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Left Hand Threads

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  • catfish7251
    I have a HF 7X10 mini lathe and am new to threading. Is it possible to cut left hand Acme threads for a vice on it. Thanks Catfish.
    Message 1 of 9 , Jan 25, 2004
      I have a HF 7X10 mini lathe and am new to threading.
      Is it possible to cut left hand Acme threads for a vice on it.

      Thanks Catfish.
    • Corey
      Sure it is. Set the feed lever behind the headstock to reverse (down). And you will have to grind a special toolbit. c catfish7251 wrote: I
      Message 2 of 9 , Jan 25, 2004
        Sure it is. Set the feed lever behind the headstock to reverse (down). And you will have to grind a special toolbit.

        c

        catfish7251 <cleon@...> wrote:
        I have a HF 7X10 mini lathe and am new to threading.
        Is it possible to cut left hand Acme threads for a vice on it.

        Thanks Catfish.




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      • jjfear
        Catfish, Those are really two different questions. Any lathe with the ability to cut threads, can also cut lefthand threads. Almost every book on lathe
        Message 3 of 9 , Jan 25, 2004
          Catfish,

          Those are really two different questions. Any lathe with the ability
          to cut threads, can also cut lefthand threads. Almost every book on
          lathe operations will contain instructions for doing this. As someone
          new to thread cutting, I would suggest that you invest a little time
          and money in securing and reading one or more of those kind of books.
          A good source is Lindsay Books(www.lindsaybks.com) who sells reprints
          of older books which are better than modern books which devote space
          to CNC-CAM.

          Cutting ACME treads is more dificult either right or left. The Acme
          thread has a special thread form and can only be cut on a lathe with a
          form tool ground to the exact shape of the size of the thread needed.
          Seventy-five years ago, that might have been a common skill, but even
          experienced machinists find this a daunting task, and would be almost
          impossible for a beginner to accomplish successfully.

          The reason is that Acme thread rods in all sizes and both left and
          right hand threads are readily available from the normal industrial
          suppliers. They are not cheap, but compared to the time and effort to
          actually machine one, it pays.

          That would be my suggestion that you learn how to thread on a much
          simpler project


          --- In mlathemods@yahoogroups.com, "catfish7251" <cleon@m...> wrote:
          > I have a HF 7X10 mini lathe and am new to threading.
          > Is it possible to cut left hand Acme threads for a vice on it.
          >
          > Thanks Catfish.
        • Donald Qualls
          ... Yes. The mini-lathe cuts threads equally well in right hand or left hand; you ll need to set the tumble reverse and cut away from the chuck, and of course
          Message 4 of 9 , Jan 25, 2004
            catfish7251 wrote:
            > I have a HF 7X10 mini lathe and am new to threading.
            > Is it possible to cut left hand Acme threads for a vice on it.

            Yes. The mini-lathe cuts threads equally well in right hand or left
            hand; you'll need to set the tumble reverse and cut away from the chuck,
            and of course you'll need an accurately ground tool.

            That said, the mini-lathe is marginal on power to cut a thread like the
            Acme unless you use some trickery -- one way to improve things would be
            to eliminate chip crowding by using a pointed tool with the correct side
            angle cut cut in the leading and trailing slopes, then nibble out the
            gullet of the thread with a square tipped tool. You'll also most likely
            find it tricky to cut a coarse thread, like what you'll probably want
            for a vise, because the rapid feed both causes the advantage of the feed
            train to work against the lathe (the lead screw is turning faster than
            the spindle for any thread coarser than 16 tpi) and makes it hard to
            slow the spindle enough to keep proper track of the cut progress (though
            this is less of a problem when cutting away from the headstock as with a
            left hand thread).

            All things equal, it's probably easier and, by the time you ruin a few
            tool bits, might be cheaper to simply buy a length of the proper size LH
            Acme threaded rod from Enco or another supplier.

            --
            I may be a scwewy wabbit, but I'm not going to Alcatwaz!
            -- E. J. Fudd, 1954

            Donald Qualls, aka The Silent Observer
            Lathe Building Pages http://silent1.home.netcom.com/HomebuiltLathe.htm
            Speedway 7x12 Lathe Pages http://silent1.home.netcom.com/my7x12.htm

            Opinions expressed are my own -- take them for what they're worth
            and don't expect them to be perfect.
          • xlch58@swbell.net
            Actually, almost all threads require a special thread form. Most people are lazy and leave the tip sharp, but the root of a standard thread is not a , the
            Message 5 of 9 , Jan 25, 2004
              Actually, almost all threads require a special thread form. Most people
              are lazy and leave the tip sharp, but the root of a standard thread is
              not a , the width of the flat depending on the tpi.

