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Carbide Tool Nose Radius: Another ?

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  • Carbide Tool Nose Radius: Another ?

    I recently purchased my first cemented carbide lathe tool. I always used HHS up to now. It's a 1/4" tool and the catalog specified a 1/64" nose radius. When I got it, it looked very sharp. I can't detect any radius at all. Is this normal? Will this be more prone to breakage, especially in a interrupted cut? Should I try to put a radius on it?

    Another question. I know carbide is much harder than HHS. But can I use a regular wheel to just touch up this cutter or will I have to get one made for carbide?

    Paul A.

    Paul A.

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

  • #2
    Yes,I would and do put more radius on brazed points,usually about a 1/32"

    No,a regular wheel won't do for grinding carbide,but they are used for grinding back the steel shank under the carbide.

    I use a green silicon carbide wheel to do roughing and a diamond pocket hone for touch up and cutting the radius,you can get them at a good hardware store or tool store for about $12.00,they sell under the brand name Diasharp or something similar.
    I just need one more tool,just one!


    • #3
      Green silicon carbide wheels cut carbide
      reasonably well. Get a diamond or other dresser for the wheel as you will need to
      freshen it fairly often. Do NOT cool the
      carbide in water, it will shatter from the
      stress of quenching. Likewise interrupted
      cuts and carbide don't get along, if the
      interuption is just a gentle undulation in
      the surface level it will be ok, but a
      sharp hit such as a keyway or the corners or
      a hex bar will blow the tips right off. Use
      HSS for these. You can cut at 2-3x the speed with carbide compared to HSS. Those
      tiny tips at the right speed and feed result
      in a dull mirror finish. Steve


      • #4
        I agree, use diamond for the radius, but you should probably go ahead and get an S/C wheel anyway, they don't cost much. Your best bet is to avoid brazed carbide as much as possible. Inserts are SO much better (even cheap ones). I sometimes use brazed for oddball cutters, because of their low cost.