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Making a Taper Attachment for SB9 Mod A

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  • Making a Taper Attachment for SB9 Mod A

    I have to own a taper attachment for my lathe. For some reason it just don't seem complete with out one. Ebay prices are out of my league. I'm thinking on making on. I've collected every picture I could find on taper attachments for over a year. Just a few weeks ago I came across the Logan design for the first time. It realy looks simple and straight forward. I can't imagine why the other styles exist at all with the seemingly simple approach of the Logan. Are they just Rube Goldbergs or do they actually excell in one manner or another? Actually, working off of the Logan design I can't see why micrometer adjustments couldn't be incorporated. Any ideas? The Logan is first and then a bunch of others.

    Thanks for any input you can give me.

    [This message has been edited by Your Old Dog (edited 03-17-2005).]
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    Thank you to our families of soldiers, many of whom have given so much more then the rest of us for the Freedom we enjoy.

    It is true, there is nothing free about freedom, don't be so quick to give it away.

  • #2
    I am planning on making one from the Jan/Feb issue of HSM based on Foster's article. Most of the work will be on a milling machine cutting the pieces to size. (I priced out the plate from metal express at about $100.) I may delay the Project a bit, until I can add a DRO and power feed to the mill. I am modifying the design a bit, and will include a micrometer to set the angle so that the mic and bar-slider form a sine-bar. A spring will hold the bar against the micrometer during setting, while the lockdown screw is tightened. I will also likely make a new top-slide from one of the Metal Lathe Castings, so the connecting mechanism will be a bit different. I havent drawn up anything yet so details are not known.
    E-mail me if you have any questions.


    • #3
      I don't remember if the Foster article is the "sine bar" one or not.

      The one I am thinking of had a 24" bar, and two round blocks. The length allowed the round blocks to be used as if they were sine bar rods, one would put a piece equal to the taper per foot between the block and its landing at which ever end gave the taper "hand" you need, and get a precise taper angle directly.

      The Logan one is rather crude, (the simpler one). It may spring under cutting load and not give a right taper. There is no connection to the carriage, just to the crosslide. There is then a drag force on the extension to the "bar follower", giving a twist to the crosslide. There is also a springing applied by cutting force to the taper attachement bar, which is carried by its ends.

      The better ones are connected to both the carriage and crosslide, so that they localize the pull or push of cutting force relative to a piece which links to the carriage. That puts less twist on the crosslide, and the force on the taper setting bar is not carried out to the attachment points in the same way.

      Many have a relatively thin bar as an attachment to the bed. That is because of the way the force is balanced against the carriage.

      I think if you look at the Logan one (at least the simpler one) and compare to others you will see what I mean.

      CNC machines only go through the motions.

      Ideas expressed may be mine, or from anyone else in the universe.
      Not responsible for clerical errors. Or those made by lay people either.
      Number formats and units may be chosen at random depending on what day it is.
      I reserve the right to use a number system with any integer base without prior notice.
      Generalizations are understood to be "often" true, but not true in every case.


      • #4
        I have not purchased from this company but the kit looks quite adaptable.




        • #5
          Thanks for the help.

          Endmill: If I do the Logan style I'll remember the spring loaded feature. I hadn't figured out how to attach my mics.

          J Tiers: Thanks for taking the time. After reading what you wrote and examining the photos I can understand completely every point you made and I have to admit most had excaped me at first. It's not likely I'll be making any tapers longer than 4 inches and I may be able to overcome any bulge in the taper by taking lighter finishing cuts.

          Piston Skirt: Thanks for the link. I've have a shot of the photo but had forgotten how I came across it.

          I probably should have mentioed my use of this taper attachment would be for pieces under 6 inches and mostly for Morse tooling. The other use for this would not require any great deal of accuracy

          Thanks guys.
          - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
          Thank you to our families of soldiers, many of whom have given so much more then the rest of us for the Freedom we enjoy.

          It is true, there is nothing free about freedom, don't be so quick to give it away.


          • #6
            If you don't have a copy of the article by John Foster, get a back issue from Village Press. It is an excellent design, and incorporates a telescoping lead screw, making it better than the factory attachment. It is Jan/Feb 2004.

            It is one of the best taper attachment designs I have seen.
            Jim H.


            • #7
              That Logan one is neat.
              I made one some years ago for a Myford because [a] I couldn't afford the Myford one and [b] I needed to do 12" plus tapers.
              Don't have any pics as it was sold pre digital camera but here's a sketch from memory.


              All screwed together from bright bar stock except the sliding members which were ground flat stock.
              Can be built with a drill press and hand tools so it's an ideal beginners project even though you finish up with an accurate attachment at the end of the day.

              John S.

              Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.


              • #8
                Thanks for the link to the drawing. That looks pretty straightforward and would likely work for my needs quite well. Unless something else comes along I may just settle on that design.

                I liked the notion of the sinebar setup mentioned above but think it may be overkill for what I'm doing. Hell, then I'd have to learn about sign bars !! thanks again all.
                - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
                Thank you to our families of soldiers, many of whom have given so much more then the rest of us for the Freedom we enjoy.

                It is true, there is nothing free about freedom, don't be so quick to give it away.