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Posted photos re R8 mini-mill

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  • mathprof53575
    I just posted two pictures (in album Bob Wilson s R8 mini-mill ) that show (a) the amount of play in the castellated pieces that couple the z-axis slow feed
    Message 1 of 17 , Feb 1, 2002
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      I just posted two pictures (in album "Bob Wilson's R8 mini-mill")
      that show (a) the amount of play in the castellated pieces that
      couple the z-axis slow feed and (b) a spring to keep a lock handle
      from flopping around.
      (a) I posted earlier a note that the z-axis backlash on my HF R8 mini-
      mill was mostly in the play between the teeth of the two castellated
      pieces that engage when you slide the fast-feed handle inward. The
      photo shows a piece of 0.015 brass between the adjacent teeth. I have
      been thinking of ways to deal with this, ranging over machining a
      whole new piece or two on the original plan, or using a wholly new
      way to couple the worm-driven pinion to the shaft, or modifying the
      existing pieces. My present plan is: cut a slight notch in the center
      of each tooth on the outer piece, the one the three handles screw
      into, then us a cold chisel at the notch to slightly spread the
      metal. Of course I could ruin the piece, but LMS has replacements and
      I think the risk is small. But I would welcome other ideas!
      (b) I found the way the lock handles would flop down in the way of
      other things sometimes a nuisance, so I just added a small
      compression spring under each one. The exact spring is not critical.
      Works fine.
      Bob Wilson
    • wit01us
      Bob, I think you are on the right track when you say make a whole new way to engage the fine feed. I have been looking in catologs for a 2 disk system with a
      Message 2 of 17 , Feb 1, 2002
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        Bob,

        I think you are on the right track when you say make a whole new
        way to engage the fine feed. I have been looking in catologs for a 2
        disk system with a spring batween them. I think I will just make the
        pieces. I am going to change the "squar gears" on the stock mill
        deseign to a cone shaped "gear". This will allow you to engage the
        fine adjustment with the "corse handle" in any location.

        I am also replacing ALL the gears in the mill head with harden steel
        gears! I broke a gear about an hour ago and now I done for the
        weekend! :(

        As soon as I come up with something I will let you know. I believe
        these parts will have to be EDMed.

        Mark W.






        --- In GrizHFMinimill@y..., "mathprof53575" <wilson@m...> wrote:
        > I just posted two pictures (in album "Bob Wilson's R8 mini-mill")
        > that show (a) the amount of play in the castellated pieces that
        > couple the z-axis slow feed and (b) a spring to keep a lock handle
        > from flopping around.
        > (a) I posted earlier a note that the z-axis backlash on my HF R8
        mini-
        > mill was mostly in the play between the teeth of the two
        castellated
        > pieces that engage when you slide the fast-feed handle inward. The
        > photo shows a piece of 0.015 brass between the adjacent teeth. I
        have
        > been thinking of ways to deal with this, ranging over machining a
        > whole new piece or two on the original plan, or using a wholly new
        > way to couple the worm-driven pinion to the shaft, or modifying the
        > existing pieces. My present plan is: cut a slight notch in the
        center
        > of each tooth on the outer piece, the one the three handles screw
        > into, then us a cold chisel at the notch to slightly spread the
        > metal. Of course I could ruin the piece, but LMS has replacements
        and
        > I think the risk is small. But I would welcome other ideas!
        > (b) I found the way the lock handles would flop down in the way of
        > other things sometimes a nuisance, so I just added a small
        > compression spring under each one. The exact spring is not
        critical.
        > Works fine.
        > Bob Wilson
      • mathprof53575
        ... 2 ... the ... Mark, What I worry about is how much torque the coupling has to carry. I considered various clutch designs and anything I could make easily
        Message 3 of 17 , Feb 1, 2002
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          --- In GrizHFMinimill@y..., "wit01us" <mwitkowski@w...> wrote:
          > Bob,
          >
          > I think you are on the right track when you say make a whole new
          > way to engage the fine feed. I have been looking in catologs for a
          2
          > disk system with a spring batween them. I think I will just make
          the
          > pieces. I am going to change the "squar gears" on the stock mill
          > deseign to a cone shaped "gear". This will allow you to engage the
          > fine adjustment with the "corse handle" in any location.
          >
          >...
          >
          > Mark W.

