Loading ...
Sorry, an error occurred while loading the content.

RE: [MedievalSawdust] Re: Vice screws ?

Expand Messages
  • Lindey, Edward F III LTC RET
    The chart for your percentage is all about thread engagement amount, not a looser or tighter fit. The fit is based on the diameter you cut. That is why good
    Message 1 of 8 , Nov 17, 2012
    • 0 Attachment

      The chart for your percentage is all about thread engagement amount, not a looser or tighter fit. The fit is based on the diameter you cut. That is why good die sets are adjustable, for example. You loosen or tighten the diameter of the die slightly, to compensate for the difference in what you need and what the die is currently cutting with the specific material you are using.

       

      Did you really mean you were cutting .0005 at a time on a lathe or did you mean .005? The basic idea is still the same for a custom fit. Get it close with your mics, check it with the nut, cut a few more thousands off, deburr, check again, etc.

       

      So much for metal screws and threads.

       

      On to wood threads.

       

      To answer the previous question about the screw box cutting threads too close in size to the tapped nut. Assuming you are making the Roy Underhill style of box, you need to add a jack screw to his design. Put it so it touches the back of the cutter and will push the cutter forward toward the tapped hole. You will use this adjustment to move the cutter in or out to cut a small amount more or less off the threads on the rod. This is how you get the threaded rod to properly fit your nut. Once again it is a, cut it, deburr, check the fit, cut again, etc.

       

      On the larger threads, you may be taking too big a “bite” using only one cutter, making it too hard to turn, breaking the dowel, etc. If so, you need to install a second cutter on the opposite side of the box. It should be as close to exactly the same as the first one as possible. You also will have to adjust the depth of the slot it rests in as the thread on the opposite side will be deeper.

       

      Good luck

       

      Edward of Freeholt

      Vert, a double-bitted axe and on a chief embattled Or an arrow sable


      From: medievalsawdust@yahoogroups.com [mailto: medievalsawdust@yahoogroups.com ] On Behalf Of d6crawler
      Sent: Saturday, November 17, 2012 11:46 AM
      To: medievalsawdust@yahoogroups.com
      Subject: Re: [MedievalSawdust] Re: Vice screws ?

       

       

      Metal screw threads are also cut based on a target fitment. If you need a tight fit for a particular application then you consult a chart that tells you how big of a hole to drill or how large of a rod to use for an 85% fit, etc.

       

      When cutting threads by hand on a lathe you keep the nut handy to know when you have gotten it to the fit you would like. Once you are close you cut a bit, check, cut another .0005, check, ...

       

      Daniel

       


      From: K <kaisaerpren@...>
      To: medievalsawdust@yahoogroups.com
      Sent: Saturday, November 17, 2012 8:20 AM
      Subject: [MedievalSawdust] Re: Vice screws ?

       

       

      Hi;
      I have done this. I also have 2 smaller comercially made screw boxes.
      I found/find that I have a problem with the finished screws. when you make a screw box with the tap that you will use to make that nuts, the screw is to tight in the nut. Metal bolts and nuts are not Exactly the same size. the nut is made a tiny bit big and the bolt is made a tiny bit smaller. otherwise the friction would be too great and ruin the assembly.
      I have solved this by carving the larger screws. and chasing the smaller ones.
      or another solution would be to make certain that the nut is bone dry when you make it and the screw is slightly green when you make it.

      K
      Oh and when you calculate pitch and screw size, Always go from the greater diameter. it just works easier.
      also change the angle between threads to 90 degrees for larger threads.
      historically, very few screwboxes seem to have been made. they do show up occasionally, Heron (also called Hero)illustrated one over 2000 years ago. however most of the evidence I've seen seems to indicate that most screws were made by "chasing" or carving methods.

       

    • Peter Ellison
      Thanks all that commented I really do appreciate the emails. Here is the current status: I got two sample turning blanks (3 square by a 12 ) one was hard
      Message 2 of 8 , Nov 20, 2012
      • 0 Attachment
        Thanks all that commented I really do appreciate the emails.

