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Unusual lathe boring bar

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  • Unusual lathe boring bar

    I just stumbled on this on ebay UK, a bit of a gimmick, or a useful addition to tooling?

    https://www.ebay.co.uk/itm/384886722...3ABFBM2MifiZtg

  • #2
    Not really.
    Most advantage is in CNC lathes for ID and OD turning
    with the same tool. It saves a tool change cycle.

    --D
    DZER

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    • #3
      I'd say it has some use for a home type even working with manual machine. As Doozer states it saves a tool change. And that's just as handy for us non CNC types as it is for a CNC machine. So for specific jobs needed both ID and OD work on a bunch of parts it saves time on the tool changes.

      It would be a nice project to find a bigger size of TC or WM inserts and make up a slightly undersize boring bar that can cut on both corners to permit both ID and OD turning without the need for a tool change for small repetitive parts.


      Click image for larger version

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      Chilliwack BC, Canada

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      • #4
        I wouldn't mind having one. Inside, outside, or after trepanning the inside outer of a post inside a hole.
        Andy

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        • #5
          What's the deal with these two versions?

          Click image for larger version

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          Click image for larger version

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          http://pauleschoen.com/pix/PM08_P76_P54.png
          Paul , P S Technology, Inc. and MrTibbs
          USA Maryland 21030

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          • #6
            I would assume that the first is so the right hand insert can do a facing cut without dragging the other insert? The second is for times where you want both tips to be at the same point when the dial is the same? And facing isn't a requirement?

            So many questions.... ?
            Chilliwack BC, Canada

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            • #7
              Originally posted by Doozer View Post
              Most advantage is in CNC lathes for ID and OD turning
              What advantage does it offer over a single insert tool and reversing the spindle?

              I like their non-iso descriptions 'brown', 'brown 2' and 'brown 3'. Do they offer a 'brown 1' version?

              Possibly for boring (ID turning), it might be useful with a roughing insert one side and a finishing insert the other.

              As suggested above, it is offered on the same principles as a standard turning tool, a left hand, right hand and neutral version.

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              • #8
                As noted, this bar is pretty specifically intended for use on CNC lathes, allowing both OD and ID turning using only one tool position.

                I can't say I understand why the one has an offset insert, but really, this whole thing isn't meant for home-shop use. Sure, you CAN use it in the home shop, but that's really not what it's meant for.

                Doc.
                Doc's Machine. (Probably not what you expect.)

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                • #9
                  Originally posted by djc View Post

                  What advantage does it offer over a single insert tool and reversing the spindle?

                  .
                  You do not have to reverse the spindle, simply move the tool at rapid speed.

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                  • #10






                    You do not have to reverse the spindle, simply move the tool at rapid speed.
                    this works if your going from ID -> OD or visa-versa. but if you wanted to cut with the 2nd insert on the other of the bore, you'd still need to reverse the spindle. though you could design a tool that flipped the 2nd insert upside down, but with that you couldn't do what the other could.
                    better view:

                    here's my guess: I think the height offset is more a consequence then a feature. Note the offset height bar also has asymmetrical inserts, I think they tip them to keep the width of the bar minimum & a height offset is required to present the insert tangentially.

                    OR

                    the left most insert is for od turning & the right insert of the left tool is for ID work, that tip would let you bring the tool in above center allowing for better tool rigidity (more shank under it)



                    Click image for larger version

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                    "it is no measure of mental health to be well adjusted to a profoundly sick society." -- krishnamurti
                    "look deep into nature, and then you will understand everything better." -- albert einstien
                    "any intelligent fool can make things bigger and more complex...It takes a touch of genius - and a lot of courage to move in the opposite direction."

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                    • #11
                      Originally posted by mtraven View Post
                      but if you wanted to cut with the 2nd insert on the other of the bore, you'd still need to reverse the spindle.
                      -That's not what it's for. Again, theoretically you could, but there's no reason to. Barring further information, I'm quite convinced this for conventional turning on both the ID and OD of a part, using one tool slot in your turret or in your gang-tool array.

                      here's my guess: I think the height offset is more a consequence then a feature.
                      -First, it's a length difference. The insert height is the same, just that insert is slightly longer on the shank. I still don't really understand why, but there must be a reason.

                      Note the offset height bar also has asymmetrical inserts[.]
                      -Nope, all four shown are the same size CCMT, it's just the angle in the image that makes it look a little different.

                      the left most insert is for od turning & the right insert of the left tool is for ID work, that tip would let you bring the tool in above center allowing for better tool rigidity (more shank under it)
                      -I'm not sure there's a reason to have different tool heights on a CNC turning center. I know on my gang-tool machine, there's not even an easy way to adjust it, on round-shank tools like this.

                      But that's irrelevant- again, the two inserts are the same height, just different lengths on the shank. My best guess- and that's all that it is- for the reason for the length difference, is for boring. If the spindle is turning clockwise (in reverse compared to typical manual lathes) the "longer" insert can bore without worrying about the other insert accidentally contacting the end of the bore.

                      Seems kind of odd it'd be for clockwise machines only- there's definitely plenty of those out there, but there's also an F-ton of gang-tool machines that turn counterclockwise like normal.

                      I'd be curious to know the official reason for that offset.

                      Doc.
                      Doc's Machine. (Probably not what you expect.)

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                      • #12
                        I have used boring bars to turn external surfaces occasionally, when it was the best shape for ackward jobs, but having both right and left handed bars from 4mm to 25mm, a double headed one won't be in my wish list. One disadvantage of the double headed in a bore is that a larger shank and stiffer single headed one would do a better job in the same start size bore, I'm not up against the clock.

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                        • #13
                          Originally posted by Doc Nickel View Post

                          I'd be curious to know the official reason for that offset.

                          Doc.
                          Quite possibly for facing operations, I would not like to drag a secondary insert backwards across the part face.



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                          • #14
                            Originally posted by Bented View Post
                            Quite possibly for facing operations, I would not like to drag a secondary insert backwards across the part face.
                            -Oh, had not thought of that, I suspect you're exactly right.

                            Brain was stuck in turn/bore mode.

                            Doc.
                            Doc's Machine. (Probably not what you expect.)

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                            • #15
                              -That's not what it's for. Again, theoretically you could, but there's no reason to. Barring further information, I'm quite convinced this for conventional turning on both the ID and OD of a part, using one tool slot in your turret or in your gang-tool array.
                              pretty sure I said that.

                              -First, it's a length difference. The insert height is the same, just that insert is slightly longer on the shank. I still don't really understand why, but there must be a reason.
                              there is also a length difference(likely for facing as Bented pointed out), but there is 100% also a height & angle difference. are you looking at the pics on a phone or something? Not sure how your not seeing that. I do see your point about a height change though...so I really dont know.

                              Nope, all four shown are the same size CCMT, it's just the angle in the image that makes it look a little different.
                              I was referring to the placement of the inserts being symmetrical WRT the centerline.
                              "it is no measure of mental health to be well adjusted to a profoundly sick society." -- krishnamurti
                              "look deep into nature, and then you will understand everything better." -- albert einstien
                              "any intelligent fool can make things bigger and more complex...It takes a touch of genius - and a lot of courage to move in the opposite direction."

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