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  • #16
    Originally posted by Paul Alciatore View Post
    A die can make drunken threads on straight stock. He really needs a way to guide the die. Of course, on straight stock he could single point the threads first and just use the die to finish up, but that would probably be too labor intensive for this situation. He needs something quick and dirty that gives a usable thread.

    The big boys probably roll the threads first, then bend them.
    I like that...... drunken threads. That's about what it looks like sometimes too.
    I'm just thinking I'll go with making the die holder and drill the 5/16" hole through it. A couple, 3 that is set screws to hold the die, mill a couple flats for a wrench and it's done.
    Setting up in any machine to do this is way too labor intensive.

    JL.............

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    • #17
      Originally posted by Norman Bain View Post
      Ok; I am going to jump out of the box here and suggest an alternate approach.

      It is that the U-bolts be formed in a press; rather then pulled around a bending die. The bottom of the die need only be a u-channel of suitable OD. The inner for the die need only be a pipe of suitable ID.

      Strengthen the bottom die to stop it spreading. Strengthen the upper die by infill of the tube and add a flat for the press to push on.

      It would need a "guide" to keep the bend true to the press; not sure if this is better in the upper or lower of the die pair.

      Now ... given we have a mechanism that can press without damaging the threads, the threads can be added to the stock before bending.
      And with that, you CAN thread first, as your forming die can avoid the threads if designed with a bit of cleverness.
      CNC machines only go through the motions

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      • #18
        Thought I would try posting some pics. Trying some experimental stuff here. Be patient !!!



        JL................




        Last edited by JoeLee; 10-24-2017, 10:06 PM.

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        • #19
          Looking at the pictures of the u-bolt in the bender leads me to thinking that:
          * The stock could be cut to the finished length.
          * The threads could be cut before the bending; while stock is straight.
          * A nut could be added to one end before bending to hold the stock in the correct position.
          * Bend and it is done; no finishing required.

          The holder may need a small mod to make the nut sit nice and hold the stock in just the right position. Perhaps also a short sleeve of PVC or similar to stop any damage to the thread.

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          • #20
            put me in the thread first, bend later camp. Make a tailstock die holder for your lathe and thread one side at a time. Then bend. Not sure what you have for a lathe, but something with a collet closer and backstop would make really short work of that. I doubt your bending operation would mar up the threads enough to worry about them.

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            • #21
              Originally posted by Dan Dubeau View Post
              put me in the thread first, bend later camp. Make a tailstock die holder for your lathe and thread one side at a time. Then bend. Not sure what you have for a lathe, but something with a collet closer and backstop would make really short work of that. I doubt your bending operation would mar up the threads enough to worry about them.
              Agree.

              How long is the threading vs the total length of the straight legs? You will have to bend slightly over the parallel point, but unless the threading goes way back on the legs, that should not be an issue.
              CNC machines only go through the motions

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              • #22
                Originally posted by JoeLee View Post
                I do have a set of bolt dies which allow for starting straight and square. The problem is I need about 3" of leg length to use the bolt die. If any shorter the guide end of the bolt die hits the bend in the U-bolt. Most of these U-bolts I'm making do not require legs that long. I don't want to thread 1 1/2" - 2" of leg just to start a straight thread.
                thread them first. screw on an extension so the end sticks out far enough to work with the fixture.

                doubt your bending operation would mar up the threads enough to worry about them.
                if it does, put a piece of tubing over it to project it
                in Toronto Ontario - where are you?

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                • #23
                  Or, change the approach.

                  If you have a press, a quick and dirty "wipe-down" die might work for you, and it would never need to touch the threaded area. You might need to tweak the 180 deg angle due to spring-back, but that also need not affect the threaded section.

                  Basically a piece the diameter of the ID, pushed down by the ram. That passes between two blocks so the bolt is bent as it is pushed down between the blocks. Yes, it is special purpose, but it is a purpose that may recur. You can move the blocks yo make different bends.
                  CNC machines only go through the motions

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                  • #24
                    Originally posted by Norman Bain View Post
                    Looking at the pictures of the u-bolt in the bender leads me to thinking that:
                    * The stock could be cut to the finished length.
                    * The threads could be cut before the bending; while stock is straight.
                    * A nut could be added to one end before bending to hold the stock in the correct position.
                    * Bend and it is done; no finishing required.

                    The holder may need a small mod to make the nut sit nice and hold the stock in just the right position. Perhaps also a short sleeve of PVC or similar to stop any damage to the thread.
                    On some of the larger dia. U-bolts, because of the length of the legs I can thread one end, put a nut and washer on it to hold it in place and roll it. I have done that before.
                    I have also tried to cut to approx. length and start a thread on the other end but I could never get it right. The other issue is I could roll a better more consistent U if I left a foot or so on the other end and kind of helped it along as I rolled it.
                    It's been a long time since I used this and can't remember all the issues I had with it other than starting the threads.
                    I do remember that rolling them with out worrying about threads made it a lot easier. I would then put the hex die in a socket with a T handle and run the die to the desired length.
                    But that often left me with the "drunken threads"

                    I never did finish the rod holder as I just used vise grips to hold the rod from pulling through. The V in the holder lines up with the center of the die. I wasn't quite sure how I was going to secure the rod in it so the vise grips did the job.

                    I think I'm just going to make a die holder and go with that.

                    JL................

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                    • #25
                      Originally posted by J Tiers View Post
                      Agree.

                      How long is the threading vs the total length of the straight legs? You will have to bend slightly over the parallel point, but unless the threading goes way back on the legs, that should not be an issue.
                      It can vary depending on what the U-bolt is being used for.

                      JL...................

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                      • #26
                        I'm still offering die holder spinning in bench drill and U bolt in vise.
                        Location: Helsinki, Finland, Europe

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