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making a grade 8 bolt

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  • #31
    Originally posted by Mcgyver View Post

    Would you know how to dress the wheel? The wheel obviously has to be tilted to match the helix .....but thread profiles are not tilted, i.e. they're in a plane aligned with the axis. So how do you dress the sides of the wheel, to what angle? I've pondered grinding threads but wonder about the wheel geometry and dressing
    I read a little on such a thread grinding machine at one point. The machine being described had a full time "crush dresser" that rode against the wheel to maintain the shape. I guessed at the time that this meant a roller with the thread profile.

    The grinding wheel would need to be presented at an angle to the work that matched the helix angle of the thread pitch. And the work turned and fed at the thread pitch rate much like single pointing.

    At least that's what I got out of reading that paragraph or two about thread grinders a few years back. The reference to the thread grinding being for use in making taps. Using the grinder allowed for some amount of relief being ground into the threads so when the gullets were ground away that the teeth had the proper cutting clearances.
    Chilliwack BC, Canada


    • #32
      Originally posted by Mcgyver View Post

      I think you'd heat treat afterwards to save the rolling dies. I won't go to the mat (haha) on this as I haven't enough direct knowledge, but what you says is contrary to what I've read and contrary somewhat to experience in that metal does have a grain that doesn't start to go away unless you normalize. Cutting threads interrupts the grain, rolling does not.

      whats your source that that rolled is only stronger if heat treated after, and why? A friend runs a good size fastener manufacturer, i'll see if he has any insight
      you lose the cold work hardening and only benefit is the better ”grain flow”

      Some source that I was able to come up in a hurry:
      edit: better source

      Based on quick look 150ksi yield is the practical upper limit for thread rolling so grade 8 would be borderline possible but no doubt more wear and tear for machines.

      Last edited by MattiJ; 09-15-2021, 12:58 PM.
      Location: Helsinki, Finland, Europe


      • #33
        Originally posted by Richard P Wilson View Post
        You guys can slag off McMaster all you like, but you don't know how insanely jealous it makes me here in the UK to read of this one stop store that seems to sell EVERYTHING a machinist needs. We've got nothing like that over here.
        They have been doing a great job for about 125 years too! I have only been dealing with them for a little over 50 years. I am super impressed at how well they made the transition to the internet too. I have the luck of having one of their warehouses right in my backyard and I got a personal tour of the place when I contacted them about some suggestions. This also means same day delivery or pick up there in an hour! They told me a lot about their operations while I was there and it is amazing to say the least.

        We are very lucky!


        • #34
          Some of you may find this short series of videos very enlightening and interesting.
          The three part series of videos consists of a tour of ARP Fasteners and covers all steps of how these components are made.
          This company is probably not only the largest manufacture of high performance automotive fasteners but also thee go-to source for extremely high grade mission critical fasteners for various industries. Need something special? If they don't already have it they'll make whatever you need. They claim higher than aerospace industry standards!

          I've used them numerous times in the past and have always been impressed with their quality. Their downloadable catalog is also a fantastic wealth of information regarding some of the finer points of fastener design and metallurgy.
          Be sure to watch all 3 videos.

          Home, down in the valley behind the Red Angus
          Bad Decisions Make Good Stories​

          Location: British Columbia


          • #35
            FWIW, long time ago we had a job using some high strength bolts, USA made. The job was to drill a number of small axial and cross holes. We needed to have the bolts annealed for the drilling. Called the manufacturer, Unbrako, to ask what they were made of, info the heat treater needed for annealing and re-heat treating. The company said "none of your business". They said they could use any material they wanted as long as the bolts met the strength specs. We sent them to a metal tester to determine the alloy (which I don't recall now).

            Another job we made wheel studs for a vintage Maserati, different thread pitch on each end. The customer spec'd the material . We machined to length with the important end chamfer angles specified by the thread rolling company. The chamfer angle is important so after distortion from rolling the thread starts easily. The thread rollers have to centerless grind the roll area to precise diameter, then roll. Off to the heat treater to complete the parts. I recall they were well over a hundred bucks per stud.