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machining long, skinny rods

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  • machining long, skinny rods

    I need to make what are basically some really long, skinny bolts. 6" long, .187" diameter, .250" head at one end, 10-24x5/8" threads at the other. Material will be O-1 or 4140. Diameter of the .187" shank is +/- .002".

    I need about a dozen of them, though I might make more later. I can do it by the "ghetto" method of pulling a bit at a time out of the collet in the headstock, machining it in sections, and finishing off any steps with sandpaper, but what would be the "right" way to do these?

    A) box tool. I've never used one. Once, when working in a production shop, I found one under the bench and was trying to set it up when the supervisor stopped me, "those things never work" and had me continue making long screws the same way I described above.

    B) centerless grinding. I don't have one, I don't know any shop around here that has one. Probably couldn't afford one, and one cheap enough to buy would probably take more TLC than I can budget for it. I have other occasional projects that could sure use one, though.

    C) center grinding. I don't have a toolpost grinder, but I have a 3-ton Storm-Vulcan crankshaft grinder that will hold .0005" repeatably. I could rough the rods on the lathe, then grind and let the rods "spark out" on the grinder for each position of the wheel.

    D) start with .187" rod, make a clamp to hold one end while I heat it red hot and beat it into a lump with a hammer. Then machine the lump as needed.

    E) start with .187" rod, weld lump onto end.

    The head forms a slide stop and has a broached hex, so I'm not considering solutions that involve sleeving the .187" shaft up to .250".

    Comments?

  • #2
    Here is one way designed for precisely what you are doing. While it requires you to make a tool, who doesn't want to do that!? Then if you need to make more, you are set up, and you have a neat gadget for other projects. Not my idea, this from the fertile mind of Frank Ford:

    http://www.frets.com/HomeShopTech/To...ifollower.html

    Loads of other cool stuff on his web site.

    Comment


    • #3
      I'd forgotten about Frank's cute little cutter rig! And I've admired the pictures several times...

      Comment


      • #4
        Originally posted by TRX View Post
        Once, when working in a production shop, I found one under the bench and was trying to set it up when the supervisor stopped me, "those things never work" and had me continue making long screws the same way I described above.
        Now you know how they got to be a supervisor, they weren't working out running the machines . A box tool is just a cutter and follower in one piece. Properly set up (not difficult) they do a fine job.

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        • #5
          For the heading operation make yourself an upsetting die.This one could be easily modified to include a recess for the size head you need-

          https://www.youtube.com/watch?v=qDRjYu4BZLE
          I just need one more tool,just one!

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          • #6
            Another informative video available from the same link is "Using the Blacksmith's third hand for riveting".
            Kansas City area

            Comment


            • #7
              You could buy the rod, thread both ends and then silver solder a nut on one end.
              Paul A.
              SE Texas

              Make it fit.
              You can't win and there IS a penalty for trying!

              Comment


              • #8
                Use 1/4" rod, thread one end and silver solder the head on. Easy and quick.

                Brian
                OPEN EYES, OPEN EARS, OPEN MIND

                THINK HARDER

                BETTER TO HAVE TOOLS YOU DON'T NEED THAN TO NEED TOOLS YOU DON'T HAVE

                MY NAME IS BRIAN AND I AM A TOOLOHOLIC

                Comment


                • #9
                  Originally posted by alanganes View Post
                  Here is one way designed for precisely what you are doing. While it requires you to make a tool, who doesn't want to do that!? Then if you need to make more, you are set up, and you have a neat gadget for other projects. Not my idea, this from the fertile mind of Frank Ford:

                  http://www.frets.com/HomeShopTech/To...ifollower.html

                  Loads of other cool stuff on his web site.
                  That's basically a Swiss screw machining solution - keep a guide bushing next to the cutting tool.

                  Comment


                  • #10
                    I would go with the silver solder solution.....just for interest you could google and find a swiss lathe operation and get a quote. Shipping costs would be negligible
                    .

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                    • #11
                      Hope I can explain this without pics or drawings.
                      A drill bushing held in barstock to keep small diameter rod from pushing away and the cutter just pass the bushing where the work exits the bushing. Works well for small runs. I haven't threaded this way yet because the cutter was not easily adjustable. Lathe bit clamped and adjusted by loosening clamp screws then turning set screw to move bit into work. No dial to verify cutter infeed and set-up too "thrown together" to easily use dial indicator. I don't even have the "quick set-up" to photo anymore.
                      Started a drawing to make tool for this and lost drawing with 'puter crash and haven't gotten back to it. Was going to make so cutter had its' own crossfeed and bushing exchangable for universal use.
                      Krutch


                      Mentally confused and prone to wandering!

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                      • #12
                        Since sleeving is not an option because of broached head, how about silver soldering something like this ? :-


                        Or even use a Loctite if the temperature/stress conditions allow ?

                        Cheers


                        .

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                        • #13
                          It's the slide stop part that disinclines me from a two-piece solution.

                          Comment


                          • #14
                            TRX,

                            I missed the part in the OP about not considering a 2 piece solution. If you were going to need a lot of them I would recommend cold forming. You could start with a .187 shaft and cold form the hex, slot and most anything else. The price would likely be prohibitive for a small run though.

                            Brian
                            OPEN EYES, OPEN EARS, OPEN MIND

                            THINK HARDER

                            BETTER TO HAVE TOOLS YOU DON'T NEED THAN TO NEED TOOLS YOU DON'T HAVE

                            MY NAME IS BRIAN AND I AM A TOOLOHOLIC

                            Comment


                            • #15
                              Is there some design information anywhere that would tell me how much pressure would be needed to cold form a head on a .187" 4140 shaft?

                              Being a hobby project I don't mind making some dies to hold the part. Is this something that has to be struck, or would a big hydraulic press work?

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