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adjustable automatic half-nut release setup.

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  • steveh8861
    Hi all, I m new to the group and to lathing. I just bought a Enco 7x10 and am enjoying learning a new tool. After reading about an adjustable carriage feed
    Message 1 of 5 , Jun 16, 2005
      Hi all, I'm new to the group and to lathing. I just bought a Enco
      7x10 and am enjoying learning a new tool.
      After reading about an adjustable carriage feed stop in the
      current "The Home Shop Machinist" mag, I decided this would be my
      first lathe mod after ruining a few fittings I was making by not
      being quick enough on the half nut lever.

      So here is a link to many pics of what I came up with->
      http://kihco1.onfinite.com/album/493425/

      The link shows my first version with a thumb screw for fine
      adjustment and the newer version with micrometer adjustment and a
      better rear clamp washer.
      The slide has 6" of travel and another 1" of Mic adjustment.
      The Mic is useful for threading to offset the compound movement.
      I decided not to even try and make this mod fit onto the already
      crowded Mini lathe. So I external mount it next to the lathe.
      My testing has shown repeatability in the carriage stop to be less
      than .001"! It's very accurate.
      A 1/4 turn on the lever locks the slide in rough position and then
      fine tune with the mic adjuster.
      I tried a shaft with a ball bearing instead of the simple bolt head
      on the half nut lever. It made no difference in accuracy at all.
      When not in use the slide goes near the head stock and is out of the
      way of all lathe parts.
      Forgive some of the crude machining. I don't have milling
      capabilites yet and had to whip out my Mig welder for much of it.:-)

      Steve
    • Richard Garnish
      Looks like a very neat solution to the requirement. How positively does it disengage the halfnuts when it hits the stop? I d be worried about it scrubbing
      Message 2 of 5 , Jun 17, 2005
        Looks like a very neat solution to the requirement. How positively does
        it disengage the halfnuts when it hits the stop? I'd be worried about
        it scrubbing the crests of the thread when it disengages (also, with
        acme-threaded leadscrews, the thread timing drifts if the halfnuts are
        not fully disengaged.)

        I was distantly considering something involving a spring-loaded catch
        release to avoid this, but if your solution disengages smartly enough,
        it shows I'm thinking too complicated (as usual!)

        Richard

        On Fri, 2005-06-17 at 03:23, steveh8861 wrote:
        > Hi all, I'm new to the group and to lathing. I just bought a Enco
        > 7x10 and am enjoying learning a new tool.
        > After reading about an adjustable carriage feed stop in the
        > current "The Home Shop Machinist" mag, I decided this would be my
        > first lathe mod after ruining a few fittings I was making by not
        > being quick enough on the half nut lever.
        >
        > So here is a link to many pics of what I came up with->
        > http://kihco1.onfinite.com/album/493425/
        >
        > The link shows my first version with a thumb screw for fine
        > adjustment and the newer version with micrometer adjustment and a
        > better rear clamp washer.
        > The slide has 6" of travel and another 1" of Mic adjustment.
        > The Mic is useful for threading to offset the compound movement.
        > I decided not to even try and make this mod fit onto the already
        > crowded Mini lathe. So I external mount it next to the lathe.
        > My testing has shown repeatability in the carriage stop to be less
        > than .001"! It's very accurate.
        > A 1/4 turn on the lever locks the slide in rough position and then
        > fine tune with the mic adjuster.
        > I tried a shaft with a ball bearing instead of the simple bolt head
        > on the half nut lever. It made no difference in accuracy at all.
        > When not in use the slide goes near the head stock and is out of the
        > way of all lathe parts.
        > Forgive some of the crude machining. I don't have milling
        > capabilites yet and had to whip out my Mig welder for much of it.:-)
        >
        > Steve
        >
        >
        >
        >
        >
        >
        >
        > Yahoo! Groups Links
        >
        >
        >
        >
        >
      • steveh8861
        ... positively does ... about ... with ... are ... catch ... enough, ... Richard, It completely unlocks the half nut. You can even hear it sort of click when
        Message 3 of 5 , Jun 17, 2005
          --- In mlathemods@yahoogroups.com, Richard Garnish <rdg@m...> wrote:
          > Looks like a very neat solution to the requirement. How
          positively does
          > it disengage the halfnuts when it hits the stop? I'd be worried
          about
          > it scrubbing the crests of the thread when it disengages (also,
          with
          > acme-threaded leadscrews, the thread timing drifts if the halfnuts
          are
          > not fully disengaged.)
          >
          > I was distantly considering something involving a spring-loaded
          catch
          > release to avoid this, but if your solution disengages smartly
          enough,
          > it shows I'm thinking too complicated (as usual!)
          >
          > Richard