              jjfear wrote:

              > Cutting ACME treads is more dificult either right or left. The Acme
              > thread has a special thread form and can only be cut on a lathe with a
              > form tool ground to the exact shape of the size of the thread needed.
              > Seventy-five years ago, that might have been a common skill, but even
              > experienced machinists find this a daunting task, and would be almost
              > impossible for a beginner to accomplish successfully.
            • catboat15@aol.com
              In a message dated 1/25/2004 6:19:08 PM Pacific Standard Time, xlch58@swbell.net writes: The Acme ... I think the usual suppliers carry Acme thread gauges,
              Message 6 of 9 , Jan 25, 2004
                In a message dated 1/25/2004 6:19:08 PM Pacific Standard Time,
                xlch58@... writes:
                The Acme
                > thread has a special thread form
                I think the usual suppliers carry Acme thread gauges, like our ordinary "fish
                tail" but instead of the 60 degree V notch (sorry, to the Brits, a 55 degreee
                notch) but with the Acme thread shape on the end. Should go fairly easy if
                your lathe is in good shape and you go slow, plenty of lube and light cuts as it
                is a form tool and chatter could be a problem.


                [Non-text portions of this message have been removed]
              • sculptor1@collegeclub.com
                Certainly. But I agree with the poster who stated doubts concering the power of the mini lathe to cut coarse threads. I have difficult time cutting threads
                Message 7 of 9 , Jan 25, 2004
                  Certainly. But I agree with the poster who stated doubts concering the power of the mini lathe to cut coarse threads. I have difficult time cutting threads above 16 tpi with my 9X20 under power for the same reason. I would make a hand crank for the spindle, reverse the LS, and grind a tool to form. Acme threads have a 29 degree side and a flat point. Pick up a machinist's manual such as Machinery's Handbook and it will have all the specs and proceedure to cut the thread. I would NOT try to cut it using the lathe's motor. It is a sure way to pop the controller or strip one of the plastic drive components. The Mini-lathe has no resetable clutch to protect the machine's controller in the event the user overloads the lead screw (by cutting to agressivily, running the bit into the chuck jaws....etc) so when that happens something breaks and has to be replaced. I've stripped the plastic drive key out of 3 pulleys and broke two controllers when I first bought it because there are no damage control devices like industrial lathes have (expendable phenolic gears, slip clutch, etc...).

                  Regards,

                  Gabe
                  catfish7251 <cleon@...> wrote:

                  >
                  >
                  >
                  >
                  > I have a HF 7X10 mini lathe and am new to threading.
                  > Is it possible to cut left hand Acme threads for a vice on it.
                  >
                  >Thanks Catfish.
                  >
                  >
                  >
                  >
                  >
                  >
                  >
                  >Yahoo! Groups Links
                  >
                  >To visit your group on the web, go to:
                  >http://groups.yahoo.com/group/mlathemods/
                  >
                  >To unsubscribe from this group, send an email to:
                  >mlathemods-unsubscribe@yahoogroups.com
                  >
                  >Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
                  >
                  >
                  >
                  >
                  >
                  >
                  >
                  >
                  >



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                • John Barrett
                  Having cut a few in my time (a long time ago!) it was imperative to cut the square portion first, and oh so carefully form the flanks. Outside threads are easy
                  Message 8 of 9 , Jan 26, 2004
                    Having cut a few in my time (a long time ago!) it was imperative to cut the
                    square portion first, and oh so carefully form the flanks. Outside threads
                    are easy enough but the internal one will cause you to swear a little! I
                    owned a minilathe for a while and it is quite nice at thread cutting but it
                    will be down on power and it will stress the components. If you are
                    determined to generate your own LH threads, why not consider a LH ACME tap
                    and die? I have seen a number on ebay recently at sensible money because
                    no-one knows how to use them anymore!
                    Regards
                    John Barrett.
                    -----Original Message-----
                    From: sculptor1@... [mailto:sculptor1@...]
                    Sent: 26 January 2004 04:03
                    To: mlathemods@yahoogroups.com
                    Subject: Re: [mlathemods] Left Hand Threads


