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Not so chasing threads

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  • aquanutscrr
    OK gentlemen, I ve got a problem and need your help. I ve been pulling my hair out trying to figure out what is going on. I m trying to thread a 1.1/2-8 OD
    Message 1 of 9 , Sep 4, 2007
      OK gentlemen, I've got a problem and need your help. I've been
      pulling my hair out trying to figure out what is going on. I'm
      trying to thread a 1.1/2-8 OD thread so I can check my ID threads.
      The problem I'm having is my gear train seams to be off by 1/3. I
      make a wrinkle on the part, back-off and reset for the next pass. I
      hit the same number every time (1) and for some reason it offsets
      about one third of a turn. I do it again and the same thing
      happens. Do it again and it will fall into my first groove. I
      always hit the same mark on the thread dial. I have a 20 stud gear,
      80 idle gear, and 56 gear box gear.

      It used to work. I've done threads before. The only change I made
      was to replace a worn-our idle gear bushing. I wore slam out, so I
      made another one out of brass to replace it. You really miss power
      feeds when you don't have them.

      What do you think could be happening? It's a 10K, 1975 version,
      4.5' bed.

      Thanks in advance,
      David
    • Rich Dean
      David, the threading dial not needed. Your leadscrew matches the thread. pull in the 1/2 nuts anytime. Your trouble may be wornout 1/2 nut threads or they are
      Message 2 of 9 , Sep 4, 2007
        David,
        the threading dial not needed. Your leadscrew matches the thread.
        pull in the 1/2 nuts anytime.
        Your trouble may be wornout 1/2 nut threads or they are not fully
        engaging everytime and riding in the tread flank = an offset.
        Is th thread actually 8 TPI? (to check the gearing)
        RichD

        aquanutscrr wrote:
        > OK gentlemen, I've got a problem and need your help. I've been
        > pulling my hair out trying to figure out what is going on. I'm
        > trying to thread a 1.1/2-8 OD thread so I can check my ID threads.
        > The problem I'm having is my gear train seams to be off by 1/3. I
        > make a wrinkle on the part, back-off and reset for the next pass. I
        > hit the same number every time (1) and for some reason it offsets
        > about one third of a turn. I do it again and the same thing
        > happens. Do it again and it will fall into my first groove. I
        > always hit the same mark on the thread dial. I have a 20 stud gear,
        > 80 idle gear, and 56 gear box gear.
        >
        > It used to work. I've done threads before. The only change I made
        > was to replace a worn-our idle gear bushing. I wore slam out, so I
        > made another one out of brass to replace it. You really miss power
        > feeds when you don't have them.
        >
        > What do you think could be happening? It's a 10K, 1975 version,
        > 4.5' bed.
        >
        > Thanks in advance,
        > David
      • aquanutscrr
        I will measure them again for sure, but I don t get 8TPI. It is somewhere around 10TPI. This is the strangest thing... David ... threads. ... I ... pass. I
        Message 3 of 9 , Sep 4, 2007
          I will measure them again for sure, but I don't get 8TPI. It is
          somewhere around 10TPI. This is the strangest thing...

          David




          --- In southbend10k@yahoogroups.com, Rich Dean <cmsteam@...> wrote:
          >
          > David,
          > the threading dial not needed. Your leadscrew matches the thread.
          > pull in the 1/2 nuts anytime.
          > Your trouble may be wornout 1/2 nut threads or they are not fully
          > engaging everytime and riding in the tread flank = an offset.
          > Is th thread actually 8 TPI? (to check the gearing)
          > RichD
          >
          > aquanutscrr wrote:
          > > OK gentlemen, I've got a problem and need your help. I've been
          > > pulling my hair out trying to figure out what is going on. I'm
          > > trying to thread a 1.1/2-8 OD thread so I can check my ID
          threads.
          > > The problem I'm having is my gear train seams to be off by 1/3.
          I
          > > make a wrinkle on the part, back-off and reset for the next
          pass. I
          > > hit the same number every time (1) and for some reason it
          offsets
          > > about one third of a turn. I do it again and the same thing
          > > happens. Do it again and it will fall into my first groove. I
          > > always hit the same mark on the thread dial. I have a 20 stud
          gear,
          > > 80 idle gear, and 56 gear box gear.
          > >
          > > It used to work. I've done threads before. The only change I
          made
          > > was to replace a worn-our idle gear bushing. I wore slam out,
          so I
          > > made another one out of brass to replace it. You really miss
          power
          > > feeds when you don't have them.
          > >
          > > What do you think could be happening? It's a 10K, 1975 version,
          > > 4.5' bed.
          > >
          > > Thanks in advance,
          > > David
          >
        • Jim B.
          Are you sure you are using the half nuts and not the Clutch? For threading you must use the half nuts. The fact that the pitch is faster leads me to believe
          Message 4 of 9 , Sep 4, 2007
            Are you sure you are using the half nuts and not the Clutch?
            For threading you must use the half nuts.
             
