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Best inserts for finishing gummy 1018?

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  • Best inserts for finishing gummy 1018?

    Lots of carbide inserts work nicely if you can get enough speed, but on a smaller work pieces this is often not possible. So what is your favorite tooling?

    Sharp (dggt, ccgt xxgt) inserts intended for aluminium seem to work pretty well but I have also seen some recommendations for cermets, for example Sumitomo T1500 in sharpened versions like DCGT.

    Just some time a go I decided to give ceramics a try and based on a very quick test I have to say I am impressed. Re-sharpened Kennametal KY1615 seem to work quite nicely.
    Anyone else using ceramic inserts to finish cut soft steels?

    It's the best thing since sliced bread on crappy steel:
    Location: Helsinki, Finland, Europe

  • #2
    Looks pretty nice. I will have to try that sometime. Thanks!
    Kansas City area

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    • #3
      I am surprised, I thought ceramics were supposed to be run at extremely high speeds, much more than carbide. Never tried them but will keep it in mind now.

      (I like your homemade holder !)

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      • #4
        Originally posted by Sparky_NY View Post
        I am surprised, I thought ceramics were supposed to be run at extremely high speeds, much more than carbide. Never tried them but will keep it in mind now.

        (I like your homemade holder !)
        Yeah, that's true at least with hardened steels. I was busy trying my teeth on hard turning so I didn't realize to take a facing cut to see how low SFM the ceramic would actually work with 1018CR. But I guess it has possibly bigger usable SFM area than anything else because the ceramic has very low tendency to "weld" and make build-up-edge with steel.
        Location: Helsinki, Finland, Europe

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        • #5
          What do you mean "Re-sharpened"? Did you buy them resharpened or sharpen yourself.

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          • #6
            Originally posted by Axkiker View Post
            What do you mean "Re-sharpened"? Did you buy them resharpened or sharpen yourself.
            Chipped inserts DIY sharpened. 5$ chinese diamond wheel on a 15$ bench grinder saves the purchase cost on the first sharpening
            Finish honed real hastily on a 2-5micron diamond lapping compound.
            Location: Helsinki, Finland, Europe

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            • #7
              Originally posted by MattiJ View Post
              Chipped inserts DIY sharpened. 5$ chinese diamond wheel on a 15$ bench grinder saves the purchase cost on the first sharpening
              Finish honed real hastily on a 2-5micron diamond lapping compound.
              Ahhhh makes sense.

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              • #8
                Ahhhh, The joy of HSS! So easily shaped and sharpened. ;-

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                • #9
                  I thought we were talking about ceramic inserts?
                  Kansas City area

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                  • #10
                    I've found CCGT inserts give a lovely finish in all materials, even crappy mystery steel. I tend to do the interrupted/ rust crust cuts with CCMT and then finish with CCGT. I haven't really pushed DOC with CCGT on steel, but my only worry would be flex>jam>chipped insert. They produce a much lower cutting pressure too, so they're ideal for small hobby lathes.

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                    • #11
                      I don't really see anything in that pic to be too proud of. Insert looks dull and the shiny surface with a bur on the end is not a clean cut.

                      I'll contribute a bit.
                      Last couple days I've been turning 1018 bar stock. From 1.5"-2.25" in diameter 9xx rpm with tpg 321, 322, 323, carbide inserts. I was making multiple parts and needed to hit the size within a couple thou. I'd need to run out to the shop to check what the feed and grade inserts are.

                      ETA...
                      910 rpm, .0042 per rev, doc range .050-.002, insert grade I55
                      Last edited by Boostinjdm; 01-21-2017, 10:48 PM.

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                      • #12
                        Originally posted by Boostinjdm View Post
                        I don't really see anything in that pic to be too proud of. Insert looks dull and the shiny surface with a bur on the end is not a clean cut.

                        I'll contribute a bit.
                        Last couple days I've been turning 1018 bar stock. From 1.5"-2.25" in diameter 9xx rpm with tpg 321, 322, 323, carbide inserts. I was making multiple parts and needed to hit the size within a couple thou. I'd need to run out to the shop to check what the feed and grade inserts are.
                        Damn, I'll need a better microscope if others can see dull insert on a crappy cell phone pic

                        A couple of thou tolerance in 1018 is not more difficult than dozens of thou. Less than 0,01mm or 4 tenths gets tricky with less than 100% success rate on a old worn out clunker.
                        Location: Helsinki, Finland, Europe

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                        • #13
                          I think it looks fine. The burr on the end is easily fixed with a file.
                          Kansas City area

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                          • #14
                            You're the one that said, "It's the best thing since sliced bread on crappy steel." Your pic does not support that. That's all.
                            I not saying that TPG inserts are the best thing either, but they're cheap, work on lots of materials, and are very flexible as far as holder options.

                            To put some perspective on my previous post, I consider most people that claim to work to tenths FOS. Especially hobbyists and self proclaimed, but untrained machinists. I am most definitely not a machinist. I'm a welder/fab/repair guy. I machine a lot of stuff as a means to an end when repairing or building something.
                            Last edited by Boostinjdm; 01-21-2017, 09:33 PM.

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                            • #15
                              Originally posted by Boostinjdm View Post
                              You're the one that said, "It's the best thing since sliced bread on crappy steel." Your pic does not support that. That's all.
                              I not saying that TPG inserts are the best thing either, but they're cheap, work on lots of materials, and are very flexible as far as holder options.

                              To put some perspective on my previous post, I consider most people that claim to work to tenths FOS. Especially hobbyists and self proclaimed, but untrained machinists. I am most definitely not a machinist. I'm a welder/fab/repair guy. I machine a lot of stuff as a means to an end when repairing or building something.
                              I think we really need to see the mirror finish you get on with your TPG inserts.

                              Getting a picture of the shiny surface finish proved to be a tricky but here is another:
                              About halfway there is a 0,035mm or 0,0014" step after I tested 7 tenth cut of depth. Even less than 7 tenths DOC seemed to work, reasonably well for dull insert

                              IMO more remarkable is that this was done AFTER turning hardened >HRC60 bearing race with the same "dull insert".
                              Last edited by MattiJ; 01-21-2017, 10:11 PM.
                              Location: Helsinki, Finland, Europe

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