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Bottoming drills?

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  • Bottoming drills?

    I need to drill some small dia. holes to a precise depth with out the point going through the other side of the material.
    I could use end mills, but what do you do if you need an odd size,say an x/32 or x/64 hole?
    A "d" bit with the end squared?

  • #2
    Two drill of the same size. One regular drill point, the other ground (by hand) to a 180؛ flat bottom drill.

    Drill hole with regular one, point to the required depth. Bring in the flat bottom drill just to clean out the angles left from the first one.


    • #3
      Sharpen similar to an end mill?


      • #4
        If you had a belt sander and about 3 minutes
        you could hand grind one. No black magic.



        • #5
          Drill with regular drill, then use boring head to flatten the bottom.
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          • #6
            Originally posted by Black_Moons View Post
            Drill with regular drill, then use boring head to flatten the bottom.
            That doesn't always get you a flat bottom. The width of the end of the boring tool must be equal to half the diameter of the hole, as most of us don't have facing heads.

            I can have a flat bottom drill ground and used before you could finish your first cut with the boring head.


            • #7
              As others have said, grind a flat-bottom drill. I have an easier time grinding a flat-bottom drill than a normal drill, it's pretty easy. Stick a square up to the side of the drill and grind the end until it's square to the side of the drill, then put on a little relief.

              The other option - if one had a tool/cutter grinder or surface grinder with a spin index, and a lot of end mills - would be to grind down the flutes of an end mill until it was of the right diameter. It would still cut on the end, but not on the side.