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i need a countersink, what type?

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  • #16
    I use multiflute countersinks, 4 flute and 6 flute. I have never had good results from the "zero" flute or single flute types. I use a LOT of flush head cap screws for assembling my designs both steel and aluminum. For those I use six flute countersinks of the correct size for the head in question. To seat a flush head cap screw properly the hole is countersunk until the tool produces a straight edged hole of perhaps .020" depth at the top. This brings the head of the screw flush to the surface. The other types of countersinks don't do this well or at all in my experience.

    The main secret to clean edges with no chatter is to clamp the work and to use a machine that doesn't have a lot of play in the spindle (cheap drill press= chatter). Low rpm and good pressure are also important. When countersinking use a cutting oil. It makes a big difference.
    Free software for calculating bolt circles and similar: Click Here


    • #17
      I prefer the single flute type First then the one with the hole. Multi flute counter sinks are just a get buy want last long.
      Every Mans Work Is A Portrait of Him Self


      • #18
        I have a 4 flute countersink that has never needed sharpening and still works well. I used it for 4 years working on aircraft and in my shop ever since. That's 38 years now. It's indestructible.

        I just had a look at it. The brand is Severance.
        Last edited by Evan; 11-04-2009, 05:48 PM.
        Free software for calculating bolt circles and similar: Click Here


        • #19
          That is because it is a Severance brand . That is the only multi flute brand that is good. Yes I have a few of their 6 flute design. But all in all the single flute M.A. Ford is the best. And besides I know you work in a lot of aluminun . The work superb in that . But for all around I still say single flute.
          Last edited by lane; 11-04-2009, 06:28 PM.
          Every Mans Work Is A Portrait of Him Self


          • #20
            I just looked up Severance and they are still in business (since 1941) and they still make the exact same products.

            Here is what they have to say about countersinks:

            1, 4 or 6 Flutes?
            In general, a six-fluted countersink
            will remove more material per
            revolution than will a four-flute or
            single-flute tool. While the single-
            flute countersink is slow-cutting, it
            will work well in a non-rigid
            machining setup.
            Four flutes
            provide more chip clearance than
            six. This is a consideration in
            machining stringy materials such as
            some plastics and non-ferrous
            alloys. Other factors being equal,
            the six flute countersink will give
            more service life than the four-flute
            tool because the cutting load is
            distributed over more edges.
            Free software for calculating bolt circles and similar: Click Here


            • #21
              i have a couple MA Ford single and multi flute countersinks that i picked up from enco and have been using for several years with good results.

              most of them are pretty big and get used to make countersunk holes for flat head cap screws. a 3 fluter seems to work good on aluminum with little or no chatter.

              avoid the cheapie hardware store hss 6 flute ones like the plague. they usually have a 1/4" shank and love to snap after about a dozen uses or so...

              i tend to use single flute CS's for hand deburring work. i have one 3/4" cs that fit perfectly into a piece of DOM 4130 tubing, so i silver soldered it in and that sees probably 75% of the hand deburring that happens in my shop.


              • #22
                I found the single flute MA Ford type to be faster cutting with less effort that the multi flutes, some of the multi flutes required a great deal of effort on the handle to actually cut.

                One thing in my favour is that I have a very rigid twin spindle drill and one spindle is powered by a geared motor with tooth belt drive to give one speed of 70 rpm, no way this puppy slips.

                The very load speed with immense torque and positive drive means it will run these 32mm [ 1-1/4" ] countersinks straight into laser cut 12mm thick steel plates very quickly. As I remarked in another post this was a sub con job and there were literally 1,000's of holes over a period of time.
                The part was the base of bar stools that were screwed to the floor, 3 or 4 holes in each in quantities of 500 at a time

                If I could have found a countersink any better, at any cost i would have.


                Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.