                    Certainly. But I agree with the poster who stated doubts concering the
                    power of the mini lathe to cut coarse threads. I have difficult time
                    cutting threads above 16 tpi with my 9X20 under power for the same reason.
                    I would make a hand crank for the spindle, reverse the LS, and grind a tool
                    to form. Acme threads have a 29 degree side and a flat point. Pick up a
                    machinist's manual such as Machinery's Handbook and it will have all the
                    specs and proceedure to cut the thread. I would NOT try to cut it using
                    the lathe's motor. It is a sure way to pop the controller or strip one of
                    the plastic drive components. The Mini-lathe has no resetable clutch to
                    protect the machine's controller in the event the user overloads the lead
                    screw (by cutting to agressivily, running the bit into the chuck
                    jaws....etc) so when that happens something breaks and has to be replaced.
                    I've stripped the plastic drive key out of 3 pulleys and broke two
                    controllers when I first bought it because there are no damage control
                    devices like industrial lathes have (expendable phenolic gears, slip clutch,
                    etc...).

                    Regards,

                    Gabe
                    catfish7251 <cleon@...> wrote:

                    >
                    >
                    >
                    >
                    > I have a HF 7X10 mini lathe and am new to threading.
                    > Is it possible to cut left hand Acme threads for a vice on it.
                    >
                    >Thanks Catfish.
                    >
                    >
                    >
                    >
                    >
                    >
                    >
                    >Yahoo! Groups Links
                    >
                    >To visit your group on the web, go to:
                    >http://groups.yahoo.com/group/mlathemods/
                    >
                    >To unsubscribe from this group, send an email to:
                    >mlathemods-unsubscribe@yahoogroups.com
                    >
                    >Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
                    >
                    >
                    >
                    >
                    >
                    >
                    >
                    >
                    >



                    --------------------------------------------------------------------------
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                    of a lifetime!
                    <http://navisite.collegeclub.com/channels/travel >

                    CollegeClub.com makes college life even better.

                    [Non-text portions of this message have been removed]



                    ----------------------------------------------------------------------------
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                    Yahoo! Groups Links

                    a.. To visit your group on the web, go to:
                    http://groups.yahoo.com/group/mlathemods/

                    b.. To unsubscribe from this group, send an email to:
                    mlathemods-unsubscribe@yahoogroups.com

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                    [Non-text portions of this message have been removed]
                  • tony_m_baker
                    Well, I m afraid I have to disagree with you about it being too dificult. I have have cut hundreds of acme threads in a lathe on valve stems, and if you buy an
                    Message 9 of 9 , Feb 13, 2004
                      Well, I'm afraid I have to disagree with you about it being too
                      dificult. I have have cut hundreds of acme threads in a lathe on
                      valve stems, and if you buy an acme thread gage and spend a little
                      time getting your tool ground right it is no different than cutting
                      vform threads. I might advise a beginner to practice vform threads
                      first, until they get comfortable with the general process of
                      threading, but a little practice is all it takes. My only word of
                      warning is to keep your depth of cut light. If you try to take too
                      deep of a cut the tool can dig into the part causing the part to try
                      to climb the toolbit. This will either break the toolbit, ruin the
                      part or both. Besides the whole point of have a lathe is to make
                      things. Right?

                      --- In mlathemods@yahoogroups.com, "jjfear" <jjfear@i...> wrote:
                      > Catfish,
                      >
                      > Those are really two different questions. Any lathe with the
                      ability
                      > to cut threads, can also cut lefthand threads. Almost every book on
                      > lathe operations will contain instructions for doing this. As
                      someone
                      > new to thread cutting, I would suggest that you invest a little time
                      > and money in securing and reading one or more of those kind of
                      books.
                      > A good source is Lindsay Books(www.lindsaybks.com) who sells
                      reprints
                      > of older books which are better than modern books which devote space
                      > to CNC-CAM.
                      >
                      > Cutting ACME treads is more dificult either right or left. The Acme
                      > thread has a special thread form and can only be cut on a lathe
                      with a
                      > form tool ground to the exact shape of the size of the thread
                      needed.
                      > Seventy-five years ago, that might have been a common skill, but
                      even
                      > experienced machinists find this a daunting task, and would be
                      almost
                      > impossible for a beginner to accomplish successfully.
                      >
                      > The reason is that Acme thread rods in all sizes and both left and
                      > right hand threads are readily available from the normal industrial
                      > suppliers. They are not cheap, but compared to the time and effort
                      to
                      > actually machine one, it pays.
                      >
                      > That would be my suggestion that you learn how to thread on a much
                      > simpler project
                      >
                      >
                      > --- In mlathemods@yahoogroups.com, "catfish7251" <cleon@m...> wrote:
                      > > I have a HF 7X10 mini lathe and am new to threading.
                      > > Is it possible to cut left hand Acme threads for a vice on it.
                      > >
                      > > Thanks Catfish.
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