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Countersink Question

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  • Countersink Question

    Ther are a few different angles of countersinks to get... But i'm curious, waht are flat head screw angles? As i would like to buy a set of countersinks that fit the angle of flathead screws. I was told imperial screws are 82.something degrees and metric are 90? Only heard this from one person who wasn't too sure either, and don't have anything to look it up in. So what angle should i get to suit flathead screws?

    Also how many flutes does everyone find works the best? I have currently a 3 flute countersink... it worsk great in aluminum, but in steel i pretty much always get chatter no matter how what rpm - feed combo i use.

  • #2
    Some common angles for flat heads.
    82 deg (US),
    100 deg (US) for thin materials,
    90 deg (Metric screws),

    Ed Pacenka


    • #3
      82* like said is the most common in the US.

      I always love the term"chatterless countersink",talk false advertizing.

      I use single flutes by MA Ford and KEO,but they will walk a hole over on a drillpress.

      I have had the best luck with the combined drill and countersinks,they are quicker anyway because they drill the clearence hole and counter sink in one shot.
      I just need one more tool,just one!


      • #4
        I use Morse 3 flutes 82incl angle, no chatter, no walk, excellent tool. Hard to find, looks like a 3 fluted drill


        • #5
          I'm with wierd.

          I'll take those single flute sinks anyday.
          They can pull a hole over if the part is held by one corner though.

          Those chatterless sinks frequently require back gear, and the job to be clamped to operate as advertised.



          • #6
            M A Ford Uniflute (Series 61) if it's a light chamfer or deburr. Triflute (Series 66) for deeper countersinking. Single flutes are the slowest cutting but chatter the least. 3 flutes are a good compromise, faster cutting with good surface finish.
            Barry Milton


            • #7
              I've been using single flute for years in all materials, Ford Uniflute and Weldon "fish eye".

              Just recently found out these are recommended only for soft, nonferrous materials. Oh well, I have sharpening fixtures for both so I'll continue usage in every type material.