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Ground Toolroom Stones: New Idea To Me

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  • Ground Toolroom Stones: New Idea To Me

    I found this video while surfing YouTube. I was not aware that grinding stones could be ground to make them flatter. He uses a diamond wheel on a surface grinder to do it.

    https://www.youtube.com/watch?v=DVLXsq7pi9Y

    He talks about having two such stones and rubbing them together to cut down any embedded chips in the one you are using. I started to think that perhaps you could purchase three of them and rub them together to get them all flat. I wonder if that would work.
    Paul A.

    Make it fit.
    You can't win and there is a penalty for trying!

  • #2
    You Tube is chock full of different ways to flatten sharpening stones. Mostly from wood workers.

    Comment


    • #3
      I resurface my stones either by surface grinding or diamond lapping.
      For surface grinding I hold them in a precision screwless vise with a parallel under each end. A regular J or K hardness wheel will dust them off nicely.
      For diamond lapping I use a coarse 3 x 8 diamond stone. This is diamond grit glued to a steel plate.
      Last edited by Toolguy; 06-13-2017, 08:56 AM.

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      • #4
        $500 for a pair of flat stones????? WOW ! Anyone ready to order ????

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

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        • #5
          That's why he buys $10 stones and dresses them flat with his surface grinder. At least that is what I understood from the videos.



          Originally posted by JoeLee View Post
          $500 for a pair of flat stones????? WOW ! Anyone ready to order ????

          JL..................
          Paul A.

          Make it fit.
          You can't win and there is a penalty for trying!

          Comment


          • #6
            Some pretty big claims. $190 on Amazon...

            Guaranteed to better than .0005" flatness across the entire area of the diamond surface.
            Use it to flatten any abrasive of any coarseness.
            https://www.youtube.com/watch?v=22rUzTizM6Q

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            • #7
              One will need many lengthy words, sentences, and paragraphs to educate me on just WHY any of this matters.

              I use stones to knock off high spots. (flatness doesn't matter)

              I use stones to sharpen edge tools. Flatness sort of matters, but I control most of it during the process.

              I've got one flat hard stone that puts a polish on anything that needs it. It also does a great job of showing where other stones have left something less than ideal.

              But really, $25 is way to much to pay for something you are just going to rub away. ;-)

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              • #8
                There was a rather long and well analyzed article in one of the Machinist's Bedside Reader volumes on how and why using THREE (or more?) reference surfaces in the right order to do something like this would result in all three surfaces being as flat or as straight as one is willing to put into such a project. And since each stone has two sides I would guess that once "close enough" that rubbing the faces together and regularly flipping them around to mix up the faces and directions would enhance and maintain this.

                And if one was patient enough I don't see why a surface grinder would be required. The stones would do a fine, if slow, job of truing themselves up.

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                • #9
                  Originally posted by CalM View Post
                  One will need many lengthy words, sentences, and paragraphs to educate me on just WHY any of this matters.

                  I use stones to knock off high spots. (flatness doesn't matter)

                  I use stones to sharpen edge tools. Flatness sort of matters, but I control most of it during the process.

                  I've got one flat hard stone that puts a polish on anything that needs it. It also does a great job of showing where other stones have left something less than ideal.

                  But really, $25 is way to much to pay for something you are just going to rub away. ;-)
                  Stefan mentioned this in passing in one of his videos over the past few months, I don't remember which one offhand. Apparently one thing that makes these "dead flat" stones very useful, at least if they are a very fine grade, is that the distribution of light stoning force over such a large area (large compared to a stone that is almost flat but riding on high spots) against another flat surface means it can be used for identifying high spots and burrs without really removing any material to speak of from the other surface. He mentioned this in the context of stoning machine tables, the idea of which made him (and I'm sure most of us) cringe until he learned this and tried it for himself. The right stone, used the right way, from what he says, can very effectively identify minute high spots on mill tables and the like, without abrading the surface. Perhaps Stefan will chime in here and do a better job explaining it than I attempted to do, haha.
                  Max
                  http://joyofprecision.com/

                  Comment


                  • #10
                    Originally posted by CalM View Post
                    One will need many lengthy words, sentences, and paragraphs to educate me on just WHY any of this matters.

                    I use stones to knock off high spots. (flatness doesn't matter)

                    I use stones to sharpen edge tools. Flatness sort of matters, but I control most of it during the process.

                    I've got one flat hard stone that puts a polish on anything that needs it. It also does a great job of showing where other stones have left something less than ideal.

                    But really, $25 is way to much to pay for something you are just going to rub away. ;-)
                    In the CNC world on high dollar production machines, I'm seeing a lot of damage being done by people that think they are doing the right thing.

