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Q: O1 for bolts?

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  • Q: O1 for bolts?

    Have an old tractor that popped its brake caliper on one side.
    Two broken bolts. (caliper mounting bolts)
    Inspection on the other side revealed 1 broken (but stuck in place)
    bolt.. and one still hang'n in there.

    So at the tractor supply (& auto parts store) I learn that these bolts
    (for this tractor) aren't available as separate parts -- I'd have to get
    the whole brake kit for both sides.

    The bolts appear hardened.

    I have a 10" piece of O1 that I could just get 4 bolts out of.

    I could either home-heat-treat or send them out.

    Question is, is O1 going to be any good for bolt? I'm afraid I might
    get them too brittle in a homebrew torch'n'dunk treatment.

    The lathe isn't ready yet so I have time to pick some proper stock.

    I assume they're only hardened for abrasion resistance?

    Thanks.

    Tony

  • #2
    Originally posted by Tony
    Question is, is O1 going to be any good for bolt? I'm afraid I might get them too brittle in a homebrew torch'n'dunk treatment.
    It will be too hard as quenched -- around 65 Rockwell. Just put it in the toaster oven at 600° F for an hour, and you'll be at 56 Rockwell and very tough.
    "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

    Comment


    • #3
      I think that it really depends on the failure mode of the original bolts - if they failed from brittle failure you'd want to go with something tougher, if they failed from yield or shear you might swap out some tough for hard. Brittle failure will leave a surface looking kind of crystalline on the break, yield usually has the bolt necked down on each side of the failure, shear can usually be seen by an offset to the join in the bolt.

      If it failed on a thread root you might be looking at a difficult replacement - most bolts should have the threads rolled in for strength, single pointing in the thread will make a significantly weaker bolt with the failure point in the threaded section.

      That being said I've got 'temporary' fixes holding up 20+ years later, so I'd just make the bolts from the O1 and try to hit the sweet spot in hard/tough.

      Comment


      • #4
        Originally posted by rkepler
        most bolts should have the threads rolled in for strength, single pointing in the thread will make a significantly weaker bolt with the failure point in the threaded section.
        Russ, most bolts are thread rolled for manufacturing efficiency, but as Carol Smith points out in his book, most threads are heat treated after thread rolling, which eliminates any strength benefits.

        Bolts that have been thread rolled after heat treat are very expensive. Most aircraft (NAS) bolts are made this way.

        Here's the How It's Made video of a French Canadian company making high-quality bolts. The threads are rolled at 2:17, and the heat treat process starts at 3:30. The bolts are heated to 870° C, quenched, and then annealed, after they're thread rolled:

        http://www.youtube.com/watch?v=3kxcw08p_oY
        Last edited by lazlo; 11-29-2011, 09:31 AM.
        "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

        Comment


        • #5
          You have a tractor with disc brakes?
          Mike

          My Dad always said, "If you want people to do things for you on the farm, you have to buy a machine they can sit on that does most of the work."

          Comment


          • #6
            Originally posted by lazlo
            Russ, most bolts are thread rolled for manufacturing efficiency, but as Carol Smith points out in his book, most threads are heat treated after thread rolling, which eliminates any strength benefits.

            Bolts that have been thread rolled after heat treat are very expensive. Most aircraft (NAS) bolts are made this way.
            There are 'hot rolled' bolts as well that split the difference.

            But the point I was trying to make was that a bolt rolled and then heat treated will have better strength in the thread than a bolt that was single pointed and heat treated; so if the failure was in the thread area of a commercial rolled bolt then a single pointed replacement was not likely to be applicable.

            (I'm skipping over a million caveats, mostly on the observed failure mode. If a determination was made on that and the original alloy {or bolt grade} then a replacement could be suggested.)

            Comment


            • #7
              Originally posted by Tony
              Question is, is O1 going to be any good for bolt? I'm afraid I might get them too brittle in a homebrew torch'n'dunk treatment.
              I guess the real question is how much of an issue would it be if they failed again? If it doesn't really matter, I would heat and dunk then temper.

              If you want to avoid grain growth from overheating, which may make it break more easily, it might be worth sending out for a real heat treat. Unfortunately, the heat treaters around SoCal seem to not like treating O1.
              Hemi-proprietor,
              Esoteric Garage

              Comment


              • #8
                Disc Brakes

                If I remember correctly the J I Case 580 series backhoes had disc brakes. This would be the the models from the late 1990's. They were an arrangement of some discs with balls and ramps. Not only were they disc brakes, they ran in oil. So yes there are tractors with disc brakes.

                The real point is they were noted for having the bolts loosen and then break.
                So part of our check the oil and water service was to check the brakes for an oil leak. This was an indication of loose bolts. This is a fifteen year old memory so there could be some errors in actual facts.

                Comment


                • #9
                  Some late model International W6/9 models had disc brakes, these would be from the early 50's.........
                  Opportunity knocks once, temptation leans on the doorbell.....

                  Comment


                  • #10
                    I think the first thing I'd do is check McMaster-Carr www.mcmaster.com and see what bolts are available off the shelf from them.

                    If I had to make some I think I'd use 1144, which has a tensile strength of around 100,000 psi or more. Another choice might be pre-heat treated 4140.

                    I wouldn't recommend O-1. I don't think it is particularly good for high-strength bolts.
                    ----------
                    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

                    Comment


                    • #11
                      What size bolt?

                      Comment


                      • #12
                        so 600* in toaster oven and then let cool to room? or quench?
                        temper after that? (just curious)

                        here is a pic of the bolt in question. I haven't been able to find it
                        locally. One guy told me he'd seen them before and I was going to
                        have to find a machinist who could make them but expect to "pay through
                        the nose" (!)

                        13mm head, 10mm shank, 8mm threads: (about 1.25" long)



                        here's the end view of the break. Looks like failure in tension. Were these
                        tightened too much perhaps?



                        ignore the deformation on the tip.. that was from trying to get that little
                        bit out.

                        -Tony

                        Comment


                        • #13
                          That head is similar to or the same as a "Wheel bolt"

                          The fact that the shank is bigger than the threads throws a monkey wrench into the whole shebang.

                          Comment


                          • #14
                            That looks a lot like a "shoulder bolt", except for the chamfer under the head. Look in McMaster-Carr at shoulder bolts and see if they have metric ones.

                            Steve

                            Comment


                            • #15
                              If you can get a shoulder bolt that would work you can make a washer with the taper on it, shorten the shoulder to the right length and then shorten the thread if needed and rethread to the shoulder.

                              A little creative engineering is needed here. Never make what you can buy and modify.
                              It's only ink and paper

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