            The fact that the pitch is faster leads me to believe you are using the clutch.
             
            Been there done that
             

            Jim B.

            "Any intelligent fool can make things bigger and more complex.... It takes a touch of genius -- and a lot of courage to move in the opposite direction"

            Albert Einstein/ EF Schumacher (ATCMB)

             


            From: southbend10k@yahoogroups.com [mailto:southbend10k@yahoogroups.com] On Behalf Of aquanutscrr
            Sent: Tuesday, September 04, 2007 4:33 PM
            To: southbend10k@yahoogroups.com
            Subject: [southbend10k] Re: Not so chasing threads

            I will measure them again for sure, but I don't get 8TPI. It is
            somewhere around 10TPI. This is the strangest thing...

            David

            --- In southbend10k@ yahoogroups. com, Rich Dean <cmsteam@... > wrote:

            >
            > David,
            > the
            threading dial not needed. Your leadscrew matches the thread.
            > pull in
            the 1/2 nuts anytime.
            > Your trouble may be wornout 1/2 nut threads or
            they are not fully
            > engaging everytime and riding in the tread flank = an
            offset.
            > Is th thread actually 8 TPI? (to check the gearing)
            >
            RichD
            >
            > aquanutscrr wrote:
            > > OK gentlemen, I've got a
            problem and need your help. I've been
            > > pulling my hair out trying
            to figure out what is going on. I'm
            > > trying to thread a 1.1/2-8 OD
            thread so I can check my ID
            threads.
            > > The problem I'm having is
            my gear train seams to be off by 1/3.
            I
            > > make a wrinkle on the
            part, back-off and reset for the next
            pass. I
            > > hit the same
            number every time (1) and for some reason it
            offsets
            > > about one
            third of a turn. I do it again and the same thing
            > > happens. Do it
            again and it will fall into my first groove. I
            > > always hit the same
            mark on the thread dial. I have a 20 stud
            gear,
            > > 80 idle gear,
            and 56 gear box gear.
            > >
            > > It used to work. I've done
            threads before. The only change I
            made
            > > was to replace a
            worn-our idle gear bushing. I wore slam out,
            so I
            > > made another
            one out of brass to replace it. You really miss
            power
            > > feeds
            when you don't have them.
            > >
            > > What do you think could be
            happening? It's a 10K, 1975 version,
            > > 4.5' bed.
            > >
            > > Thanks in advance,
            > > David
            >

          • Rich Dean
            David, then there is definetly a gear setup problem between the spindle and leadscrew. Rich
            Message 5 of 9 , Sep 4, 2007
              David,
              then there is definetly a gear setup problem between the spindle
              and leadscrew.
              Rich

              aquanutscrr wrote:
              > I will measure them again for sure, but I don't get 8TPI. It is
              > somewhere around 10TPI. This is the strangest thing...
              >
              > David
              >
            • nwinblad@comcast.net
              Check your gear train again. I ll bet you are using a 48 tooth instead of a 56 tooth. Neal ... From: aquanutscrr OK gentlemen, I ve
              Message 6 of 9 , Sep 4, 2007
                Check your gear train again. I'll bet you are using a 48 tooth instead of a 56 tooth.
                 
                Neal
                 
                -------------- Original message --------------
                From: "aquanutscrr" <aquanutscrr@...>

                OK gentlemen, I've got a problem and need your help. I've been
                pulling my hair out trying to figure out what is going on. I'm
                trying to thread a 1.1/2-8 OD thread so I can check my ID threads.
                The problem I'm having is my gear train seams to be off by 1/3. I
                make a wrinkle on the part, back-off and reset for the next pass. I
                hit the same number every time (1) and for some reason it offsets
                about one third of a turn. I do it again and the same thing
                happens. Do it again and it will fall into my first groove. I
                always hit the same mark on the thread dial. I have a 20 stud gear,
                80 idle gear, and 56 gear box gear.

