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Carbide Insert Sharpening Fixture

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  • Carbide Insert Sharpening Fixture

    This is waht I made over the weekend, a little holding fixture for sharpening my TPG and SPG carbide inserts. Over the years I've collected a good cup full of inserts, most with slightly chipped edges. As we all know when that happens you replace the insert, what a waste especially when the insert didn't last long. I also have several packs of inserts that have honed edges that I bought during the experamental years of owning my lathe only to find out that I needed a dead sharpe edge for a good finish. Now I can finally use those inserts after a light dressing to give them a dead sharpe edge. I can also set the fixture up at an angle in a vise or on a sine table to give the insert a chip breaker groove or to create a positive or negative rake.
    The base is made out of 1018 and the clamp is made out of 01. I may harden the clamp, haven't decided yet.

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






  • #2
    Good idea JL !
    What diamond wheel grit are you using?
    Any other grinder setup photos?

    Thanks for sharing.
    Dan

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    • #3
      Very nice craftsmanship! Well done.

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      • #4
        The diamond wheel is 120 grit.

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

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        • #5
          Nice job, but how are you handling the carbide dust? Nasty stuff.

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          • #6
            Originally posted by lakeside53 View Post
            Nice job, but how are you handling the carbide dust? Nasty stuff.
            I have a dust collector set up on the grinder. Not much dust from grinding that little insert as I only need to remove about .003 - .005 to clean up most inserts. If the radius is broken off half way down the side of the insert then it's not worth the time. You have to throw them out at some point.


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

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            • #7
              Nice grinder! I envy you the compact build of a hydraulic reciprocation table. You should consider building a more enclosed table guard and fit the machine with a coolant system as I did my manual Kent KGS-200. I got lucky; my next door neighbor made the table guard for me in exchange for me letting him use my high pressure washer. Nearly two years later he still hasn't cleaned the siding on the north side of his house, but I have my machine about as good as it'll ever get. Your machine looks "as new", so if you were to make a better guard it may be impossible to match that paint finish (unless you did it yourself.)

              As for re-sharpening carbide inserts, I've got little time enough to be using the inserts, let alone re-sharpen them. Besides, I only have a few lathe tools that can use flat-topped TPG inserts and have near lifetime supply of those in carbide, coated carbide, cermet and whisker-reinforced ceramic. I have left and right hand turning tools CTGPL-16-3C and CTGPR-16-3C which take TPG32x and Valenite VNCD-7463 and VNCD-7462 1/2" and 5/8" solid carbide boring bars that take TPG22x size inserts. I think if I were to use my Norton SD180 grinding wheel to do what you've done, the inserts might not be secure in the holders any more because the mechanical chipbreakers between the clamp and the insert may not hold. My uncoated inserts are already dead sharp anyhow. I have yet to wear out or chip a single insert completely, though one is on it's last edge. I use far more negative rake insert with have molded in chipbreakers. The TPG inserts are used only rarely for very slow feed rate finishing.

              Never "throw away" carbide inserts that you can't re-sharpen....RECYCLE them! Scrap carbide gets between $9 and $12 a pound lately.

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              • #8
                Pixman, I have a design in my head for a better / more improved dust collector intake. I just haven't got around to it yet. This one will cover the width of the chuck. The one you see in the picture was just an experiment that has more or less become permanent. It catches about 90% of the dust, how do I know that??? well there is hardly ever any dust that collects on the table behind the intake, with the exception of dressing the wheel. I don't use coolant on any of my machines so a full enclosure, like a back splash isn't needed. I do have paint to match, I also have the formula just in case I need more someday. I did restore the machine and all the accessories I have for it.

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

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                • #9
                  It is always best to grind carbide with coolant because if "microfracturing" which occurs at the cut zone. It reduces the "damage level" within the carbide or ceramic and with cutting tools that means they'll last quite a bit longer. That said, grinding coolants for carbide are different than others. Those coolants have a chemical composition which helps prevent leaching out of cobalt from the carbide.

                  I find coolant is SO nice when grinding just about anything, especially when using the newer seeded gel wheels from Norton and Radiac. With coolant running parts can actually come out flatter as the wheel doesn't "hog in" towards the center of the cut.

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                  • #10
                    I do have a mister that I could use. Would that help if I used the proper coolant??

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

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                    • #11
                      That is a nice little fixture. I don't know if would make sense to do so but one thing that came to mind when I was looking at it was that you could grind the other 3 sides down at various angles and use those for grinding reliefs. Your clamp design should be able to adapt to most useful angles.

                      bob

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                      • #12
                        Originally posted by rowbare View Post
                        That is a nice little fixture. I don't know if would make sense to do so but one thing that came to mind when I was looking at it was that you could grind the other 3 sides down at various angles and use those for grinding reliefs. Your clamp design should be able to adapt to most useful angles.

                        bob
                        My original thought for relief angles was to either set the fixture on a sine plate or just hold it at the desired angle in my tool makers vise. The fixture is just under .500 in thickness so I can't do much with any of the sides as far as using them as a mounting surface.
                        Unless I misunderstand what your saying.

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

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