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Stub reamer question, how is the hole used?

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  • Stub reamer question, how is the hole used?

    Supposedly, the hole through typical stub reamers is for some form of floating reamer holder that used a pin in the hole. So says my old 1940s Audels handbook. I have never found a picture or explanation of that type holder, and I am wondering how it worked.

    The simple possibility would be that the pin was a loose fit, allowing both sliding along the pin, and also moving sidewise on the pin, "across the hole", due to having a "rattle fit" on the pin. That seems a bit questionable, but of course might be the deal.

    Does anyone know, or have one of the holders to illustrate the principle?

    Here is a pic of a typical reamer, showing the hole. This one is 0.562 reamed size, with a 0.625" shank, so you can see the general size of the hole, sitting next to a floating holder I made (which uses a totally different "float" mechanism, not the hole).

    1601

    Keep eye on ball.
    Hashim Khan

  • #2
    Maybe it's made for a T bar or Tommy bar ?

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    • #3
      Originally posted by 754 View Post
      Maybe it's made for a T bar or Tommy bar ?
      It would of course "work" to use it.

      The specific description was that the hole was used in the holder for use in a machine (turret lathe) as part of the "floating" means. I can think of some ways t do that, but they all seem kinda mickey-mouse.
      1601

      Keep eye on ball.
      Hashim Khan

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      • #4
        Its not Mickey Mouse if it works.. no surprise to me if its one more form of short tooling designed for turret work.

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        • #5
          Originally posted by 754 View Post
          Its not Mickey Mouse if it works.. .....
          True enough. I was thinking though, that the pin deal was not something that I would expect to stand up well to all-day every day use. The pin hole size seems to be around 1/4 inch, and I don't think of that size as good for taking the torque and banging for the long term.

          I'd expect both the pin and the hole to be beaten up and burred up a bit after not too long in that sort of service. But I suppose the pins are replaceable, and the reamer itself won't last forever, it is actually consumable tooling.

          I could have saved myself some trouble if I had made the holder that way. I suppose the recess for the reamer shank is small enough to keep the reamer from getting too much off-angle on it as it comes around to use position.

          And I have seen before where the operator "helps" a tool get lined up with the work by holding it up as it approaches the work. Not fond of that idea myself, I like my fingers.
          Last edited by J Tiers; 08-07-2020, 02:06 AM.
          1601

          Keep eye on ball.
          Hashim Khan

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          • #6
            Originally posted by 754 View Post
            Maybe it's made for a T bar or Tommy bar ?
            No, it's there so it can be hung on a peg board.

            JL...............

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            • #7
              I believe they work much as you thought. I'd be surprised if there weren't some videos showing them in use, however a quick look brought up this.
              Much like the floating tap holders I've seen but much different than the floating chambering reamer holders I've seen gunsmiths use.

              https://www.indiamart.com/proddetail...725294033.html

              The purpose of the Floating Reamer Holder is to compensate misalignment between tool and work- where reaming, tapping or similar operations are being performed in different stations after holes are drilled. It is available in different tapers.
              Click image for larger version

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              Home, down in the valley behind the Red Angus
              Bad Decisions Make Good Stories​

              Location: British Columbia

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              • #8
                I’ve used reamers like that, they fitted a Chuck on a tapping machine, you had to stick a pin through to hold them, think the machine was snow, there were taps like it too, long time ago mind, the head was a floaty one, or at least it was supposed to.
                mark

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                • #9
                  Hmmmm. Substantial looking on youtube found nothing of the type, although there was one that was a very long kludge made with two bolts as pivots, similar to a Cardan joint.

                  It is not even entirely clear how the indiamart one works.

                  As mentioned, my assumption is that between sliding along the pin, and a sloppy fit on the pin, it can self-align.
                  Last edited by J Tiers; 08-07-2020, 10:54 AM.
                  1601

                  Keep eye on ball.
                  Hashim Khan

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                  • #10
                    Not a great image or reference, only one I see, page 33 in:http://www.aittools.com/sites/defaul...ut_catalog.pdf
                    Posted the wrong link.
                    Last edited by reggie_obe; 08-07-2020, 03:44 PM.

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                    • #11
                      Originally posted by reggie_obe View Post
                      Not a great image or reference, only one I see, page 33 in:http://www.aittools.com/sites/defaul...ut_catalog.pdf
                      That's not the same deal as far as I can see. I'm wondering about the old style as would be in the 1940s, perhaps. I know what to do as far as new types, just made one.

                      Curious how the hole worked into the system.
                      1601

                      Keep eye on ball.
                      Hashim Khan

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                      • #12
                        Bump.... still looking for info, now wondering since the hole loose on pin theory would also suggest the ability to tilt off-axis.

                        Since most of the screw machine/turret lathe floating holders hold the reamer rigidly parallel, I'm wondering what the purpose or advantage would be to being able to tilt off-axis. Seems in most cases it might be more of a problem than a feature.

                        Would the off-axis tilt feature be something for gunsmithing? I'd think anyone setting up a rifle for target shooting etc would want the chamber very much straight and on-axis with the bore, but then I am not a gunsmith, and know little about the craft.

                        I suppose the tilt can compensate for the machine having errors, such as a sagging tailstock ram, etc. But it seems that whatever has already been done, drilling, boring, etc, will already be in error due to the very same cause, and the reamer will tend to follow the hole, so there is little advantage.

                        And, then why would not the turret lathe, which gets, very frankly, beaten to hell doing production, might have the same problem, yet the commercial holders seem to be rigidly held parallel to their shanks.
                        Last edited by J Tiers; 08-09-2020, 11:48 PM.
                        1601

                        Keep eye on ball.
                        Hashim Khan

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                        • #13
                          maybe its one of the mysteries in machining? the main difference is parts drilled and reamed in the same setup and parts that are not, though.

                          https://www.practicalmachinist.com/v...loating+reamer

                          https://www.practicalmachinist.com/v...loating+reamer

                          "Ich hab meinen Röhm Pendelhalter wieder verkauft. Macht mMn mehr Sinn die Reibahlen sauber auf Rundlauf zu spannen." (stefan gotteswinter)
                          Last edited by dian; 08-10-2020, 02:15 AM.

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                          • #14
                            Well the question was really why one would want a turret lathe reamer with tilt, since those reamers are specifically short ones for turret lathes.

                            Your references are not very "definitive" as to that, since the responses seem to vary from talking about long-shanked machine reamers, to arguing about it, to "early ones were like that because it was cheaper".

                            In any case, there is a difference between standard reamers/holders vs reamers and holders used in turret lathes, where reamers, as mentioned, are very short, and holders seem generally to have radial float only, in the catalogs I have. In fact they often have ball bearing setups (presumably similar to a ball thrust bearing with flat "races") specifically to hold them in alignment. And, many have only a few thou of radial movement, although some have up to maybe 15 or 20 thou radial only movement.
                            1601

                            Keep eye on ball.
                            Hashim Khan

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