          Richard,
          It completely unlocks the half nut. You can even hear it sort of
          click when it unlocks. I have tested it and tested it marveling at
          how accurate it is for something so simple.
          I think one should make sure the half-nut mechanism is well
          maintained and lubed for an easy clean release though.
          The device simply needs to be very rigid to avoid any deflection as
          the slightest deflection will be transferred.
          Using the mic for adjustment does show up some variance in the stop.
          In that if I turn the mic .010" the carriage stop may not directly
          change .010". It seems to vary by .001-.003 depending how much I
          turn the mic. I suspect I don't have the mic at exactly 90' to the
          stop on the half-nut lever so I have an angle throwing off it's
          adjustment.
          But once you set it, it will always stop at the same point with
          better than .001" accuracy.

          Steve
        • Richard Garnish
          Steve, Looks like I ve found my next mini lathe upgrade project! Thanks for that, Richard
          Message 4 of 5 , Jun 17, 2005
            Steve,

            Looks like I've found my next mini lathe upgrade project!

            Thanks for that,

            Richard

            On Fri, 2005-06-17 at 15:48, steveh8861 wrote:
            > --- In mlathemods@yahoogroups.com, Richard Garnish <rdg@m...> wrote:
            > > Looks like a very neat solution to the requirement. How
            > positively does
            > > it disengage the halfnuts when it hits the stop? I'd be worried
            > about
            > > it scrubbing the crests of the thread when it disengages (also,
            > with
            > > acme-threaded leadscrews, the thread timing drifts if the halfnuts
            > are
            > > not fully disengaged.)
            > >
            > > I was distantly considering something involving a spring-loaded
            > catch
            > > release to avoid this, but if your solution disengages smartly
            > enough,
            > > it shows I'm thinking too complicated (as usual!)
            > >
            > > Richard
            >
            >
            > Richard,
            > It completely unlocks the half nut. You can even hear it sort of
            > click when it unlocks. I have tested it and tested it marveling at
            > how accurate it is for something so simple.
            > I think one should make sure the half-nut mechanism is well
            > maintained and lubed for an easy clean release though.
            > The device simply needs to be very rigid to avoid any deflection as
            > the slightest deflection will be transferred.
            > Using the mic for adjustment does show up some variance in the stop.
            > In that if I turn the mic .010" the carriage stop may not directly
            > change .010". It seems to vary by .001-.003 depending how much I
            > turn the mic. I suspect I don't have the mic at exactly 90' to the
            > stop on the half-nut lever so I have an angle throwing off it's
            > adjustment.
            > But once you set it, it will always stop at the same point with
            > better than .001" accuracy.
            >
            > Steve
            >
            >
            >
            >
            >
            >
            > Yahoo! Groups Links
            >
            >
            >
            >
          • steveh8861
            ... much reading all the info available on these machines from others. A spring loaded trigger assembly might workout nice also. I m not sure if it could be
            Message 5 of 5 , Jun 17, 2005
              --- In mlathemods@yahoogroups.com, Richard Garnish <rdg@m...> wrote:
              > Steve,
              >
              > Looks like I've found my next mini lathe upgrade project!
              >
              > Thanks for that,
              >
              > Your welcome. I am happy to contribute something. I have learned so
              much reading all the info available on these machines from others.
              A spring loaded "trigger" assembly might workout nice also.
              I'm not sure if it could be any more accurate though and a spring
              might be harder to control compared to the smooth gradual "lever type"
              release. But I'm sure my assembly can be improved.

              Steve
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