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My Taper Attachment -- and Backlash

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  • My Taper Attachment -- and Backlash

    Whipped this up not long ago and I wish I'd made it sooner.
    Little beefier than it probably needs to be but was made from materials
    I had on hand:



    There's a little 2min video too:

    http://www.youtube.com/watch?v=ceD8U-TgOH0

    Works a treat, but I get some backlash on the return stroke and I can't quite figure out where
    its coming from. Not an issue -- heck its even convenient as I won't get any cutting on the return --
    but everythings pretty darn rigid. Backlash is maybe 0.080" or so.. eyeball.

    You can see it in the vid when I end the cut at 2:06 and earlier on the dry run at ~0:38.

    At first I was sure it was my round bronze bush.. but I can tighten that connection down pretty
    hard and don't see 0.080" motion when changing directions.

    Attached it to the bed instead of the ways with 4 bolts. I can "index" down the bed if I need too..
    if I really need to work at the tail end I'll drill 2 more holes.

  • #2
    does your carriage move? (rotate)

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    • #3
      Nice looking rig. Years ago I got into the habit of using the compound to set the depth of cut while using taper attachments. That eliminates backlash & repeatability problems.

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      • #4
        Basic, well made, i like it.

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        • #5
          Yes I use the compound to set DOC -- I think thats the only way in'it? In the image above you can see it
          set perpendicular to the lathe axis.

          Sasquatch -- good question! I don't think it does. At least I never noticed it rotate. I'll have to check.
          I know if I'm doing aggressive cutting I get a spring cut on the return, for what that might mean.

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          • #6
            Do the arms which hold the sine bar flex vertically as you cut? This can cause some difference between forward and back cuts, although I'd expect 8 thou rather than 80 thou.

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            • #7
              Is it possible that the slotted bar at the rear is flexing? It is quite long and thin. And there may be some stiction on the bushing.

              Putting a dial indicator on it with the magnetic base on the saddle may pick up something.

              Geoff

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              • #8
                Nice, but lacks support bracing under the sine bar holders. Long length arms and only support they have is about what, 5 mm at the bed side end. Put a piece of flat bar under both of them, weld or bolt it to the bed side piece and the arms.
                Amount of experience is in direct proportion to the value of broken equipment.

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                • #9
                  Perhaps.
                  It's all 5/8" CRS, though.
                  I'll have a look around with an indicator.

                  Again, not a big deal in practice -- just bugs me not knowing where it comes from.

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                  • #10
                    The only thing I can see from looking at the pictures would be if the cross slide gib is pretty loose.

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                    • #11
                      Nice ....do you remove the cross slide nut during operation ??

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                      • #12
                        My factory taper attachment has a lot of backlash in it. It's not flex it's in the coupling between the cross slide feed mechanism and the taper attachment push pull attachment to the cross slide. Best I can tell. If I move the carriage to the left to get the cross slide to start the tapper. And then move the cross slide hand wheal I loose the tapper action so I induce back lash.

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                        • #13
                          Looks good!

                          I've been thinking of making something similar for Sheldon that I have to make it eaisier to taper barrel blanks.

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                          • #14
                            Originally posted by Tony View Post
                            Yes I use the compound to set DOC -- I think thats the only way in'it? In the image above you can see it
                            set perpendicular to the lathe axis.

                            Sasquatch -- good question! I don't think it does. At least I never noticed it rotate. I'll have to check.
                            I know if I'm doing aggressive cutting I get a spring cut on the return, for what that might mean.
                            I was watching a Tubalcain vid where he demonstrates his shop-made taper attachment and his carriage moves on the cross axis noticeably.

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