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Making Hex from 3/4" Round

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  • Making Hex from 3/4" Round

    I've got a little project in mind that requires about 5 or 6" of hex stock, which I don't have, and don't want to order just for that small bit.

    I do have a few pieces of 3/4" round, probably 17-4, each of which already has one flat milled about 12-15" along the length.

    I've been trying to come up with a clever way to hold and index it to mill the other flats in either a Bridgeport or a shaper. I have no dividing head or rotary table. Do have vee blocks. Also have the little square and hex 5C collet blocks, but that seems like would leave too much sticking out, to work successfully.

    This doesn't have to be real precise, just close enough so it looks reasonably correct visually, and will chuck up in a 3 jaw close enough so that further drill/boring/reaming, etc. operations are (visually) concentric to the external surfaces. I don't have to have nice crisp corners. In fact I think I'd prefer some slight radius left, but that'll depend on how deep those existing flats are. (which I haven't measured yet)

    Any good ideas?
    Lynn (Huntsville, AL)

  • #2
    Making Hex stock

    Lynn,
    Here's my two cents, whether it is a good idea or not, only time will tell. I would take the round stock and chuck it up in the collet hex block. Support the other end with your V block, shimming as necessary and using table stops to keep the two supports relatively co-planar ( though not critical). Machine the first face to the proper depth ( and make note of the spindle depth for reference). Rotate the hex block to the next position and machine the next face, keeping an eye on the depth as you get close. Repeat the hex block rotation for the remaining four faces and you should be done. Just my thoughts.
    Fred Townroe

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    • #3
      Turn one end down for a press fit into a hex nut,use the flats along with a parallel to index the part.

      Edit that,if you did a nut on each end of the stock timed to each other,you could then use a couple toe clamps to hold the piece by the flats and mill the section inbetween.
      Last edited by wierdscience; 09-25-2011, 06:02 PM.
      I just need one more tool,just one!

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      • #4
        If you don't need real precision I'd drill and tap the end and screw in a hex bolt. Clamp the rod in a vise and line up each flat parallel to the table.

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        • #5
          See here:

          http://bbs.homeshopmachinist.net/showthread.php?t=3002
          Free software for calculating bolt circles and similar: Click Here

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          • #6
            Originally posted by jime
            If you don't need real precision I'd drill and tap the end and screw in a hex bolt. Clamp the rod in a vise and line up each flat parallel to the table.
            Or clamp the head of the bolt in the vice, just need to make sure it's tight and threadlocked.

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            • #7
              Originally posted by lynnl
              I've got a little project in mind that requires about 5 or 6" of hex stock...............

              Any good ideas?

              Quickest way I can think of. 12" lengths available.

              http://www.mcmaster.com/#stainless-steel/=e7xjyp


              Rex

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              • #8
                The nearest hex you can make with sharp corners from 3/4 is 5/8. Is that what you want? If you have the 5C square and hex blocks and a 3/4 collet you are home free but you have to hex the stub held in the collet in a separate operation.

                The material will bow because when you machine it you removed stressed metal from one side. Watch for this as you cut. If you go all the way around leaving a little stock then take a finish cut, you can minimise the effect. You will need some outboard spport. A center or tailstock wotu be perfect but a simple deflection stop may be all that's required.
                Last edited by Forrest Addy; 09-25-2011, 08:50 PM.

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                • #9
                  Originally posted by loply
                  Or clamp the head of the bolt in the vice, just need to make sure it's tight and threadlocked.
                  Almost the same thing, but not quite - I did 4 of these columns (x 6 flutes) with hex bolts screwed into each end and the heads lined up and gripped in the vice - plenty good enough for visual effect!

                  Tel

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                  • #10
                    Wow, all good ideas! Thanks to all of you!

                    Now my forehead is all red and bruised, from all the slaps and "...why didn't I think of that's..."

                    Actually Forrest, I would've preferred to end up with 3/4" hex, but since I already have this stock, 5/8" will do for this purpose. Or maybe a little > 5/8, since I don't need sharp corners. Could use round, but wanted something that won't be rolling around and off onto the floor, plus hex will look better.

                    When finished it'll look like a large hex pencil, with a sharpened end and the lead broken. It's a little device for setting wire clamps, e.g. temporary jig for soldering/brazing, etc. It's in one of the "MetalWorking" books.
                    Lynn (Huntsville, AL)

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                    • #11
                      Hm. It only take one flat to keap something from rolling

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                      • #12
                        Yeabbut... the picture of the one in the book just looks nice to me.

                        I'll want to sit around and admire it often, after I make it.
                        Lynn (Huntsville, AL)

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