        Here is the current status:

        I got two "sample" turning blanks (3" square by a 12") one was hard maple, the other sycamore (it was cheaper for some reason).  My plan to was to practice before cutting a large maple one.

        I chiseled away at about 2 inches of thread on the hard maple blank, about 6 turns into the nut.  The manually cut threads are pretty close to the right patch.  My major diameter was too thick so that caused me to thing I had the wrong pitch.

        My screwbox cutter is the wrong shape and not sharp enough, so I decided to abandon that part of the project for now.  A two and a half inch major diameter screw needs two cutters.  I'm not sure I'm smart enough to get that to work.

        I took a short cut, a bit strange because I'm mostly a hand tool using primate.  The chiseling was just too slow.

        I mounted the screwbox on the mini-mill, chucked up a 60 degree 1/2" router bit, lined it up where the cutter should have been and manually turned the screw into the screwbox past the router bit.  Other that some chewed up threads, that look a lot like the ones I did with a chisel they threads came out pretty decent.  The will not win a beauty contest, but they are strong and hold fast.  I'd like to state this process is NOT for the faint of heart, even with everything mounts securely to the table there is lots of vibration and chips flying everywhere.

        The hard maple one threads are a little smoother than the sycamore.  Since the maple was the one I did first, likely if I did another one it would come out better.

        One thing that I did note is that you can't find a large triangular file at a home store or Menard's.  So I'll be making a triangular sanding block so that I can smooth out the tooling marks and make things work a little better.

        I have a Moxon vise that I make with the 6 threads/inch 1.5" screws that I have not been happy with so I decided to drill out the holes and tap them with the new manual tap since I have two fully functional screws.  So far that process has gone pretty well.

        I'll try and get some pictures eventually of the results.

        I'll send another update in a couple of days.

        Peter

      • nelsonhaynes@aol.com
        My mentor told me that you would have better success cutting threads if you soak maple in linseed oil overnight. In a message dated 11/20/2012 9:50:07 P.M.
        Message 3 of 8 , Nov 21, 2012
        • 0 Attachment
          My mentor told me that you would have better success cutting threads if you soak maple in linseed oil overnight.
           
          In a message dated 11/20/2012 9:50:07 P.M. Eastern Standard Time, pellison@... writes:
           

          Thanks all that commented I really do appreciate the emails.

          Here is the current status:

          I got two "sample" turning blanks (3" square by a 12") one was hard maple, the other sycamore (it was cheaper for some reason).  My plan to was to practice before cutting a large maple one.

          I chiseled away at about 2 inches of thread on the hard maple blank, about 6 turns into the nut.  The manually cut threads are pretty close to the right patch.  My major diameter was too thick so that caused me to thing I had the wrong pitch.

          My screwbox cutter is the wrong shape and not sharp enough, so I decided to abandon that part of the project for now.  A two and a half inch major diameter screw needs two cutters.  I'm not sure I'm smart enough to get that to work.

          I took a short cut, a bit strange because I'm mostly a hand tool using primate.  The chiseling was just too slow.

          I mounted the screwbox on the mini-mill, chucked up a 60 degree 1/2" router bit, lined it up where the cutter should have been and manually turned the screw into the screwbox past the router bit.  Other that some chewed up threads, that look a lot like the ones I did with a chisel they threads came out pretty decent.  The will not win a beauty contest, but they are strong and hold fast.  I'd like to state this process is NOT for the faint of heart, even with everything mounts securely to the table there is lots of vibration and chips flying everywhere.

          The hard maple one threads are a little smoother than the sycamore.  Since the maple was the one I did first, likely if I did another one it would come out better.

          One thing that I did note is that you can't find a large triangular file at a home store or Menard's.  So I'll be making a triangular sanding block so that I can smooth out the tooling marks and make things work a little better.

          I have a Moxon vise that I make with the 6 threads/inch 1.5" screws that I have not been happy with so I decided to drill out the holes and tap them with the new manual tap since I have two fully functional screws.  So far that process has gone pretty well.

          I'll try and get some pictures eventually of the results.

          I'll send another update in a couple of days.

