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Is it possible to machine a Oval Shaft

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  • #16
    thats a press job not a turning job, but ovals could be turned. Think a relieving device used when making a cutter. Such a thing was an accessory on some lathes, moving the X axis in and out while the work rotated. There's some good videos of a great DIY version, the Eureka, if you do a search. Hardly worth making a ton of tooling for a snow shovel, but does offer an answer to the Q.
    in Toronto Ontario - where are you?

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    • #17
      link? (i only see an eureka spinning lathe.)

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      • #18
        Not so long ago an hexagon shaped was shown here being machined so, an oval would be as simple, I guess
        Helder Ferreira
        Setubal, Portugal

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        • #19
          As long as you can get a decent grip on it you can machine almost any shape shaft. An L shaped shaft could be an issue as the leg comes around taking off your hand or slamming into the ways, but if the leg is short enough and you can keep your body parts out of the way...
          *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

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          • #20
            I presume you're looking to make one from solid?

            If so you can do that profile in a lathe, with a bit of hand blending after. Just turn it between centers, using offset center holes. Or a 4 jaw, and offset tail center holes.

            Alternatively, you can do it in a mill (turret mill, with the work hanging off the front of the table pointing vertical and the head swung to the side) with a boring head, with the tool turned inside out.

            A few other ways to do it, but I won't get into swage blocks, and presses etc lol.

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            • #21
              The makers obviously pressed a round tube to make the handle. With some experimentation on short tube lengths, the profile could be approximated. A lot easier to do than something which would take a cnc or a copy lathe to do.

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              • #22
                squish that cat!

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                • #23
                  Its just a guess on my part, but I think that the oval handle was run thru an extruding die to get that shape.
                  Sarge41

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                  • #24
                    Recon you have nailed it, Sarge.

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                    • #25
                      Yeah, you press a round tube into oval shape

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                      • #26
                        You certainly can turn an oval. One method involves oscillating the center of rotation of the workpiece, another oscillating the cutter in time with the spindle.

                        I first came across the first method at the Old Schwamb Mill many years ago. The Old Schwamb Mill, in Arlington, Massachusetts operated for many years manufacturing primarily oval wooden frames. The frames were mounted on special faceplates on huge lathes, and there was a mechanism behind the faceplate that caused it to oscillate as it revolved. The wood was cut by handheld scrapers that remained stationary. Everything was run off lineshafts which were originally water powered. A truly fascinating place to visit, I believe it is still open today.

                        Here is a link to an oval turning video:

                        https://www.youtube.com/watch?v=w5I2Yph57FI

                        There is no reason why a chuck could not be equipped with a similar oscillating mechanism to allow turning a shaft.

                        I believe that machinery used to back off taps oscillates the cutter.

                        A third method was used in ornamental turning lathes. The headstock was on a pivot, and could oscillate from front to back driven by a cam on the spindle. These typically used a milling cutter to shape the slowly turning workpiece.

                        By far though, the most interesting method was that used for the oval picture frames, as the degree of “ovality” could be easily adjusted. No need to make new cams or anything like that.

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                        • #27
                          FWIW, here's a chopped glass reinforced urethane resin oval handle cast around a round tube. Honestly, I'd say that shovel was overdesigned. The 2 stainless buttons should be more than enough anti-rotation for the shaft shoveling snow. Kayak paddles get by with 1, as do painting extension sticks and many other devices.

                          Click image for larger version

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                          Location: Jersey City NJ USA

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                          • #28
                            There's three options.

                            First is a pure and proper mathematical ellipse. Second would be a football shape. That would be what you get when you use two offset centers to turn round segments. And third would be a proper oval where there's two half circles where the ends of the halves are connected by two short straight segments. And fourth bonus shape would be what I suspect you have. A "fat oval" made from two partial circular arcs with larger radius also circular arc segments instead of flats to join the smaller arcs.

                            The first and third cannot be done simply. To cut them on a manual lathe you'd need some manner of cam controlled cutter that moves back and forth following the shape of the cam to move the cutter in and out as you advance along the cut.

                            The second option is what you get when you use two offset centers and the shape is two constant radius cuts that form a pointed football like shape.

                            Your handle appears to be closer to a true ellipse than an oval. Or perhaps it is an example of option 4.

                            If you tried to do this shape with the two offset centers football shape it would be a very poor fit. At least it would take a LOT of filing to make it fit. And I don't think it would be a good fit even then unless you removed way more material. And at that point you might as well have started with round stock and just cut and filed it down directly.

                            Another option for you to consider would be to cut the shape on the mill using a rotating horizontal setup to support the work. I'd cast a mold of the ID of the segment you want the joiner to fit in some sort of epoxy putty. Doesn't need to be very deep either. I'd then cut off a 1/4" thick segment of this ID shape for the shaping template. Carefully drill a hole right in the center of it that will allow you to fit through about a 3/8 stub. Now glue the template to the end of a piece of stock (aluminium round bar I'm guessing) and over a similar size stub to fit the hole which has a center hole in the stub. Set up the work in something like a spindexer or rotary table and with a tail stock to support the end with the template and center hole. Index the work around in something like 10° steps. Raise the table or lower the cutter until it just touches the putty by a couple of thou. Run passes along the length you need. By the time you do this for 36 facets and then "shoe shine" it with some coarse or medium emery strip to dull down the peaks it should be a pretty nice fit into the handle. From there do whatever else you need to secure or fit it depending on your goal.

                            Chilliwack BC, Canada

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                            • #29
                              A rose engine (lathe) is pretty much designed to do ovals at its beginners level. But also various types of wood copy lathes, manual and automatic.

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                              • #30
                                Here was my one and only attempt at turning an oval on the lathe. It was done with the offset center method.

                                You may only view thumbnails in this gallery. This gallery has 4 photos.

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