlash will go away. The scales only measure actual movement
        > of the slides, not the handle turning.
        >
        > You won't even notice it anymore.
        >
        > Just my 2 cents'
        >
        > Jerry F.
        >
        >
        >
        > --- In GrizHFMinimill@yahoogroups.com, "j_t_wright" <buildit@p...>
        wrote:
        > > Folks,
        > >
        > > Did anyone ever try Kayla's suggestion to modify
        > > the Grizzly X and Y feed nuts to minimize backlash
        > > (see photo section and message 1297)? Mine is currently
        > > about 10 thou on both axis (and so not a burning
        > > issue), but it would be nice to reduce it further.
        > >
        > > I am doing a bunch of mods (L-bracket on column,
        > > lead shot in column, and DRO's), and thought that
        > > I might as well look at this while I have things
        > > torn down. Nuts are just $9.95 at LMS :-)
        > >
        > > Kayla's strategy is to cut the nut through 90%
        > > of the way (going from bottom to top), adding
        > > a set screw at the base of the cut, and applying
        > > pressure against the back section of the nut using
        > > the set screw.
        > >
        > > Thanks for any feedback.
        > >
        > > Jim
      • slimgauge
        The only reason I know what nut you re talking about is that I just took my X-Y table apart. Anything I should know about getting this nut back in right ?
        Message 3 of 12 , Oct 2, 2003
          The only reason I know what nut you're talking about is that I just
          took my X-Y table apart. Anything I should know about getting this
          nut back in right ? Thanks.
        • jjfear
          Jim, Just my opinion, First I never make a cut without locking down the table that I m not moving. Second, climb milling is not generally recommended, even on
          Message 4 of 12 , Oct 2, 2003
            Jim,

            Just my opinion, First I never make a cut without locking down the
            table that I'm not moving.

            Second, climb milling is not generally recommended, even on ful sized
            machines, but there are times and certain operations where it cannot
            be avoided. When those times occur, expect to make special
            accomodations---smaller cuts, slower speed, careful entry, etc.

            And no, I don't necessarily run thwe table back every time I need to
            go back and forth. I make a specific decision each time as to whether
            the risks of climb milling are worth the time saved. For example, if
            I am cutting a 1/2 inch slot, I use a 1/2" end mill and cut uphill.
            But, I know that that will probably result in a slot several thou
            over.500. So, if it has to be exact, I use a 3/8" or 7/16" end mill,
            and make the uphill cut. Without stopping the mill, but reducing
            speed a little, I unloosen the other table and move over the required
            distance. Then I relock that table, and make the downhill pass. I
            don't really have a problem with any jumping.

            A through cut, requires more care, but there is usually no reasonnot
            to use the proper size end mill to begin with. If you just want to
            take off some metal on the return table travel, just keep the cut
            small. If the other table is securely locked, any jump on contact
            would have littel effect.

            As I said earlier, DRO's make this a piece of cake.

            Two things I have noticed over the years about beginning machinists,
            is how surprised they are about how much metal can be removed at one
            time, and how many repetetive movements are required to complete any
            Operation.

            And, I suffered the same surprises when I acquired my first Unimat.

            And, I didn't cure it with my Atlas 6", nor with my Atlas 12".

            I just finally figured out that machining consists of many repetetive
            actions that can lull you into inattentiveness or cause you to try to
            take shortcuts, both of which usually result in ruined work or danger.

            I know people(and I'm sure most of you do to) that you wouldn't let
            near a machine. I, myself border on that group. In fact, I took up
            machining to teach myself those characteristics of patience, attention
            to detail, and ability to deal with routine.

            Sorry for the personal rant, but I thought it might resonate with
            other members, bot new and old.