          Mark,
          What I worry about is how much torque the coupling has to carry. I
          considered various clutch designs and anything I could make easily (I
          am not set up for EDM!) that would fit in the available space seemed
          like it might slip. And that would sort of be backlash all over
          again, the head would not have moved as far as the dial said it did.
          I will certainly be interested in what you come up with!
          What I am going to try for is to "spread" each tooth so it just fits
          but also file the end to a slightly pointed shape so it more easily
          engages in the opposing notch, somewhat of a typical gear-tooth shape.
          Bob Wilson
        • Billy Moore
          Hello Bob: Have the R8 MiniMill also and likewise on the castelated course feed handle , Mine is also sloppy but not as much as the slop in the fine feed.
          Message 4 of 17 , Feb 1, 2002
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            Hello Bob:  Have the R8 MiniMill also and likewise on the castelated course feed handle , Mine is also sloppy but not as much as the slop in the fine feed.  Have not played with it much this winter as I have been under the weather and did not feel like it. Need to loosen the screws and see what adjusting the position of the bracket that houses the gears will do. The springs looks like a neat trick.... Keep up the good work and keep us posted how the project comes out.
            Bill,  Harrogate, Tn.   WA4LQN
            ----- Original Message -----
            Sent: Friday, February 01, 2002 18:08
            Subject: [GrizHFMinimill] Posted photos re R8 mini-mill

            I just posted two pictures (in album "Bob Wilson's R8 mini-mill")
            that show (a) the amount of play in the castellated pieces that
            couple the z-axis slow feed and (b) a spring to keep a lock handle
            from flopping around.
            (a) I posted earlier a note that the z-axis backlash on my HF R8 mini-
            mill was mostly in the play between the teeth of the two castellated
            pieces that engage when you slide the fast-feed handle inward. The
            photo shows a piece of 0.015 brass between the adjacent teeth. I have
            been thinking of ways to deal with this, ranging over machining a
            whole new piece or two on the  original plan, or using a wholly new
            way to couple the worm-driven pinion to the shaft, or modifying the
            existing pieces. My present plan is: cut a slight notch in the center
            of each tooth on the outer piece, the one the three handles screw
            into, then us a cold chisel at the notch to slightly spread the
            metal. Of course I could ruin the piece, but LMS has replacements and
            I think the risk is small. But I would welcome other ideas!
            (b) I found the way the lock handles would flop down in the way of
            other things sometimes a nuisance, so I just added a small
            compression spring under each one. The exact spring is not critical.
            Works fine.
            Bob Wilson





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          • w_r_miller2001
            ... Man, am I glad the REX has a belt drive in the head. I ve accidently left the spindle lock in several times, and have had no broken parts. Sometimes it s
            Message 5 of 17 , Feb 1, 2002
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              > I am also replacing ALL the gears in the mill head with harden
              >steel gears! I broke a gear about an hour ago and now I done for
              >the weekend! :(

              Man, am I glad the REX has a belt drive in the head. I've accidently
              left the spindle lock in several times, and have had no broken parts.

              Sometimes it's the small things.... ;)

              Bill M.
            • fromday2
              Hi, I found that I had a lot of play between the rack and pinion, I shimmed the rack out, do not remember how much but it seems it was either .018 or .024. It
              Message 6 of 17 , Feb 1, 2002
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                Hi,

                I found that I had a lot of play between the rack and pinion, I
                shimmed the rack out, do not remember how much but it seems it was
                either .018 or .024. It helped a lot.

                Also the worm gear under the cover had a lot of play and would move
                fore and aft. I drilled and tapped the cover for a screw to press on
                the end of the worm and reduce the end play. It helped some but not
                as much as shimming the rack.

                The "square gears" are now the biggest problem I have. If I had gear
                cutting capability I would look at making gears with a angled tooth.
                As they engaged the angles would lock solid. A screw threaded into
                the end of the pinion could hold them engaged.