                    Comment


                    • #11
                      Originally posted by mars-red View Post
                      Stefan mentioned this in passing in one of his videos over the past few months, I don't remember which one offhand. Apparently one thing that makes these "dead flat" stones very useful, at least if they are a very fine grade, is that the distribution of light stoning force over such a large area (large compared to a stone that is almost flat but riding on high spots) against another flat surface means it can be used for identifying high spots and burrs without really removing any material to speak of from the other surface. He mentioned this in the context of stoning machine tables, the idea of which made him (and I'm sure most of us) cringe until he learned this and tried it for himself. The right stone, used the right way, from what he says, can very effectively identify minute high spots on mill tables and the like, without abrading the surface. Perhaps Stefan will chime in here and do a better job explaining it than I attempted to do, haha.
                      The guy in this video spends most of the (somewhat long) video explaining all of the things he uses these for, and explains the mechanism of how and why they work in almost the exact terms you use. It makes sense to me anyhow. Not sure I need a set for the sort of things I do, but then again I have any number of things I don't actually "need"...

                      I thought this was really interesting and pretty cool, really.

                      Comment


                      • #12
                        Apparently his intent is to produce stones that are exceptionally flat. That way they do not bite into a precision surface and only take off any burrs. He shows the stone being rubbed across an almost mirror finish and it does not cut into it.

                        I have some diamond stones that are as you describe; diamond grit glued to a steel plate. I would wonder just how flat they are. And if they are not themselves flat, then they could not make the stone you are working on it flat.



                        Originally posted by Toolguy View Post
                        I resurface my stones either by surface grinding or diamond lapping.
                        For surface grinding I hold them in a precision screwless vise with a parallel under each end. A regular J or K hardness wheel will dust them off nicely.
                        For diamond lapping I use a coarse 3 x 8 diamond stone. This is diamond grit glued to a steel plate.
                        Paul A.

                        Make it fit.
                        You can't win and there is a penalty for trying!

                        Comment


                        • #13
                          Working three surfaces against each other is the classic way of producing a flat. The idea is that the only way that three surfaces can mate with each other in all combinations and in all orientations (rotations) is if they are all flat. With two surfaces, one could be concave and the other convex. But when you add the third one, then all three must be flat. Optical workers make originally made optical flats that way using a process they call grinding: we call it lapping. It works best with round surfaces and doing it with stones that are narrow rectangles would be more difficult as they would only meet in a small square when oriented at 90* to each other. Working them at that 90* angle, as well as in line with each other is vital to preventing a warped (propeller) shape. Unfortunately, stones are almost always narrow rectangles. A procedure would need to be invented to prevent a propeller shaped warp.

                          The author of the video stated that he tried lapping (the three stone approach) to produce such stones and found it a failure. He did not elaborate any further and I would love to put the question to him. Did they not get flat? Was the surface not satisfactory for some other reason? He seems to feel that a surface grinder with a diamond wheel was the only way.



                          Originally posted by BCRider View Post
                          There was a rather long and well analyzed article in one of the Machinist's Bedside Reader volumes on how and why using THREE (or more?) reference surfaces in the right order to do something like this would result in all three surfaces being as flat or as straight as one is willing to put into such a project. And since each stone has two sides I would guess that once "close enough" that rubbing the faces together and regularly flipping them around to mix up the faces and directions would enhance and maintain this.

                          And if one was patient enough I don't see why a surface grinder would be required. The stones would do a fine, if slow, job of truing themselves up.
                          Paul A.

                          Make it fit.
                          You can't win and there is a penalty for trying!

                          Comment


                          • #14
                            I think it's a given that most rectangular stones are concave on one side and convex on the other. The video author addresses this problem by putting the convex side down on the chuck but shimming it with .015" plastic shim in three places so it sits solidly while the other side is trued. With the other side flat, the stone can then be flipped so the first side is trued.

                            It isn't at all clear to me how you could lap a convex stone flat by hand. I'm sure that if I tried it I'd just lap facets, but would not get the whole thing into one plane.

                            That video sold me. I ordered a pair of dual-grit Norton stones and will start looking for a way to grind them flat.

                            metalmagpie

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                            • #15
                              I am an FNG, however the whole lapping 3 stones together to get a flat plane sounds fine in theory, however I tried a couple of gray stones I have here that I use to clean up chisel faces, I also ran one against my hand grinder with similar wheel on it. The action of this seems to be more of a tear than a grind. I can see pebbles being pulled from the stone, vs grinds which is what I would guess is the desired effect. Again this is my .02c, I may be very much off base here. I will also order a few of those norton stones when time comes. I have to reassemble my surface grinder first.
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