            Jerry Fear



            -- In GrizHFMinimill@yahoogroups.com, "j_t_wright" <buildit@p...> wrote:
            > dds6263,
            >
            > I have had problems with mild steel on the unlocked
            > axis when cutting back and forth (climb milling in
            > the back direction to speed things up). I have
            > had to tighten up the gibs to where they are really
            > quite stiff to avoid the table jumping in the "climb
            > milling" direction :-(
            >
            > Do folks generally crank the table back between
            > cuts to avoid this? I did this at first, but
            > abandoned it as generally I got by ok while working
            > aluminum. Hmmm, steel is a bit more demanding....
            >
            > Jim
            >
            > > > > Thanks for any feedback.
            > > > >
            > > > > Jim
          • j_t_wright
            Jerry, Thanks for the advice. Experience is everything! I have also found this to be a pleasant way to get a little needed discipline around patience... Jim
            Message 5 of 12 , Oct 3, 2003
              Jerry,

              Thanks for the advice. Experience is everything!
              I have also found this to be a pleasant way to get
              a little needed discipline around patience...

              Jim

              --- In GrizHFMinimill@yahoogroups.com, "jjfear" <jjfear@i...> wrote:
              > Jim,
              >
              > Just my opinion, First I never make a cut without locking down the
              > table that I'm not moving.
              >
              > Second, climb milling is not generally recommended, even on ful
              sized
              > machines, but there are times and certain operations where it cannot
              > be avoided. When those times occur, expect to make special
              > accomodations---smaller cuts, slower speed, careful entry, etc.
              >
              > And no, I don't necessarily run thwe table back every time I need to
              > go back and forth. I make a specific decision each time as to
              whether
              > the risks of climb milling are worth the time saved. For example,
              if
              > I am cutting a 1/2 inch slot, I use a 1/2" end mill and cut uphill.
              > But, I know that that will probably result in a slot several thou
              > over.500. So, if it has to be exact, I use a 3/8" or 7/16" end
              mill,
              > and make the uphill cut. Without stopping the mill, but reducing
              > speed a little, I unloosen the other table and move over the
              required
              > distance. Then I relock that table, and make the downhill pass. I
              > don't really have a problem with any jumping.
              >
              > A through cut, requires more care, but there is usually no reasonnot
              > to use the proper size end mill to begin with. If you just want to
              > take off some metal on the return table travel, just keep the cut
              > small. If the other table is securely locked, any jump on contact
              > would have littel effect.
              >
              > As I said earlier, DRO's make this a piece of cake.
              >
              > Two things I have noticed over the years about beginning machinists,
              > is how surprised they are about how much metal can be removed at one
              > time, and how many repetetive movements are required to complete any
              > Operation.
              >
              > And, I suffered the same surprises when I acquired my first Unimat.
              >
              > And, I didn't cure it with my Atlas 6", nor with my Atlas 12".
              >
              > I just finally figured out that machining consists of many
              repetetive
              > actions that can lull you into inattentiveness or cause you to try
              to
              > take shortcuts, both of which usually result in ruined work or
              danger.
              >
              > I know people(and I'm sure most of you do to) that you wouldn't let
              > near a machine. I, myself border on that group. In fact, I took up
              > machining to teach myself those characteristics of patience,
              attention
              > to detail, and ability to deal with routine.
              >
              > Sorry for the personal rant, but I thought it might resonate with
              > other members, bot new and old.
              >
              > Jerry Fear
              >
              >
              >
              > -- In GrizHFMinimill@yahoogroups.com, "j_t_wright" <buildit@p...>
              wrote:
              > > dds6263,
              > >
              > > I have had problems with mild steel on the unlocked
              > > axis when cutting back and forth (climb milling in
              > > the back direction to speed things up). I have
              > > had to tighten up the gibs to where they are really
              > > quite stiff to avoid the table jumping in the "climb
              > > milling" direction :-(
              > >
              > > Do folks generally crank the table back between
              > > cuts to avoid this? I did this at first, but
              > > abandoned it as generally I got by ok while working
              > > aluminum. Hmmm, steel is a bit more demanding....
              > >
              > > Jim
              > >
              > > > > > Thanks for any feedback.
              > > > > >
              > > > > > Jim
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