                Al Day

                --- In GrizHFMinimill@y..., "mathprof53575" <wilson@m...> wrote:
                > --- In GrizHFMinimill@y..., "wit01us" <mwitkowski@w...> wrote:
                > > Bob,
                > >
                > > I think you are on the right track when you say make a whole new
                > > way to engage the fine feed. I have been looking in catologs for
                a
                > 2
                > > disk system with a spring batween them. I think I will just make
                > the
                > > pieces. I am going to change the "squar gears" on the stock mill
                > > deseign to a cone shaped "gear". This will allow you to engage
                the
                > > fine adjustment with the "corse handle" in any location.
                > >
                > >...
                > >
                > > Mark W.
                >
                > Mark,
                > What I worry about is how much torque the coupling has to carry. I
                > considered various clutch designs and anything I could make easily
                (I
                > am not set up for EDM!) that would fit in the available space
                seemed
                > like it might slip. And that would sort of be backlash all over
                > again, the head would not have moved as far as the dial said it did.
                > I will certainly be interested in what you come up with!
                > What I am going to try for is to "spread" each tooth so it just
                fits
                > but also file the end to a slightly pointed shape so it more easily
                > engages in the opposing notch, somewhat of a typical gear-tooth
                shape.
                > Bob Wilson
              • wit01us
                Bill, I made a spring loaded pin that is atached to the mill so I don t have to worry about leaving the spindle lock in. I m one of the forgetfull type and
                Message 7 of 17 , Feb 2, 2002
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                  Bill,

                  I made a spring loaded pin that is atached to the mill so I don't
                  have to worry about leaving the spindle lock in. I'm one of the
                  forgetfull type and would have done it sooner or latter. I broke the
                  gear by tryng to take too much off in a pass...I was flying some AL.

                  Live and Learn.

                  Mark W.







                  --- In GrizHFMinimill@y..., "w_r_miller2001" <wmiller45@e...> wrote:
                  > > I am also replacing ALL the gears in the mill head with harden
                  > >steel gears! I broke a gear about an hour ago and now I done for
                  > >the weekend! :(
                  >
                  > Man, am I glad the REX has a belt drive in the head. I've
                  accidently
                  > left the spindle lock in several times, and have had no broken
                  parts.
                  >
                  > Sometimes it's the small things.... ;)
                  >
                  > Bill M.
                • w_r_miller2001
                  ... the ... AL. ... I have thought of this also, but don t like the fact I have to hold it in with one hand, turn the drawbar wrench with the other, and watch
                  Message 8 of 17 , Feb 3, 2002
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                    --- In GrizHFMinimill@y..., "wit01us" <mwitkowski@w...> wrote:
                    > Bill,
                    >
                    > I made a spring loaded pin that is atached to the mill so I don't
                    > have to worry about leaving the spindle lock in. I'm one of the
                    > forgetfull type and would have done it sooner or latter. I broke
                    the
                    > gear by tryng to take too much off in a pass...I was flying some
                    AL.
                    >
                    > Live and Learn.
                    >
                    > Mark W.

                    I have thought of this also, but don't like the fact I have to hold
                    it in with one hand, turn the drawbar wrench with the other, and
                    watch my end mill fall out of the collet. Ouch. This happened a
                    couple of times early on when I had one hand holding the spindle
                    lock instead of the tool.

                    I'm toying with the idea of a squeeze type that mounts on the lower
                    front of the headstock (I have a couple of threaded holes there) and
                    wraps around the exposed portion of the spindle. The tension handle
                    would be positioned such that I could get a finger or two under the
                    cutter so it doesn't fall out onto the vise or workpiece. Likely
                    this will be to complex, and I'll end up doing something like you
                    did. ;)

                    Bill M.
                  • Rob Zwissler
                    I have thought of constructing a mounted pin (not spring loaded), which must be withdrawn to trigger a small relay (or run the wiring directly), so that the
                    Message 9 of 17 , Feb 3, 2002
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                      I have thought of constructing a mounted pin (not spring loaded), which
                      must be withdrawn to trigger a small relay (or run the wiring directly),
                      so that the spindle cannot be turned on until the pin is withdrawn. It
                      could be a relatively small part, and you could even incorporate a status
                      LED on the housing so it's real obvious when it is/isn't safe.

