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OT-Turning Onyx

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  • OT-Turning Onyx

    We just got back from a holiday in Turkey. While in Cappadocia we were in a shop that produced onyx ornaments. The worker was turning the onyx blanks on an old metal lathe, he did not know English, and I could not get close to the machine, but he seemed to say that he was using diamond tooling. For the fun or it, I bought a chunk of raw onyx. Has anyone ever turned the stuff? Will HSS or carbide cut it? Thanks, John.

  • #2
    Let's see. Turning an onyx.

    Couldn't you tug on the ring in hs nose.

    Har! Har! Har! I'm yust fulla yokes!

    Hope you don't mind me "pulling" your leg. (Snirk! Chortle!)

    Sorry about the hi jack but I thought the theme was bovine. (Hee hee. Get it bovine - devine.) Sometime I just kill myself.

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    • #3
      Onyx or Onyx?

      Originally posted by JohnWFoster
      We just got back from a holiday in Turkey. While in Cappadocia we were in a shop that produced onyx ornaments. The worker was turning the onyx blanks on an old metal lathe, he did not know English, and I could not get close to the machine, but he seemed to say that he was using diamond tooling. For the fun or it, I bought a chunk of raw onyx. Has anyone ever turned the stuff? Will HSS or carbide cut it? Thanks, John.
      Well, there's Onyx, and there's Onyx. Some Onyx is cryptocrystaline quartz, the same thing as agate. Other Onyx is a form of calcite. The calcite form is about hardness 3, and easily cut with HSS, but the rock might chip. The agate form is about hardness 7, but very tough. Carbide might cut it, but I think the tool would probably chip. I haven't tried either. Basically if a pocket knife scratches it, it's calcite, if not, it's quartz.

      A lapidary would use diamond or silicon carbide wheels to cut the calcite form. The agate form could be cut with silicon carbide wheels, but it's slow work. Diamond works better. For doing one piece, the cheap diamond grinding bits would probably do the job. Either way, just keep it wet to keep the dust down and keep the tool intact.

      Mike
      .
      Mike

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      • #4
        Most onyx I've seen has been pretty soft, and is easily worked with wood working tools. Many types of stone, marble for example, can easily be cut with files and saws, though it doesn't leave them much good for anything else.

        Ken.

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