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Choosing steel type

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  • Choosing steel type

    I've read around the net, looked through machinery Handbook, and searched here to try to determine the right steel to buy for making a carriage stop for my Lathe using my new Mill.

    I've gathered:
    CR1018 may warp and have hard inclusions.
    Hot rolled is weaker.
    Leaded steel will machine well but rust badly.

    There is an awful lot to learn about steels but I'd rather get going on the fun part.

    Does it really matter in this case since aluminum is probably good enough?

    Any advice appreciated.

    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."

  • #2
    For what you're making, all of the materials you've mentioned would be quite strong enough for the application. Get whatever makes sense to you and have at it. Good luck!


    • #3
      For a carriage stop, I don't see why aluminum wouldn't work. Mine is made from plastic. I have a channel on one edge which is threaded, and I lay a piece of threaded rod into that. I place it roughly for length, then can turn it for fine adjustment. A simple clamp holds the rod in place. It'a a bit mickey mouse, but it works. The end of the threaded rod has another plastic piece on it that acts as the actual contact point where the side of the carriage touches.

      The choice of materials for any particular project is based on more than one factor of course, but the basic ones are temperature of operation, strength and fatigue resistance requirements, resistance to corrosion in various environments, and ability to resist wear. The expansion co-efficient can be important, and so will be the method by which the parts need to be fastened together, or to something. Sometimes weight is important, and looks as well. If a machined surface has to be smooth, that can determine what range of materials should be used. Most of this is common sense, but metallurgy and properties of materials is a big range where there is much to know. I know I'll never stop learning about materials.

      I base a lot of my choices on availability, if there are no critical requirements. Often it's based on ease of machining, and often on looks. Once I get up to speed on welding, I'll have to make sure I don't use materials that are hard to weld, or lose properties from the process, or are dangerous when heated to that degree, etc.
      I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-


      • #4
        Hot rolled warping only comes into play with larger flattish components with high precision - like a cross slide slider, 3 inches across and half an inch thick.

        For a smallish block-like unit with a few holes, clamped to something - just ignore the warping. It will hardly be noticeably.

        Aluminium is good for larger projects, but for smaller things that might get impact treatment I'd choose steel. Ally would do it fine, it's just aesthetics for me really.


        • #5
          Thanks guys:

          I guess I was over thinking this.

          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."


          • #6
            You are over thinking this...

            The warping in cold rolled is the material relieving surface stresses from the cold rolling process. The ammount of warpage would be insignificant in something as small as a stop block. Even then, you can usually negate any warping by skinning both sides.

            Hot rolled strength versus cold rolled is also insignificant for what you're doing. The real 'down side' with hot rolled is that the thickness is less controlled and it usually has a surface with hard scale on it.

            Leaded, like 12L14 does indeed machine beautifully, it really does cut like butter.... or maybe more like aluminum. The rust issue probably won't come up for your application because your stop will probably always have a thin film of oil on it.

            I'd agree that making the stop from aluminum would be fine as well.

            Remember: for 99% of all machine part applications low carbon, either hot or cold rolled is just fine.


            • #7
              Aluminum machines well and so does 12L14. If it is something one time and not critical the better choice is the easier to machine metal. CR1018 looks terrible and needs handwork to make the project look nice. With the correct conditions 12L14 will look VERY nice and so will 6061 aluminum, even cast acrylic turns out nice.