                      Rob


                      --- w_r_miller2001 <wmiller45@...> wrote:
                      > --- In GrizHFMinimill@y..., "wit01us" <mwitkowski@w...> wrote:
                      > > Bill,
                      > >
                      > > I made a spring loaded pin that is atached to the mill so I don't
                      > > have to worry about leaving the spindle lock in. I'm one of the
                      > > forgetfull type and would have done it sooner or latter. I broke
                      > the
                      > > gear by tryng to take too much off in a pass...I was flying some
                      > AL.
                      > >
                      > > Live and Learn.
                      > >
                      > > Mark W.
                      >
                      > I have thought of this also, but don't like the fact I have to hold
                      > it in with one hand, turn the drawbar wrench with the other, and
                      > watch my end mill fall out of the collet. Ouch. This happened a
                      > couple of times early on when I had one hand holding the spindle
                      > lock instead of the tool.
                      >
                      > I'm toying with the idea of a squeeze type that mounts on the lower
                      > front of the headstock (I have a couple of threaded holes there) and
                      > wraps around the exposed portion of the spindle. The tension handle
                      > would be positioned such that I could get a finger or two under the
                      > cutter so it doesn't fall out onto the vise or workpiece. Likely
                      > this will be to complex, and I'll end up doing something like you
                      > did. ;)
                      >
                      > Bill M.
                      >
                      >
                      >


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                    • w_r_miller2001
                      An electrical interlock mechanism would be ideal, but I personally don t like messing with electrical/electronics. Maybe it s because it was my job for so many
                      Message 10 of 17 , Feb 3, 2002
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                        An electrical interlock mechanism would be ideal, but I personally
                        don't like messing with electrical/electronics. Maybe it's because
                        it was my job for so many years. Any volunteers to design it up? :)

                        Bill M.


                        --- In GrizHFMinimill@y..., Rob Zwissler <robzr@y...> wrote:
                        > I have thought of constructing a mounted pin (not spring loaded),
                        which
                        > must be withdrawn to trigger a small relay (or run the wiring
                        directly),
                        > so that the spindle cannot be turned on until the pin is
                        withdrawn. It
                        > could be a relatively small part, and you could even incorporate a
                        status
                        > LED on the housing so it's real obvious when it is/isn't safe.
                        >
                        > Rob
                      • Barry Young
                        Good Pics Bill, and thanks for the tip about the floppy handles. Barry Young ... __________________________________________________ Do You Yahoo!? Great stuff
                        Message 11 of 17 , Feb 3, 2002
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                          Good Pics Bill, and thanks for the tip about the
                          floppy handles.

                          Barry Young


                          --- mathprof53575 <wilson@...> wrote:
                          > I just posted two pictures (in album "Bob Wilson's
                          > R8 mini-mill")
                          > that show (a) the amount of play in the castellated
                          > pieces that
                          > couple the z-axis slow feed and (b) a spring to keep
                          > a lock handle
                          > from flopping around.
                          > (a) I posted earlier a note that the z-axis backlash
                          > on my HF R8 mini-
                          > mill was mostly in the play between the teeth of the
                          > two castellated
                          > pieces that engage when you slide the fast-feed
                          > handle inward. The
                          > photo shows a piece of 0.015 brass between the
                          > adjacent teeth. I have
                          > been thinking of ways to deal with this, ranging
                          > over machining a
                          > whole new piece or two on the original plan, or
                          > using a wholly new
                          > way to couple the worm-driven pinion to the shaft,
                          > or modifying the
                          > existing pieces. My present plan is: cut a slight
                          > notch in the center
                          > of each tooth on the outer piece, the one the three
                          > handles screw
                          > into, then us a cold chisel at the notch to slightly
                          > spread the
                          > metal. Of course I could ruin the piece, but LMS has
                          > replacements and
                          > I think the risk is small. But I would welcome other
                          > ideas!
                          > (b) I found the way the lock handles would flop down
                          > in the way of
                          > other things sometimes a nuisance, so I just added a
                          > small
                          > compression spring under each one. The exact spring
                          > is not critical.
                          > Works fine.
                          > Bob Wilson
                          >
                          >
                          >
                          >
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                          >


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                        • Barry Young
                          Hey Bob, How about having the dog cluth parts hard chromed? You could build the existing faces up that way and get an unbelievably wear resistant surface in
                          Message 12 of 17 , Feb 3, 2002
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                            Hey Bob, How about having the dog cluth parts hard
                            chromed? You could build the existing faces up that
                            way and get an unbelievably wear resistant surface in
                            the bargain.

