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  • Another Freehand Lathe Tool

    When I read this thread, http://bbs.homeshopmachinist.net/thr...turning-system I decided that I needed something of this nature, but I wanted something a bit heavier and more robust. And I didn’t really like nor see the need for the pantograph tracer. So after a bit of pondering and conjuring, I built this:



    This plate bolts to the cross slide of my lathe and has an array of 1/4-20 holes to accept a pivot pin and various motion limiting stops that I made. Note the pivot pin in the corner near the motor.



    A “radius bar” fits into a groove at the bottom of the tool and controls the curvature of the cut.



    I can do concave and convex radius cuts.



    More to come…

  • #2
    First real creation was this lamp finial:



    It works well using it freehand:



    And I can use it as a ball turner, also:



    Just playing:



    More to come….

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    • #3
      I made a setting device to set the cutting radius reasonably precisely. Here I’m setting it to 4” concave:



      And here it is at 2” convex radius. The surface that the cutting bit is against is equal to 0” on the rule. The cap screw keeps the cutting edge back behind the end of the “foot” and that make the tool stable. Below the cap screw is a template follower. For template work, I align the cutting tool and follower against the setting surface.



      For template work, the cutting tool and the follower must be ground to the same radius and aligned vertically.

      I’m not using the pantograph system of the “Turnado” tool. I made a holder to align the template directly below the workpiece. I think this will work better by eliminating any inevitable looseness in the panto pivots. The drawback to this method is that it somewhat limits the max diameter of my workpiece. Here is the template holder mounted on the table




      I decided to jump in head first and turn a largish piece to a pattern. So I made a template of 1/8” thick acrylic, put a piece of 2-1/4” dia. X 9-1/2” long aluminum in the lathe, and started learning.

      This will be a candle holder, so first I turned a tenon on what will be the bottom. This will fit into a base, yet to be made.



      More to come…..
      Last edited by john hobdeclipe; 04-20-2019, 09:46 PM.

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      • #4
        Rough out the shape manually using the carriage and cross slide feeds.



        Set up the template and start cutting to final shape:



        Flip the template and do the other end. A 5/16” stud is threaded into the bottom of the tenon, gripped in the 4 jaw chuck, then the tenon is centered. Note the stop screwed to the table, lower left, to keep me out of trouble:



        And here is the finished piece, after polishing:



        This is fun! I think I could play with this for the next ten years and not get bored.

        Next I need to make a way to accurately set the height of the cutter, and incorporate it into the setting device. And work out a more accurate method of grinding the cutter and the template follower to match.
        Last edited by john hobdeclipe; 04-20-2019, 09:40 PM.

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        • #5
          I like it!

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          • #6
            very nice!

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            • #7
              yes, Very!
              "A machinist's (WHAP!) best friend (WHAP! WHAP!) is his hammer. (WHAP!)" - Fred Tanner, foreman, Lunenburg Foundry and Engineering machine shop, circa 1979

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              • #8
                Yes! John, you need to submit this to George as an article for the magazine!!!!
                I cut it off twice; it's still too short
                Oregon, USA

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                • #9
                  This pleases me. Glad I could share something that was inspirational.

                  I was thinking about the Turnado again yesterday, so it's fortuitous that this should be posted. Great execution.

                  Comment


                  • #10
                    Thanks, guys.

                    Originally posted by Sun God View Post
                    This pleases me. Glad I could share something that was inspirational.

                    I was thinking about the Turnado again yesterday, so it's fortuitous that this should be posted. Great execution.
                    And thanks especially to you for the original post!

                    I had done a bit of freehand turning of brass and aluminum using a makeshift tool rest and woodworking lathe tools, but I was never fully comfortable with it. This rig is much safer, I think. It was the use of wood lathe tools that led me to a design with a long handle.

                    Comment


                    • #11
                      I have often puzzled how to do curvy shapes and have a need to do so right now. I cant see how the template is followed by the cutter. What part of the cutter body follows the template.?

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                      • #12
                        Originally posted by plunger View Post
                        I have often puzzled how to do curvy shapes and have a need to do so right now. I cant see how the template is followed by the cutter. What part of the cutter body follows the template.?
                        I'll get a better picture of that aspect and post it later today.

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                        • #13
                          Originally posted by Tim Clarke View Post
                          Yes! John, you need to submit this to George as an article for the magazine!!!!
                          Yes, would love to have this in one of the magazines. PM me if interested.
                          George
                          Traverse City, MI

                          Comment


                          • #14
                            Originally posted by plunger View Post
                            I have often puzzled how to do curvy shapes and have a need to do so right now. I cant see how the template is followed by the cutter. What part of the cutter body follows the template.?
                            Here's a better pic of the cutter/follower arrangement. Note that the template is about 5/8" above the table. On the tool itself, the follower protrudes from the front of the body, directly below the cutter. The follower is held in place by a brass machine screw.

                            And note that both the cutter and the follower are about 3/16" behind the front of the foot, so that the downforce from cutting keeps the whole rig stable.

                            Comment


                            • #15
                              Nice job John. Well thought out and executed. I like the template idea. I can see that being very handy for ornamental stuff.

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