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square holes?

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  • square holes?

    anyone have any good ideas on how to
    do this? (EDM, notwithstanding)

    would like to put a 10mm (~0.4")
    square hole in a 1" round.. about 1/2"

    tried my hand at making a square broach
    from a piece of 10mmX10mm HSS (lathe toolbit)
    .. and "squeezing" it through in the vice
    (dont have a press.. yet!)

    i think the taper on the homemade broach
    was too short, and it ended up jamming and shattering like a piece of glass. broke my heart.

    am i looking at doing hard time
    with a file in my hand?


  • #2
    You could buy a proper broach, but at $200+ you might want to start filing - besides, it builds character.


    • #3
      did anyone hear me sigh?

      character, here i come.

      (thanks, thrud)



      • #4
        Would this work?

        Drill small holes in each corner (1/16", maybe even 1/32").

        Drill a large hole through the center (25/64).

        (Optional) Drill medium sized holes through the material remaining in each corner.

        Use a small end mill to remove the remaining material. You'll have to work from both sides, since the small end mill probably won't be long enough.

        Wouldn't be much filing to do after all that is done.
        Any products mentioned in my posts have been endorsed by their manufacturer.


        • #5
          Do you have a mill or a milling attachment for your lathe?


          • #6
            I think you'd find that filing isn't that bad, if you have a proper file with at least one "safe" edge. Drill it 10mm, then file out the corners. I bet it wouldn't take more than 15 minutes.

            Winchman's idea of drilling out the corners is good, but on round stock you'll have to be pretty careful the small drill doesn't wander when you start it.

            You can also nibble out the corners with a shaper-style cutter held in the milling machine spindle and operated with the quill (the milling spindle locked against rotation), but by the time you make the cutter you could mostly like file it. Or you can do the same thing with the cutter held in the lathe toolpost, the work bolted to a faceplate, and the tool racked back and forth with the carriage handwheel to nibble out the corners.

            [This message has been edited by SGW (edited 10-09-2003).]
            Try to make a living, not a killing. -- Utah Phillips
            Don't believe everything you know. -- Bumper sticker
            Everybody is ignorant, only on different subjects. -- Will Rogers
            There are lots of people who mistake their imagination for their memory. - Josh Billings
            Law of Logical Argument - Anything is possible if you don't know what you are talking about.
            Don't own anything you have to feed or paint. - Hood River Blackie


            • #7
              They do make drills for making square holes. There's a floating bit, captive in a housing that is chucked. During operation, the bit makes an orbit, and the lips end up doing a square dance. Never seen it, didn't believe it, can't refute it. It came from a metalworking text.
              I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-


              • #8
                Regarding square hole drill,If memory serves it is called Watts System. Consisting of triangular drill, square bushing and special floating holder. Used one at LMSC, Sunnyvale in 1969 or so, only worked in aluminum and only in .100"/.150" deep. any thicher stock and drill flexed and tolerance was not acceptable

                "Make Chips Not Sparks"
                \"Make Chips Not Sparks\"


                • #9
                  I did what winchman suggested just recently. Made a 0.4" square hole 0.4" deep using a 3/32 carbide end mill. Went pretty fast and worked well. No filing. I did drill the center out first tho.


                  • #10
                    Yup. I know all about making square-holed bushings.

                    They come from the store, and are called socket sets. Your size is 3/8" + some filing. Good strong steel, welds nicely too. (alternative to filing is splitting the bushing diagonally across the square hole, putting over a 10 mm sq bar, and welding it back together.)

                    It sound like I'm joking. I'm not. NO WAY would I try to file a square hole in آ½" stuff, when a socket costs 1$.

                    Alternative sources are door handles (Europe) have square shafts of 9, 9.5 or 9.7 mm, and bushings in brass, steel or cheapo.


                    • #11
                      Set it up in the lathe and shave it out square with a boring bar like you would a "desperate keyway"
                      I just need one more tool,just one!


                      • #12
                        Perhaps this can help.


                        • #13
                          A friend of mine has a watts drill. You have to drill out the center, then use the watts to remove the corners. He used to go about 2" deep in steel to make couplings w/ 3/4" sq. holes. I think it works on the same principle as drilling a hole in a piece of sheet metal and getting a 3 sided hole.


                          • #14

                            Not sure how critical it is or what you're making, but could you make a square punch, heat a piece of steel with a round hole to red and hammer the square punch through? Then turn it back to 1" diameter.

                            All of the gear, no idea...


                            • #15
                              Not very high tech but how about milling a slot in two pieces of steel. Then weld the two together and turn the outside.