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Straight Reamers Making a Tapered Hole???

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  • Straight Reamers Making a Tapered Hole???

    Hello,

    I have that 64th set of Reamers, from Grizzly, and needed to make a fairly precise 0.500 hole. So, I first drilled the hole with a 31/64 drill bit then reamed it to size. The hole is tapered from 0.500 to 0.512 and is a through hole 1.250 deep. The drilling was done on a lathe. Does anybody know why this happened?

    Thanks,

    Brian
    There are only 10 types of people in the world: Those who understand binary and those who don't.

  • #2
    Rigidly held reamer? held at an angle?

    Reamer needs to float, and be held dead parallel to the bore, or it will do that.

    Also, reaming with a lot of "pecking" (pulling reamer out to clear chips) will tend to bell-mouth the hole.
    1601

    Keep eye on ball.
    Hashim Khan

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    • #3
      Originally posted by Rif
      Hello,

      I have that 64th set of Reamers, from Grizzly, and needed to make a fairly precise 0.500 hole. So, I first drilled the hole with a 31/64 drill bit then reamed it to size. The hole is tapered from 0.500 to 0.512 and is a through hole 1.250 deep. The drilling was done on a lathe. Does anybody know why this happened?

      Thanks,

      Brian
      Assuming that you held the reamer in your tailstock with a drill chuck, it could be that the tialstock is not centered on the center of the lathe chuck that holds the workpiece. That would cause a taper.....That's only a guess. I'm assuming that your chuck does not have a large TIR.

      When I first got my 13 X 40 lathe, it would cut straight rods to a taper over 6" or so. I discovered that the tailstock was not lined up. I used an indicator to reset it with a center in the tailstock chuck..

      Just a guess.......it does seem confusing.

      Comment


      • #4
        Reamed Hole

        Did you measure the reamer? How did you hold the reamer? Is the reamer straight? Is your tail stock correctly aligned. For sensitive hold reaming a "floating holder" must be used. This alleviated alignment problems.

        JRW

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        • #5
          Might of been caused by to much force applied to the reamer and it bowed a tad. Then again the drill could of did it before you reamed it. Or it could be the pull of the moon.
          Wow... where did the time go. I could of swore I was only out there for an hour.

          Comment


          • #6
            Hello,

            I'll measure the reamer tomorrow night and see if the reamer was a contributing factor.

            I did remove the reamer frequently in order to clear chips.

            The tailstock should be on center within 0.003 and the drill chuck is practically brand new. The quill is new, as well, as I made it myself.

            Is this a case where one of those floating reamer holders, that they use for chambering barrels, would come in handy?

            Regards,

            Brian
            There are only 10 types of people in the world: Those who understand binary and those who don't.

            Comment


            • #7
              Not meaning to invade someones post, but how about a picture or good description of the floating reamer holder? Or plans to build one? JIM
              jim

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              • #8
                Here's a link to the Manson Precision floating chamber reamer holder at Brownells: http://tinyurl.com/d2shtx.

                David
                Montezuma, IA
                David Kaiser
                “You can have peace. Or you can have freedom. Don't ever count on having both at once.”
                ― Robert A. Heinlein

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                • #9
                  The most likely cause is that the hole wasn't started dead centre.
                  Free software for calculating bolt circles and similar: Click Here

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                  • #10
                    Or the drill wandered.

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                    • #11
                      Hello,

                      I started the hole with a center drill and stepped up through about 3 drill sizes before I reamed the hole to size. May that have provided a chance for the drill to wander?

                      The machine, that I am using, also has considerable wear as the tailstock is shimmed by over 0.010. I would guess that the tailstock ways probably ramp down, from right to left.

                      Maybe, when I make another part like this, I should bore it to size instead or at least bore the first 0.5 of the hole to start the reamer straight?

                      Thanks,

                      Briant
                      There are only 10 types of people in the world: Those who understand binary and those who don't.

                      Comment


                      • #12
                        Here is a good photo of one that you could make yourself...



                        and a couple of good articles on their use:

                        http://www.bryantcustom.com/articles/rebarrel.htm

                        http://www.benchrest.com/forums/showthread.php?p=415341

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