                            Barry Young


                            --- mathprof53575 <wilson@...> wrote:
                            > --- In GrizHFMinimill@y..., "wit01us"
                            > <mwitkowski@w...> wrote:
                            > > Bob,
                            > >
                            > > I think you are on the right track when you say
                            > make a whole new
                            > > way to engage the fine feed. I have been looking
                            > in catologs for a
                            > 2
                            > > disk system with a spring batween them. I think I
                            > will just make
                            > the
                            > > pieces. I am going to change the "squar gears" on
                            > the stock mill
                            > > deseign to a cone shaped "gear". This will allow
                            > you to engage the
                            > > fine adjustment with the "corse handle" in any
                            > location.
                            > >
                            > >...
                            > >
                            > > Mark W.
                            >
                            > Mark,
                            > What I worry about is how much torque the coupling
                            > has to carry. I
                            > considered various clutch designs and anything I
                            > could make easily (I
                            > am not set up for EDM!) that would fit in the
                            > available space seemed
                            > like it might slip. And that would sort of be
                            > backlash all over
                            > again, the head would not have moved as far as the
                            > dial said it did.
                            > I will certainly be interested in what you come up
                            > with!
                            > What I am going to try for is to "spread" each tooth
                            > so it just fits
                            > but also file the end to a slightly pointed shape so
                            > it more easily
                            > engages in the opposing notch, somewhat of a typical
                            > gear-tooth shape.
                            > Bob Wilson
                            >
                            >
                            >
                            > To unsubscribe from this group, send an email to:
                            > GrizHFMinimill-unsubscribe@yahoogroups.com
                            >
                            >
                            >
                            > Your use of Yahoo! Groups is subject to
                            > http://docs.yahoo.com/info/terms/
                            >
                            >


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                          • mathprof53575
                            ... As Mark said, I think the best thing is to find a whole new way to couple the slow feed worm pinion to the shaft that is also the pinion of the
                            Message 13 of 17 , Feb 3, 2002
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                              --- In GrizHFMinimill@y..., Barry Young <barryjyoung@y...> wrote:
                              >
                              >
                              > Hey Bob, How about having the dog cluth parts hard
                              > chromed? You could build the existing faces up that
                              > way and get an unbelievably wear resistant surface in
                              > the bargain.
                              >
                              > Barry Young
                              >
                              >
                              As Mark said, I think the best thing is to find a whole new way to
                              couple the slow feed worm pinion to the shaft that is also the pinion
                              of the rack-and-pinion. Here is an idea I had, I might try when I
                              find some time:
                              (a) In the lathe (I have had an old 9" Atlas for years, I hope this
                              does not get me thrown out of the group since it is not a mini-
                              lathe...) completely remove the "castle" dogs from the pinion, make a
                              nice face square to the axis.
                              (b) Turn a piece, I will call it a bushing with a flange at one end,
                              that fits closely over the shaft (12mm). The bushing tapers, I
                              haven't decided what angle, narrow at the end away from the flange.
                              The bushing has slots in it: In fact it amounts to a collet. The
                              flange has holes in it for machine screws that go into tapped holes
                              to hold it to the clean face produced in (a).
                              (c) Turn a new hub for the three handle spokes, bored and keyed as
                              the original, but where the original has the castle instead this has
                              a hollow section sticking out along the shaft which is internally
                              tapered slightly more than the collet.
                              (d) Thread the end of the shaft, where the snap ring is, and make a
                              knob that threads on there.
                              Now when you turn the knob it pushes the hub in toward the pinion,
                              trapping the collet between the hollow section and the shaft and
                              compressing it onto the shaft "collet-like". When you loosen the knob
                              this releases the collet: It might be necessary to have a spring
                              pushing the pinion and hub apart, just like when you tap on the
                              drawbar to release a collet...
                              This seems to me to have minimal risk, nothing except the pinion is
                              made so it could not work in the original way, except that you might
                              have to make a nut to replace the snap ring if you had completed step
                              (d). And LMS sells the pinions.
                              And it seems to me that this could transmit a lot of torque, just
                              like a 12mm collet holding a cutter. There must be quite a bit of
                              torque here: The 12mm part of the shaft is smaller than the pinion
                              section of the shaft, so the linear force is greater than the weight
                              of the head plus the drag of the gibbs plus whatever other loads are
                              on it.
                              OK, who sees what I have wrong?
                              Bob Wilson
                            • wit01us
                              Bob, I like your idea......I m going to work on something like that. I said on an eariler post about two cone shaped gears. Well, you gave me the answer by
                              Message 14 of 17 , Feb 3, 2002
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                                Bob,

                                I like your idea......I'm going to work on something like that. I
                                said on an eariler post about two cone shaped gears. Well, you gave
                                me the answer by saying "collet type" of engagement. I will get rid
                                of the "gear" idea and stick with the cone idea. I will use a spring
                                to disengage the cone and use a "draw bar" type to engage the cone.

