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Re: [MedievalSawdust] Need advice on cutting a wooden screw

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  • Alex Haugland
    It is also possible and probably easier to file on a lathe, which can be a very effective way to round out and center a hand-forging for the tap (as well as
    Message 1 of 16 , Oct 31, 2011
      It is also possible and probably easier to file on a lathe, which can be a very effective way to round out and center a hand-forging for the tap (as well as set the feed taper after filing your teeth, at least if you're copying a modern tap design)  for the poor-man's approach, you could also chuck up the forging in a drill press and probably file it close enough to round for the purpose of making a tap.  Just use something clamped to the table to act as a guide fence to stabilize the file on.

      --Alysaundre Weldon
      Barony of Adiantum, An Tir

      On 10/31/2011 11:57 AM, conradh@... wrote:  


      As St. Roy describes in his book (not the video), forging the hollows into
      the blank tap before filing can save a hell of a lot of filing. As can
      drawing out the stem of the tap. The challenge comes in forging so
      carefully as to leave the stem reasonably concentric and the surface of
      the blank cylindrical enough between the fullered hollows to do accurate
      layout of the teeth. A lathe would help a lot for truing it up. Makes me
      wonder if the old-time tap makers didn't forge and then turn their blanks.
      You _can_ turn iron on a lathe with handheld chisels if you're very
      careful and keep the toolrest really close--and if your lathe is heavy and
      rigid. George Stephenson, in the 1820's, is supposed to have turned
      castings for his pioneering locomotive on a great wheel lathe, with the
      help of two husky turnwheels and a lot of gin, no doubt. For a modern
      worker, turning the blank past a spinning sanding drum or small stemmed
      grindstone would be less scary if less authentic.


      Ulfhedinn


    • conradh@efn.org
      ... Thanks for mentioning what I should have! If you do this in the drill press, it really helps to make a little conical dead center or pilot pin for the
      Message 2 of 16 , Nov 1, 2011
        > It is also possible and probably easier to file on a lathe, which can be
        > a very effective way to round out and center a hand-forging for the tap
        > (as well as set the feed taper after filing your teeth, at least if
        > you're copying a modern tap design) for the poor-man's approach, you
        > could also chuck up the forging in a drill press and probably file it
        > close enough to round for the purpose of making a tap. Just use
        > something clamped to the table to act as a guide fence to stabilize the
        > file on.
        >
        > --Alysaundre Weldon
        > Barony of Adiantum, An Tir
        >
        Thanks for mentioning what I should have!

        If you do this in the drill press, it really helps to make a little
        conical dead center or pilot pin for the bottom end of the workpiece,
        something that can mount in the center hole of the drill press table.
        Turns the drill press into an expedient lathe.

        Lathe filing works great for smoothing a piece. For serious shaping, a
        problem can develop where the piece goes more and more out of round the
        longer you file. I think it may be a rhythmic bouncing effect, like the
        way a dirt road develops corrugations from bouncing wheels--a high spot on
        the workpiece reduces the file pressure on the surface just beyond it.

        The file rest you mention helps. So does changing speeds on the lathe
        several times--it breaks up the rhythm of the bouncing before it can get
        bad.

        Ulfhedinn
      • khpv_lsc
        Thanks you to all those who have put forward suggestions about this. I had read Roy Underhill s books and have the basic ideas from there. I can t readily
        Message 3 of 16 , Nov 2, 2011
          Thanks you to all those who have put forward suggestions about this.

          I had read Roy Underhill's books and have the basic ideas from there. I can't readily re-read these since the main library in Christchurch is still closed from the earthquake earlier this year.

          I don't want to use commercial kit - I very much want to make the screw and nut from scratch.

          --- In medievalsawdust@yahoogroups.com, "Peter Ellison" <pellison@...> wrote:
          >
          > Sorry for the reply to my own post, but I forgot to include a good article on making a screw box:
          >
          > http://www.wkfinetools.com/contrib/dAssis/art/TapDie/TapDie-01.asp

          This is very good, and fills in a few details I had forgotten.

          The suggestion by Ulfhedinn about precutting a guide for the thread with a saw and depth-stop is also a very good one.

          > >
          > >> Roy
          > Underhill has a
          > > chapter in one of his books on the subject....
          > If
          > >> someone does
          > > not beat me to it and I have time
          > later I can check to see
          > >> which
          > > one.

          I'll let you know how it goes.

          In service,
          Lowrens
        • Broom
          ... Oh, Ulfhedinn, you and your fancy power drill! THIS is the way to do it: www.liveleak.com/view?i=1a6_1319771245 | Broom IAmBroom @ gmail . com
          Message 4 of 16 , Nov 2, 2011
            > If you do this in the drill press, it really helps to make a little
            > conical dead center or pilot pin for the bottom end of the workpiece,
            > something that can mount in the center hole of the drill press table.
            > Turns the drill press into an expedient lathe.

            Oh, Ulfhedinn, you and your fancy power drill! THIS is the way to do it:
            www.liveleak.com/view?i=1a6_1319771245

            ' | Broom IAmBroom @ gmail . com
            ' | cellphone: 412-389-1997
            ' | 923 Haslage Ave, Pittsburgh, PA 15212
            '\|/ "Discere et docere", which means:
            '/|\ "Thank God for secular humanism."
            //|\\ - John F. Kennedy, according to Mort Sahl
          • conradh@efn.org
            ... Couldn t open the link, but much of this is based on stuff I ve seen or done in the past. Right now, frex, my metalworking lathe is down with out-of-round
            Message 5 of 16 , Nov 2, 2011
              >> If you do this in the drill press, it really helps to make a little
              >> conical dead center or pilot pin for the bottom end of the workpiece,
              >> something that can mount in the center hole of the drill press table.
              >> Turns the drill press into an expedient lathe.
              >
              > Oh, Ulfhedinn, you and your fancy power drill! THIS is the way to do it:
              > www.liveleak.com/view?i=1a6_1319771245



              Couldn't open the link, but much of this is based on stuff I've seen or
              done in the past. Right now, frex, my metalworking lathe is down with
              out-of-round Babbit bearings and my "fancy power drill" needs a new motor!
              So I'm as interested in the suggestions here as the OP is!

              Ulfhedinn
            • Broom
              ... Mostly it was a humorous reply. The link is a video of a Marrakesh man operating a hand-pulled bow-lathe, pressing his gouge against a makeshift rest with
              Message 6 of 16 , Nov 3, 2011
                >>> Turns the drill press into an expedient lathe.
                >>
                >> Oh, Ulfhedinn, you and your fancy power drill! THIS is the way to do it:
                >>   www.liveleak.com/view?i=1a6_1319771245
                >
                > Couldn't open the link, but much of this is based on stuff I've seen or
                > done in the past.  Right now, frex, my metalworking lathe is down with
                > out-of-round Babbit bearings and my "fancy power drill" needs a new motor!
                >  So I'm as interested in the suggestions here as the OP is!

                Mostly it was a humorous reply.

                The link is a video of a Marrakesh man operating a hand-pulled
                bow-lathe, pressing his gouge against a makeshift rest with his bare
                foot to turn out chess pieces. Amazingly simple: string, "C"-frame,
                two pivot points, a rest (iron bar?), and a gouge.

                ' | Broom IAmBroom @ gmail . com
                ' | cellphone: 412-389-1997
                '\|/ 923 Haslage Ave, Pittsburgh, PA 15212
                '/|\ "Discere et docere", which means:
                //|\\ "Life is overrated and always fatal." - baka-san, Fark
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