                It used to work. I've done threads before. The only change I made
                was to replace a worn-our idle gear bushing. I wore slam out, so I
                made another one out of brass to replace it. You really miss power
                feeds when you don't have them.

                What do you think could be happening? It's a 10K, 1975 version,
                4.5' bed.

                Thanks in advance,
                David

              • aquanutscrr
                Alright, I ve got some more info. I ve gone through the manual and found something intersting. This lathe has a 24 tooth reverse gear. I ve confirmed that it
                Message 7 of 9 , Sep 4, 2007
                  Alright, I've got some more info. I've gone through the manual and
                  found something intersting. This lathe has a 24 tooth reverse gear.
                  I've confirmed that it is riding on the 24 tooth gear and not the 20
                  tooth gear. I also measure the pitch I get with the gear box in 8TPI
                  and I get ~.150. If you multiply this time the ratio of 20/24 which is
                  ~.8333 you get ~.125. That is what is supposed to be.

                  Now my next question, how is the gear train configured. I can't tell
                  by the book. The reverse gear, idle gear and gearbox gear all line up
                  in the same plane. The spur gear in out in space. How does the spur
                  gear get messed with the others and in the same plane? Can someone
                  take a photo of their 10K for me please? Or email it to
                  aquanut@...?

                  Thanks a million gentlemen,
                  David
                • guycad@netzero.net
                  It seems that your headstock is offset. You will have to loosen the headstock holding bolts and slide it on the bed until the stud gear lines up with the gear
                  Message 8 of 9 , Sep 5, 2007
                    It seems that your headstock is offset.

                    You will have to loosen the headstock holding bolts and slide it on the bed until the stud gear lines up with the gear train. Then You will need to tight it again. You will notice the pitch diameter of the 24T gear your gear train is meshing on is not the same as the changeable gears. (20 DP) the changeable gear train is 18 DP

                    Besides the 24T gear, you should have a 20T gear that can be changed. (there is a nut holding it in place) This gear has to line up with the other gears.

                    If you go on the discussion group files you will find an excel spread sheet called SB gear box feeds. Using this spread sheet, I get exactly the same feed rate as you measured, using a 24 T gear on the gear train.

                    Guy Cadrin

                    Guy Cadrin
                  • aquanutscrr
                    Guy Cadrin, You nailed it! I just finished fixing the headstock. I was again trying to figure out why the gears didn t line up when I noticed the headstock
                    Message 9 of 9 , Sep 5, 2007
                      Guy Cadrin,

                      You nailed it! I just finished fixing the headstock. I was again
                      trying to figure out why the gears didn't line up when I noticed the
                      headstock sitting about a half inch further back than the bed. I was
                      thinking out loud... huh, that's strange, why did they offset it and
                      not make it flush with the bed? Bingo! The bolts were lose. I
                      disasembled everything and gave it a good cleaning. Reinstalled the
                      headstock and everything else in the correct position and what do you
                      know... it all lined back up the way it was supposed to. I'm back in
                      business now. Thanks all!

                      David



                      --- In southbend10k@yahoogroups.com, "guycad@..." <guycad@...> wrote:
                      >
                      > It seems that your headstock is offset.
                      >
                      > You will have to loosen the headstock holding bolts and slide it on
                      the bed until the stud gear lines up with the gear train. Then You
                      will need to tight it again. You will notice the pitch diameter of
                      the 24T gear your gear train is meshing on is not the same as the
                      changeable gears. (20 DP) the changeable gear train is 18 DP
                      >
                      > Besides the 24T gear, you should have a 20T gear that can be
                      changed. (there is a nut holding it in place) This gear has to line
                      up with the other gears.
                      >
                      > If you go on the discussion group files you will find an excel
                      spread sheet called SB gear box feeds. Using this spread sheet, I
                      get exactly the same feed rate as you measured, using a 24 T gear on
                      the gear train.
                      >
                      > Guy Cadrin
                      >
                      > Guy Cadrin
                      >
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