          Peter

        • Jerry Harder
          It takes a lot of work to make a good tool, the better the tool the more work. I have a conflicting and duel line of thought on making tools and caring for
          Message 4 of 8 , Dec 30, 2012
          • 0 Attachment

            It takes a lot of work to make a good tool, the better the tool the more work. I have a conflicting and duel line of thought on making tools and caring for tools. Tools should be appropriately respected and cared for. On the other hand, tools, all, tools, are disposable implements that are designed to make something else. Heat treatment of metal tools even today with modern alloys and furnaces that can be set for exact temperatures is still an art. What is good for one tool and tool application is not the best for another, and the perfect process for one tool and application may may need to be changed when the size of tool is the only variable that has changed. My point is don't get too caught up in heat treatment processes. A mild steel un-heat-treated blade in your screw-cutter may need to be honed more often, maybe even several times before one screw is finished but is much much easier to shape and can be done very precisely with hand files and then finished by honing. I am guessing that your planing on making a hand full of wooden screws, not several thousand. If that's the case making the blades of a high quality shape in a poorer quality metal will get the job done better that a poorly shaped m2 blade that you have ground on for hours with a small hand grinder which admittedly may last you nearly forever in all its poor quality grandeur. As both a woodworker and a smith I will say that all can be done with the right materials and a little practice. Annealing a carbon steel make it soft (so you can file it) heating and quenching makes it hard and brittle (so it will hold an edge longer) and tempering removes brittleness (so your tool doesn't brake like glass when you drop, strike, or hit something unexpectedly with it). If learning these skills are on your back burner instead of your back pocket then don't let that get in the way of your making a good tool to do the job you are doing. The job of your tool is to teach you how the tools to thread nuts and rods were made and then to make a few. It doesn't need to last forever.


            I am very interested in screws (and medieval threaded fasteners in general and not just wood ones) and would like to see your documentation for the threading devices you mentioned. I have a picture of Hero's but it is confusing, and is a drawing not from a primary source.



            On 11/21/2012 7:41 AM, nelsonhaynes@... wrote:
             

            My mentor told me that you would have better success cutting threads if you soak maple in linseed oil overnight.
             
            In a message dated 11/20/2012 9:50:07 P.M. Eastern Standard Time, pellison@... writes:
             

            Thanks all that commented I really do appreciate the emails.

            Here is the current status:

            I got two "sample" turning blanks (3" square by a 12") one was hard maple, the other sycamore (it was cheaper for some reason).  My plan to was to practice before cutting a large maple one.

            I chiseled away at about 2 inches of thread on the hard maple blank, about 6 turns into the nut.  The manually cut threads are pretty close to the right patch.  My major diameter was too thick so that caused me to thing I had the wrong pitch.

            My screwbox cutter is the wrong shape and not sharp enough, so I decided to abandon that part of the project for now.  A two and a half inch major diameter screw needs two cutters.  I'm not sure I'm smart enough to get that to work.

            I took a short cut, a bit strange because I'm mostly a hand tool using primate.  The chiseling was just too slow.

            I mounted the screwbox on the mini-mill, chucked up a 60 degree 1/2" router bit, lined it up where the cutter should have been and manually turned the screw into the screwbox past the router bit.  Other that some chewed up threads, that look a lot like the ones I did with a chisel they threads came out pretty decent.  The will not win a beauty contest, but they are strong and hold fast.  I'd like to state this process is NOT for the faint of heart, even with everything mounts securely to the table there is lots of vibration and chips flying everywhere.

            The hard maple one threads are a little smoother than the sycamore.  Since the maple was the one I did first, likely if I did another one it would come out better.

            One thing that I did note is that you can't find a large triangular file at a home store or Menard's.  So I'll be making a triangular sanding block so that I can smooth out the tooling marks and make things work a little better.

            I have a Moxon vise that I make with the 6 threads/inch 1.5" screws that I have not been happy with so I decided to drill out the holes and tap them with the new manual tap since I have two fully functional screws.  So far that process has gone pretty well.

            I'll try and get some pictures eventually of the results.

            I'll send another update in a couple of days.

            Peter


          Your message has been successfully submitted and would be delivered to recipients shortly.