                                If ayone has anything to add PLEASE feel free to add to this. I
                                believe with all the good ideas out there we can make this work.

                                thank's all

                                Mark W.

                                Sorry about the spelling........






                                --- In GrizHFMinimill@y..., "mathprof53575" <wilson@m...> wrote:
                                > --- In GrizHFMinimill@y..., Barry Young <barryjyoung@y...> wrote:
                                > >
                                > >
                                > > Hey Bob, How about having the dog cluth parts hard
                                > > chromed? You could build the existing faces up that
                                > > way and get an unbelievably wear resistant surface in
                                > > the bargain.
                                > >
                                > > Barry Young
                                > >
                                > >
                                > As Mark said, I think the best thing is to find a whole new way to
                                > couple the slow feed worm pinion to the shaft that is also the
                                pinion
                                > of the rack-and-pinion. Here is an idea I had, I might try when I
                                > find some time:
                                > (a) In the lathe (I have had an old 9" Atlas for years, I hope this
                                > does not get me thrown out of the group since it is not a mini-
                                > lathe...) completely remove the "castle" dogs from the pinion, make
                                a
                                > nice face square to the axis.
                                > (b) Turn a piece, I will call it a bushing with a flange at one
                                end,
                                > that fits closely over the shaft (12mm). The bushing tapers, I
                                > haven't decided what angle, narrow at the end away from the flange.
                                > The bushing has slots in it: In fact it amounts to a collet. The
                                > flange has holes in it for machine screws that go into tapped holes
                                > to hold it to the clean face produced in (a).
                                > (c) Turn a new hub for the three handle spokes, bored and keyed as
                                > the original, but where the original has the castle instead this
                                has
                                > a hollow section sticking out along the shaft which is internally
                                > tapered slightly more than the collet.
                                > (d) Thread the end of the shaft, where the snap ring is, and make a
                                > knob that threads on there.
                                > Now when you turn the knob it pushes the hub in toward the pinion,
                                > trapping the collet between the hollow section and the shaft and
                                > compressing it onto the shaft "collet-like". When you loosen the
                                knob
                                > this releases the collet: It might be necessary to have a spring
                                > pushing the pinion and hub apart, just like when you tap on the
                                > drawbar to release a collet...
                                > This seems to me to have minimal risk, nothing except the pinion is
                                > made so it could not work in the original way, except that you
                                might
                                > have to make a nut to replace the snap ring if you had completed
                                step
                                > (d). And LMS sells the pinions.
                                > And it seems to me that this could transmit a lot of torque, just
                                > like a 12mm collet holding a cutter. There must be quite a bit of
                                > torque here: The 12mm part of the shaft is smaller than the pinion
                                > section of the shaft, so the linear force is greater than the
                                weight
                                > of the head plus the drag of the gibbs plus whatever other loads
                                are
                                > on it.
                                > OK, who sees what I have wrong?
                                > Bob Wilson
                              • mathprof53575
                                ... This is another thing on my to do eventually list but it probably won t move to the top until I break a gear... I can think of two fundamentally
                                Message 15 of 17 , Feb 5, 2002
                                • 0 Attachment
                                  --- In GrizHFMinimill@y..., "w_r_miller2001" <wmiller45@e...> wrote:
                                  > An electrical interlock mechanism would be ideal, but I personally
                                  > don't like messing with electrical/electronics. Maybe it's because
                                  > it was my job for so many years. Any volunteers to design it up? :)
                                  >
                                  > Bill M.
                                  >
                                  This is another thing on my "to do eventually" list but it probably
                                  won't move to the top until I break a gear...
                                  I can think of two fundamentally different ways to do this: The
                                  easier is to have a spring loaded pin, always present and you just
                                  push it in rather than the original that you have to hunt around and
                                  find, with a sensor for when it is pushed in. The simplest sensor is
                                  probably a little vane that triggers an optointerrupter, another
                                  option is a magnet and a reed switch, you might even be able to use a
                                  sensor for a burglar alarm so it is already sealed somewhat against
                                  swarf and oil and ... The signal from that kills the motor when the
                                  pin is in: The PC board already has, I think, two screw terminals
                                  that are just jumpered together, for use with the reversing switch
                                  when the PC board is used on a lathe, that if not connected disable
                                  the motor. And as I recall that is a low current connection, not
                                  really in series with the motor, so it would be easy to have the
                                  sensor break that connection.
                                  The other way of doing it, that would be a bit more complicated but
                                  would deal with the complaint some have raised about the spring
                                  loaded pin, that you need a hand free to hold it in, would work the
                                  other way around. If the motor is off and you push a button, a
                                  solenoid would push the pin in against a spring, and (electronically)
                                  latch it until you were through with the locked spindle. One could go
                                  all the way and keep it locked until you turned the motor back on and
                                  it would sequence pulling the pin out before starting the motor, but
                                  frequently you want to turn the spindle by hand before starting the
                                  motor so a separate "unlock" button would be better. (Or push the
                                  same button a second time but I think it is a cleaner interface to
                                  have one lock, one unlock button...)
                                  The second would not be too much harder: Since I don't yet have a
                                  spring loaded pin I am not sure how much pain it is, so how much is
                                  it worth doing the second scheme?
                                  Bob Wilson
                                • Rob Zwissler
                                  Wow, my idea for this was much less complex. All you d need is a L shaped bracket that bolts onto the mill with two of the allen head screws on top (next to
                                  Message 16 of 17 , Feb 5, 2002
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                                    Wow, my idea for this was much less complex.

