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Name that Bolt!

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  • Name that Bolt!

    I need a bolt that is very roughly 3/8 in diameter and about 6 in long, that can be tightened and removed with hand tools, with access only to the threaded side. I'm planning on a couple dozen ft-lb of torque (think "arm tight"). Load would be a couple hundred pounds peak in tension, basically zilch in shear, well maybe a dozen or so pounds peak. Intended lifetime is like forever outdoors, so stainless or at least galvo, but I'll tar it up good so plain ole steel is OK too, no china-metal please... Not a directly human-life-critical application, but if all bolts failed and someone were underneath when it failed (admittedly VERY unlikely) the 40 pounds or so, from 30 feet or so, would leave a mark, hence the crazy level of overbuilding... The application is one of those carpentry-gone-wild things involving a tripod and a roof and stuff.

    If you know what a double ended dowel screw is, I am looking for the opposite sex, sort of, two hex ends with threads in the middle and one hex head being small enough to push the nut over.

    I'll probably end up buying longer bolts, grinding on flats, cleaning up the threads (I'm quite familiar with that, from shortening bolts and screws), install, loosely tighten nut past my homemade flats, then clamp one wrench on the nut and another on my homemade flats, crank away, all done. If I'm really feeling ambitious, I would spend minutes to hours making an indexing block on my mill that will fit my grinder, so as to possibly save myself seconds to minutes of work time on the grinder, we'll see about that.

    However, this can't be the first time in the history of mechanical engineering that someones gotten themselves in a situation like this. Someone must make a screw with a funny name that comes from the factory with a handy dandy hex drive embedded in the threaded end, or maybe a real small diameter hex head cut into the threaded end. Even just a slot in the end might work (or might spread the threads, making it impossible to ever remove again). Why, I could probably buy a bolt like this for like a buck or two online. I only need about four, and I enjoy paying money for quality, so I can't imagine price being an issue.

    It takes me a pitiful couple paragraphs to describe what I want to buy. Someone tell me what a bolt like this is called, so I can google for it? "opposite of double ended dowel screw" isn't getting me much of anywhere...

  • #2
    'f it were me, I'd look serious at "anchor bolts"
    Lag screw threads for the wood side, 3/8 NC on the outboard side. Available in SS from the local fastener house. Install with a doble nut set up with a ratchet and open end. for 3/8" prolly drill a +/- 1/4" pilot hole.
    Design to 0.0001", measure to 1/32", cut with an axe, grind to fit


    • #3
      Are you talking about a standoff?

      ...or a sexbolt?

      Last edited by Mike Burdick; 12-21-2009, 05:42 PM.


      • #4
        I can't follow your description completely but a couple of things come to mind. Carriage bolts usually galvanized finish used to bolt wood. They have a square sholder under a dome shaped head to hold rotation. These are often used in places that you can't get wrench access to hold the head end. Coupling nuts are hex shaped and used to join bolts or rods. They can be Loc-Tited into place so they don't move. The turn buckle that has a combination of right and left hand threads can be rotated from the middle to pull things together.
        Byron Boucher
        Burnet, TX


        • #5
          Your explanation of what you want is either convoluted or I have completely missed your explanation.

          From one view point you want a bolt with threads on one end and a hex drive on that end and no head on the other end.

          Then you ask for a bolt with threads in the middle and a hex drive on each end to push a nut over.

          Then you ask for a bolt with an internal hex or slot in the end with no indication where the threads are located.

          Could you be more specific as to what you want? Pick one of the three you described please.
          It's only ink and paper


          • #6
            Sounds like something that the struts on my Mustang have on the end.

            The strut comes up through the support and a rubber washer followed by a metal washer and a nut is attached. The end of the strut has threads and a screwdriver slot cut in it. The idea being, one can insert a screwdriver in the slot, loosen the nut with a wrench and then (supposedly) spin the nut off by hand. To tighten reverse the sequence.

            As for a fastener like that... I have no clue. Make a few.

            Civil engineers build targets, Mechanical engineers build weapons.


            • #7
              Lindapter Hollo-Bolt

              This work??



              Or maybe a nut solution like this>>

              Now that I read your thread better, dont think the hollo-bolt is your solution...
              Last edited by cuemaker; 12-21-2009, 06:05 PM.


              • #8
                A carriage bolt should do the trick.. no need to get fancy.
                Wow... where did the time go. I could of swore I was only out there for an hour.


                • #9
                  Let me re-think a bit here. If you dont want to grind a set of flats on the end of a bolt or a screw driver slot what about a "T" nut on the end that you wont be able to get to after assembly?

                  Maybe a section view of the device you are making would help us out a bit.

                  Civil engineers build targets, Mechanical engineers build weapons.


                  • #10
                    Is it April 1st already? I don't even remember Christmas or the New Year
                    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
                    Thank you to our families of soldiers, many of whom have given so much more then the rest of us for the Freedom we enjoy.

                    It is true, there is nothing free about freedom, don't be so quick to give it away.


                    • #11
                      Why don't you just use a long setscrew and braze (or have someone tig weld) a nut onto the headed side. That way you could still adjust with either a wrench on the nutted side or a allen key on the other side.


                      • #12
                        I get the picture that rockrat does ---- like the end of an auto shock absorber or strut .... course I dont know where to get such an animal.

                        Go to the wrecking yard and buy a handful of shocks and cut the shaft off, welding a hex head on the other end?? thats for sure some good metal....
                        If everything seems to be going well, you have obviously overlooked something........


                        • #13
                          If I'm following your explanition... How bout' a long 3/8 allen set screw with a rod (coupling) nut screwed onto the end. You can screw the stud back down into your hole with a long allen key
                          Joe B


                          • #14
                            My dodge dakota's sway bar connecting links have ball joints on them. The studs have a small hex to keep the stud from spinning while you tighten the nut. Couldn't you machine a small hex in the threaded end of a bolt.


                            • #15
                              If I were you, I'd either get some threaded rod and machine two flats on the end, or drill a hole perpendicular to the bolt axis, and stick a phillips screwdriver in the hole to turn it.