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My part-off tool worked perfectly

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  • My part-off tool worked perfectly

    In the diamond file thread I mentioned that I was making a part-off tool that would also deburr the OD of the parts by rounding the ends slightly. (the rounding part was what the files are for) I used it for the run of parts, and almost every one parted off with no burrs.

    I angled the end of the parting tool, so that the parted piece would be cut off clean, leaving the inside "fin" on the "stock", and I then ran the parting tool a little farther to remove that and finish the rounding.

    The length of the tool was customized for the thickness of the stock tube, so that the rounding would be done just before cutoff.

    Stock was then pulled out to a stop, and the next section parted off. Worked like a champ. Way better than last time, where I had a bunch of second ops needed to remove burrs created by the part-off operation.

    Pics when I find where I put the camera (I already took the pics). No pics of the final part itself, as some other things were done to it. But a representative piece of tubing is shown.
    CNC machines only go through the motions

  • #2
    no pics, no praise 😉
    "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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    • #3
      So, I found where I had put down the camera. NOT where I would have expected, it was inexplicably in the laundry area.

      Anyhow:

      Profile of the cutter. At top you can see the rounded end of the tube that resulted from it. The radius on the left side of the cutter is slightly back of that on the right side, so as to cut the radius when the cutter is advanced to cut off the ring of "fin" after the parted-off portion has been cut loose. The right side of the tip is very slightly "ahead of" the left, so as to cut off the part and leave the fin on the stock at left.

      The difference between the sides is less than it really should be, although it worked. That's one reason I want some good round diamond files, to ease it back a tad, since this task may come up again.



      The work in the chuck, and the stop used to hold the length to the correct dimension. (I loosened the chuck, and pulled the tube out until it hit the stop, then tightened the chuck.) It happened that the center drill holder that is holding the stop had the same size hole as the shank on the stop. I needed the smaller diameter in order to clear the toolpost. The ram, and any chuck I had were too big, and would require a larger stickout. (one of the rare times the 4 way is inconvenient)



      Very handy. Took a good deal less time than when I last made these parts.

      Originally posted by mtraven View Post
      no pics, no praise 😉
      "Praise"? That happens in a different venue, and refers to someone else................
      Last edited by J Tiers; 04-22-2022, 02:13 AM.
      CNC machines only go through the motions

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      • #4
        Good work. This is one reason why everyone should understand cutting tool geometry and be able to shape high speed steel for the purpose at hand.

        If you only use inserts then you won't be able to do things like this.

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        • #5
          Originally posted by strokersix View Post
          Good work. This is one reason why everyone should understand cutting tool geometry and be able to shape high speed steel for the purpose at hand.

          If you only use inserts then you won't be able to do things like this.
          Good point and as JT's photo graphically illustrates this is yet another classic example of the usefulness of HSS tooling, the geometry, and the ability to apply to create a purpose built custom tool bit.
          Lets face it most of the work we do in our shops often requires custom tooling in order to create custom parts.
          I love my carbide tooling for what it can do but I also love the HSS for what I can make it do for me.

          Good solution and thanks for taking the time to illustrate the results.
          Home, down in the valley behind the Red Angus
          Bad Decisions Make Good Stories​

          Location: British Columbia

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          • #6
            Originally posted by strokersix View Post
            Good work. This is one reason why everyone should understand cutting tool geometry and be able to shape high speed steel for the purpose at hand.

            If you only use inserts then you won't be able to do things like this.
            Yep. The foundational goal of machining is simply to present an appropriate cutting edge to the work piece to accomplish the task at hand. There are many ways to do that of course, but that's the end goal.

            Nice job Jerry.

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            • #7
              We have at the museum some brazed on carbide tipped lathe tools ground to exact profiles by the cutter grinder of some machine shop. They are works of art, but not much use to us as they are such odd shapes.

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              • #8
                Hi Jerry

                Am I thinking or reading wrong but does the work have to be of a certain diameter for the tool to work as designed. And that might be the
                point, a special tool for this one job.
                John Titor, when are you.

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                • #9
                  Originally posted by Mike Amick View Post
                  Hi Jerry

                  Am I thinking or reading wrong but does the work have to be of a certain diameter for the tool to work as designed. And that might be the
                  point, a special tool for this one job.
                  Yes, as I said, the thickness of the tube determines how long it needs to be to round off just before/as it is cutting through and finishing the parting. So these things are custom to a job.

                  Hence the files, I will need to do others at some time, and the files will help to get the locations of the "shoulders" timed correctly. You want the parted piece to be rounded first,then immediately cut off, then the stock to be rounded as you get rid of the "fin" left on it (or, I suppose, the "pip" left as a solid piece drops off).

                  Takes a bit of tuning, but if you have many to do, it is very worthwhile to get right.
                  CNC machines only go through the motions

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                  • #10
                    Nice work Tiers,have similar grooving or parting inserts from Kennametal but have never modified the radius portion.

                    Comment


                    • #11
                      Originally posted by J Tiers View Post
                      "Praise"? That happens in a different venue, and refers to someone else................
                      ehh, I was tired & just being a smart ass.

                      Tool looks very handy, takes me a couple of cutters & usually a file to accomplish the same thing, less accurately / consistantly.

                      curious how you did those radii (i'm work on a jig myself)?...they look nice & consistent. or maybe that discussion is over in the diamond file thread?

                      "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."

                      Comment


                      • #12
                        I love the idea. I think I would store the tool in a container with the wall thickness it was made for clearly marked on it. Ready for the next batch.
                        Paul A.
                        SE Texas

                        And if you look REAL close at an analog signal,
                        You will find that it has discrete steps.

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                        • #13
                          Originally posted by mtraven View Post

                          ehh, I was tired & just being a smart ass.

                          Tool looks very handy, takes me a couple of cutters & usually a file to accomplish the same thing, less accurately / consistantly.

                          curious how you did those radii (i'm work on a jig myself)?...they look nice & consistent. or maybe that discussion is over in the diamond file thread?
                          They are straight off the grinder wheel. It just so happened that they worked out OK (not perfectly). I don't have a radius attachment for the grinder, so I'd not be able to do a different radius on it.

                          And, to make that, I went to my stash of cutters that someone else ground for unknown purposes.... In there was one that actually was broken, but could be modified to be what I wanted, so I took it to the grinder.
                          CNC machines only go through the motions

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                          • #14
                            Originally posted by J Tiers View Post
                            So, I found where I had put down the camera. NOT where I would have expected, it was inexplicably in the laundry area.


                            That demo on how HSS bits are still valuable. I have shaped a few...

                            Yhanks for sharing, I kiked it.. JR

                            Liked it. JR
                            Last edited by JRouche; 04-23-2022, 05:04 AM.

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                            • #15
                              Originally posted by strokersix View Post
                              Good work. This is one reason why everyone should understand cutting tool geometry and be able to shape high speed steel for the purpose at hand.

                              If you only use inserts then you won't be able to do things like this.
                              Not exactly true, a simple parting operation is easily accomplished by cutting the radii before parting using a straight insert tool.

                              Click image for larger version

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