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Turning a long taper

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  • Turning a long taper

    I have a few tapers to turn that are longer than the guide on my taper turning attachment. I have been thinking of buying a piece of ground bar to make a new guide and then milling a new sliding block.

    I know that I can turn one end and then move the attachment and carry on but I am trying to make it as smooth as possible. I don’t really want to offset the tailstock.

    Has anyone else done this? Or is there another option I hadn't thought about?

  • #2
    Originally posted by Darrp View Post
    ...I don’t really want to offset the tailstock.
    Why?

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    • #3
      I wonder how hard doing a taper with a CNC lathe is

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      • #4
        Originally posted by 3 Phase Lightbulb View Post
        I wonder how hard doing a taper with a CNC lathe is
        Simple, starting dia, ending dia and length. or angle and length, either way.

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        • #5
          Originally posted by mihit View Post
          Why?
          Well firstly, I have never turned a taper this way before. We took in school in the '80s and I don't remember how to set up the taper diameters.

          Secondly, if I had a longer bar I would use it when I do some more in a month or two.

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          • #6
            There are many options, but knowing the approximate stock size and taper can determine the action needed

            You could make your lathe a follower lathe or offset the tailstock, or install a boring head in the tailstock for easy adjustment of taper, using the boring head as a dead center without moving the tail stock. What material ?
            If the part is long and thin like a cue stick, then it is a whole "nuther" world

            Rich

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            • #7
              Go ahead and offset your tail stock provided the taper is within the range of offset travel. It's easy to use a dial gauge to reset the tailstock back to dead nutz true.

              When you're done with the tapers chuck up a piece of bar or pipe that is just a bit bigger than the tail stock. Turn it down to match or close to the diameter of the tailstock quill. A few thou one way or the other won't matter. Just measure both and divide the difference in two. You only need them to be close so the dial gauge in the tool post doesn't need to skip over a big step.

              Using the dial gauge in the toolpost... I did give that part away didn't I ..... match the quill back to zero using gauge readings stepping from the turned piece to the quill until they match or show half the diameter difference depending on how close you got your turned piece to matching the quill diameter. Easy peasy and if it takes you more than about 10 minutes to re-zero your offset then you're spending too much time thinking that you're too clever for your britches....

              And in fact using the gauge this way is a good way to offset the tail stock in the first place. But do make the slug or stub of pipe 5 to 10 thou too large the first time and then skim it back to true for the restoration of the zero. That's because we can't trust our three jaw chuck, right?
              Last edited by BCRider; 12-10-2018, 12:53 AM.

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              • #8
                Originally posted by Darrp View Post
                Well firstly, I have never turned a taper this way before. We took in school in the '80s and I don't remember how to set up the taper diameters.

                Secondly, if I had a longer bar I would use it when I do some more in a month or two.
                It's kinda my "go-to" method for taper turning. (Aint no fancy attachments 'round 'ere!)
                DTI on the tool post, zero at the major dia, run the carriage to the other end and offset the required amount.
                I re-aIign with a dead centre in headstock and tail stock, just push em close together and sight it.

                *edit* This is for between centres, and "long" tapers (machine tapers etc not pipe centres)
                Last edited by mihit; 12-10-2018, 04:15 AM.

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                • #9
                  Originally posted by Sparky_NY View Post
                  Simple, starting dia, ending dia and length. or angle and length, either way.


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                  • #10
                    What about an offsetable center in the tailstock? My Mentor had one for turning rifle barrels and that is one of my future projects.

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                    • #11
                      This style of offset centre? https://www.ebay.co.uk/itm/Taper-Off...UQL0:rk:4:pf:0

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                      • #12
                        I've seen where folks used a boring head mounted to a suitable arbor as an offsettable center. They turned a "bar" to suit of course.

                        But again, why? I think it's related to not knowing how to restore the tailstock to zero afterwards. But if we have an easy to use method as I described above why bother with an offsettable center? We'd need to use a dial gauge to similarly set the offsettable center to zero as a starting point and offset it by the amount required anyway. So why not just do it with the tailstock itself to start with when it's not hard to restore the zero? Plus with any tooling of this sort we introduce another possible source of error. The more "stuff" to flex the more we need to worry about that. And if the slide on that offsettable tool or boring head is not set dead nutz to level that's a possible "cosine error" source that will alter the taper.

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                        • #13
                          Originally posted by Darrp View Post
                          Well firstly, I have never turned a taper this way before.
                          thats a bit "you can't there from here". We'd all be stuck watching the idiot Kardashians on TV if we didn't venture where we'd not gone before.

                          What sort of taper are we talking about? The tail stock doesn't work for steep tapers, but usually when they are long tapers the angle is small

                          Its really easy. Put a dial indicator on the work, and move the tailstock toward you 1/2 the amount you want the diam to be less than the other end.
                          Last edited by Mcgyver; 12-10-2018, 12:43 PM.
                          .

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                          • #14
                            Well thanks for the tips and suggestions guys!

                            It is a .204 cal rifle barrel that I bought several years ago. It’s very heavy contour about .900 at the muzzle. I have since bought a complete rifle with a heavy barrel in that calibre, so now I want something a little (lot) lighter.

                            I think I will try the offset tailstock method... BCrider, thanks for the detailed description.

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                            • #15
                              Mcgyver, who are the Kardashians?

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