                                    All you'd need is a L shaped bracket that bolts onto the mill with
                                    two of the allen head screws on top (next to the motor, the ones that
                                    align the gears). You'd probably have to get longer ones to accomodate
                                    the thickness of the bracket. Then, you'd have a pin with a handle of
                                    choice (expanded & knurled IMO!). This could all be aluminum. You'd
                                    want about 1" of movement in the pin. Then, you'd want an wire
                                    terminating onto the pin, and one terminating on the brack, such that
                                    when the pin is pulled out, it makes contact with the side on the
                                    bracket. There's your switching mechanism right there. Depending on
                                    the guage of the wire, you might just want to run a relay into the
                                    box with the switch, or wire it up directly if it's not that big of
                                    wire (maybe 12 g or smaller).

                                    The pin should not be spring loaded, so that you don't need to hold
                                    it - this frees your hands up for removing the tool and loosening the
                                    drawbar. I think ideally the pin would "clip" into the outer position,
                                    in my mind the brass wire terminals would clip together (like both U
                                    shaped, such that when you pull hte pin back, one U seats in the other
                                    U. if there is tension at the receiving U, it would create a locking
                                    mechanism. You could bend some brass or probably find these parts
                                    existing.

                                    Rob


                                    --- mathprof53575 <wilson@...> wrote:
                                    > --- In GrizHFMinimill@y..., "w_r_miller2001" <wmiller45@e...> wrote:
                                    > > An electrical interlock mechanism would be ideal, but I personally
                                    > > don't like messing with electrical/electronics. Maybe it's because
                                    > > it was my job for so many years. Any volunteers to design it up? :)
                                    > >
                                    > > Bill M.
                                    > >
                                    > This is another thing on my "to do eventually" list but it probably
                                    > won't move to the top until I break a gear...
                                    > I can think of two fundamentally different ways to do this: The
                                    > easier is to have a spring loaded pin, always present and you just
                                    > push it in rather than the original that you have to hunt around and
                                    > find, with a sensor for when it is pushed in. The simplest sensor is
                                    > probably a little vane that triggers an optointerrupter, another
                                    > option is a magnet and a reed switch, you might even be able to use a
                                    > sensor for a burglar alarm so it is already sealed somewhat against
                                    > swarf and oil and ... The signal from that kills the motor when the
                                    > pin is in: The PC board already has, I think, two screw terminals
                                    > that are just jumpered together, for use with the reversing switch
                                    > when the PC board is used on a lathe, that if not connected disable
                                    > the motor. And as I recall that is a low current connection, not
                                    > really in series with the motor, so it would be easy to have the
                                    > sensor break that connection.
                                    > The other way of doing it, that would be a bit more complicated but
                                    > would deal with the complaint some have raised about the spring
                                    > loaded pin, that you need a hand free to hold it in, would work the
                                    > other way around. If the motor is off and you push a button, a
                                    > solenoid would push the pin in against a spring, and (electronically)
                                    > latch it until you were through with the locked spindle. One could go
                                    > all the way and keep it locked until you turned the motor back on and
                                    > it would sequence pulling the pin out before starting the motor, but
                                    > frequently you want to turn the spindle by hand before starting the
                                    > motor so a separate "unlock" button would be better. (Or push the
                                    > same button a second time but I think it is a cleaner interface to
                                    > have one lock, one unlock button...)
                                    > The second would not be too much harder: Since I don't yet have a
                                    > spring loaded pin I am not sure how much pain it is, so how much is
                                    > it worth doing the second scheme?
                                    > Bob Wilson
                                    >
                                    >


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                                  • Barry Young
                                    I guess the only thing I see wrong with your logic is the amount of torque you would have to put on the knob to make it grip effectively. But then, I really
                                    Message 17 of 17 , Feb 5, 2002
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                                      I guess the only thing I see wrong with your logic is
                                      the amount of torque you would have to put on the knob
                                      to make it grip effectively.

                                      But then, I really don't see what all the fuss over
                                      slop in the elevating mechanism is about anyway. None
                                      of you actually try to cut with the head unclamped do
                                      you? I use a magnetic indicator when making fine
                                      adjustments in Z anyway. Maybe I am missing the point.

                                      Barry Young
                                      Who has worked on way too many sloppy machines to
                                      think that backlash is a big deal.



                                      > As Mark said, I think the best thing is to find a
                                      > whole new way to
                                      > couple the slow feed worm pinion to the shaft that
                                      > is also the pinion
                                      > of the rack-and-pinion. Here is an idea I had, I
                                      > might try when I
                                      > find some time:
                                      > (a) In the lathe (I have had an old 9" Atlas for
                                      > years, I hope this
                                      > does not get me thrown out of the group since it is
                                      > not a mini-
                                      > lathe...) completely remove the "castle" dogs from
                                      > the pinion, make a
                                      > nice face square to the axis.
                                      > (b) Turn a piece, I will call it a bushing with a
                                      > flange at one end,
                                      > that fits closely over the shaft (12mm). The bushing
                                      > tapers, I
                                      > haven't decided what angle, narrow at the end away
                                      > from the flange.
                                      > The bushing has slots in it: In fact it amounts to a
                                      > collet. The
                                      > flange has holes in it for machine screws that go
                                      > into tapped holes
                                      > to hold it to the clean face produced in (a).
                                      > (c) Turn a new hub for the three handle spokes,
                                      > bored and keyed as
                                      > the original, but where the original has the castle
                                      > instead this has
                                      > a hollow section sticking out along the shaft which
                                      > is internally
                                      > tapered slightly more than the collet.
                                      > (d) Thread the end of the shaft, where the snap ring
                                      > is, and make a
                                      > knob that threads on there.
                                      > Now when you turn the knob it pushes the hub in
                                      > toward the pinion,
                                      > trapping the collet between the hollow section and
                                      > the shaft and
                                      > compressing it onto the shaft "collet-like". When
                                      > you loosen the knob
                                      > this releases the collet: It might be necessary to
                                      > have a spring
                                      > pushing the pinion and hub apart, just like when you
                                      > tap on the
                                      > drawbar to release a collet...
                                      > This seems to me to have minimal risk, nothing
                                      > except the pinion is
                                      > made so it could not work in the original way,
                                      > except that you might
                                      > have to make a nut to replace the snap ring if you
                                      > had completed step
                                      > (d). And LMS sells the pinions.
                                      > And it seems to me that this could transmit a lot of
                                      > torque, just
                                      > like a 12mm collet holding a cutter. There must be
                                      > quite a bit of
                                      > torque here: The 12mm part of the shaft is smaller
                                      > than the pinion
                                      > section of the shaft, so the linear force is greater
                                      > than the weight
                                      > of the head plus the drag of the gibbs plus whatever
                                      > other loads are
                                      > on it.
                                      > OK, who sees what I have wrong?
                                      > Bob Wilson
                                      >
                                      >
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